Systematical characterization of GRF gene family in sorghum, and their potential functions in aphid resistance.

Sorghum (Sorghum bicolor) is the fifth important cereal and an industrial energy crop in the world. Growth Regulation Factors (GRFs) play an important role in response to environmental stress, however, the knowledge of GRFs relating to the pest resistance is lacking. Here, we identified 8 GRF genes harboring the typical QLQ (glutamine, leucine, glutamine) and WRC (tryptophan, arginine, cysteine) domains in Sorghum, which could be classified into 4 clades through phylogenetic analysis. The SbGRF genes express in most tissues, while more than half of them express at the highest level in inflorescence. To further investigate their possible role in stress response, we analyzed the transcriptomics data. The results showed that SbGRFs could respond to the abiotic stresses including heat, salt and drought stress. Furthermore, combined the data with qRT-PCR, SbGRF1, 2, 4 and 7 were identified as dominant genes response to the aphid-induced stress. SSR markers close to these genes were also searched. Above all, we summarized the SbGRFs and provided their potential roles in aphid response.