The floral organ number4 gene encoding a putative ortholog of Arabidopsis CLAVATA3 regulates apical meristem size in rice.
To understand the molecular mechanism regulating meristem development in the monocot rice (Oryza sativa), we describe here the isolation and characterization of three floral organ number4 (fon4) alleles and the cloning of the FON4 gene. The fon4 mutants showed abnormal enlargement of the embryonic and vegetative shoot apical meristems (SAMs) and the inflorescence and floral meristems. Likely due to enlarged SAMs, fon4 mutants produced thick culms (stems) and increased numbers of both primary rachis branches and floral organs. We identified FON4 using a map-based cloning approach and found it encodes a small putatively secreted protein, which is the putative ortholog of the Arabidopsis (Arabidopsis thaliana) CLAVATA3 (CLV3) gene. FON4 transcripts mainly accumulated in the small group of cells at the apex of the SAMs, whereas the rice ortholog of CLV1 (FON1) is expressed throughout the SAMs, suggesting that the putative FON4 ligand might be sequestered as a possible mechanism for rice meristem regulation. Exogenous application of the peptides FON4p and CLV3p corresponding to the CLV3/ESR-related (CLE) motifs of FON4 and CLV3, respectively, resulted in termination of SAMs in rice, and treatment with CLV3p caused consumption of both rice and Arabidopsis root meristems, suggesting that the CLV pathway in limiting meristem size is conserved in both rice and Arabidopsis. However, exogenous FON4p did not have an obvious effect on limiting both rice and Arabidopsis root meristems, suggesting that the CLE motifs of Arabidopsis CLV3 and FON4 are potentially functionally divergent.
Chu
Huangwei
H
Shanghai Jiaotong University, Shanghai Institutes for Biological Sciences, Shanghai, China.
Qian
Qian
Q
Liang
Wanqi
W
Yin
Changsong
C
Tan
Hexin
H
Yao
Xuan
X
Yuan
Zheng
Z
Yang
Jun
J
Huang
Hai
H
Luo
Da
D
Ma
Hong
H
Zhang
Dabing
D
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003001:Cloning, Molecular; D035264:Flowers / Q000235:genetics / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D018519:Meristem / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development*
C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins