부산대학교 도서관

Heat stress is a major environmental stress type that can limit plant growth and development. To survive sudden temperature increases, plants utilize the heat shock response, an ancient signaling pathway. Initial results had suggested a role for brassinosteroids (BRs) in this response. Brassinosteroids are growth‐promoting steroid hormones whose activity is mediated by transcription factors of the BES1/BZR1 subfamily. Here, we provide evidence that BES1 can contribute to heat stress signaling. In response to heat, BES1 is activated even in the absence of BRs and directly binds to heat shock elements (HSEs), known binding sites of heat shock transcription factors (HSFs). HSFs of the HSFA1 type can interact with BES1 and facilitate its activity in HSE binding. These findings lead us to propose an extended model of the heat stress response in plants, in which the recruitment of BES1 is a means of heat stress signaling cross‐talk with a central growth regulatory pathway. Synopsis: The heat shock response is an ancient biological pathway, utilized across the kingdoms for heat shock protection. Here, the transcription factor BES1, a central component of brassinosteroid (BR) signaling, is found to contribute to it in plants. BES1 is de‐phosphorylated and activated by heat stress, through means that are independent of canonical BR signaling, but can be promoted by BRs.BES1 de‐phosphorylation by heat is inhibited by the plant hormone abscisic acid (ABA), employing ABA‐repressed PP2C phosphatases, including ABI1.BES1 can interact with the heat shock factor HSFA1a, bind to heat shock elements in the promoters of heat shock proteins of the HSP70 and HSP90 type and increase heat stress tolerance of Arabidopsis thaliana plants. [ABSTRACT FROM AUTHOR]