Key Laboratory of Biotechnology and Bioresources Utilization-Ministry of Education, Institute of Plant Resources, Dalian Minzu University, Dalian, 116600, PR China; Divisions of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, PR China.
Key Laboratory of Biotechnology and Bioresources Utilization-Ministry of Education, Institute of Plant Resources, Dalian Minzu University, Dalian, 116600, PR China.
Plant Physiol Biochem. 2021 May;162:410-420. doi: 10.1016/j.plaphy.2021.03.007. Epub 2021 Mar 11.
Yellowhorn (Xanthoceras sorbifolium) is an important edible woody oil tree species that is endemic to China. Drought and heat stresses are factors severely limiting the high-quality development of the yellowhorn industry. Transcription factors (TFs) play critical roles in regulating the response of woody plant species to water deficit or high temperature. However, the MYB TFs that respond to combined drought and heat stress in yellowhorn remain unclear. Here, we first investigated the physiological changes in 5 yellowhorn varieties in response to combined stress treatments. We observed significant changes in antioxidant enzyme activities and photosynthesis. The Maigaiti variety yielded the best results and was selected for subsequent experiments. An R2R3-type MYB TF, designated XsMYB44, was isolated from the leaves of yellowhorn. XsMYB44 expression was strongly induced by combined stress. Suppression of XsMYB44 expression via virus-induced gene silencing weakened yellowhorn tolerance to both individual and combined drought and heat stress, and the increased susceptibility was coupled with decreased plant height, fresh weight and relative water content and inhibited stomatal closure. Moreover, compared with the individual stresses, the combined stress caused increased reactive oxygen species levels and decreased antioxidant enzyme activities and proline content in XsMYB44-silenced plants. Furthermore, the expression levels of several defense-related genes were reduced in the XsMYB44-silenced plants. Overall, we studied the physiological characteristics of 5 yellowhorn varieties, and the results demonstrated that XsMYB44 acts as a positive regulator in the yellowhorn response to combined stress by triggering stomatal closure to maintain water levels and by modulating ROS homeostasis.
黄杞（Xanthoceras sorbifolium）是一种重要的木本食用油树种，为中国特有。干旱和高温胁迫是严重限制黄杞产业高质量发展的因素。转录因子（TFs）在调控木本植物对水分亏缺或高温的响应中起着关键作用。然而，响应黄杞复合干旱和热胁迫的 MYB TFs 尚不清楚。在这里，我们首先研究了 5 个黄杞品种对复合胁迫处理的生理变化。我们观察到抗氧化酶活性和光合作用的显著变化。Maigaiti 品种表现最好，被选为后续实验的品种。从黄杞叶片中分离出一个 R2R3 型 MYB TF，命名为 XsMYB44。XsMYB44 的表达受复合胁迫强烈诱导。通过病毒诱导的基因沉默抑制 XsMYB44 的表达，削弱了黄杞对单独和复合干旱和热胁迫的耐受性，增加的敏感性伴随着株高、鲜重和相对水含量的降低，抑制了气孔关闭。此外，与单一胁迫相比，复合胁迫导致 XsMYB44 沉默植物中活性氧水平升高，抗氧化酶活性和脯氨酸含量降低。此外，XsMYB44 沉默植物中一些防御相关基因的表达水平降低。总的来说，我们研究了 5 个黄杞品种的生理特性，结果表明 XsMYB44 通过触发气孔关闭来维持水分水平，并通过调节 ROS 稳态，作为黄杞对复合胁迫响应的正调控因子发挥作用。
