A C-terminal encoded peptide, ZmCEP1, is essential for kernel development in maize.

C-Terminal Encoded Peptides (CEPs) are peptide hormones which act as mobile signals coordinating important developmental program. Previous studies have unraveled that CEPs are able to regulate plant growth and abiotic stress via cell-to-cell communications in Arabidopsis and rice, however, little is known about their roles in maize. Here, we examined the spatiotemporal expression patterns of ZmCEP1 and clarified that ZmCEP1 is highly expressed in young ears and tassels, particularly in the vascular bundles of ear. Heterogeneous expression of ZmCEP1 in Arabidopsis results in smaller plant and seed size. Similarly, overexpression of ZmCEP1 in maize decreased the plant and ear height, ear length, kernel size and 100-kernel weight. Consistently, exogenous application of the synthesized ZmCEP1 peptide to the roots of Arabidopsis and maize elicited the same response in the light of root elongation. Knockout of ZmCEP1 through CRISPR/Cas9 significantly increased plant and ear height, kernel size and 100-kernel weight. Transcriptomic analysis revealed that knockout of ZmCEP1 upregulated a subset of genes involved in the nitrogen metabolism, nitrate transport, sugar transport and auxin response. Thus, these results provided an insight into the genetic and molecular function of ZmCEP1 in regulating kernel development and plant growth, and guidance for maize breeding.