Roles of Germin-like Protein Family in Response to Seed Germination and Shoot Branching in Brassica napus

Germin-like proteins (GLPs) play important roles in the regulation of various plant development processes, such as seed vigor, root and leaf development and disease resistance, while the roles of <i>GLPs</i> on agronomic traits are rarely studied in <i>Brassica napus</i>. Here, we identified <i>GLPs</i> family genes in rapeseed and analyzed their potential functions. There are 77 <i>GLPs</i> family genes (<i>BnGLPs</i>) in the Zhongshuang11 rapeseed reference genome, divided into a, b, c, d, e, f six subfamilies. Tissue expression profile analysis of <i>BnGLPs</i> revealed the following: e subfamily genes were highly expressed in early stages of silique, cotyledon, vegetative rosette and leaf development; f subfamily genes were highly expressed in seed development; genes of a subfamily were mainly expressed in the root; and genes of b, c, d subfamily exhibited low-level or no expression in above mentioned tissues. RT-qPCR analysis confirmed that the transcripts of two f subfamily members decreased dramatically during seed germination, suggesting that f subfamily proteins may play vital roles in the early stage of seed germination. Transcriptome analysis of axillary buds in sequential developing stages revealed that the transcripts of eight e subfamily genes showed a rapid increase at the beginning of shoot branching, implying that the e subfamily members played vital roles in branch development. These results demonstrate that rapeseed <i>BnGLPs</i> likely play essential roles in seedling development, root development and plant architecture, indicating that harnessing certain <i>BnGLPs</i> may contribute to the improvement of rapeseed yield.