Summary Soil contamination with arsenic (As) can cause phytotoxicity and reduce crop yield. The mechanisms of As toxicity and tolerance are not fully understood. In this study, we used a forward genetics approach to isolate a rice mutant, ahs1, that exhibits hypersensitivity to both arsenate and arsenite. Through genomic resequencing and complementation tests, we identified OsLPD1 as the causal gene, which encodes a putative lipoamide dehydrogenase. OsLPD1 was expressed in the outer cell layer of roots, root meristem cells, and in the mesophyll and vascular tissues of leaves. Subcellular localization and immunoblot analysis demonstrated that OsLPD1 is localized in the stroma of plastids. In vitro assays showed that OsLPD1 exhibited lipoamide dehydrogenase (LPD) activity, which was strongly inhibited by arsenite, but not by arsenate. The ahs1 and OsLPD1 knockout mutants exhibited significantly reduced NADH/NAD+ and GSH/GSSG ratios, along with increased levels of reactive oxygen species and greater oxidative stress in the roots compared with wild‐type (WT) plants under As treatment. Additionally, loss‐of‐function of OsLPD1 also resulted in decreased fatty acid concentrations in rice grain. Taken together, our finding reveals that OsLPD1 plays an important role for maintaining redox homeostasis, conferring tolerance to arsenic stress, and regulating fatty acid biosynthesis in rice.

中文翻译：

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质体定位的硫辛酰胺脱氢酶 1 对于水稻的氧化还原稳态、砷胁迫耐受性和脂肪酸生物合成至关重要

概括 土壤砷 (As) 污染会导致植物毒性并降低作物产量。砷的毒性和耐受性机制尚不完全清楚。 在这项研究中，我们使用正向遗传学方法来分离水稻突变体，啊哈斯1，对砷酸盐和亚砷酸盐均表现出超敏性。通过基因组重测序和互补测试，我们确定了奥斯LPD1作为因果基因，编码假定的硫辛酰胺脱氢酶。 奥斯LPD1在根的外细胞层、根分生组织细胞以及叶子的叶肉和维管组织中表达。亚细胞定位和免疫印迹分析表明 OsLPD1 位于质体基质中。体外分析表明，OsLPD1 表现出硫辛酰胺脱氢酶 (LPD) 活性，该活性受到亚砷酸盐的强烈抑制，但不受砷酸盐的抑制。这啊哈斯1和奥斯LPD1敲除突变体表现出 NADH/NAD 显着降低+与砷处理下的野生型 (WT) 植物相比，GSH/GSSG 比率增加，活性氧水平增加，根部氧化应激更大。此外，OsLPD1 功能丧失也导致米粒中脂肪酸浓度降低。 综上所述，我们的研究结果表明，OsLPD1 在维持水稻氧化还原稳态、赋予砷胁迫耐受性以及调节脂肪酸生物合成方面发挥着重要作用。