- [Lab Seminar-2011-12-27]
This publication focus on the interaction between stress and development in the Arabidopsis root. They profile five different cell types(epidemis,cortex,endodermis,endodermis and stele) in response to low PH, -S, NaCl and –Fe. And mutyple evidence show the cell identity regulator play an directly role in the stress responding. (L.B. Lin)
——Cell Identity Regulators Link Development and Stress Responses in the Arabidopsis Root
Anjali S. Iyer-Pascuzzi, Terry Jackson, Hongchang Cui, Jalean J. Petricka, Wolfgang Busch, Hironaka Tsukagoshi, and Philip N. Benfey
Developmental Cell, Vol 21, 18 October 2011| doi:10.1016/j.devcel.2011.09.009.
- [Lab Seminar-2011-12-20]
They discovered that the enzymephospholipase D2 (PLD2) binds directly to the small GTPase Rac2, resulting in PLD2 functioning as a guanine nucleotide exchange factor (GEF), because it switches Rac2 from the GDP-bound to the GTP-bound states. PLD2-initiated Rac2 activation enhances cell adhesion, chemotaxis, and phagocytosis. The benefit to the cell is that PLD2 brings spatially separated molecules together in a membrane environment, ready for fast intracellular signaling and cell function. (H.Y. Yao)
——Phospholipase D2 (PLD2) is a guanine nucleotide exchange factor (GEF) for the GTPase Rac2
Madhu Mahankali, Hong-Juan Peng, Karen M. Henkels, Mary C. Dinauer, and Julian Gomez-Cambronero
PNAS, Vol 108, 06 December 2011| doi:10.1073/pnas.1114692108.
- [Lab Seminar-2011-12-13]
In the mammalian genome, 5′-CpG-3′ dinucleotides are frequently methylated, correlating with transcriptional silencing. Genome-wide demethylation is thought to occur only twice during development, in primordial germ cells and in the pre-implantation embryo. These demethylation events are followed by de novo methylation, setting up a pattern inherited throughout development and modified only at tissue-specific loci. We studied DNA methylation in differentiating mouse erythroblasts in vivo by using genomic-scale reduced representation bisulfite sequencing (RRBS).
Demethylation at the erythroid-specific b-globin locus was coincident with global DNA demethylation at most genomic elements. Global demethylation was continuous throughout differentiation and
required rapid DNA replication. Hence, DNA demethylation can occur globally during somatic cell differentiation, providing an experimental model for its study in development and disease.
(Y.J. Ye)
——Global DNA Demethylation During Mouse Erythropoiesis in Vivo
Jeffrey R. Shearstone, Ramona Pop, Christoph Bock, Patrick Boyle, Alexander Meissner, Merav Socolovsky
Science, Vol 334, 11 November 2011| doi:10.1126/science.1207306.
- [Lab Seminar-2011-12-06]
Plant virus cell to cell movement occurs via plasmodesmata. They encode one or more specialized movement proteins (MP) facilitating virus transport. But how MP and plasmodesmata interact with cellular factors to conduct this process remains largely hypothetical. Here reports the MP of a tubule-forming virus cruit the plant Plasmodesmata Located Proteins (PDLP) to mediate tubule assembly and virus movement. Interestingly, PDLP1 is transported to plasmodesmata through a specific route within the secretory pathway in a myosin-dependent manner.This pathway can be hijacked by the plant virus to promote its transport between plant cells. (L.J. Zhou)
——Tubule-Guided Cell-to-Cell Movement of a Plant Virus Requires Class XI Myosin Motors
Khalid Amari, Alexander Lerich, Corinne Schmitt-Keichinger, Valerian V. Dolja, Christophe Ritzenthaler
Plos Pathogens, advance online, 27 October 2011| doi:10.1371/journal.ppat.1002327.
- [Lab Seminar-2011-11-29]
NO is a very importent regulator in plant development and defense. This research found that NO application could cause root apical meristem defects. NO decreased PIN1 fluorescence in root. The use of both chemical treatments and mutants with altered NO levels demonstrates that high levels of NO reduce auxin transport and response by a PIN1-dependent mechanism, and root meristem activity is reduced concomitantly. (Y.J. Chu)
——Nitric oxide causes root apical meristem defects and growth inhibition while reducing PIN-FORMED 1
(PIN1)-dependent acropetal auxin transport
María Fernández-Marcos, Luis Sanz, Daniel R. Lewis, Gloria K. Muday, and Oscar Lorenzo
PNAS, Vol 108, 08 November 2011| doi:10.1073/pnas.1108644108.
- [Lab Seminar-2011-11-22]
The plant hormone cytokinin and auxin interacted with each other in many developmental and physiological processes. This study found that beside the interaction at transcriptional regulation level, cytokinin also regulated the recycling of auxin efflux carrier PIN1 to the plasma membrane by redirecting it for lytic degradation in vacuoles. This cytokinin activity requires cytokinin receptors but does not involve transcriptional regulation, revealing a new rapid and nontranscriptional pathway. (X.Y. Zhou)
——Cytokinin Modulates Endocytic Trafficking of PIN1 Auxin Efflux Carrier to Control Plant Organogenesis
Peter Marhavy´, Agnieszka Bielach, Lindy Abas, Anas Abuzeineh, Jerome Duclercq, Hirokazu Tanaka, Marke´ ta Parezova´ , Jan Petra´sek, Jirı´ Friml, Ju¨ rgen Kleine-Vehn, and Eva Benkova
Developmental Cell, Vol 21, 18 October 2011| doi:10.1016/j.devcel.2011.08.014.
- [Lab Seminar-2011-11-15]
Innate immune responses are triggered by the activation of pattern-recognition receptors (PRRs).The Arabidopsis PRR FLAGELLIN-SENSING 2 (FLS2) senses bacterial flagellin and initiates immune signaling through association with BAK1. The molecular mechanisms underlying the attenuation of FLS2 activation are largely unknown. We report that flagellin induces recruitment of two closely related U-box E3 ubiquitin ligases, PUB12 and PUB13, to FLS2 receptor complex in Arabidopsis. BAK1 phosphorylates PUB12 and PUB13 and is required for FLS2-PUB12/13 association. PUB12 and PUB13 polyubiquitinate FLS2 and promote flagellin-induced FLS2 degradation, and the pub12 and pub13 mutants displayed elevated immune responses to flagellin treatment. Our study has revealed a unique regulatory circuit of direct ubiquitination and turnover of FLS2 by BAK1-mediated phosphorylation and recruitment of specific E3 ligases for attenuation of immune signaling.(W. Wang)
——Direct Ubiquitination of Pattern Recognition Receptor FLS2 Attenuates Plant Innate Immunity
Dongping Lu, Wenwei Lin, Xiquan Gao, Shujing Wu, Cheng Cheng, Julian Avila, Antje Heese, Timothy P. Devarenne, Ping He, Libo Shan
Science, Vol 332, 17 June 2011| doi:10.1126/science.1204903.
- [Lab Seminar-2011-11-08]
'Florigen' was proposed 75 years ago to be synthesized in the leaf and transported to the shoot apex, where it induces flowering. Only recently have genetic and biochemical studies established that florigen is encoded by FLOWERING LOCUS T (FT), a gene that is universally conserved in higher plants. Nonetheless, the exact function of florigen during floral induction remains poorly understood and receptors for florigen have not been identified. Here we show that the rice FT homologue Hd3a interacts with 14-3-3 proteins in the apical cells of shoots, yielding a complex that translocates to the nucleus and binds to the Oryza sativa (Os)FD1 transcription factor, a rice homologue of Arabidopsis thaliana FD. The resultant ternary 'florigen activation complex' (FAC) induces transcription of OsMADS15, a homologue of A. thaliana APETALA1 (AP1), which leads to flowering. We have determined the 2.4 Å crystal structure of rice FAC, which provides a mechanistic basis for florigen function in flowering. Our results indicate that 14-3-3 proteins act as intracellular receptors for florigen in shoot apical cells, and offer new approaches to manipulate flowering in various crops and trees. (J.J. Zhang)
——14-3-3 proteins act as intracellular receptors for rice Hd3a florigen
ChikaNakashima, Yekti Asih Purwestri, Shojiro Tamaki,Yuka Ogaki, Chihiro Shimada,AtsushiNakagawa, ChojiroKojima & Ko Shimamoto
Nature, Vol 476, 18 August 2011| doi:10.1038/nature10272.
- [Lab Seminar-2011-11-01]
In plants, cytokinesis is mediated by the phragmoplast, an array of microtubules, actin filaments and associated molecules that act as a framework for the future cell wall. The MAPKKK, nucleus- and phragmoplast-localized protein kinase 1 (NPK1) and the NPK1-activating kinesin-like protein 1 (NACK1) have been identified important regulators of this process. In this study, cyclin-dependent kinases (CDKs) is proved to phosphorylate both NPK1 and NACK1 before metaphase, inhibiting the interaction between these proteins. Failure to inactivate CDKs after metaphase prevents dephosphorylation of these two proteins, causing incomplete mitosis. (H.B. Gao)
——Shosphorylation of a mitotic kinesin-like protein and a MAPKKK by cyclin-dependent kinases (CDKs) is involved in the transition to cytokinesis in plants
Michiko Sasabe, Véronique Boudolf, Lieven De Veylder, Dirk Inzé, Pascal Genschik, and Yasunori Machid
PNAS, advance online, 15 September 2011| doi:10.1073/pnas.1110174108.
- [Lab Seminar-2011-10-25]
Some well-known genes which take part in conservative pathway may have new biological functions. Scientists found that two potato FTs (SP6A and SP3D) have different functions: SP6A promotes tuberization under SD, while SP3D promotes flowering under LD. Another outstanding work discovered that Arabidopsis FT is also involved in blue light - H+-ATPase mediated stomatal opening. (J.Wang)
——Control of flowering and storage organ formation in potato by FLOWERING LOCUS T
Cristina Navarro, Jose´ A. Abelenda, Eduard Cruz-Oro´, Carlos A. Cue´llar, Shojiro Tamaki, Javier Silva, Ko Shimamoto & Salome´ Prat
Nature, Vol 478, 06 October 2011| doi:10.1038/nature10431.
- [Lab Seminar-2011-10-18]
The microbial infection induces the rapid synthesis of NO and accumulation of reactive oxygen intermediates, leading to the hypersensitive response. However, the underlying mechanism and the coordination of their synthesis remain unknown. The nitric oxide moiety can be added to a reactive cysteine thiol to form an S- nitrosothiol (SNO), and the process is called S-nitrosylation. The authors revealed that increases in SNO concentration could facilitate the hypersensitive response, and NO could mediate the S-nitrosylation of the NADPH oxidase and then inhibit the formation of reactive oxygen intermediates, thus forming a negative feedback loop and limiting cell death development during the hypersensitive response. (J.J. Xiang)
——S-nitrosylation of NADPH oxidase regulates cell death in plant immunity
Byung-Wook Yun, Angela Feechan, Minghui Yin, Noor B. B. Saidi, Thierry Le Bihan, Manda Yu, John W. Moore, Jeong -Gu Kang, Eunjung Kwon, Steven H. Spoel, Jacqueline A. Pallas & Gary J. Loake
Nature, advance online, 02 October 2011| doi:10.1038/nature10427.
- [Lab Seminar-2011-10-11]
The microbial infection induces the rapid synthesis of NO and accumulation of reactive oxygen intermediates, leading to the hypersensitive response. However, the underlying mechanism and the coordination of their synthesis remain unknown. The nitric oxide moiety can be added to a reactive cysteine thiol to form an S- nitrosothiol (SNO), and the process is called S-nitrosylation. The authors revealed that increases in SNO concentration could facilitate the hypersensitive response, and NO could mediate the S-nitrosylation of the NADPH oxidase and then inhibit the formation of reactive oxygen intermediates, thus forming a negative feedback loop and limiting cell death development during the hypersensitive response. (J.J. Xiang)
——S-nitrosylation of NADPH oxidase regulates cell death in plant immunity
Byung-Wook Yun, Angela Feechan, Minghui Yin, Noor B. B. Saidi, Thierry Le Bihan, Manda Yu, John W. Moore, Jeong -Gu Kang, Eunjung Kwon, Steven H. Spoel, Jacqueline A. Pallas & Gary J. Loake
Nature, advance online, 02 October 2011| doi:10.1038/nature10427.
- [Lab Seminar-2011-09-27]
SSRP1 is isolated for activation of imprinted FWA-GFP in ovules before fertilization and seeds after pollination. Further studies showed it contributes to DNA demehthylation. Decreased transcription is observed with maternally expressed genes in ssrp mutant. However, the paternally expressed gene transcription is increase. Different from dme1met1, the double mutant ssrp1met1 shows limited activation of FWA-GFP in central cell. These results suggest the active DNA demethylation by DME requires SSRP1 function and the epigenetic mechanisms are complex. (L.L. Yin)
——HMG Domain Containing SSRP1 Is Required for DNA Demethylation and Genomic Imprinting in Arabidopsis
Yoko Ikeda, Yuki Kinoshita, Daichi Susaki, Yuriko Ikeda, Megumi Iwano, Seiji Takayama, Tetsuya Higashiyama, Tetsuji Kakutani, and Tetsu Kinoshita
Developmental Cell, Vol 21, 13 September 2011| doi:10.1016/j.devcel.2011.08.013.
- [Lab Seminar-2011-09-20]
The CDD complex is important in many cellular and developmental processes in both plants and animals. The Arabidopsis CDD component DET1 can repress transcription, physically interacts with the core circadian clock components, CCA1 and LHY, for binding and repressing CCA/LHY target genes, suggesting a direct involvement of DET1 in mediating the transcriptional repression in the circadian clock. (M.Q. Xing)
——Interaction of Arabidopsis DET1 with CCA1and LHY in Mediating Transcriptional Repression in the Plant Circadian Clock
On Sun Lau, Xi Huang, Jean-Benoit Charron, Jae-Hoon Lee, Gang Li, and Xing Wang Dengi
Molecular Cell, Vol 43, 2 September 2011| doi:10.1016/j.molcel.2011.07.013.
- [Lab Seminar-2011-09-13]
Pyruvate import into plastids is required for several biosynthetic pathways, such as those for fatty acids, terpenoids and branched-chainamino acids. However, the molecular nature of the corresponding carrier has remained unclear. Using differential transcriptome analyses of the genera Flaveria, they identified a novel protein BASS2, and demonstrated, using evidence from both gain-of-function and loss-offunction experiments, that BASS2 is a plastid-localized sodium-dependent pyruvate transporter. (J.J. Xu)
——A plastidial sodium-dependent pyruvate transporter
Tsuyoshi Furumoto, Teppei Yamaguchi, Yumiko Ohshima-Ichie, Masayoshi Nakamura, Yoshiko Tsuchida-Iwata,
Masaki Shimamura, Junichi Ohnishi, Shingo Hata, Udo Gowik, Peter Westhoff, Andrea Bra¨utigam, Andreas P. M. Weber & Katsura Izui
Nature, Vol 476, 25 August 2011| doi:10.1038/nature10250.
- [Lab Seminar-2011-09-06]
Cell-to-cell communication in plants includes the selective trafficking of transcription factors and other signals through plasmodesmata. The KNOTTED1 (KN1) homeobox (KNOX) family transcription factors, which use this pathway, are essential for stem cell establishment and/or maintenance. Here the David Jackson Lab at show that KN1 trafficking requires the chaperonin complex (TRiC), which belongs to a group of cytosolic chaperones that fold specific substrate proteins.
They used gl1; pRbcS-GFP- GL1 -KN1C as a marker line to screen the locus affecting the trafficking of KN1. Luckily, they got a subunit of the chaperonin complex TRiC, CCT8. Genetic and physical interaction data show a functional relevance for chaperonins in KNOX family-dependent stem cell maintenance. Furthermore, tissue- specific complementation assays indicate a mechanistic basis for chaperonin function during the posttranslocational refolding process. This study shows that chaperonins are essential for the cell-to-cell trafficking of a subset of mobile transcription factors and demonstrates the importance of chaperonin-dependent protein trafficking for plant stem cell function. (S.T. Tan)
——Chaperonins Facilitate KNOTTED1 Cell-to-Cell Trafficking and Stem Cell Function
Xianfeng Morgan Xu, Jing Wang, Zhenyu Xuan, Alexander Goldshmidt, Philippa G. M. Borrill, Nisha Hariharan, Jae Yean Kim, David Jackson
Science, Vol 333, 26 August 2011| doi:10.1126/science.1205727.
- [Lab Seminar-2011-08-23]
ITR1 was an iron transporter at the root suface for plant controling iron uptake.Their study suggest IRT1 endocytosis was monoubiquitin-dependent,which keep the plasma membrane pool of IRT1 low to ensure proper iron uptake and to prevent metal toxicity. (B.J. Yang)
——Monoubiquitin-dependent endocytosis of the IRON-REGULATED TRANSPORTER 1 (IRT1) transporter controls iron uptake in plants
Marie Barberona, Enric Zelaznya, Stéphanie Robertb, Geneviève Conéjéroa, Cathy Curiea, Jìˇ rí Friml,
and Grégory Vert
PNAS, advance online, 21 August 2011| doi:
10.1073/pnas.1100659108.
- [Lab Seminar-2011-08-16]
Plant perception of UV-B radiation as an environmental stimulus is known to affect growth and development; however, neither the photoreceptor protein specifically sensing UV-B radiation nor the photoperception mechanism has yet been molecularly identified. Here we show that plant perception of UV-B is mediated by UVR8 as a UV-B–specific photoreceptor, and they support a tryptophan-based perception mechanism, with tryptophan-285 as a key residue. The UV-B–driven monomerization of the UVR8 dimers signals the receptor activation, which then is followed by interaction with COP1, the central regulator of light signaling, to relay the signal. Thereby this signaling cascade controlled by UVR8 mediates UV-B photomorphogenic responses securing plant acclimation and thus promotes survival in sunlight. (H. Zhang)
——Perception of UV-B by the Arabidopsis UVR8 Protein
Luca Rizzini, Jean-Jacques Favory, Catherine Cloix, Davide Faggionato, Andrew O’Hara, Eirini Kaiserli, Ralf Baumeister, Eberhard Schäfer, Ferenc Nagy, Gareth I. Jenkins, Roman Ulm
Science, Vol 332, 1 April 2011| doi:10.1126/science.1200660.
- [Lab Seminar-2011-08-09]
The receptor internalization from and the subsequent either recycling back to the cell surface,or trafficking to hydrolytic compartment for degradation is a major mechanism that controls receptor abundance and the intensity both in animal and plant.However, little information is available regarding how activated receptor are sorted for recycling or degradation.And we dont know more about how the cell recognize the difference between activated and nonactivated receptor.That is what the author try to tell us in this article,by revealing the BR signaling pathway of plant. (L.B. Lin)
——Methylation of a Phosphatase Specifies Dephosphorylation and Degradation of Activated Brassinosteroid Receptors
Guang Wu, Xiuling Wang, Xianbin Li, Yuji Kamiya, Marisa S. Otegui, Joanne Chory
Science Signaling, Vol 4, 10 May 2011| doi:10.1126/scisignal.2001258.
- [Lab Seminar-2011-08-02]
Plants recognize pathogens through two major classes of receptors.Initially, plants sense microbes via perception of conserved microbeassociated molecular patterns (MAMPs) by pattern-recognition receptors (PRRs) located on the cell surface to result in MAMP-triggered immunity (MTI). Then, to counter MTI, evolutionarily diverse plant
pathogens independently evolved mechanisms to secrete and deliver effector proteins into host cells. Plants deploy a second set of polymorphic intracellular immune
receptors to recognize specific effectors to result in a high-amplitude MTI response.
In this publication, to systematically map physical interactions between proteins from Arabidopsis and pathogens,authors mapped binary protein-protein interactions
between these 552 immune and pathogen proteins and the ~8000 full-length Arabidopsis
proteins used to generate the Arabidopsis interactome. Further analysis demonstrate that pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life-cycle strategies. (H.Y. Yao)
——Independently Evolved Virulence Effectors Converge onto Hubs in a Plant Immune System Network
M. Shahid Mukhtar, et al.
Science, Vol 333, 29 July 2011| doi:10.1126/science.1203659.
- [Lab Seminar-2011-07-19]
ELF3 is both necessary and suf-ficient to form a complex between ELF4 and LUX, and the complex is diurnally regulated, peaking at dusk. ELF3, ELF4 and LUX are required for the proper expression of the growth-promoting tran-scription factors encoded by PHYTOCHROME INTERACTING
FACTOR 4 (PIF4) and PIF5 (also known as PHYTOCHROMEINTERACTING FACTOR 3-LIKE 6) under diurnal conditions。Therefore, the evening complex underlies the molecular basis for circadian gating of hypocotyl growth in the early evening. (Y.J. Ye)
——The ELF4–ELF3–LUX complex links the circadian
clock to diurnal control of hypocotyl growth
Dmitri A. Nusinow, Anne Helfer, Elizabeth E. Hamilton, Jasmine J. King, Takato Imaizumi, Thomas F. Schultz,
Eva M. Farre´ & Steve A. Kay
Nature, Vol 475, 21 July 2011| doi:10.1038/nature10182.
- [Lab Seminar-2011-07-12]
Cryptochromes are blue light receptors that controls light-dependent gene expression through suppressing activity of multifunctional E3 ubiquitin ligase COP1. It is reported that both Arabidopsis CRY1 and CRY2 interact with the SPA1 protein in response to blue light. The interaction disrupts the COP1-SPA1 interaction and strengthens the CRY2-COP1 interaction, respectively. In either case, the E3 ligase activity is inhibited, and allows the accumulation of transcription factors. (L.J. Zhou)
——Arabidopsis cryptochrome 1 interacts with SPA1 to suppress COP1 activity in response to blue light
Bin Liu, Zecheng Zuo, Hongtao Liu, Xuanming Liu, and Chentao Lin
Genes & Development, Vol 25, 21 April 2011| doi:
10.1101/gad.2025011.
- [Lab Seminar-2011-07-5]
Proline hydroxylases are essential in cell war synthesization, which is catalyzed by prolyl 4-hydroxylases(P4Hs). Genetic disruption of P4H resulted in the blockage of polarized growth in root hairs and reduced arabinosylation of extensins(EXTs). So correct glycosylation on EXTs is essential for cell-wall self-assembly and root hair elongation. (Y.J. Chu)
——O-Glycosylated Cell Wall Proteins Are Essential in Root Hair Growth
Silvia M. Velasquez, Martiniano M. Ricardi, Javier Gloazzo Dorosz, Paula V. Fernandez, Alejandro D. Nadra, Laercio Pol-Fachin, Jack Egelund, Sascha Gille, Jesper Harholt, Marina Ciancia, Hugo Verli, Markus Pauly, Antony Bacic, Carl Erik Olsen, Peter Ulvskov, Bent Larsen Petersen, Chris Somerville, Norberto D. Iusem, Jose M. Estevez
Science , Vol 322, 17 June 2011| doi:
10.1126/science.1206657.
- [Lab Seminar-2011-06-28]
The transcriptome analysis of embryos derived from a cross between the polymorphic Landsberg erecta and Columbia accession shows that there is a strong genome-wide dominance of maternal transcripts at the early stage and the paternal contribution increases later. Genetic analysis indicates this process was regulated by maternal chromatin siRNA pathway and Histone turnover related chromatin organization. (X. Y. Zhou)
——Maternal Epigenetic Pathways Control Parental Contributions to Arabidopsis Early Embryogenesis
Daphne´ Autran, Celia Baroux, Michael T. Raissig, Thomas Lenormand, Michael Wittig, Stefan Grob, Andrea Steimer, Matthias Barann, Ulrich C. Klostermeier, Olivier Leblanc, Jean-Philippe Vielle-Calzada, Phillip Rosenstiel, Daniel Grimanelli, and Ueli Grossniklaus
Cell, Vol 145, 271 May 2011| doi:
10.1016/j.cell.2011.04.014.
- [Lab Seminar-2011-06-21]
S-type anion channels are important components involved in ABA signaling and stomatal closure. In this study, SLAH3(SLAC1 homolog3) was indentified as S-type anion mediating nitrate eflux. CPK21 dependent SLAH3 phosphorylation and activation could be blocked by ABI1/2, which is inhibited through the ABA receptor-phosphatase complex RCAR. Thus, the identification of SLAH3 as the nitrate-, calcium-, and ABA-sensitive guard cell anion channel sheds new light on the relationship of the stomatal response and nitrate metabolism. (W. Wang)
——Stomatal Closure by Fast Abscisic Acid Signaling Is Mediated by the Guard Cell Anion Channel SLAH3 and the Receptor RCAR1
Dietmar Geiger, Tobias Maierhofer, Khaled A. S. AL-Rasheid, Sönke Scherzer, Patrick Mumm, Anja Liese, Peter Ache, Christian Wellmann, Irene Marten, Erwin Grill, Tina Romeis, Rainer Hedrich
Science Signaling, Vol 4, 21 May 2011| doi:
10.1126/scisignal.2001346.
- [Lab Seminar-2011-06-14]
It was reported that initial abiotic stress can interfere with disease-resistance signaling. Conversely, initial plant immune signaling may interrupt subsequent abscisic acid (ABA) signal transduction. However, the processes involved in this crosstalk between these signaling networks have not been determined.
Here the author firstly isolated a small-molecular antagonist of ABA signaling, DFPM. It negatively affects ABA signal transduction through activation of plant immune signaling. DFPM could interferes with events at the level of or downstream of intracellular Ca2+ signaling. (L. Song)
——Chemical Genetics Reveals Negative Regulation of Abscisic Acid Signaling by a Plant Immune Response Pathway
Tae-Houn Kim, Felix Hauser, Tracy Ha, Shaowu Xue, Maik Bohmer, Noriyuki Nishimura, Shintaro Munemasa,
Katharine Hubbard, Nora Peine, Byeong-ha Lee, Stephen Lee, Nadia Robert, Jane E. Parker, and Julian I. Schroeder
Current Biology, Vol 21, 7 June 2011| doi:
10.1016/j.cub.2011.04.045.
- [Lab Seminar-2011-06-07]
The map cloned QTL DTH8 (days to heading on chromosome 8), a putative CCAAT-box binding protein HAP3 subunit, can control the flowering time, plant height and yield of rice at same time. (J. J. Zhang)
——Pseudomonas sax Genes Overcome Aliphatic Isothiocyanate–Mediated Non-Host Resistance in Arabidopsis
Xiangjin Wei, Junfeng Xu, Hongnian Guo, Ling Jiang, Saihua Chen, Chuanyuan Yu, Zhenling Zhou,
Peisong Hu, Huqu Zhai, and Jianmin Wan
Plant Physiology, Vol 153, 4 August 2010| doi:
10.1104/pp.110.156943.
- [Lab Seminar-2011-05-24]
The authors found the glutamate receptor-like proteins (GLR) which act as Ca2+ influx plasma membrane channels to facilitate Ca2+ influx, modulate apical [Ca2+]cyt gradient and affect pollen tube growth. The paper shows that D-serine can activate GLR’s channel activity which is very similar to the amino acid-mediated communication also observed in animal nervous systems.(Y. Tang)
——Glutamate Receptor–Like Genes Form Ca2+ Channels in Pollen Tubes and Are Regulated by Pistil D-Serine
Erwan Michard, Pedro T. Lima, Filipe Borges, Ana Catarina Silva, Maria Teresa Portes,
João E. Carvalho, Matthew Gilliham, Lai-Hua Liu, Gerhard Obermeyer, José A. Feijó
Science, Vol 332, 22 April 2011| doi:
10.1126/science.1201101.
- [Lab Seminar-2011-05-17]
Plant natural products restrict non-host pathogens. We found that sulforaphane (4-methylsulfinylbutyl isothiocyanate), a natural product derived from aliphatic glucosinolates, inhibits growth in Arabidopsis of non-host Pseudomonas
bacteria in planta. Multiple sax genes (saxCAB/F/D/G) were identified in Pseudomonas species virulent on Arabidopsis.
These sax genes are required to overwhelm isothiocyanate-based defenses and facilitate a disease outcome.Introduction
of saxCAB genes into non-host strains enabled them to overcome these Arabidopsis defenses. (J. Wang)
——Pseudomonas sax Genes Overcome Aliphatic Isothiocyanate–Mediated Non-Host Resistance in Arabidopsis
Jun Fan, Casey Crooks, Gary Creissen, Lionel Hill, Shirley Fairhurst, Peter Doerner, Chris Lamb
Science, Vol 311, 4 March 2011| doi:
10.1126/science.1199707.
- [Lab Seminar-2011-05-10]
Polycomb Repressive Complex 2 （PRC2）,the important epigenetic regulation system, is conserved among Drosophila, mammals and plants.Bypassing genomic imprinting can generate homozygous null mutants of Arabidopsis PRC2. H3K27me3 is globally lost in these mutants. Through genomic expression analysis and physiological experiments on prc2 mutants, it is shown that PRC2 is required to switch from embryonic to seedling phase. (H.B. Gao)
——Polycomb Repressive Complex 2 Controls the Embryo-to-Seedling Phase Transition
Daniel Bouyer, Francois Roudier, Maren Heese, Ellen D. Andersen, Delphine Gey, Moritz K.
Nowack, Justin Goodrich, Jean-Pierre Renou, Paul E. Grini, Vincent Colot, Arp Schnittger
Plos Genetics, Vol 7, 10 March 2011| doi:
10.1371/journal.pgen.1002014.
- [Lab Seminar-2011-05-03]
In the shoot apical meristem of Arabidopsis, CLAVATA3 peptide (CLV3p) represses the expression of WUSCHEL through Receptor like kinase CLAVATA1 and CLAVATA 2, thus maintaining the stem-cell homeostasis. And the flagellin receptor like kinase FLS2 perceives bacterial flagellin and launches immunity response. The authors revealed that CLV3p could trigger immune signaling via FLS2, and the CLV3p-FLS2 signaling pathway is independent from the stem-cell maintenance signaling pathway by CLAVATA1 and CLAVATA 2. (J.J. Xiang)
——Stem-cell-triggered immunity through CLV3p–FLS2
signalling
Horim Lee, Ok-Kyong Chah & Jen Sheen
Nature, advance online, 2011| doi:10.1038/nature09958.
- [Lab Seminar-2011-04-26]
HD-ZIPⅢ family genes which are targets of miR165/166 ,are important transcription factors to regulate the development of SAM. AGO10 is also a critical regulator of SAM maintenance. The authors demonstrate that AGO10 can specifically interacts with miR165/166, and prevent their incorporation into AGO10 to upregulate HD-ZIPⅢ family genes. The interaction is determined by a distinct structure of the miR165/166 but not its catalytic activity. (L.L. Yin)
——Arabidopsis Argonaute10 Specifically Sequesters miR166/165 to Regulate Shoot Apical Meristem Development
Hongliang Zhu, Fuqu Hu, Ronghui Wang, Xin Zhou, Sing-Hoi Sze, Lisa Wen Liou, Ashley Barefoot, Martin Dickman,and Xiuren Zhang
Cell, Vol 145, 15 April 2011| doi:
10.1016/j.cell.2011.03.024.
- [Lab Seminar-2011-04-19]
Genetic studies indicate that the AFB4 clade of auxin receptors have a novel
function in auxin signaling and seedling development. AFB4 and AFB5 are
required for picloram response and appear to be the major targets of this
class of herbicide.Unlike other members of the F-box family proteins, afb4-2
is hypersensitive to IAA in the hypocotyl, indicating that AFB4 is a
negative regulator of auxin response in the developing seedling. (M. Q. Xing)
——The AFB4 Auxin Receptor Is a Negative Regulator of Auxin Signaling in Seedlings
Katie Greenham, Aaron Santner, Cristina Castillejo, Sutton Mooney, Ilkka Sairanen, Karin Ljung, and Mark Estelle
Current Biology, Vol 21, 22 March 2011| doi:
10.1016/j.cub.2011.02.029.
- [Lab Seminar-2011-04-12]
When BR levels are low, BIN2 phosphorylates and inactivates the BZR1 transcription factor to inhibit growth in plants. BR promotes growth by inducing dephosphorylation of BZR1, but the phosphatase that dephosphorylates BZR1 has remained unknown. Here, using tandem afnity purication, protein phosphatase 2A(PP2A)was identified as a BZR1-interacting protein. Genetic analyses demonstrated a positive role for PP2A in brassinosteroid signalling and BZR1 dephosphorylation. Members of the B' regulatory subunits of PP2A directly interact with BZR1's putative PEST domain. (P. Li)
——PP2A activates brassinosteroid-responsive gene expression and plant growth by dephosphorylating BZR1
Wenqiang Tang, Min Yuan, Ruiju Wang, Yihong Yang, Chunming Wang, Juan A. Oses-Prieto, Tae-Wuk Kim, Hong-Wei Zhou, Zhiping Deng, Srinivas S. Gampala, Joshua M. Gendron, Else M. Jonassen, Cathrine Lillo, Alison DeLong, Alma L. Burlingame, Ying Sun and Zhi-Yong Wang
Nature Cell Biology, Vol 13, 18 February 2011| doi:
10.1038/ncb2151.
- [Lab Seminar-2011-03-29]
C4 photosynthesis allows increased photosynthetic efficiency because carbon dioxide (CO2) is concentrated around the key enzyme RuBisCO. C4 photosynthesis is normally associated with the compartmentation of photosynthesis between mesophyll (M) and bundle sheath (BS) cells. The mechanisms regulating the differential accumulation of photosynthesis proteins in these specialized cells are fundamental to our understanding of how C4 photosynthesis operates.
This report showed that two independent lineages of C4 plant have conserved mechanisms controlling the expression of NAD-ME and NADP-ME. Sequences in the transcribed region of the genes are sufficient for their BS-specific accumulation. Orthologous genes from C3 species also contained conserved regulatory elements that conferred BS specificity when placed into C4 species. These results suggest that engineering C4 photosynthesis in rice to increase yield may be possible.
(J.J. Xu)
——Independent and Parallel Recruitment of Preexisting Mechanisms Underlying C4 Photosynthesis
Naomi J. Brown, Christine A. Newell, Susan Stanley, Jit E. Chen, Abigail J. Perrin, Kaisa Kajala, Julian M. Hibberd
Science, Vol 31, 18 March 2011| doi:
10.1126/science.1201248.
- [Lab Seminar-2011-03-22]
Phototropism is an adaptation response, through which plants grow towards the light. It involves light perception and asymmetric distribution of the plant hormone auxin. Friml Group identify a crucial part of the mechanism for phototropism, revealing how light perception initiates auxin redistribution that leads to directional growth. They show that light polarizes the cellular localization of the auxin efflux carrier PIN3 in hypocotyl endodermis cells, resulting in changes in auxin distribution and differential growth. In the dark, high expression and activity of the PINOID (PID) kinase correlates with apolar targeting of PIN3 to all cell sides. Following illumination, light represses PINOID transcription and PIN3 is polarized specifically to the inner cell sides by GNOM ARF GTPase GEF (guanine nucleotide exchange factor)-dependent trafficking. Thus, differential trafficking at the shaded and illuminated hypocotyl side aligns PIN3 polarity with the light direction, and presumably redirects auxin flow towards the shaded side, where auxin promotes growth, causing hypocotyls to bend towards the light. These results imply that PID phosphorylation-dependent recruitment of PIN proteins into distinct trafficking pathways is a mechanism to polarize auxin fluxes in response to different environmental and endogenous cues.
(S.T.Tan)
——Light-mediated polarization of the PIN3 auxin transporter for the phototropic response in Arabidopsis
Zhaojun Ding, Carlos S. Galván-Ampudia, Emilie Demarsy, Lukasz Langowski, Jürgen Kleine-Vehn,
Yuanwei Fan, Miyo T. Morita, Masao Tasaka, Christian Fankhauser, Remko Offringa and Jiri´ Friml
Nature Cell Biology, advance online, 13 March 2011| doi:
10.1038/ncb2208.
- [Lab Seminar-2011-03-15]
Asymmetric polar distribution of PIN proteins is vital for auxin transport. In order to identify components for PIN polarity, Feraru and coworkers identified four regulator of pin polarity(repp) mutants by forward genetic screen. Using genetic and pharmacological way, they found cesa3,a subunit of the cellulose synthase complex, is critical for regulation of the polar localization of PIN transporters. Their studies reveal a link between the extracellular matrix to the dynamic localization of PIN auxin carrier proteins. (B.J. Yang)
——PIN Polarity Maintenance by the Cell Wall in Arabidopsis
Elena Feraru, Mugurel Ioan Feraru,Jurgen Kleine-Vehn, Alexandre Martiniere, Gre´gory Mouille, Steffen Vanneste,
Samantha Vernhettes, John Runions, and Jiri´ Friml
Current Biology, Vol 21, 22 February 2011| doi:
10.1016/j.cub.2011.01.036.
- [Lab Seminar-2011-03-08]
How the asymmetry of zygote division is regulated and connected to the
daughter cell fates is largely unknown. In Arabidopsis, early embryo
patterning is regulated by WOX homeobox genes, which expression is
restricted to apical (WOX2) and basal (WOX8/9) cells. But asymmetric
expression of WOX8 during axis initiation is independent of auxin , the axis
patterning signal . This paper shows that the zinc-finger transcription
factor WRKY2 directly activates WOX8 transcription in zygote and basal
embryo lineage. In wrky2 mutants, egg cells polarize normally but zygotes
fail to reestablish polar organelle positioning from a transient symmetric
state, resulting in equal cell division and distorted embryo development.
Both defects are rescued by overexpressing WOX8. WRKY2 repolarizes the
zygote via WOX8 transcription in the zygote itself . (H. Zhang)
——Transcriptional Activation of Arabidopsis Axis Patterning Genes WOX8/9 Links Zygote Polarity to Embryo Development
Minako Ueda, Zhongjuan Zhang and Thomas Laux
Developmental Cell, Vol 20, 15 February 2011| doi:
10.1016/j.devcel.2011.01.009.
- [Lab Seminar-2011-03-01]
The plant defence strategy compose of resistant(R)-gene-mediated immunity and the broad-spectrum basal defence. Here they report the identification of novel genes invoved in resistance against Hyaloperonospora arabidopsi-dis (Hpa) in Arabidopsis. these gene contributed in the R-gene-mediated PCD were also detective in basal resistant,establishing an interconnection between two distinct defence mechanisms. What's more,these new defence genes are under circadian control by CIRCADIAN CLOCK-ASSOCIAT 1(CCA1),allowing plants to prepare infection at dawn when the pathogen normally disperses the spores.In this way,this group establish a molecular link between the plant circadian clock and R-mediated defence and reveal a new interface between the plant host and biotrophic pathogens. (L.B. Lin)
——Timing of plant immune responses by a central circadian regulator
WeiWang, Jinyoung Yang Barnaby, Yasuomi Tada, Hairi Li, Mahmut To¨r, Daniela Caldelari, Dae-un Lee,
Xiang-Dong Fu & Xinnian Dong
Nature, Vol 470, 3 February 2011| doi:
10.1038/nature09766.
- [Lab Seminar-2011-02-22]
LUX, as an evening-expressed putative transcription factor essential for circadian rhythmicity, directly regulates the expression of PSEUDO RESPONSE REGULATOR9 (PRR9), a major component of the morning transcriptional feedback
circuit, through association with the newly discovered DNA binding site. Furthermore, LUX binds to its own
promoter, defining a new negative autoregulatory feedback loop within the core clock.
EARLY FLOWERING 3 (ELF3) has been implicated as a repressor of light signaling to the clock and, paradoxically, as an activator of the light-induced genes CCA1 and LHY. ELF3 associates physically with the promoter of PRR9, a repressor of CCA1 and LHY expression. The repressive function of ELF3 is via a direct ELF3 target, PRR9 in a double-negative connection. (H. Y. Yao)
——LUX ARRHYTHMO Encodes a Nighttime Repressor of Circadian Gene Expression in the Arabidopsis Core Clock
Anne Helfer, Dmitri A. Nusinow, Brenda Y. Chow, Andrew R. Gehrke, Martha L. Bulyk, and Steve A. Kay
Current Biology, Vol 21, 25 January 2011| doi:
10.1016/j.cub.2010.12.021.
——Temporal Repression of Core Circadian Genes Is Mediated through EARLY FLOWERING 3 in Arabidopsis
Laura E. Dixon, Kirsten Knox, Laszlo Kozma-Bognar, Megan M. Southern, Alexandra Pokhilko, and Andrew J. Millar
Current Biology, Vol 21, 25 January 2011| doi:
10.1016/j.cub.2010.12.013.
- [Lab Seminar-2011-01-18]
Vegetative phase change is very important for plant development. According to previous results, MiRNA156 plays a pivotal role in this phase change. Mi156 is expressed at a very high level in early shoot development and decrease, leading to the onset of the adult phase. However, it always was debated on the source tissue that generation of the signal. To determine the source of the factors, the authors examined the effect of root and leaf ablation on the timing of the vegetative phase change. There was no visible effect on root and cotyledon ablation, but ablation of leaf primordial delayed this transition in a miR156-dependent manner. The treatment produced an increase in the abundance of miR156, which was attributable to an increase in the transcription of some of the miR156 genes in Arabidopsis, and decreased the expression of SPL genes regulated by miR156. miR156 levels were also elevated by leaf ablation in tobacco and maize. These results conclude that vegetative phase change is initiated by signals produced by leaf primordia, which act as a miR156 dependent maner. (L. L. Gao)
——Vegetative phase change is mediated by a leaf-derived signal that represses the transcription of miR156
Li Yang, Susan R. Conway and R. Scott Poethig
Development, advance online, 9 December 2010| doi:
10.1242/dev.058578.
- [Lab Seminar-2011-01-11]
In this article a long intronic noncoding RNA (termed as COLDAIR) was found to have important influence on vernalization-mediated epigenetic repression of FLC.
COLDAIR physically associates with a component of PRC2 and targets PRC2 to FLC. these
results show that COLDAIR is required for establishing stable repressive chromatin at
FLC through its interaction with PRC2. (W.J. Jia)
——Vernalization-Mediated Epigenetic Silencing by a Long Intronic Noncoding RNA
Jae Bok Heo and Sibum Sung
Science, advance online, 2 December 2010| doi:
10.1126/science.1197349.
- [Lab Seminar-2011-01-04]
Cytokinin-auxin crosstalk antagonized gene BRX is a target of the prototypical ARF and transiently enhances PIN3 expression to promote meristem growth in young root. Cytokinin induction of SHY2 restricts BRX expression to down-regulate PIN3 and thus limit meristem growth. Cross-regulatory antagonism between BRX and SHY2 spatio-temporally determine ARF activity in the protophloem. And this may represent a switch in the transition toward differentiation in various developmental contexts. (Y.J. Chu)
——Spatio-temporal sequence of cross-regulatory events in root meristem growth
Emanuele Scacchi, Paula Salinas, Bojan Gujas, Luca Santuari, Naden Krogan, Laura Ragni, Thomas Berleth,
and Christian S. Hardtke
PNAS, 2010, Vol 107| 28 December 2010| doi:
10.1073/pnas.1014716108.
- [Lab Seminar-2010-12-28]
Through a yeast two-hybrid screening, a key repressor of JA signaling JAZ1 was found as a RGA-interacting partner. Future data suggests that there may be widespread interaction between DELLAs and JAZ proteins. DELLAs interact with JAZs to reduce the interaction between JAZs and MYC2, a key transcriptional activator of JA signaling, and then enhance the MYC2 binding to downstream genes. The results of this article identified DELLAs, as central regulators mediated the crosstalk of various phytohormones, also as a key node in the GA and JA crosstalk. (X.Y. Zhou)
——DELLAs Modulate Jasmonate Signaling via Competitive Binding to JAZs
Xingliang Hou, Li Yen Candy Lee, Kuaifei Xia, Yuanyuan Yan, and Hao Yu
Developmental Cell, 2010, Vol 19| 14 December 2010| doi:10.1016/j.devcel.2010.10.024.
- [Lab Seminar-2010-12-21]
In many flowering plants, vernalization is a checkpoint vital to the transition from the vegetative stage to the reproductive stage. Through the study of Cultivated beets, this group analysed two paralogs of FLOWERING LOCUS(FT), BvFT1 and BvFT2. Interestingly, the two genes acts on antagonisticly, BvFT1 represses flowering and crucial for the vernalization while BvFT1 promotes the flowering. A series of experimental results suggest that the sugar beet has evolved a different way to regulate the vernalization. (W. Wang)
——An Antagonistic Pair of FT Homologs Mediates the Control of Flowering Time in Sugar Beet
Pierre A. Pin, Reyes Benlloch, Dominique Bonnet, Elisabeth Wremerth-Weich, Thomas Kraft, Jan J. L. Gielen, Ove Nilsson
Science, 2010, Vol 330| 3 December 2010| doi:10.1126/science.1197004.
- [Lab Seminar-2010-12-14]
The plant hormone auxin regulates multiple aspects of plant growth and development, including cell division. Arabidopsis thaliana S-Phase Kinase-Associated Protein 2A (SKP2A) is an F-box protein, which could directly and specifically bind auxin. As we all know, after auxin perception by TIR1, the Aux/IAA proteins are quickly recognized and labeled with ubiquitin for their degradation, but here auxin could induce the ubiquitin-dependent degradation of SKP2A both in vivo and in vitro. Auxin also enhanced the interaction between SKP2A and a cell cycle transcription factor DPB. A mutation in SKP2A leads to auxin resistant root growth. So this article indicates that SKP2A is an auxin binding protein that connects auxin signaling with cell division. (L. Song)
——The Arabidopsis Cell Cycle F-Box Protein SKP2A Binds to Auxin
Silvia Jurado, Zamira Abraham, Concepción Manzano, Gema López-Torrejón, Luis F. Pacios, and Juan C. Del Pozo
The Plant Cell, 2010, advance online publication| doi:10.1105/tpc.110.078972.
- [Lab Seminar-2010-12-07]
Transcript profiling and chromatin-immunoprecipitation microarray (ChIP-chip) experiments identify 953 BR-regulated BZR1 target (BRBT) genes. Functional studies of selected BRBTs further demonstrate roles in BR promotion of cell elongation. The BRBT genes reveal numerous molecular links between the BR-signaling pathway and downstream components involved in developmental and physiological processes. Furthermore, the results reveal extensive crosstalk between BR and other hormonal and light-signaling pathways at multiple levels
.
(X. Yang)
——Integration of Brassinosteroid Signal Transduction with the Transcription Network for Plant Growth Regulation in Arabidopsis
Yu Sun, Xi-Ying Fan, Dong-Mei Cao, Wenqiang Tang, Kun He, Jia-Ying Zhu, Jun-Xian He, Ming-Yi Bai,
Shengwei Zhu, Eunkyoo Oh, Sunita Patil, Tae-Wuk Kim, Hongkai Ji, Wing Hong Wong, Seung Y. Rhee, and Zhi-Yong Wang
Developmental Cell, Vol 19| 16 November 2010| doi:10.1016/j.devcel.2010.10.010.
- [Lab Seminar-2010-11-30]
Using high-resolution expression data from the Arabidopsis root，they identified a transcription factor, UPBEAT1 (UPB1), that regulates the balance between cellular proliferation and differentiation. Genomewide expression profiling coupled with ChIP-chip analysis revealed that UPB1 directly regulates the expression of a set of peroxidases that modulate the balance of reactive oxygen species (ROS) between the zones of cell proliferation and the zone of cell elongation .Disruption of UPB1 activity alters this ROS balance, leading to a delay in the onset of differentiation. Modulation of either ROS balance or peroxidase activity through chemical reagents affects the onset of differentiation in a manner consistent with the postulated UPB1 function. This pathway functions independently of auxin and cytokinin plant hormonal signaling.
(J. J. Zhang)
——Transcriptional Regulation of ROS Controls Transition from Proliferation to Differentiation in the Root
Hironaka Tsukagoshi, Wolfgang Busch, and Philip N. Benfey
Cell, Vol 143| 12 November 2010| doi:10.1016/j.cell.2010.10.020.
- [Lab Seminar-2010-11-18]
Identification of cell-specific genetic programs is essential for the evolving understanding of developmental regulation. But this is currently a major technical challenge. This paper provides a simple method. They used a biotin ligase recognition peptide which fused to nuclear envelop protein to pull down the nuclei. By using a cell special promoter, they could purify the nuclei which they needed. These nuclei were suitable for expression profiling of RNA or chromatin profiling. This method should be applicable to many plant.
(Y. Tang)
——A Simple Method for Gene Expression and Chromatin Profiling of Individual Cell Types within a Tissue
Roger B. Deal and Steven Henikoff
Developmental Cell, Vol 18| 15 June 2010| doi:10.1016/j.devcel.2010.05.013.
- [Lab Seminar-2010-11-12]
Hd3a expression is induced by Ehd1 expression when blue light coincides with the morning phase . Ghd7 was acutely induced when phytochrome signals coincided with a photosensitive phase set differently by distinct photoperiods and this induction repressed Ehd1 the next morning. Thus, two distinct gating mechanisms—of the floral promoter Ehd1 and the floral repressor Ghd7—could enable manipulation of slight differences in day length to control Hd3a transcription with a critical day-length threshold.
(J. Wang)
——A pair of floral regulators sets critical day length for Hd3a florigen expression in rice
Hironori Itoh, Yasunori Nonoue, Masahiro Yano & Takeshi Izawa
Nature Genetics, Vol 42| 1 July 2010| doi:10.1038/ng.606.
- [Lab Seminar-2010-11-02]
The PIN family of auxin efflux transporters exhibit polar plasma membrane(PM) localization and constantly recycle between the PM and endosomes. Auxin it-self inhibits PIN endocytosis and promotes its PM localization. In this paper, the mechanism underling this process is studied and a modle that ABP1 involved nontranscriptional auxin signaling regulates clathrin-mediated endocytosis is proposed.
(H.B. Gao)
——ABP1 Mediates Auxin Inhibition of Clathrin-Dependent Endocytosis in Arabidopsis
Ste´ phanie Robert, Jurgen Kleine-Vehn, Elke Barbez, Michael Sauer, Tomasz Paciorek, Pawel Baster, Steffen Vanneste, Jing Zhang, Sibu Simon, Milada Covanova, Kenichiro Hayashi, Pankaj Dhonukshe, Zhenbiao Yang, Sebastian Y. Bednarek, Alan M. Jones, Christian Luschnig, Fernando Aniento, Eva Zamalova´, and Jiri′ Friml
Cell, Vol 143| 1 October 2010| doi:10.1016/j.cell.2010.09.027.
- [Lab Seminar-2010-10-20]
Auxin plays important roles in plant growth and development. However, the research on auxin signal transduction focuses on nuclear signaling, involving the binding of auxin and its receptor TIR1 and the resulted degradation of Aux/IAA proteins, little is known about the cytoplasmic signaling pathway. Using Arabidopsis leaf epidermal pavement cells as a research subject, the authors revealed auxin could activate ROP GTPase ROP2 and ROP6, thus coordinating the interdigitated growth of pavement cells, and the activation of these ROPs is dependent on ABP1. (J.J. Xiang)
——Cell Surface- and Rho GTPase-Based Auxin Signaling Controls Cellular Interdigitation in Arabidopsis
Tongda Xu, Mingzhang Wen, Shingo Nagawa, Ying Fu, Jin-Gui Chen, Ming-Jing Wu, Catherine Perrot-Rechenmann, Jiri´ Friml, Alan M. Jones, and Zhenbiao Yang
Cell, Vol 143| 1 October 2010| doi:10.1016/j.cell.2010.09.003.
- [Lab Seminar-2010-10-12]
The GA controls many important aspects of plant development. Degradation of DELLA proteins is the key step of the GA signaling pathway. DELLA proteins repress GA responses, at least in part, by interfering with the DNA binding activity of PIF. The authors identify two GATA family transcription factors GNC and GNL as important downstream targets of DELLA and PIF. GNC and GNL can regulate germination, greening, elongation growth and flowering time as the target genes of PIF.
(L.L. Yin)
——The GATA-type transcription factors GNC and GNL/CGA1 repress gibberellin signaling downstream from DELLA
proteins and PHYTOCHROMEINTERACTING FACTORS
Rene´ Richter, Carina Behringer, Isabel Karin Muller, and Claus Schwechheimer
Genes & Development, Vol 24|16 September 2010| doi:10.1101/gad.594910.
- [Lab Seminar-2010-09-28]
Auxin moving down the main stem inhibits branch activity by preventing the establishment of auxin transport out of axillary branches; and that SLs act by dampening auxin transport, thus enhancing competition between branches.
(P. Li)
——Strigolactones enhance competition between shoot branches by dampening auxin transport
Scott Crawford, Naoki Shinohara, Tobias Sieberer, Lisa Williamson, Gilu George, Jo Hepworth, Dörte Müller, Malgorzata A. Domagalska and Ottoline Leyser
Development, Vol 137|5 September 2010| doi:10.1242/dev.051987.
- [Lab Seminar-2010-09-21]
Genetic suppressor screens in Arabidopsis against cotylimide compounds identified genes that positively regulate strigolactone levels. Further functional analyses indicate strigolactones sensitize seeds and seedlings to light-adapted development by regulating the accumulation of the COP1 ubiquitin ligase, involved in light signaling.
(M.Q. Xing)
——A small-molecule screen identifies new functions for the plant hormone strigolactoney
Yuichiro Tsuchiya, Danielle Vidaurre, Shigeo Toh, Atsushi Hanada, Eiji Nambara, Yuji Kamiya, Shinjiro Yamaguchi & Peter McCourt
Nature Chemical Biology, Vol 435|5 September 2010| doi:10.1038/nchembio.435.
- [Lab Seminar-2010-09-14]
How plants position newly formed organs during postembryonic development is a major unanswered question. In the root, this requires that subsets of cells be specified to generate LR primordia.
Moreno-Risueno et al presented evidence that in the Arabidopsis primary root, a process involving oscillating gene expression, which hascharacteristics of a biological clock, is the first step in positioning new LRs. Auxin may contribute to this process, but it does not appear to be sufficient to initiate a prebranch site. (J.J. Xu)
—— Oscillating Gene Expression Determines Competence for Periodic Arabidopsis Root Branching
Miguel A. Moreno-Risueno, Jaimie M. Van Norman, Antonio Moreno, Jingyuan Zhang, Sebastian E. Ahnert,3 Philip N. Benfey
Science, Vol 329|10 September 2010| doi:10.1126/science.1191937.
- [Lab Seminar-2010-09-07]
Prior work has indicated that immuno-proteasomes promote the generation of relevant peptides for presentation by MHC class I molecules, but the mechanism is unclear. Seifert etal. (2010) now show i-proteasomes function to protect cell viability under conditions of IFN-induced oxidative stress. IFN strigger the production of reactive oxygen species(ROS), which induce protein oxidation and the formation of nascent, oxidant-damaged proteins. They find that the ubiquitylation machinery is upregulated in response to IFNs, for degrade defective ribosomal products (DRiPs) by i-proteasomes. i-proteasome-defciency in cells and in murine innammation models results in the accumulation of harmful protein aggregates and increased sensitivity to apoptosis. So, it is vital for the preservation of cell viability upon IFN-induced oxidative stress by the enhanced proteolytic activity of the i-proteasome. At last, their work suggest that rather than having a specific role in the production of classI antigens, i-proteasomes increase the peptide supply for antigen presentation as part of a more general role in the maintenance of protein homeostasis. (B. J. Yang)
——Immunoproteasomes Preserve Protein Homeostasis upon Interferon-Induced Oxidative Stress
Ulrike Seifert, Lukasz P. Bialy, Frederic Ebstein, Dawadschargal Bech-Otschir, Antje Voigt, Friederike Schroter,
Timour Prozorovski, Nicole Lange, Janos Steffen, Melanie Rieger, Ulrike Kuckelkorn, Orhan Aktas,bPeter-M. Kloetzel, and Elke Kruger
Cell, Vol 142| 20 August 2010| doi:10.1016/j.cell.2010.07.036.
- [Lab Seminar-2010-09-02]
Tyrosine sulfation is an important posttranscriptional modification found in some peptide hormones in both animals and plants. Tyrosylprotein sulfotransferase (TPST) completes this process in cis-Golgi. There is only one copy of TPST in Arabidopsis, contributing to all tyrosine sulfation processes logically.
Yoshikatsu Matsubayashi and his colleagues found PSK and PSY1, two formerly discovered tysosine sulfated peptides affecting root development, could only rescue length of differentiation zone rather than the normal size of root meristem, so they searched the Arabidopsis genome for genes encoding sulfated peptides and got the RGF1 (Root Meristem Growth Factor 1)。They overexpressed RGF1 in Arabidopsis and the mature peptide, which is 13 amino acids long and carries a tyrosine sulfation. Chemically synthesized sulfated form of RGF1 could rescue the root meristem size of lipid medium cultured tpst-1 seedlings in a dose dependent manner. Further study demonstrated RGFs were sufficient for maintenance of postembryonic root stem cell niche by regulating the expression levels and patterns of PLT transcription factors in the roots, independently of the auxin pathway. (S.T. Tan)
—— Secreted Peptide Signals Required for Maintenance of Root Stem Cell Niche in Arabidopsis
Yo Matsuzaki, Mari Ogawa-Ohnishi, Ayaka Mori, Yoshikatsu Matsubayashi
Science, Vol 329|27 August 2010| doi:10.1126/science.1191132.
- [Lab Seminar-2010-08-24]
To explore the mechanisms underlying the dominant/recessive relationship,
which determine the final phenotype of the diploid organism, Authors have
examined the monoallelic expression of S-locus protein 11 genes (SP11),
which encode the male determinants of self-incompatibility in Brassica. SP11
expression was monoallelic in some S heterozygotes, and that the promoter
regions of recessive SP11 alleles were specifically methylated in the anther
tapetum.
This paper shows that this methylation is controlled by trans-acting small
non-coding RNA (sRNA). Inverted genomic sequences are similar to the
recessive SP11 promoters in the flanking regions of dominant SP11 alleles.
These sequences were specifically expressed in the anther tapetum and
processed into 24-nucleotide sRNA, named SP11 methylation inducer (Smi).
Introduction of the Smi genomic region into the recessive S homozygotes
triggered the methylation of the promoter of recessive SP11 alleles and
repressed their transcription. (H. Zhang)
——Trans-acting small RNA determines dominance relationships in Brassica self-incompatibility
Yoshiaki Tarutani, Hiroshi Shiba, Megumi Iwano, Tomohiro Kakizaki, Go Suzuki, Masao Watanabe, Akira Isogai & Seiji Takayama
Nature, Vol 466|19 August 2010| doi:10.1038.
- [Lab Seminar-2010-08-20]
Plant cells have been thought to be totipotent, because they are able to regenerate the full array of plant tissues from already differentiated organs, however, the mechanisms behind this totipotency still remain elusive. On March, 16th, 2010, a group in the USA demonstrate that callus derived from aerial organs resembles the tip of a root meristem. Moreover, they found that the ectopic activation of a lateral root intiation program from cells equivalent to root pericycle cells is the common mechanism of callus formation from these organs. (S. Y. Wang)
——Arabidopsis Regeneration from Multiple Tissues Occurs via a Root Development Pathway
Kaoru Sugimoto, Yuling Jiao, and Elliot M. Meyerowitz
Developmental Cell, Vol 18|16 March 2010| doi:10.1016.
- [Lab Seminar-2010-08-11]
The phytohormones cytokinin and auxin play antagonistic roles in the maintenance of the shoot apical meristem(SAM). Whereas local accumulation of the SAM, cytokinin is essential for maintaining meristem activity and cell cycle progression. There is cross talk between auxin and cytokinin affects the stem-cell.
Two A-type ARABIDOPSIS RESPONSE REGULATOR (ARR) genes, ARR7 and ARR15 , which are negative regulators of Cytokinin signaling, have important meristematic functions. The author shows us ARR7 and ARR15 might play a role in mediating auxin signaling by the AUXIN RESPONSE FACTOR5/MP transcription factor. This work also shed light on the mechanism underlying the ability of ARR7/ARR15 to integrate cytokinin and auxin signal. Although the major regulatory input for ARR7/ARR15 have now been identified, it remains to be show how their activity is relyed to the WUS/CLV network. (L. B. Lin)
——Hormonal control of the shoot stem-cell niche
Zhong Zhao, Stig U. Andersen, Karin Ljung, Karel Dolezal, Andrej Miotk, Sebastian J. Schultheiss & Jan U. Lohmann
Nature, Vol 465|24 June 2010| doi:10.1038.
- [Lab Seminar-2010-07-27]
Ubiquitination and deubiquitination have been implicated in various cellular processes. However, little is known about the role of ubiquitin in the development of cellular organelles. In this paper, AtAMSH3 was characterized to hydrolyzes K48- and K63-linked ubiquitin chains. amsh3 mutants fail to form a central lytic vacuole and mis-sort vacuolar protein cargo to the intercellular space. AMSH3 is also required for efficient endocytosis of FM4-64 and PIN2. They thus present evidence for a role of deubiquitination in intracellular trafficking and vacuole biogenesis. (H. Y. Yao)
——The Deubiquitinating Enzyme AMSH3 Is Required for Intracellular Trafficking and Vacuole Biogenesis in Arabidopsis
Erika Isono, Anthi Katsiarimpa, Isabel Karin Muller, Franziska Anzenberger, York-Dieter Stierhof, Niko Geldner, Joanne Chory, and Claus Schwechheimer
The Plant Cell, online| 11 June 2010| doi:10.1105.
- [Lab Seminar-2010-07-16]
When a plant sees light after emerging from the ground，the red/far-red photoreceptors, phytochromes， translocate from the cytoplasm to subnuclear foci called phytochrome nuclear bodies. In this paper, the author first identified a mutant, hemera, who is impaired in
phytochrome responses. Then, they show that HEMERA acts specifically in phytochrome signaling and these results implicate phytochrome nuclear bodies as sites of proteolysis. (L. L. Gao)
——Arabidopsis HEMERA/pTAC12 Initiates Photomorphogenesis by Phytochromes
Meng Chen, Rafaelo M. Galva, Meina Li, Brian Burger, Jane Bugea, Jack Bolado, and Joanne Chory
Cell, Vol 141| 25 June 2010| doi:10.1016.
- [Lab Seminar-2010-07-06]
Coordinated control of cell divisions leading to proper patterning and growth in multicellular organisms development. The SHR and SCR have important functions in pattern formation of Arabidopsis root. This paper show SHR regulates the spatiotemporal activation of specific genes involved in cell division. SHR and SCR directly activate a D-type cyclin, CYCD6;1, to control the formative cell division, so as to the organ patterning
——Spatiotemporal regulation of cell-cycle genes by SHORTROOT links patterning and growth
R. Sozzani, H. Cui, M. A. Moreno-Risueno, W. Busch, J. M. Van Norman, T. Vernoux, S. M. Brady, W. Dewitte, J. A. H. Murray & P. N. Benfey
Nature, Vol 466| 1 July 2010| doi:10.1038.
- [Lab Seminar-2010-06-22]
this study has described the successful use in plant cells of genetically
encoded H2O2 and Ca2+ sensors localized within cell organelles.
Moreover, it presented the analysis of H2O2 and Ca2+
dynamics within plant peroxisomes providing unambiguous
in vivo evidence that [Ca2+]p elevations allows a more rapid
catabolism of H2O2 by the increase of CAT3 within peroxisomes. (W.J. Jia)
——H2O2 in plant peroxisomes: an in vivo analysis uncovers a Ca2+-dependent scavenging system
Alex Costa, Ilaria Drago, Smrutisanjita Behera, Michela Zottini, Paola Pizzo, Julian I. Schroeder, Tullio Pozzan and Fiorella Lo Schiavo
The Plant Journal, Vol 62|25 March 2010| doi: 10.1111.
- [Lab Seminar-2010-06-13]
Two transcription factors SHR and SCR are crucial for Arabidopsis root radial pattern formation. Vascular cylinder cells produce SHR and then it move into the endodermis to activate SCR and then they activate microRNA165/6 together. miRNA165/6 can move toward Vascular cylinder result in a concentration gradient of its target gene HD-ZIP Ⅲ, which can direct the root cells differentiation to form a radial pattern. (X.Y. Zhou)
——Cell signalling by microRNA165/6 directs gene dose-dependent root cell fate
Annelie Carlsbecker, Ji-Young Lee, Christina J. Roberts, Jan Dettmer, Satu Lehesranta, Jing Zhou,
Ove Lindgren, Miguel A. Moreno-Risueno6, Anne Vaten, Siripong Thitamadee, Ana Campilho, Jose Sebastian,
John L. Bowman, YkaHelariutta & Philip N. Benfey
Nature, Vol 465|20 May 2010| doi:10.1038.
- [Lab Seminar-2010-06-01]
Flower plant female gametogenesis is initiated from a single gametic cell, formed after meiosis of megaspore mother cell (MMC). Many genes were found to control female gametogenesis except sRNA pathway. The authors identified a dominant allele, ago9. Pre-meiotic ovules show multiple MMCs in ago9 T-DNA insertional lines. AGO9 preferentially interacts with 24-nucleotide sRNAs and is necessary for sRNA-dependent silencing in flowering plants female gametogenesis. (Y. J. Chu)
——Control of female gamete formation by a small RNA pathway in Arabidopsis
Vianey Olmedo-Monfil, NoeDuran-Figueroa, Mario Arteaga-Vazquez, Edgar Demesa-Arevalo, Daphne Autran, Daniel Grimanelli, R. Keith Slotkin, Robert A. Martienssen & Jean-Philippe Vielle-Calzada
Nature, Vol 464|25 March 2010| doi:10.1038.
- [Lab Seminar-2010-05-25]
In Arabidopsis,cell-cell communications and inductive signaling are vital for developmental patterning like embryogenesis.Through microarray-based approach, the authors identified a list of TMOs which are transcriptionally dependent on MP.Among them, TMO7 was found to function downstream of MP in embryonic root initiation. Strikingly, it could moves from its transcription sites to the hypophysis nucleus, representing a novel mobile signal in embryonic root specification. (W. Wang)
——MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor
Alexandra Schlereth, Barbara Moller, Weilin Liu, Marika Kientz, Jacky Flipse, Eike H. Rademacher,
Markus Schmid, Gerd Jurgens & Dolf Weijers
Nature, Vol 464|8 April 2010| doi:10.1038.
- [Lab Seminar-2010-05-18]
Innate immunity is the first line of inducible defence against microbial infection in plants. MAPK cascade mediated signalling is an essential step in the establishment of resistance to pathogens. The receptor recognition of pathogen- or microbe-associated molecular, such as flagellin, initiates MAPK cascades and global transcriptional changes to boost immunity.
Calcium signaling is an essential and conserved primary mediator in plant defence responses. This paper first discover the crosstalk between calcium signaling and MAPK cascade. Some specific CDPKs work with MAPK cascade is initial in MAMP signalling. (C. Dai)
——Differential innate immune signalling via Ca2+ sensor protein kinases
Marie Boudsocq, Matthew R. Willmann, Matthew McCormack, Horim Lee, Libo Shan, Ping He, Jenifer Bush, Shu-Hua Cheng & Jen Sheen
Nature, Vol 464| 18 March 2010| doi:10.1038.
- [Lab Seminar-2010-05-06]
Jasmonates are lipid-derived signals that mediate plant stress responses and development processes. The F-box protein COI1 as central regulatory unit, JAZ proteins interact with COI1 and are subsequently degraded by the 26S proteasome. However, the molecular mechanism of JAZ protein repress gene expression has not been unraveled.
This paper indicated that the transcriptional repressor NINJA, through interacts with JAZ and TPL proteins, negatively regulates JA signaling. (L. Song)
——NINJA connects the co-repressor TOPLESS to jasmonate signalling.
Laurens Pauwels, Gemma Fernandez Barbero, Jan Geerinck, Sofie Tilleman, Wim Grunewald, Amparo Cuellar Perez, Jose Manuel Chico, Robin Vanden Bossche, Jared Sewell, Eduardo Gil, Gloria Garcıa-Casado, Erwin Witters, Dirk Inze, Jeff A. Long, Geert De Jaeger, Roberto Solano & Alain Goossens
Nature, Vol 464| 1 April 2010| doi:10.1038.
- [Lab Seminar-2010-04-29]
The haploid plants play the pivotal role in genetic studies and breeding. The haploid can converted to the normal diploid by artificial manipulating such as colchicines treatment and gain the stabilized homozygous diploid in one generation. Therefore the haploid can dramatically accelerate the breeding. The haploid can be produced via tissue culture but many species are not adapted to this method, or rare interspecific crossed but which the molecular mechanism is not unambiguous.
Maruthachalam Ravi and Simon W. L. Chan publish a paper titled haploid plants produced by centromere-mediated genome elimination on the latest Nature. In this article, the authors exploited a simple method to produce the haploid in Arabidopsis seeds by manipulating a centromere-specific histone CENH3 protein. After the crossing between the mutants expressing altered CENH3 and the wild type, the genome of mutant is eliminated and obtains the haploid by meiotic nonreduction. This method maybe used in any plant species based on universality of CENH3 in eukaryotes. (X. X. Han)
——Haploid plants produced by centromere-mediated genome elimination
Maruthachalam Ravi & Simon W. L. Chan
Nature, Vol 464|25 March 2010| doi:10.1038.
