Timing Mechanism Dependent on Cell Division Is Invoked by Polycomb Eviction in Plant Stem Cells

Sun, Bo; Looi, Liang-Sheng; Guo, Siyi; He, Zemiao; Gan, Eng‐Seng; Huang, Jian; Xu, Yifeng; Wee, Wan-Yi; Ito, Toshiro

doi:10.1126/science.1248559

Cited by 186 publications

(181 citation statements)

References 46 publications

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“…Within the SAM, WUS is expressed specifically in the stem cell organizing center and acts both independently and complementarily with STM in the maintenance of stem cell activity (Laux et al, 1996;Mayer et al, 1998). During flower development, AG terminates stem cell maintenance by repressing WUS by directly or indirectly recruiting PRC2 and LHP1 (Liu et al, 2011;Sun et al, 2014). Interestingly, AtZRF1a/b are not required for the repression of AG and WUS, because expression levels of both AG and WUS are down-regulated in the atzrf1a atzrf1b mutant.…”

Section: Discussionmentioning

confidence: 99%

ZRF1 Chromatin Regulators Have Polycomb Silencing and Independent Roles in Development

Feng

Chen²,

Berr³

et al. 2016

Plant Physiol.

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Section: Discussionmentioning

confidence: 99%

ZRF1 Chromatin Regulators Have Polycomb Silencing and Independent Roles in Development

Feng

Chen²,

Berr³

et al. 2016

Plant Physiol.

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“…For example, Arabidopsis floral homeotic regulator AGAMOUS (AG) requires about 2 d to induce one of its direct targets, KNUCKLES (KNU), to terminate stem cell activity in the floral meristems (Sun et al, 2009). AG reduces trimethylation at Histone H3 Lysine 27 residue in the KNU locus by the cell-division-dependent eviction of Polycomb proteins (Sun et al, 2014). Therefore, it will be intriguing to monitor the status of chromatin modification and transcriptome profiles in the OSH1 induction system over longer time periods.…”

Section: Discussionmentioning

confidence: 99%

Genome-Wide Study ofKNOXRegulatory Network Reveals Brassinosteroid Catabolic Genes Important for Shoot Meristem Function in Rice

et al. 2014

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In flowering plants, knotted1-like homeobox (KNOX) transcription factors play crucial roles in establishment and maintenance of the shoot apical meristem (SAM), from which aerial organs such as leaves, stems, and flowers initiate. We report that a rice (Oryza sativa) KNOX gene Oryza sativa homeobox1 (OSH1) represses the brassinosteroid (BR) phytohormone pathway through activation of BR catabolism genes. Inducible overexpression of OSH1 caused BR insensitivity, whereas loss of function showed a BR-overproduction phenotype. Genome-wide identification of loci bound and regulated by OSH1 revealed hormonal and transcriptional regulation as the major function of OSH1. Among these targets, BR catabolism genes CYP734A2, CYP734A4, and CYP734A6 were rapidly upregulated by OSH1 induction. Furthermore, RNA interference knockdown plants of CYP734A genes arrested growth of the SAM and mimicked some osh1 phenotypes. Thus, we suggest that local control of BR levels by KNOX genes is a key regulatory step in SAM function.

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“…In the null ag-1 mutant, FM determinacy is severely impaired, resulting in a flower-in-flower phenotype (6). AG inhibits WUS expression through both indirect and direct means (8,9). A number of other genes have been shown to regulate FM determinacy through the AG pathway or in parallel pathways, and additional players in this critical developmental process await characterization (4).…”

mentioning

confidence: 99%

FAR-RED ELONGATED HYPOCOTYL3 activates SEPALLATA2 but inhibits CLAVATA3 to regulate meristem determinacy and maintenance in Arabidopsis

Guo

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Plant meristems are responsible for the generation of all plant tissues and organs. Here we show that the transcription factor (TF) FAR-RED ELONGATED HYPOCOTYL3 (FHY3) plays an important role in both floral meristem (FM) determinacy and shoot apical meristem maintenance in Arabidopsis, in addition to its well-known multifaceted roles in plant growth and development during the vegetative stage. Through genetic analyses, we show that WUSCHEL (WUS) and CLAVATA3 (CLV3), two central players in the establishment and maintenance of meristems, are epistatic to FHY3. Using genome-wide ChIP-seq and RNA-seq data, we identify hundreds of FHY3 target genes in flowers and find that FHY3 mainly acts as a transcriptional repressor in flower development, in contrast to its transcriptional activator role in seedlings. Binding motif-enrichment analyses indicate that FHY3 may coregulate flower development with three flowerspecific MADS-domain TFs and four basic helix-loop-helix TFs that are involved in photomorphogenesis. We further demonstrate that CLV3, SEPALLATA1 (SEP1), and SEP2 are FHY3 target genes. In shoot apical meristem, FHY3 directly represses CLV3, which consequently regulates WUS to maintain the stem cell pool. Intriguingly, CLV3 expression did not change significantly in fhy3 and phytochrome B mutants before and after light treatment, indicating that FHY3 and phytochrome B are involved in light-regulated meristem activity. In FM, FHY3 directly represses CLV3, but activates SEP2, to ultimately promote FM determinacy. Taken together, our results reveal insights into the mechanisms of meristem maintenance and determinacy, and illustrate how the roles of a single TF may vary in different organs and developmental stages. meristem maintenance | meristem determinacy | FHY3 | CLV3 | SEP2 P lant meristems are responsible for the generation of all plant tissues and organs. Unlike the shoot apical meristem (SAM), whose activity is maintained throughout the life of plants, the floral meristem (FM) is precisely programmed to terminate in a process known as FM determinacy (1). WUSCHEL (WUS) plays a central role in the establishment and maintenance of SAM, inflorescence meristem, and FM, as well as in FM determinacy (2-4). WUS is expressed in the organizing center located beneath the stem cells in the meristem to promote cell proliferation by maintaining stem cell potential (2). The WUS/CLAVATA3 (CLV3) signaling pathway maintains the stabilization of meristem size and the stem cell pool (3, 5). Consistent with WUS overactivation, clv3 mutants have an enlarged SAM and increased numbers of floral organs and whorls (5). In addition to the WUS/CLV3 loop, several other pathways are known to regulate FM determinacy (4). AGAMOUS (AG) encodes a MADS-box transcription factor (TF) and is the lynchpin of the FM determinacy network (4, 6, 7). In the null ag-1 mutant, FM determinacy is severely impaired, resulting in a flower-in-flower phenotype (6). AG inhibits WUS expression through both indirect and direct means (8, 9). A number of other gene...

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Timing Mechanism Dependent on Cell Division Is Invoked by Polycomb Eviction in Plant Stem Cells

Cited by 186 publications

References 46 publications

ZRF1 Chromatin Regulators Have Polycomb Silencing and Independent Roles in Development

ZRF1 Chromatin Regulators Have Polycomb Silencing and Independent Roles in Development

Genome-Wide Study ofKNOXRegulatory Network Reveals Brassinosteroid Catabolic Genes Important for Shoot Meristem Function in Rice

FAR-RED ELONGATED HYPOCOTYL3 activates SEPALLATA2 but inhibits CLAVATA3 to regulate meristem determinacy and maintenance in Arabidopsis

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