National Key Laboratory of Plant Molecular Genetics, Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
University of the Chinese Academy of Sciences, Beijing 100049, China.
Plant Physiol. 2023 May 31;192(2):1498-1516. doi: 10.1093/plphys/kiad122.
Aluminum (Al) toxicity represents a primary constraint for crop production in acidic soils. Rice (Oryza sativa) is a highly Al-resistant species; however, the molecular mechanisms underlying its high Al resistance are still not fully understood. Here, we identified SAL1 (SENSITIVE TO ALUMINUM 1), which encodes a plasma membrane (PM)-localized PP2C.D phosphatase, as a crucial regulator of Al resistance using a forward genetic screen. SAL1 was found to interact with and inhibit the activity of PM H+-ATPases, and mutation of SAL1 increased PM H+-ATPase activity and Al uptake, causing hypersensitivity to internal Al toxicity. Furthermore, knockout of NRAT1 (NRAMP ALUMINUM TRANSPORTER 1) encoding an Al uptake transporter in a sal1 background rescued the Al-sensitive phenotype of sal1, revealing that coordination of Al accumulation in the cell, wall and symplasm is critical for Al resistance in rice. By contrast, we found that mutations of PP2C.D phosphatase-encoding genes in Arabidopsis (Arabidopsis thaliana) enhanced Al resistance, which was attributed to increased malate secretion. Our results reveal the importance of PP2C.D phosphatases in Al resistance and the different strategies used by rice and Arabidopsis to defend against Al toxicity.
铝（Al）毒性是酸性土壤中作物生产的主要限制因素。水稻（Oryza sativa）是一种高度耐铝的物种；然而，其高耐铝性的分子机制仍不完全清楚。在这里，我们使用正向遗传学筛选鉴定了 SAL1（敏感于铝 1），它编码一种质膜（PM）定位的 PP2C.D 磷酸酶，是耐铝性的关键调节因子。发现 SAL1 与 PM H+-ATPase 相互作用并抑制其活性，SAL1 突变增加了 PM H+-ATPase 活性和 Al 摄取，导致对内源 Al 毒性敏感。此外，在 sal1 背景下敲除编码 Al 摄取转运蛋白的 NRAT1（NRAMP ALUMINUM TRANSPORTER 1），恢复了 sal1 的 Al 敏感表型，表明细胞、细胞壁和共质体中 Al 积累的协调对水稻的 Al 抗性至关重要。相比之下，我们发现拟南芥（Arabidopsis thaliana）中 PP2C.D 磷酸酶编码基因的突变增强了 Al 抗性，这归因于苹果酸分泌增加。我们的结果揭示了 PP2C.D 磷酸酶在 Al 抗性中的重要性，以及水稻和拟南芥抵御 Al 毒性所采用的不同策略。
