Flower meristem maintenance by TILLERS ABSENT 1 is essential for ovule development in rice

Development ◽  
2021 ◽  
Vol 148 (24) ◽  
Author(s):  
Wakana Tanaka ◽  
Suzuha Ohmori ◽  
Naoto Kawakami ◽  
Hiro-Yuki Hirano

ABSTRACT Plant development depends on the activity of pluripotent stem cells in meristems, such as the shoot apical meristem and the flower meristem. In Arabidopsis thaliana, WUSCHEL (WUS) is essential for stem cell homeostasis in meristems and integument differentiation in ovule development. In rice (Oryza sativa), the WUS ortholog TILLERS ABSENT 1 (TAB1) promotes stem cell fate in axillary meristem development, but its function is unrelated to shoot apical meristem maintenance in vegetative development. In this study, we examined the role of TAB1 in flower development. The ovule, which originates directly from the flower meristem, failed to differentiate in tab1 mutants, suggesting that TAB1 is required for ovule formation. Expression of a stem cell marker was completely absent in the flower meristem at the ovule initiation stage, indicating that TAB1 is essential for stem cell maintenance in the ‘final’ flower meristem. The ovule defect in tab1 was partially rescued by floral organ number 2 mutation, which causes overproliferation of stem cells. Collectively, it is likely that TAB1 promotes ovule formation by maintaining stem cells at a later stage of flower development.

2016 ◽  
Vol 113 (33) ◽  
pp. 9375-9380 ◽  
Author(s):  
Dongming Li ◽  
Xing Fu ◽  
Lin Guo ◽  
Zhigang Huang ◽  
Yongpeng Li ◽  
...  

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 flower-specific 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.


2019 ◽  
Vol 71 (3) ◽  
pp. 778-792 ◽  
Author(s):  
Sharmila Singh ◽  
Alka Singh ◽  
Archita Singh ◽  
Mahima ◽  
Sandeep Yadav ◽  
...  

Abstract In higher plants, pluripotent stem cells reside in the specialized microenvironment called stem cell niches (SCNs) harbored at the shoot apical meristem (SAM) and root apical meristem (RAM), which give rise to the aerial and underground parts of a plant, respectively. The model plant Arabidopsis thaliana (Arabidopsis) has been extensively studied to decipher the intricate regulatory mechanisms involving some key transcriptions factors and phytohormones that play pivotal roles in stem cell homeostasis, meristem maintenance, and organ formation. However, there is increasing evidence to show the epigenetic regulation of the chromatin architecture, gene expression exerting an influence on an innate balance between the self-renewal of stem cells, and differentiation of the progeny cells to a specific tissue type or organ. Post-translational histone modifications, ATP-dependent chromatin remodeling, and chromatin assembly/disassembly are some of the key features involved in the modulation of chromatin architecture. Here, we discuss the major epigenetic regulators and illustrate their roles in the regulation of stem cell activity, meristem maintenance, and related organ patterning in Arabidopsis.


Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 136
Author(s):  
Tianqi Jia ◽  
Fan Li ◽  
Shuang Liu ◽  
Jin Dou ◽  
Tao Huang

WUSCHEL (WUS) protein regulates stem cell function in shoot apical meristem of Arabidopsis. The expression of WUS gene is strictly regulated by developmental cues and environmental factors. As DnaJ domain-containing proteins, SDJ1 and SDJ3 have been proven to play an important role in transcriptional activation of promoter methylated genes. Here, we showed that three DnaJ domain-containing proteins including SDJ1 and SDJ3 can bind WUS protein as a complex, which further maintain the expression of WUS gene by binding to WUS promoter. We propose a model how DnaJ domain-containing proteins are involved in the self-regulation of WUS gene in stem cells maintenance of Arabidopsis.


Development ◽  
2002 ◽  
Vol 129 (13) ◽  
pp. 3195-3206 ◽  
Author(s):  
Michael Lenhard ◽  
Gerd Jürgens ◽  
Thomas Laux

Continuous organ formation from the shoot apical meristem requires the integration of two functions: a set of undifferentiated, pluripotent stem cells is maintained at the very tip of the meristem, while their daughter cells in the periphery initiate organ primordia. The homeobox genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM) encode two major regulators of meristem formation and maintenance in Arabidopsis, yet their interaction in meristem regulation is presently unclear. Here, we have addressed this question using loss- and gain-of-function approaches. We show that stem cell specification by WUS does not require STM activity. Conversely, STM suppresses differentiation independently of WUS and is required and sufficient to promote cell division. Consistent with their independent and distinct phenotypic effects, ectopic WUS and STM activities induce the expression of different downstream target genes. Finally, the pathways regulated by WUS and STM appear to converge in the suppression of differentiation, since coexpression of both genes produced a synergistic effect, and increased WUS activity could partly compensate for loss of STM function. These results suggest that WUS and STM share labour in the shoot apical meristem: WUS specifies a subset of cells in the centre as stem cells, while STM is required to suppress differentiation throughout the meristem dome, thus allowing stem cell daughters to be amplified before they are incorporated into organs.


2017 ◽  
Author(s):  
Jérémy Gruel ◽  
Julia Deichmann ◽  
Benoit Landrein ◽  
Thomas Hitchcock ◽  
Henrik Jönsson

AbstractThe plant shoot apical meristem holds a stem cell niche from which all aerial organs originate. Using a computational approach we show that a mixture of monomers and heterodimers of the transcription factors WUSCHEL and HAIRY MERISTEM is sufficient to pattern the stem cell niche, and predict that immobile heterodimers form a regulatory ‘pocket’ surrounding the stem cells. The model achieves to reproduce an array of perturbations, including mutants and tissue size modifications. We also show its ability to reproduce the recently observed dynamical shift of the stem cell niche during the development of an axillary meristem. The work integrates recent experimental results to answer the longstanding question of how the asymmetry of expression between the stem cell marker CLAVATA3 and its activator WUSCHEL is achieved, and recent findings of plasticity in the system.


Cell Reports ◽  
2015 ◽  
Vol 10 (11) ◽  
pp. 1819-1827 ◽  
Author(s):  
Yuyi Zhou ◽  
Minami Honda ◽  
Hongliang Zhu ◽  
Zhonghui Zhang ◽  
Xinwei Guo ◽  
...  

2008 ◽  
Vol 8 ◽  
pp. 1168-1176 ◽  
Author(s):  
Laren Becker ◽  
Qin Huang ◽  
Hiroshi Mashimo

Lgr5 has recently been identified as a murine marker of intestinal stem cells. Its expression has not been well characterized in human gastrointestinal tissues, but has been reported in certain cancers. With the increasing appreciation for the role of cancer stem cells or tumor-initiating cells in certain tumors, we sought to explore the expression of Lgr5 in normal and premalignant human gastrointestinal tissues. Using standard immunostaining, we compared expression of Lgr5 in normal colon and small intestine vs. small intestinal and colonic adenomas and Barrett's esophagus. In the normal tissue, Lgr5 was expressed in the expected stem cell niche, at the base of crypts, as seen in mice. However, in premalignant lesions, Lgr5+cells were not restricted to the crypt base. Additionally, their overall numbers were increased. In colonic adenomas, Lgr5+cells were commonly found clustered at the luminal surface and rarely at the crypt base. Finally, we compared immunostaining of Lgr5 with that of CD133, a previously characterized marker for tumor-initiating cells in colon cancer, and found that they identified distinct subpopulations of cells that were in close proximity, but did not costain. Our findings suggest that (1) Lgr5 is a potential marker of intestinal stem cells in humans and (2) loss of restriction to the stem cell niche is an early event in the premalignant transformation of stem cells and may play a role in carcinogenesis.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Chengguang Wu ◽  
Long Chen ◽  
Yi-zhou Huang ◽  
Yongcan Huang ◽  
Ornella Parolini ◽  
...  

Human multipotent stem cell-based therapies have shown remarkable potential in regenerative medicine and tissue engineering applications due to their abilities of self-renewal and differentiation into multiple adult cell types under appropriate conditions. Presently, human multipotent stem cells can be isolated from different sources, but variation among their basic biology can result in suboptimal selection of seed cells in preclinical and clinical research. Thus, the goal of this study was to compare the biological characteristics of multipotent stem cells isolated from human bone marrow, placental decidua basalis, and urine, respectively. First, we found that urine-derived stem cells (USCs) displayed different morphologies compared with other stem cell types. USCs and placenta decidua basalis-derived mesenchymal stem cells (PDB-MSCs) had superior proliferation ability in contrast to bone marrow-derived mesenchymal stem cells (BMSCs); these cells grew to have the highest colony-forming unit (CFU) counts. In phenotypic analysis using flow cytometry, similarity among all stem cell marker expression was found, excluding CD29 and CD105. Regarding stem cell differentiation capability, USCs were observed to have better adipogenic and endothelial abilities as well as vascularization potential compared to BMSCs and PDB-MSCs. As for osteogenic and chondrogenic induction, BMSCs were superior to all three stem cell types. Future therapeutic indications and clinical applications of BMSCs, PDB-MSCs, and USCs should be based on their characteristics, such as growth kinetics and differentiation capabilities.


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