Comprehensive Investigation of GRF Transcription Factors and Associated Responses to Drought Stress in Oat (Avena sativa)

Growth-regulating factors (GRFs) are plant-specific transcription factors that play important roles in plant growth and development. However, no systematic analysis of <i>GRF</i> genes has been reported in oat (<i>Avena sativa</i>). In this study, we conducted a comprehensive characterization of the <i>GRF</i> gene family in oat, including their physicochemical properties, chromosomal distribution, phylogenetic relationships, gene structure, conserved domains, promoter <i>cis</i>-elements, duplication events, and drought-responsive expression. In total, 28 <i>GRF</i> genes were identified in oat. Phylogenetic analysis classified them into two main groups, which could be further subdivided into five subgroups. Gene structure and conserved motif analyses revealed that <i>AsGRF</i> genes are largely group-specific and relatively highly conserved within each subgroup. Segmental duplication has been the primary driver of <i>AsGRF</i> gene family expansion, and these genes have undergone strong purifying selection during evolution. Transcriptomic analysis identified 13 <i>AsGRF</i> genes expressed under drought stress. Subsequent qRT-PCR analysis revealed that six of these genes were significantly up-regulated. Notably, <i>AsGRF3</i> showed the highest expression level, was localized to the nucleus, and lacked transcriptional self-activation activity. In conclusion, this study provides a comprehensive analysis of the <i>AsGRF</i> gene family and serves as a valuable reference for further functional characterization of these genes in drought stress responses in oat.