State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, Frontiers Science Center for Molecular Design Breeding (MOE), China Agricultural University, Beijing 100193, China.
Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, College of Horticulture, China Agricultural University, Beijing 100193, China.
Proc Natl Acad Sci U S A. 2023 Jun 20;120(25):e2221313120. doi: 10.1073/pnas.2221313120. Epub 2023 Jun 12.
As a crucial nitrogen source, nitrate (NO) is a key nutrient for plants. Accordingly, root systems adapt to maximize NO availability, a developmental regulation also involving the phytohormone auxin. Nonetheless, the molecular mechanisms underlying this regulation remain poorly understood. Here, we identify () in Arabidopsis (), whose root growth fails to adapt to low-NO conditions. is defective in the high-affinity NO transporter NRT2.1. () mutants exhibit defects in polar auxin transport, and their low-NO-induced root phenotype depends on the PIN7 auxin exporter activity. NRT2.1 directly associates with PIN7 and antagonizes PIN7-mediated auxin efflux depending on NO levels. These results reveal a mechanism by which NRT2.1 in response to NO limitation directly regulates auxin transport activity and, thus, root growth. This adaptive mechanism contributes to the root developmental plasticity to help plants cope with changes in NO availability.
作为一种重要的氮源，硝酸盐（NO）是植物的关键营养物质。因此，根系会适应环境以最大程度地获取 NO，这种发育调控还涉及植物激素生长素。然而，这种调控的分子机制仍知之甚少。在这里，我们鉴定了拟南芥（Arabidopsis）中的一个关键调控因子（），其根的生长无法适应低 NO 条件。（）突变体在高亲和力的 NO 转运蛋白 NRT2.1 中存在缺陷。（）突变体表现出极性生长素运输缺陷，并且它们的低 NO 诱导的根表型依赖于 PIN7 生长素外排蛋白的活性。NRT2.1 直接与 PIN7 相互作用，并根据 NO 水平拮抗 PIN7 介导的生长素外排。这些结果揭示了一种机制，即 NRT2.1 响应 NO 限制直接调节生长素运输活性，从而影响根的生长。这种适应性机制有助于根的发育可塑性，帮助植物应对 NO 可用性的变化。
