SiMYB19 from Foxtail Millet (Setaria italica) Confers Transgenic Rice Tolerance to High Salt Stress in the Field

Abstract

Salt stress is a major threat to crop quality and yield. Most experiments on salt stress-related genes have been conducted at the laboratory or greenhouse scale. Consequently, there is a lack of research demonstrating the merit of exploring these genes in field crops. Here, we found that the R2R3-MYB transcription factor <i>SiMYB19</i> from foxtail millet is expressed mainly in the roots and is induced by various abiotic stressors such as salt, drought, low nitrogen, and abscisic acid. <i>SiMYB19</i> is tentatively localized to the nucleus and activates transcription. It enhances salt tolerance in transgenic rice at the germination and seedling stages. <i>SiMYB19</i> overexpression increased shoot height, grain yield, and salt tolerance in field- and salt pond-grown transgenic rice. <i>SiMYB19</i> overexpression promotes abscisic acid (ABA) accumulation in transgenic rice and upregulates the ABA synthesis gene <i>OsNCED3</i> and the ABA signal transduction pathway-related genes <i>OsPK1</i> and <i>OsABF2</i>. Thus, <i>SiMYB19</i> improves salt tolerance in transgenic rice by regulating ABA synthesis and signal transduction. Using rice heterologous expression analysis, the present study introduced a novel candidate gene for improving salt tolerance and increasing yield in crops grown in saline-alkali soil.