Zhao Chenning, Hou Hongyan, Wu Junxia, Zhu Yanqin, Shao Qingsong, Lv Aimin
National Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University, Hangzhou, 311300, China; Provincial Key Laboratory for Non-wood Forest and Quality Control and Utilization of Its Products, Zhejiang A&F University, Hangzhou, 311300, China.
National Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University, Hangzhou, 311300, China.
Plant Physiol Biochem. 2025 Oct;227:110199. doi: 10.1016/j.plaphy.2025.110199. Epub 2025 Jun 30.
Drought stress is a severe abiotic stress, limiting the plant growth, development and yield. MYB transcription factor family plays a crucial role in plants response to adversity stress, particularly drought. However, a comprehensive analysis of the MYB gene family in Dendrobium catenatum remains limited, especially regarding the functions of two-repeat MYB proteins in response to drought stress and their regulation of flavonoid biosynthesis and accumulation. Here, severe drought stress inhibited the growth of D. catenatum and decreased polysaccharides and flavonoid contents. This study identified 174 MYB genes and characterized their phylogenetic relationships, protein profiles, and expression patterns. Co-expression analysis and transient expression assay revealed that an R2R3-MYB DcMYB30 was a key regulator in drought response and flavonoid synthesis in D. catenatum. DcMYB30 was found to localize in the nucleus and was down-regulated by drought stress. In both DcMYB30-overexpressing Nicotiana benthamiana or D. catenatum, flavonoid content decreased and transcript levels of multiple flavonoid biosynthetic enzyme-coding genes were downregulated. According to these findings, it is proposed that DcMYB30 may negatively regulate flavonoid biosynthesis by down-regulating flavonoid pathway enzyme-coding genes (e.g., 4CL), thereby reducing the flavonoid biosynthesis or accumulation and drought tolerance in D. catenatum. This study provides fundamental insights for characterizing the physiological roles of two-repeat MYB transcription factors in plant stress responses.
干旱胁迫是一种严重的非生物胁迫，限制了植物的生长、发育和产量。MYB转录因子家族在植物对逆境胁迫，尤其是干旱胁迫的响应中起着关键作用。然而，关于铁皮石斛中MYB基因家族的全面分析仍然有限，特别是关于双重复MYB蛋白在响应干旱胁迫中的功能及其对黄酮类生物合成和积累的调控。在此，严重干旱胁迫抑制了铁皮石斛的生长，并降低了多糖和黄酮类含量。本研究鉴定了174个MYB基因，并对其系统发育关系、蛋白质特征和表达模式进行了表征。共表达分析和瞬时表达试验表明，一个R2R3-MYB基因DcMYB30是铁皮石斛干旱响应和黄酮类合成的关键调节因子。发现DcMYB30定位于细胞核，且受干旱胁迫下调。在过表达DcMYB30的本氏烟草或铁皮石斛中，黄酮类含量均降低，多个黄酮类生物合成酶编码基因的转录水平下调。根据这些发现，推测DcMYB30可能通过下调黄酮类途径酶编码基因（如4CL）来负调控黄酮类生物合成，从而降低铁皮石斛中黄酮类生物合成或积累以及耐旱性。本研究为阐明双重复MYB转录因子在植物胁迫响应中的生理作用提供了重要见解。
