Abstract
Plant peptide hormones play an important role in regulating plant developmental programs via cell-to-cell communication in a non-cell autonomous manner. To characterize the biological relevance of C-TERMINALLY ENCODED PEPTIDE (CEP) genes in rice, we performed a genome-wide search against public databases using a bioinformatics approach and identified six additional CEP members. Expression analysis revealed a spatial-temporal pattern of OsCEP6.1 gene in different tissues and at different developmental stages of panicle. Interestingly, the expression level of the OsCEP6.1 was also significantly up-regulated by exogenous cytokinin. Application of a chemically synthesized 15-amino acid OsCEP6.1 peptide showed that OsCEP6.1 had a negative role in regulating root and seedling growth, which was further confirmed by transgenic lines. Furthermore, the constitutive expression of OsCEP6.1 was sufficient to lead to panicle architecture and grain size variations. Scanning electron microscopy analysis revealed that the phenotypic variation of OsCEP6.1 overexpression lines resulted from decreased cell size but not reduced cell number. Moreover, starch accumulation was not significantly affected. Taken together, these data suggest that the OsCEP6.1 peptide might be involved in regulating the development of panicles and grains in rice.
Highlights
Intercellular communication is a fundamental mechanism for coordinating the development of multicellular organisms
Chromosome mapping showed that 17 C-TERMINALLY ENCODED PEPTIDE (CEP) were located on six out of ten rice chromosomes, and it is notable that OsCEP1, OsCEP2 (4), OsCEP3 and OsCEP11, OsCEP12, OsCEP13, OsCEP14 were distributed in close proximity on chromosome 3 and 5, respectively (Figure 2B)
Previous reports have predicted more than 900 putative CEP peptides across the plant genome that predominantly occur in gymnosperm and angiosperm plants, but their biological significance remains largely unknown (Ohyama et al, 2008; Delay et al, 2013; Imin et al, 2013; Roberts et al, 2013; Ogilvie et al, 2014; Tabata et al, 2014; Mohd-Radzman et al, 2015)
Summary
Intercellular communication is a fundamental mechanism for coordinating the development of multicellular organisms. Recent emerging evidences have demonstrated that CEPs are involved in the regulation of plant root/shoot growth, lateral root and root nodule development (Ohyama et al, 2008; Delay et al, 2013; Imin et al, 2013; Roberts et al, 2013; Tabata et al, 2014; Mohd-Radzman et al, 2015). Kondo et al (2006) reported that proline hydroxylation of CLV3 showed no difference in root growth inhibition compared with the peptide without modifications (Kondo et al, 2006)
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