Genome-Wide Identification and Characterization of the Abiotic-Stress-Responsive GRF Gene Family in Diploid Woodland Strawberry (Fragaria vesca)

Growth regulatory factors (GRF) are plant-specific transcription factors that play an important role in plant resistance to stress. This gene family in strawberry has not been investigated previously. In this study, 10 GRF genes were identified in the genome of the diploid woodland strawberry (Fragaria vesca). Chromosome analysis showed that the 10 FvGRF genes were unevenly distributed on five chromosomes. Phylogenetic analysis resolved the FvGRF proteins into five groups. Genes of similar structure were placed in the same group, which was indicative of functional redundance. Whole-genome duplication/segmental duplication and dispersed duplication events effectively promoted expansion of the strawberry GRF gene family. Quantitative reverse transcription-PCR analysis suggested that FvGRF genes played potential roles in the growth and development of vegetative organs. Expression profile analysis revealed that FvGRF3, FvGRF5, and FvGRF7 were up-regulated under low-temperature stress, FvGRF4 and FvGRF9 were up-regulated under high-temperature stress, FvGRF6 and FvGRF8 were up-regulated under drought stress, FvGRF3, FvGRF6, and FvGRF8 were up-regulated under salt stress, FvGRF2, FvGRF7, and FvGRF9 were up-regulated under salicylic acid treatment, and FvGRF3, FvGRF7, FvGRF9, and FvGRF10 were up-regulated under abscisic acid treatment. Promoter analysis indicated that FvGRF genes were involved in plant growth and development and stress response. These results provide a theoretical and empirical foundation for the elucidation of the mechanisms of abiotic stress responses in strawberry.