Yoshida Takumi, Sakuma Yoh, Todaka Daisuke, Maruyama Kyonoshin, Qin Feng, Mizoi Junya, Kidokoro Satoshi, Fujita Yasunari, Shinozaki Kazuo, Yamaguchi-Shinozaki Kazuko
Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Biochem Biophys Res Commun. 2008 Apr 11;368(3):515-21. doi: 10.1016/j.bbrc.2008.01.134. Epub 2008 Feb 7.
A transcription factor DREB2A functions as a key regulator not only in drought stress responses but also in heat stress (HS) responses, and activates expression of many abiotic stress-responsive-genes involved in drought and HS tolerance. HsfA3 is one of the most up-regulated heat-inducible genes in transgenic plants overexpressing DREB2A. In this study, the analyses of HsfA3 expression profile and the transactivation analysis of HsfA3 showed that the expression of HsfA3 was directly regulated by DREB2A under HS. Microarray analysis using transgenic plants overexpressing HsfA3 also showed that overexpression of HsfA3 induces many heat-inducible genes. Furthermore, we showed that thermotolerance of the HsfA3 overexpressors was increased, and that of the hsfA3 T-DNA tagged mutants was decreased. These results indicate that HsfA3 regulates expression of many heat-inducible genes in the transcriptional cascade downstream of the DREB2A stress-regulatory system and functions in acquisition of thermotolerance under the control of the DREB2A cascade.
转录因子DREB2A不仅在干旱胁迫应答中，而且在热胁迫（HS）应答中发挥关键调节作用，并激活许多参与干旱和热胁迫耐受性的非生物胁迫响应基因的表达。HsfA3是在过表达DREB2A的转基因植物中上调最明显的热诱导基因之一。在本研究中，对HsfA3表达谱的分析以及对HsfA3的反式激活分析表明，在热胁迫下HsfA3的表达受DREB2A直接调控。使用过表达HsfA3的转基因植物进行的微阵列分析还表明，HsfA3的过表达诱导了许多热诱导基因。此外，我们发现HsfA3过表达植株的耐热性增强，而hsfA3 T-DNA标签突变体的耐热性降低。这些结果表明，HsfA3在DREB2A胁迫调节系统下游的转录级联反应中调节许多热诱导基因的表达，并在DREB2A级联反应的控制下参与耐热性的获得。
