Wang Yanping, Shen Wenzhong, Chan Zhulong, Wu Yan
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University Wuhan, China ; Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences Wuhan, China.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University Wuhan, China.
Front Plant Sci. 2015 Nov 19;6:1004. doi: 10.3389/fpls.2015.01004. eCollection 2015.
Cytokinins in plants are crucial for numerous biological processes, including seed germination, cell division and differentiation, floral initiation and adaptation to abiotic stresses. The salt stress can promote reactive oxygen species (ROS) production in plants which are highly toxic and ultimately results in oxidative stress. However, the correlation between endogenous cytokinin production and ROS homeostasis in responding to salt stress is poorly understood. In this study, we analyzed the correlation of overexpressing the cytokinin biosynthetic gene AtIPT8 (adenosine phosphate-isopentenyl transferase 8) and the response of salt stress in Arabidopsis. Overproduction of cytokinins, which was resulted by the inducible overexpression of AtIPT8, significantly inhibited the primary root growth and true leaf emergence, especially under the conditions of exogenous salt, glucose and mannitol treatments. Upon cytokinin overproduction, the salt stress resistance was declined, and resulted in less survival rates and chlorophyll content. Interestingly, ROS production was obviously increased with the salt treatment, accompanied by endogenously overproduced cytokinins. The activities of catalase (CAT) and superoxide dismutase (SOD), which are responsible for scavenging ROS, were also affected. Transcription profiling revealed that the differential expressions of ROS-producing and scavenging related genes, the photosynthesis-related genes and stress responsive genes were existed in transgenic plants of overproducing cytokinins. Our results suggested that broken in the homeostasis of cytokinins in plant cells could modulate the salt stress responses through a ROS-mediated regulation in Arabidopsis.
植物中的细胞分裂素对众多生物学过程至关重要，包括种子萌发、细胞分裂与分化、花芽起始以及对非生物胁迫的适应。盐胁迫可促进植物中活性氧（ROS）的产生，ROS具有高毒性，最终导致氧化胁迫。然而，人们对响应盐胁迫时内源性细胞分裂素产生与ROS稳态之间的相关性了解甚少。在本研究中，我们分析了细胞分裂素生物合成基因AtIPT8（腺苷磷酸 - 异戊烯基转移酶8）过表达与拟南芥盐胁迫响应之间的相关性。AtIPT8的诱导型过表达导致细胞分裂素过量产生，显著抑制了主根生长和真叶出现，尤其是在外源盐、葡萄糖和甘露醇处理条件下。细胞分裂素过量产生时，盐胁迫抗性下降，导致存活率和叶绿素含量降低。有趣的是，盐处理伴随着内源性细胞分裂素过量产生，ROS的产生明显增加。负责清除ROS的过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的活性也受到影响。转录谱分析表明，细胞分裂素过量产生的转基因植物中存在与ROS产生和清除相关基因、光合作用相关基因以及胁迫响应基因的差异表达。我们的结果表明，植物细胞中细胞分裂素稳态的破坏可通过拟南芥中ROS介导的调节来调控盐胁迫响应。
