Ectopic expression of the sesame MYB transcription factor SiMYB305 promotes root growth and modulates ABA-mediated tolerance to drought and salt stresses in Arabidopsis

摘要

An increasing number of candidate genes related to abiotic stress tolerance are being discovered and proposed to improve the existing cultivars of the high oil-bearing crop sesame ( L.). However, the functional validation of these genes is remarkably lacking. In this study, we cloned a novel sesame R2-R3 MYB gene which is strongly induced by drought, sodium chloride (NaCl), abscisic acid (ABA) and mannitol. is expressed in various sesame tissues, especially in root and its protein is predicted to be located in the nucleus. Ectopic over-expression of in notably promoted root growth and improved plant tolerance to drought, NaCl and mannitol treatments. Furthermore, over-expressing lines accumulated higher content of ABA than wild-type plants under stresses and also increased sensitivity to ABA. Physiological analyses revealed that confers abiotic stress tolerance by promoting stomatal closure to reduce water loss; inducing a strong reactive oxygen species scavenging activity to alleviate cell damage and apoptosis; and also, up-regulating the expression levels of various stress-marker genes in the ABA-dependent pathways. Our data suggested that positively modulates drought, salt and osmotic stresses responses through ABA-mediated pathways. Thus, could be a promising candidate gene for the improvement of abiotic stress tolerance in crop species including sesame.