Wheat Mitochondrial Proteomes Provide New Links between Antioxidant Defense and Plant Salinity Tolerance

The mitochondrial proteome and differences associated with salt tolerance have been investigated in Australian commercial varieties of wheat. Mitochondria isolated from shoots were used to generate a wheat mitochondrial reference map; 68 unique wheat mitochondrial proteins were identified from 192 gel spots using 2D PAGE and LC−MS/MS. This analysis also provided MS/MS spectra for 199 proteotypic peptides as a foundation for the development of targeted proteomics to study the respiratory apparatus in wheat. Using this reference map and 2D DIGE, we have found quantitative differences in the shoot mitochondrial proteomes of v. Wyalkatchem and v. Janz, two commercially important wheat varieties that are known from a range of experiments to differ in salinity tolerance. These proteins included Mn-superoxide dismutase (Mn-SOD), cysteine synthase, nucleotide diphosphate kinase, and the voltage dependent anion channel (VDAC). Antibodies to the mitochondrial alternative oxidase (AOX), previously linked to reduced ROS formation from the electron transport chain and salt tolerance in Arabidopsis, also showed a commensurate higher abundance in v. Wyakatchem in both control and salt-treated conditions. Together, the data presented here suggest that differences in mitochondrial ROS defense pathways in the mitochondrial proteomes of key Australian wheat varieties correlate with whole-plant salinity tolerance.

本研究针对澳大利亚商业化种植的普通小麦品种，系统探究了其线粒体蛋白质组特征以及与耐盐性相关的蛋白差异。研究人员从小麦幼苗的地上部分分离出线粒体，以此构建小麦线粒体蛋白质组参考图谱；通过双向聚丙烯酰胺凝胶电泳（2D PAGE）结合液相色谱-串联质谱（LC−MS/MS），从192个凝胶斑点中鉴定出68种独特的小麦线粒体蛋白。本次分析还获取了199个特征肽段（proteotypic peptides）的串联质谱谱图，为开发用于研究小麦线粒体呼吸复合体的靶向蛋白质组学技术奠定了核心基础。借助该参考图谱与双向荧光差异凝胶电泳（2D DIGE），研究人员在Wyalkatchem与Janz两个商业化主推小麦品种的地上部分线粒体蛋白质组中检测到定量表达差异；过往多项实验已证实，这两个品种的耐盐性存在显著差异。差异表达蛋白包括锰超氧化物歧化酶（Mn-SOD）、半胱氨酸合酶、二磷酸核苷激酶以及电压依赖性阴离子通道（VDAC）。针对线粒体交替氧化酶（AOX）的抗体检测结果显示——过往研究表明，该酶与拟南芥（Arabidopsis）电子传递链活性氧（ROS）生成减少及耐盐性密切相关——Wyalkatchem品种在对照与盐处理两种条件下，该酶的丰度均呈现出与耐盐性相符的显著升高。综上，本研究所得数据表明，澳大利亚核心商业化小麦品种线粒体蛋白质组中，线粒体活性氧防御通路的差异与整株植物的耐盐性显著相关。