Bioinformatic and Phenotypic Analysis of AtPCP-Ba Crucial for Silique Development in Arabidopsis

Silique development exerts significant impacts on crop yield. CRPs (Cysteine-rich peptides) can mediate cell-cell communication during plant reproduction and development. However, the functional characterization and regulatory mechanisms of CRPs in silique development remain unclear. In this study, we identified many CRP genes downstream of the CRP gene <i>TPD1 (TAPETUM DETERMINANT1)</i> during silique development using a microarray assay. The novel <i>Arabidopsis thaliana</i> pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) gene <i>AtPCP-Ba</i>, along with <i>TPD1</i>, are essential for silique development. The <i>AtPCP-Ba</i> was significantly down-regulated in <i>tpd1</i> flower buds but up-regulated in <i>OE-TPD1</i> flower buds and siliques. The silencing of <i>AtPCP-Ba</i> compromised the wider silique of <i>OE-TPD1</i> plants and inhibited the morphology of <i>OE-TPD1</i> siliques to the size observed in the wild type. A total of 258 CRPs were identified with the bioinformatic analysis in <i>Arabidopsis</i>, <i>Brassica napus</i>, <i>Glycine max</i>, <i>Oryza sativa</i>, <i>Sorghum bicolor</i>, and <i>Zea mays</i>. Based on the evolutionary tree classification, all CRP members can be categorized into five subgroups. Notably, 107 CRP genes were predicted to exhibit abundant expression in flowers and fruits. Most cysteine-rich peptides exhibited high expression levels in <i>Arabidopsis</i> and <i>Brassica napus</i>. These findings suggested the involvement of the CRP <i>AtPCP-Ba</i> in the <i>TPD1</i> signaling pathway, thereby regulating silique development in <i>Arabidopsis</i>.