State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
Dev Cell. 2017 Dec 4;43(5):630-642.e4. doi: 10.1016/j.devcel.2017.09.025. Epub 2017 Oct 19.
Low temperatures affect plant growth, development, productivity, and ecological distribution. Expression of the C-repeat-binding factor (CBF) transcription factors is induced by cold stress, which in turn activates downstream cold-responsive (COR) genes that are required for the acquisition of freezing tolerance. Inducer of CBF expression 1 (ICE1) is a master regulator of CBFs, and ICE1 stability is crucial for its function. However, the regulation of ICE1 is not well understood. Here, we report that mitogen-activated protein kinase 3 (MPK3) and MPK6 interact with and phosphorylate ICE1, which reduces its stability and transcriptional activity. Consistently, the mpk3 and mpk6 single mutants and the mpk3 mpk6 double mutants show enhanced freezing tolerance, whereas MPK3/MPK6 activation attenuates freezing tolerance. Phosphor-inactive mutations of ICE1 complement freezing sensitivity in the ice1-2 mutant. These combined results indicate that MPK3/MPK6 phosphorylate and destabilize ICE1, which negatively regulates CBF expression and freezing tolerance in plants.
低温会影响植物的生长、发育、生产力和生态分布。低温胁迫会诱导 C-repeat-binding factor (CBF) 转录因子的表达，而 CBF 转录因子又会激活下游的冷响应 (COR) 基因，这些基因对于获得抗冻性是必需的。CBF 表达诱导因子 1 (ICE1) 是 CBFs 的主要调控因子，ICE1 的稳定性对于其功能至关重要。然而，ICE1 的调控机制尚不清楚。在这里，我们报告丝裂原活化蛋白激酶 3 (MPK3) 和 MPK6 与 ICE1 相互作用并磷酸化 ICE1，从而降低其稳定性和转录活性。一致地，mpk3 和 mpk6 单突变体和 mpk3 mpk6 双突变体表现出增强的抗冻性，而 MPK3/MPK6 的激活则降低了抗冻性。ICE1 的磷酸化非活性突变在 ice1-2 突变体中补偿了其对冷冻的敏感性。这些综合结果表明，MPK3/MPK6 磷酸化并使 ICE1 不稳定，从而负调控植物中 CBF 的表达和抗冻性。
