Genome-wide identification and analysis of the growth-regulating factor (GRF) family in sweet cherry

Growth-regulating factor (GRF) proteins are vital in regulating plant growth, development, and abiotic stress response. However, little information is known about the GRF gene family in the sweet cherry. This study identified nine PavGRFs from the sweet cherry genome and classified into three clades by phylogenetic, conserved motif, and gene structure analyses. Sequence analysis indicated that genes in the same clade had similar gene structures and all members contained QLQ (Gln-Leu-Gln) and WRC(Trp-Arg-Cys) domains. In addition, evolutionary analyses revealed that soybean and sweet cherry had the highest number of co-linear gene pairs, and among Rosaceae, peach and pear had a pattern of co-linear gene pairs that was largely similar to that of sweet cherry. Furthermore, the promoters of PavGRFs were found to contain many MYB-MYC elements and elements related to abiotic stress responses such as low-temperature response elements (LTRs) and damage-inducible elements (WRE3, W box), and the predicted protein-interaction network of PavGRFs discovered that most PavGRFs could interact with AtGIF1.Tissue-specific expression of the PavGRFs was analyzed using qRT-PCR, and it was found that the expression of the PavGRFs was higher during the dormant period of the flower buds and throughout fruit development. The expression patterns of PavGRFs under cold stress were investigated and four PavGRFs were found to be significantly up-regulated in expression levels under cold treatment. In conclusion, this study systematically analyzed the bioinformatics and expression patterns of PavGRFs and provided a basis for further understanding of the role of the PavGRF family in the response of the sweet cherry to cold stress and growth and development.