Identification of molecular integrators shows that nitrogen actively controls the phosphate starvation response in plants

First author: Anna Medici; Affiliations: Supagro (蒙彼利埃高等农学院): montpellier, France

Corresponding author: Gabriel Krouk

Nitrogen (N) and phosphorus (P) are key macronutrients sustaining plant growth and crop yield, and ensuring food security worldwide. Understanding how plants perceive and interpret the combinatorial nature of these signals thus has important agricultural implications within the context of: i) increased food demand, ii) limited P supply, and iii) environmental pollution due to N fertilizer usage. Here we report the discovery of an active control of P Starvation Responses (PSR) by a combination of local and long-distance N signaling pathways in plants. We show that, in Arabidopsis thaliana, the nitrate transceptor CHLORINA 1/ NITRATE TRANSPORTER 1.1 (CHL1/NRT1.1) is a component of this signaling crosstalk. We also demonstrate that this crosstalk is dependent on the control of the accumulation and turnover by N of the transcription factor PHOSPHATE STARVATION RESPONSE 1/PHR1, a master regulator of P sensing and signaling. We further show an important role of PHOSPHATE 2/PHO2 as an integrator of the N availability into the PSR since the effect of N on PSR is strongly affected in pho2 mutants. We finally show that PHO2 and NRT1.1 influence each other's transcript levels. These observations are summarized in a model representing a framework with several entry points where N signal influence PSR. Finally, we demonstrate that this phenomenon is conserved in rice (Oryza sativa) and wheat (Triticum aestivum) opening biotechnological perspectives in crop plants.

氮和磷是确保植物生长、作物产量以及全球食物安全关键的大量营养元素。因此理解植物如何感知和诠释这些信号的组合特性对于农业上食物需求的增加、磷供应的短缺以及氮肥使用造成的环境污染具有非常重要的参考意义。本文报道了植物中区域性和长距离两种氮信号通路的组合能够激活调控磷饥饿反应PSR。作者的研究显示在拟南芥中，硝酸盐转运受体CHL1/NRT1.1是该信号交联的一个组份。本文的研究显示这种信号交联依赖于植物对转录因子PHR1积累的控制，该转录因子是植物磷感应和信号转导主要的调控因子。作者进一步的研究显示pho2突变体中氮对于PSR的效应受到了很大的影响，说明PHO2在植物将可利用氮信息整合到磷饥饿反应的过程中发挥重要作用。作者还发现PHO2和NRT1.1互相影响彼此的转录水平。作者将这些发现整合进了一个模型框架中，在这个模型中存在几个氮信号影响PSR的切入点。最终，作者发现这种现象在水稻和小麦中十分保守，说明在作物中具有可观的应用前景。

doi: https://doi.org/10.1105/tpc.18.00656

Journal: Plant Cell

First Published: March 14, 2019