Liu Jianping, Sun Xinjiao, Xu Feiyun, Zhang Yingjiao, Zhang Qian, Miao Rui, Zhang Jianhua, Liang Jiansheng, Xu Weifeng
Center for Plant Water-use and Nutrition Regulation and College of Life Sciences, Joint International Research Laboratory of Water and Nutrient in Crop, Fujian Agriculture and Forestry University, Jinshan Fuzhou, 350002, China.
Department of Biology, Hong Kong Baptist University, Hong Kong, China.
Rice (N Y). 2018 Jun 28;11(1):38. doi: 10.1186/s12284-018-0230-5.
Monodehydroascorbate reductase (MDAR or MDHAR), which is responsible for growth, development and stress response in plants, is a key enzyme in the maintenance of the ascorbate acid (AsA) pool through the AsA-glutathione (AsA-GSH) cycle. High temperature affects a broad spectrum of cellular components and metabolism including AsA-GSH cycle in plants. In rice, however, the detailed roles of OsMDHAR4 in resistance against heat stress remains unclear.
Here, we report that OsMDHAR4 protein was localized to the chloroplasts. OsMDHAR4 expression was detected in all tissues surveyed and peaked in leaf blade. OsMDHAR4 was responsive to multiple stresses and was relatively strongly induced by heat treatment. In comparison with wild type, the osmdhar4 mutant exhibited improved tolerance to heat stress, whereas OsMDHAR4 overexpression lines exhibited enhanced sensitivity to heat stress. Moreover, we found that suppression of OsMDHAR4 promoted stomatal closure and hydrogen peroxide accumulation, and overexpression of OsMDHAR4 increased stomatal opening and decreased hydrogen peroxide content in rice leaves.
Taken together, these results indicated that OsMDHAR4 negatively regulates tolerance to heat stress by mediating HO-induced stomatal closure in rice.
单脱氢抗坏血酸还原酶（MDAR 或 MDHAR）负责植物的生长、发育和应激反应，是通过抗坏血酸 - 谷胱甘肽（AsA - GSH）循环维持抗坏血酸（AsA）库的关键酶。高温会影响植物广泛的细胞成分和代谢，包括 AsA - GSH 循环。然而，在水稻中，OsMDHAR4 在耐热胁迫中的具体作用仍不清楚。
在此，我们报道 OsMDHAR4 蛋白定位于叶绿体。在所有检测的组织中均检测到 OsMDHAR4 的表达，且在叶片中达到峰值。OsMDHAR4 对多种胁迫有响应，并且受热处理诱导相对较强。与野生型相比，osmdhar4 突变体对热胁迫表现出更高的耐受性，而 OsMDHAR4 过表达株系对热胁迫表现出增强的敏感性。此外，我们发现抑制 OsMDHAR4 促进气孔关闭和过氧化氢积累，而 OsMDHAR4 的过表达增加水稻叶片的气孔开放并降低过氧化氢含量。
综上所述，这些结果表明 OsMDHAR4 通过介导水稻中 HO 诱导的气孔关闭来负调控对热胁迫的耐受性。
