SiMYBS3, Encoding a Setaria italica Heterosis-Related MYB Transcription Factor, Confers Drought Tolerance in Arabidopsis

Abstract

Drought is a major limiting factor affecting grain production. Drought-tolerant crop varieties are required to ensure future grain production. Here, 5597 DEGs were identified using transcriptome data before and after drought stress in foxtail millet (<i>Setaria italica</i>) hybrid <i>Zhangza 19</i> and its parents. A total of 607 drought-tolerant genes were screened through WGCNA, and 286 heterotic genes were screened according to the expression level. Among them, 18 genes overlapped. One gene, <i>Seita.9G321800,</i> encoded MYBS3 transcription factor and showed upregulated expression after drought stress. It is highly homologous with MYBS3 in maize, rice, and sorghum and was named <i>SiMYBS3</i>. Subcellular localization analysis showed that the SiMYBS3 protein was located in the nucleus and cytoplasm, and transactivation assay showed SiMYBS3 had transcriptional activation activity in yeast cells. Overexpression of <i>SiMYBS3</i> in <i>Arabidopsis thaliana</i> conferred drought tolerance, insensitivity to ABA, and earlier flowering. Our results demonstrate that <i>SiMYBS3</i> is a drought-related heterotic gene and it can be used for enhancing drought resistance in agricultural crop breeding.