PDF(Pubmed)
Abstract：
Abscisic acid (ABA) is a drought-stress-responsive hormone that plays an important role in the stomatal activity of plant leaves. Currently, ABA glycosides have been identified in apples, but their glycosyltransferases for glycosylation modification of ABA are still unidentified. In this study, the mRNA expression of glycosyltransferase gene MdUGT73AR4 was significantly up-regulated in mature apple leaves which were treated in drought stress by Real-Time PCR. It was hypothesised that MdUGT73AR4 might play an important role in drought stress. In order to further characterise the glycosylation modification substrate of glycosyltransferase MdUGT73AR4, we demonstrated through in vitro and in vivo functional validation that MdUGT73AR4 can glycosylate ABA. Moreover, the overexpression lines of MdUGT73AR4 significantly enhance its drought stress resistance function. We also found that the adversity stress transcription factor AREB1B might be an upstream transcription factor of MdUGT73AR4 by bioinformatics, EMSA, and ChIP experiments. In conclusion, this study found that the adversity stress transcription factor AREB1B was significantly up-regulated at the onset of drought stress, which in turn positively regulated the downstream glycosyltransferase MdUGT73AR4, causing it to modify ABA by mass glycosylation and promoting the ABA synthesis pathway, resulting in the accumulation of ABA content, and displaying a stress-resistant phenotype.
摘要：
脱落酸（ABA）是一种干旱胁迫响应激素，在植物叶片的气孔活动中起重要作用。目前,已在苹果中鉴定出ABA糖苷，但它们用于ABA糖基化修饰的糖基转移酶仍未被鉴定。在这项研究中,Real-TimePCR显示，在干旱胁迫下处理的成熟苹果叶片中，糖基转移酶基因MdUGT73AR4的mRNA表达显着上调。假设MdUGT73AR4可能在干旱胁迫中起重要作用。为了进一步表征糖基转移酶MdUGT73AR4的糖基化修饰底物,我们通过体外和体内功能验证证明MdUGT73AR4可以糖基化ABA。此外，MdUGT73AR4的过表达系显著增强了其抗旱功能。生物信息学发现逆境胁迫转录因子AREB1B可能是MdUGT73AR4的上游转录因子,EMSA,和ChIP实验。总之,本研究发现逆境胁迫转录因子AREB1B在干旱胁迫开始时显著上调,反过来正向调节下游糖基转移酶MdUGT73AR4，使其通过质量糖基化修饰ABA并促进ABA合成途径，导致ABA含量的积累，并显示出抗压表型。
