Abstract：
CONCLUSIONS: TaMYB44-5A identified as a transcription factor negatively regulates drought tolerance in transgenic Arabidopsis. Drought can severely reduce yields throughout the wheat-growing season. Many studies have shown that R2R3-MYB transcription factors are involved in drought stress responses. In this study, the R2R3-MYB transcription factor MYB44-5A was identified in wheat (Triticum aestivum L.) and functionally analyzed. Three homologs of TaMYB44 were isolated, all of which localized to the nucleus. Overexpression of TaMYB44-5A reduced drought tolerance in Arabidopsis thaliana. Further analysis showed that TaMYB44-5A reduced the sensitivity of transgenic Arabidopsis to ABA. Genetic and transcriptional regulation analyses demonstrated that the expression levels of drought- and ABA-responsive genes were downregulated by TaMYB44-5A, and TaMYB44-5A directly bound to the MYB-binding site on the promoter to repress the transcription level of TaRD22-3A. Our results provide insights into a novel molecular pathway in which the R2R3-MYB transcription factor negatively regulates ABA signaling in response to drought stress.
摘要：
结论：被鉴定为转录因子的TaMYB44-5A负调控转基因拟南芥的耐旱性。干旱会在整个小麦生长季节严重减产。许多研究表明R2R3-MYB转录因子参与干旱胁迫反应。在这项研究中,在小麦（TriticumaestivumL.）中鉴定出R2R3-MYB转录因子MYB44-5A，并进行了功能分析。分离出TaMYB44的三个同源物,所有这些都位于细胞核。TaMYB44-5A的过表达降低了拟南芥的耐旱性。进一步分析表明，TaMYB44-5A降低了转基因拟南芥对ABA的敏感性。遗传和转录调控分析表明，干旱和ABA响应基因的表达水平被TaMYB44-5A下调，和TaMYB44-5A直接与启动子上的MYB结合位点结合以抑制TaRD22-3A的转录水平。我们的结果为R2R3-MYB转录因子负调控干旱胁迫下的ABA信号传导提供了新的分子途径的见解。
