Genome-wide identification and characterization of the growth-regulating factor gene family in oat (Avena sativa L.) and functional analysis of AsGRF17 under drought stress.

Oat (Avena sativa L.) is an important dual-purpose crop used for both food and feed; however, drought stress severely restricts its growth and productivity. Growth-regulating factors (GRFs) are key regulators of plant growth and development and are also involved in plant responses to abiotic stresses. Nevertheless, the GRF gene family in oat and its potential role in drought tolerance remain largely unclear. In this study, the GRF gene family in oat was systematically identified and characterized using bioinformatics analyses, including phylogenetic analysis, conserved motif analysis, and cis-acting element analysis. The expression patterns of oat GRF genes under drought, cold, salt, and abscisic acid (ABA) treatments were examined. Among the identified genes, AsGRF17 was selected for further functional characterization. The AsGRF17 gene was cloned, and its subcellular localization was analyzed. In addition, transgenic tobacco plants overexpressing AsGRF17 were generated to evaluate its function in drought tolerance using molecular biology, genetic, and physiological approaches. A total of 21 GRF family members were identified in the oat genome. Expression profiling showed that most AsGRF genes were upregulated in response to abiotic stresses, including drought, cold, and salt, as well as ABA treatment, whereas a small number of genes were downregulated. Among these members, AsGRF17 exhibited the most pronounced transcriptional response in both aboveground and underground tissues. Subcellular localization analysis revealed that AsGRF17 is localized in the nucleus. Functional characterization further demonstrated that transgenic tobacco plants overexpressing AsGRF17 displayed significantly enhanced drought tolerance compared with wild-type plants. Under drought stress, the transgenic plants showed increased antioxidant enzyme activities, reduced membrane lipid damage, and elevated soluble sugar content, indicating improved antioxidant capacity and osmotic adjustment ability. These findings suggest that AsGRF17 positively regulates plant drought tolerance, likely by enhancing antioxidant defense systems and osmotic adjustment capacity. This study provides new insights into the molecular mechanisms underlying AsGRF17-mediated drought tolerance in oat and offers a theoretical basis for the genetic improvement and breeding of drought-resistant oat cultivars.