Analysis of SRO gene family in Nitraria sibirica Pall. and the function of NsSRO1a in improving plant drought tolerance.

The SIMILAR TO RCD ONE (SRO) protein family is an important regulatory protein in plants and plays a key role in growth and development and adaptation to environmental stress. Nitraria sibirica Pall. grows in extreme environments and has significant stress resistance, so it is regarded as an ideal material for mining stress resistance genes. However, the members and functions of the SRO gene family in N. sibirica have not been studied. In this study, three SRO genes were identified in N. sibirica, named NsSRO1a, NsSRO1b and NsSRO2. Phylogenetic analysis indicated that these genes could be divided into three groups (Group I, Group II and Group III) and showed high conservation in gene structure and conserved motifs. Promoter cis-acting element analysis revealed that the promoter regions of these genes contained a variety of stress response elements. After treatment with mannitol, it was found that the expression of NsSRO1a in N. sibirica was up-regulated, suggesting that it may be a key functional gene for drought resistance. NsSRO1a was overexpressed in poplar, a woody plant model, and overexpressed plants were verified. Overexpression of NsSRO1a significantly reduced the accumulation of reactive oxygen species (ROS) and cell damage by regulating stomatal aperture and increasing chlorophyll content, proline (Pro) content, antioxidant enzyme activity and related gene expression, thus significantly improving the drought resistance of transgenic plants. These results showed that NsSRO1a enhances the drought resistance of plants by regulating ROS metabolism under drought stress, which provides an important reference for improving plant stress resistance.