School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Plant Cell. 2021 May 31;33(4):1268-1285. doi: 10.1093/plcell/koab006.
A deficiency of the essential macronutrient sulfur leads to stunted plant growth and yield loss; however, an association with a symbiotic fungus can greatly improve nutrient uptake by the host plant. Here, we identified and functionally characterized a high-affinity sulfate transporter from the endophytic fungus Serendipita indica. SiSulT fulfills all the criteria expected of a functional sulfate transporter responding to sulfur limitation: SiSulT expression was induced when S. indica was grown under low-sulfate conditions, and heterologous expression of SiSulT complemented a yeast mutant lacking sulfate transport. We generated a knockdown strain of SiSulT by RNA interference to investigate the consequences of the partial loss of this transporter for the fungus and the host plant (maize, Zea mays) during colonization. Wild-type (WT) S. indica, but not the knockdown strain (kd-SiSulT), largely compensated for low-sulfate availability and supported plant growth. Colonization by WT S. indica also allowed maize roots to allocate precious resources away from sulfate assimilation under low-sulfur conditions, as evidenced by the reduction in expression of most sulfate assimilation genes. Our study illustrates the utility of the endophyte S. indica in sulfur nutrition research and offers potential avenues for agronomically sound amelioration of plant growth in low-sulfate environments.
必需的大量营养素硫的缺乏会导致植物生长受阻和产量损失；然而，与共生真菌的关联可以大大提高宿主植物对营养物质的吸收。在这里，我们从内生真菌串珠镰刀菌中鉴定并功能表征了一种高亲和力硫酸盐转运蛋白。SiSulT 满足了作为响应硫限制的功能硫酸盐转运蛋白的所有标准：当 S. indica 在低硫酸盐条件下生长时，SiSulT 的表达被诱导，并且 SiSulT 的异源表达可以补充缺乏硫酸盐转运的酵母突变体。我们通过 RNA 干扰生成了 SiSulT 的敲低菌株，以研究在定殖过程中该转运蛋白的部分缺失对真菌和宿主植物（玉米，Zea mays）的影响。野生型（WT）串珠镰刀菌，但不是敲低菌株（kd-SiSulT），在很大程度上补偿了低硫酸盐的可用性并支持植物生长。WT 串珠镰刀菌的定殖还允许玉米根在低硫条件下从硫酸盐同化中分配宝贵的资源，这表现在大多数硫酸盐同化基因的表达减少。我们的研究说明了内生真菌串珠镰刀菌在硫营养研究中的实用性，并为在低硫环境中合理改善植物生长提供了潜在途径。
