NAC protein is a large plant specific transcription factor family, which plays important roles in the response to abiotic stresses. However, the regulation mechanism of most NAC proteins in drought stress remains to be further uncovered. In this study, we elucidated the molecular functions of a NAC protein, GhirNAC2, in response to drought stress in cotton.?GhirNAC2?was greatly induced by drought and phytohormone abscisic acid (ABA). Subcellular localization demonstrated that GhirNAC2 was located in the nucleus. Co-suppression of?GhirNAC2?in cotton led to larger stomata aperture, elevated water loss and finally reduced transgenic plants tolerance to drought stress. Furthermore, the endogenous ABA content wa... More
NAC protein is a large plant specific transcription factor family, which plays important roles in the response to abiotic stresses. However, the regulation mechanism of most NAC proteins in drought stress remains to be further uncovered. In this study, we elucidated the molecular functions of a NAC protein, GhirNAC2, in response to drought stress in cotton.?GhirNAC2?was greatly induced by drought and phytohormone abscisic acid (ABA). Subcellular localization demonstrated that GhirNAC2 was located in the nucleus. Co-suppression of?GhirNAC2?in cotton led to larger stomata aperture, elevated water loss and finally reduced transgenic plants tolerance to drought stress. Furthermore, the endogenous ABA content was significantly lower in?GhirNAC2-suppressed transgenic plant leaves compared to wild type.?In vivo?and?in vitro?studies showed that GhirNAC2 directly binds to the promoter of?GhNCED3a/3c, key genes in ABA biosynthesis, which were both down-regulated in?GhirNAC2-suppressed transgenic lines. Transient silencing of?GhNCED3a/3c?also significantly reduced the resistance to drought stress in cotton plants. However, ectopic expression of?GhirNAC2?in tobacco significantly enhanced seed germination, root growth and plant survival under drought stress. Taken together,?GhirNAC2?plays a positive role in cotton drought tolerance, which functions by modulating ABA biosynthesis and stomata closure via regulating?GhNCED3a/3c?expression.
