Li Haixiu, Liu Yuan, Qin Huihui, Lin Xuelei, Tang Ding, Wu Zhengjing, Luo Wei, Shen Yi, Dong Fengqin, Wang Yaling, Feng Tingting, Wang Lili, Li Laiyun, Chen Doudou, Zhang Yi, Murray Jeremy D, Chao Daiyin, Chong Kang, Cheng Zhukuan, Meng Zheng
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
New Phytol. 2020 Oct;228(1):163-178. doi: 10.1111/nph.16708. Epub 2020 Jun 23.
Transport and homeostasis of transition metals in chloroplasts, which are accurately regulated to ensure supply and to prevent toxicity induced by these metals, are thus crucial for chloroplast function and photosynthetic performance. However, the mechanisms that maintain the balance of transition metals in chloroplasts remain largely unknown. We have characterized an albino-revertible green 1 (arg1) rice mutant. ARG1 encodes an evolutionarily conserved protein belonging to the ATP-binding cassette (ABC) transporter family. Protoplast transfection and immunogold-labelling assays showed that ARG1 is localized in the envelopes and thylakoid membranes of chloroplasts. Measurements of metal contents, metal transport, physiological and transcriptome changes revealed that ARG1 modulates cobalt (Co) and nickel (Ni) transport and homeostasis in chloroplasts to prevent excessive Co and Ni from competing with essential metal cofactors in chlorophyll and metal-binding proteins acting in photosynthesis. Natural allelic variation in ARG1 between indica and temperate japonica subspecies of rice is coupled with their different capabilities for Co transport and Co content within chloroplasts. This variation underpins the different photosynthetic capabilities in these subspecies. Our findings link the function of the ARG1 transporter to photosynthesis, and potentially facilitate breeding of rice cultivars with improved Co homeostasis and consequently improved photosynthetic performance.
叶绿体中过渡金属的运输和稳态受到精确调控，以确保其供应并防止这些金属诱导的毒性，因此对于叶绿体功能和光合性能至关重要。然而，维持叶绿体中过渡金属平衡的机制仍 largely 未知。我们鉴定了一个白化可逆绿色 1（arg1）水稻突变体。ARG1 编码一种属于 ATP 结合盒（ABC）转运蛋白家族的进化保守蛋白。原生质体转染和免疫金标记分析表明，ARG1 定位于叶绿体的包膜和类囊体膜中。金属含量、金属运输、生理和转录组变化的测量结果显示，ARG1 调节叶绿体中的钴（Co）和镍（Ni）运输及稳态，以防止过量的 Co 和 Ni 与叶绿素中的必需金属辅因子以及参与光合作用的金属结合蛋白竞争。水稻籼稻和温带粳稻亚种之间 ARG1 的自然等位变异与其在叶绿体中的不同 Co 运输能力和 Co 含量相关。这种变异是这些亚种不同光合能力的基础。我们的发现将 ARG1 转运蛋白的功能与光合作用联系起来，并可能有助于培育具有改善的 Co 稳态从而改善光合性能的水稻品种。
