Jingya Li, Shilun Tong, Kaijun Li, Huiwen Liu, Hang Yin, Mei Yang, Youxu Jiang, Shanshui Zheng, Bing Li, Lulu He
A total of 41 MLP family genes were identified in the soybean genome, with protein lengths ranging from 125 to 319 amino acids. Phylogenetic analysis revealed that soybean MLP proteins clustered into three distinct subgroups: I, II, and IV. Collinearity analysis revealed 16 pairs of collinear genes within this family, which were predominantly distributed across various chromosomes, with higher densities observed on chromosomes 7 to 9, 15, and 17, all arising from segmental duplications. Selection pressure analysis indicated that the duplicated genes primarily experienced purifying selection throughout evolution. Promoter analysis identified numerous cis-regulatory elements associated with stress and hormone responses. Expression pattern analysis demonstrated that most MLP genes exhibited elevated transcript levels in roots. Under NaCl and ABA treatments, 19 candidate MLP genes showed varying degrees of upregulation or downregulation. Furthermore, overexpression of GmMLP9 significantly enhanced salt stress tolerance in both yeast and soybean plants. The soybean composite plants with GmMLP9-overexpressing hairy roots exhibited a lower Na+/K+ ratio and lower MDA content, but higher proline content.
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.