National Key Laboratory of Crop Biology, MOA Key Laboratory of Horticultural Crop Biology and Germplasm Innovation in Huanghuai Region, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong, China.
Department of Plant Biology, Department of Horticulture, Michigan State University, East Lansing, MI, USA.
J Exp Bot. 2020 Jun 22;71(12):3437-3449. doi: 10.1093/jxb/eraa121.
Heavy metal contamination is a major environmental and human health hazard in many areas of the world. Organic acids sequester heavy metals and protect plant roots from the effects of toxicity; however, it is largely unknown how these acids are regulated in response to heavy metal stress. Here, protein kinase SOS2L1 from apple was functionally characterized. MdSOS2L1 was found to be involved in the regulation of malate excretion, and to inhibit cadmium uptake into roots. Using the DUAL membrane system in a screen of an apple cDNA library with MdSOS2L1 as bait, a malate transporter, MdALMT14, was identified as an interactor. Bimolecular fluorescence complementation, pull-down, and co-immunoprecipitation assays further indicated the interaction of the two proteins. Transgenic analyses showed that MdSOS2L1 is required for cadmium-induced phosphorylation at the Ser358 site of MdALMT14, a modification that enhanced the stability of the MdALMT14 protein. MdSOS2L1 was also shown to enhance cadmium tolerance in an MdALMT14-dependent manner. This study sheds light on the roles of the MdSOS2L1-MdALMT14 complex in physiological responses to cadmium toxicity.
重金属污染是世界许多地区的主要环境和人类健康危害。有机酸螯合重金属，保护植物根系免受毒性影响；然而，这些酸如何响应重金属胁迫而被调节在很大程度上是未知的。在这里，从苹果中分离出了蛋白激酶 SOS2L1，并对其功能进行了鉴定。发现 MdSOS2L1 参与了苹果中苹果酸的分泌调节，并且抑制了镉进入根系。利用带有 MdSOS2L1 作为诱饵的苹果 cDNA 文库的 DUAL 膜系统进行筛选，鉴定到一个苹果酸转运蛋白 MdALMT14 是其互作蛋白。双分子荧光互补、Pull-down 和 co-immunoprecipitation 实验进一步证实了这两种蛋白的相互作用。转基因分析表明，MdSOS2L1 是镉诱导 MdALMT14 丝氨酸 358 位点磷酸化所必需的，这种修饰增强了 MdALMT14 蛋白的稳定性。MdSOS2L1 还以依赖于 MdALMT14 的方式增强了苹果对镉的耐受性。本研究揭示了 MdSOS2L1-MdALMT14 复合物在对镉毒性的生理响应中的作用。
