Instituto Multidisciplinario de Biología Vegetal, Velez Sarsfield 249, 5000, Córdoba, Argentina.
Molecular Plant Physiology, Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, 53115, Bonn, Germany.
New Phytol. 2023 Jun;238(5):1924-1941. doi: 10.1111/nph.18879. Epub 2023 Apr 5.
An environmentally responsive root system is crucial for plant growth and crop yield, especially in suboptimal soil conditions. This responsiveness enables the plant to exploit regions of high nutrient density while simultaneously minimizing abiotic stress. Despite the vital importance of root systems in regulating plant growth, significant gaps of knowledge exist in the mechanisms that regulate their architecture. Auxin defines both the frequency of lateral root (LR) initiation and the rate of LR outgrowth. Here, we describe a search for proteins that regulate root system architecture (RSA) by interacting directly with a key auxin transporter, PIN1. The native separation of Arabidopsis plasma membrane protein complexes identified several PIN1 co-purifying proteins. Among them, AZG1 was subsequently confirmed as a PIN1 interactor. Here, we show that, in Arabidopsis, AZG1 is a cytokinin (CK) import protein that co-localizes with and stabilizes PIN1, linking auxin and CK transport streams. AZG1 expression in LR primordia is sensitive to NaCl, and the frequency of LRs is AZG1-dependent under salt stress. This report therefore identifies a potential point for auxin:cytokinin crosstalk, which shapes RSA in response to NaCl.
一个对环境有响应的根系对于植物的生长和作物产量至关重要，特别是在土壤条件不佳的情况下。这种响应能力使植物能够利用高养分密度的区域，同时最大限度地减少非生物胁迫。尽管根系在调节植物生长方面具有重要意义，但在调节其结构的机制方面仍存在重大知识空白。生长素既定义了侧根（LR）起始的频率，也定义了 LR 生长的速度。在这里，我们描述了一种通过直接与关键生长素转运蛋白 PIN1 相互作用来寻找调节根系结构（RSA）的蛋白质的方法。拟南芥质膜蛋白复合物的天然分离鉴定了几种 PIN1 共纯化蛋白。其中，AZG1 随后被确认为 PIN1 的相互作用蛋白。在这里，我们表明，在拟南芥中，AZG1 是一种细胞分裂素（CK）输入蛋白，它与 PIN1 共定位并稳定 PIN1，将生长素和 CK 运输流联系起来。LR 原基中 AZG1 的表达对 NaCl 敏感，并且在盐胁迫下 LR 的频率依赖于 AZG1。因此，本报告鉴定了一个生长素：细胞分裂素交叉对话的潜在点，它可以响应 NaCl 来塑造 RSA。
