Identification and Expression Analysis of the C-TERMINALLY ENCODED PEPTIDE Family in Pisum sativum L

The C-TERMINALLY ENCODED PEPTIDE(CEP) peptides play crucial roles in plant growth and response to environmental factors. These peptides were characterized as positive regulators of symbiotic nodule development in legume plants. However, little is known about the CEP peptide family in pea. Here, we discovered in pea genome 21 CEP genes (PsCEPs), among which three genes contained additional conserved motifs corresponding to the PIP (PAMP-induced secreted peptides) consensus sequences. We characterized the expression patterns of pea PsCEP genes based on transcriptomic data, and for six PsCEP genes with high expression levels in the root and symbiotic nodules the detailed expression analysis at different stages of symbiosis and in response to nitrate treatment was performed. We suggest that at least three PsCEP genes, PsCEP1, PsCEP7 and PsCEP2, could play a role in symbiotic nodule development, whereas the PsCEP1 and PsCEP13 genes, downregulated by nitrate addition, could be involved in regulation of nitrate-dependent processes in pea. Further functional studies are required to elucidate the functions of these PsCEP genes.