CLAVATA Signaling Pathway Receptors of Arabidopsis Regulate Cell Proliferation in Fruit Organ Formation as well as in Meristems

Abstract

The CLAVATA1 (CLV1), CLV2, and CORYNE (CRN) receptors in Arabidopsis thaliana maintain cell proliferation in shoot apical meristems by restricting expression of the transcription factor WUSCHEL (WUS). Previously characterized receptor mutants generate extra fruit and floral organs that are proposed to arise from enlarged floral meristems (FMs). We identified new alleles in clv1, clv2, and crn and found that most mutants produce only extra fruit organs and generate FMs of similar dimensions as wild type. Characterization of gynoecium development in receptor mutants revealed increased cell proliferation and ectopic fruit organ initiation after FM termination. These regions of increased cell division also display expanded expression of the cell proliferation-promoting transcription factor SHOOTMERISTEMLESS (STM), similar to the expansion of WUS expression in the shoot apical meristems of strong clv1 mutants. We also examined genetic interactions between the ERECTA (ER) and BARELY ANY MERISTEM 1 (BAM1) receptor-like kinases and CLV pathway receptors. Our results suggest a model in which CLV1/BAM1 and CLV2/CRN complexes act in separate, parallel pathways in shoot meristems, while the CLV1, CLV2, and CRN receptors function together in a linear pathway during fruit development. These results demonstrate the importance of regulating cell proliferation in plants that undergo organogenesis throughout their life cycle.

RNA-seq analyses of multiple meristems of soybean: novel and alternative transcripts, evolutionary and functional implications

“…Interestingly, the current soybean genome only annotates one CLAVATA1A ( CLV1A ) gene as the ortholog of the Arabidopsis CLV1 gene regulating meristem sizes [38], while the identified XLOC_047893 nTU is a paralog of CLV1A in soybean. Both genes showed specific expression in SAM17D and SAM38D, suggesting a redundant function of CLV1A and XLOC_047893 for regulating SAM in soybean.…”

Identification and expression analysis of theLRR-RLKgene family in tomato (Solanum lycopersicum) Heinz 1706

“…Several Arabidopsis SRF genes have been reported to be coexpressed with genes involved in the organization and biogenesis of the cell wall (Eyuboglu et al 2007), which promoted us to speculate that SlLRR-RLK genes may play roles in fruit softening during the ripening process. The functions of LRR-RLK genes in fruits formation has also been previously exemplified by CLV1, CLV2, and CRN in Arabidopsis gynoecium as regulating the generation of fruit organs (Durbak and Tax 2011). Besides, in a study searching for genes responsible for the transitions in fruit size and shape during tomato domestication, putative homolog of WUS was mapped to a major QTL contributing to large tomato fruit, and a CLV1 paralog and a syntenic region containing the CLV3 gene were found to be co-localized with minor QTLs for floral organ number (Barrero et al 2006), indicating that genes homologs of the Arabidopsis CLV-WUS pathway components might play important roles in modulating meristem size and floral organ number in tomato.…”

CLAVATA-WUSCHEL signaling in the shoot meristem

“…ER is expressed in the SAM, and although er mutants do not exhibit any obvious meristem phenotype, mutants of ER and its family members ERECTA-LIKE1 and ERECTA-LIKE2 enhance clv meristem phenotypes (Durbak and Tax, 2011;Torii et al, 1996;Yokoyama et al, 1998). These effects of mutations in ER family genes on meristem size are the result of enhanced WUS expression, possibly via an HD-ZIPIIIdependent but CLV-independent signaling pathway (Chen et al, 2013;Mandel et al, 2014).…”