Regulation of SUP Expression Identifies Multiple Regulators Involved in Arabidopsis Floral Meristem Development

The CLAVATA (CLV1 and CLV3) and SHOOT MERISTEMLESS (STM) genes specifically regulate shoot meristem development in Arabidopsis. CLV and STH appear to have opposite functions: c1v1 and Clv3 mutants accumulate excess undifferentiated cells in the shoot and floral meristem, while stm mutants fail to form the undifferentiated cells of the shoot meristem during embryonic development. We have identified a weak allele of stm (stm-2) that reveals STM is not only required for the establish- ment of the shoot meristem, but is also required for the continued maintenance of undifferentiated cells in the shoot meristem and for proper proliferation of cells in the floral meristem. We have found evidence of genetic interactions between the CLV and STM loci. clv1 and c1v3 mutations partially suppressed the stm-1 and stm-2 phenotypes, and were capable of suppression in a dominant fashion. clv stm double mutants and plants homozygous for stm but heterozygous for clv, while still lacking an embryonic shoot meristem, exhibited greatly enhanced postembryonic shoot and floral meristem development. Although stm phenotypes are recessive, stm mutations dominantly suppressed clv homozygous and heterozygous phenotypes. These results indicate that the stm phenotype is sensitive to the levels of CLV activity, while the clv phenotype is sensitive to the level of STM activity. We propose that these genes play related but opposing roles in the regulation of cell division and/or cell differentiation in shoot and floral meristems.

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Quantitative live-imaging of Aquilegia floral meristems reveals distinct patterns of floral organ initiation and cell-level dynamics of floral meristem termination

10.1101/2021.10.06.463406 ◽

2021 ◽

Author(s):

Ya Min ◽

Stephanie J. Conway ◽

Elena M. Kramer

Keyword(s):

Cell Division ◽

Floral Organ ◽

Live Imaging ◽

Confocal Imaging ◽

Floral Meristem ◽

Flowering Plant ◽

Molecular Networks ◽

Floral Organs ◽

Meristem Development ◽

Floral Meristems

ABSTRACTIn-depth investigation of any developmental process in plants requires knowledge of both the underpinning molecular networks and how they directly determine patterns of cell division and expansion over time. Floral meristems (FM) produce floral organs, after which they undergo floral meristem termination (FMT), and precise control of organ initiation and FMT is crucial to reproductive success of any flowering plant. Using a live confocal imaging, we characterized developmental dynamics during floral organ primordia initiation and FMT in Aquilegia coerulea (Ranunculaceae). Our results have uncovered distinct patterns of primordium initiation between stamens and staminodes compared to carpels, and provided insight into the process of FMT, which is discernable based on cell division dynamics preceding carpel initiation. To our knowledge, this is the first quantitative live imaging of meristem development in a system with numerous whorls of floral organs as well as an apocarpous gynoecium. This study provides crucial information for our understanding of how the spatial-temporal regulation of floral meristem behavior is achieved in both an evolutionary and developmental context.

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Analyzing Floral Meristem Development

Plant Developmental Biology - Methods in Molecular Biology ◽

10.1007/978-1-60761-765-5_9 ◽

2010 ◽

pp. 131-142 ◽

Cited By ~ 4

Author(s):

Elisa Fiume ◽

Helena R. Pires ◽

Jin Sun Kim ◽

Jennifer C. Fletcher

Keyword(s):

Floral Meristem ◽

Meristem Development

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CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1

Development ◽

10.1242/dev.121.7.2057 ◽

1995 ◽

Vol 121 (7) ◽

pp. 2057-2067 ◽

Cited By ~ 26

Author(s):

S. E. Clark ◽

M. P. Running ◽

E. M. Meyerowitz

Keyword(s):

Arabidopsis Thaliana ◽

Flower Development ◽

Mature Embryo ◽

Floral Meristem ◽

Wild Type ◽

Apical Meristems ◽

Meristem Development ◽

Embryo Stage ◽

Double Heterozygosity ◽

Floral Meristems

We have previously described the phenotype of Arabidopsis thaliana plants with mutations at the CLAVATA1 (CLV1) locus (Clark, S. E., Running, M. P. and Meyerowitz, E. M. (1993) Development 119, 397–418). Our investigations demonstrated that clv1 plants develop enlarged vegetative and inflorescence apical meristems, and enlarged and indeterminate floral meristems. Here, we present an analysis of mutations at a separate locus, CLAVATA3 (CLV3), that disrupt meristem development in a manner similar to clv1 mutations. clv3 plants develop enlarged apical meristems as early as the mature embryo stage. clv3 floral meristems are also enlarged compared with wild type, and maintain a proliferating meristem throughout flower development. clv3 root meristems are unaffected, indicating that CLV3 is a specific regulator of shoot and floral meristem development. We demonstrate that the strong clv3-2 mutant is largely epistatic to clv1 mutants, and that the semi- dominance of clv1 alleles is enhanced by double heterozygosity with clv3 alleles, suggesting that these genes work in the same pathway to control meristem development. We propose that CLV1 and CLV3 are required to promote the differentiation of cells at the shoot and floral meristem.

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