Evolutionarily conserved links between regulating phosphate starvation and arbuscular mycorrhizal symbiosis in plants (EvoSymPho)

磷(P)和氮(N)一样，是所有生命所需的关键营养物质。它通常在自然环境中少量出现。因此，磷通常被认为是水生和陆地生态系统中的“限制性”养分，这意味着这种养分的可用性控制着水生和陆地植物（包括藻类）的生长和生产力。在大多数陆地植物中，与菌根真菌和以豆科植物为主的固氮根瘤菌共生，极大地促进了土壤对磷和氮的吸收。丛枝菌根（AM）和其他植物共生体的发育依赖于寄主植物的共同共生信号通路（CSSP），该通路识别微生物伙伴并刺激共生所需基因的表达。此外，AM和结瘤共生通过相互关联的响应途径受到宿主P和N状态的控制。CSSP和磷酸盐饥饿反应（PSR）途径的关键组分在藻类和陆地植物之间是保守的。然而，目前尚不清楚PSR和CSSP成分的藻类同源物的功能。最近的研究表明，AM共生是由一个受体激酶网络在CSSP下游调节的，包括表面定位的，跨膜受体样激酶（RLKs）和受体样细胞质激酶（RLCKs）。我们的项目旨在阐明RLK/RLCK蛋白与上游和下游调控步骤之间的相互作用，这对于理解陆地植物CSSP背景下RLCK在AM共生信号中的进化和分子机制至关重要。我们计划将形成AM共生关系的肝藻Marchantia paleacea与进化上距离较远的水生和陆生藻类Zygnema进行比较，后者属于现存的陆生植物姐妹群。我们期望对AM共生调节的演变以及磷酸盐传感和信号的整合获得重要的见解。我们的项目将补充MAdLand的其他建议，整合环境信号的感知，下游细胞信号和转录反应，这些都是陆地上生命复杂适应特征的基础。

Phosphorus (P) like nitrogen (N), is a critical nutrient required for all life. It generally occurs in small quantities in the natural environment. Therefore, P is usually considered the "limiting" nutrient in aquatic and terrestrial ecosystems, meaning that the availability of this nutrient controls the growth and productivity of aquatic and terrestrial plants, including algae. In most land plants, symbiosis with mycorrhizal fungi, and nitrogen-fixing rhizobia mainly in legumes, greatly facilitates soil P and N uptake. The development of arbuscular mycorrhiza (AM) as well as other plant symbioses depends on the common symbiosis signaling pathway (CSSP) in host plants which recognizes the microbial partner and stimulates the expression of genes required for the symbiosis. Furthermore, AM and nodulation symbioses are controlled by the P and N status of the host via interlinked response pathways. Key components of the CSSP and the phosphate starvation response (PSR) pathway are conserved between algae and land plants. However, the function of algal orthologues of PSR and CSSP components is currently unknown. Recent work has shown that the AM symbiosis is modulated downstream of the CSSP by a network of receptor kinases including surface localized, transmembrane receptor-like kinases (RLKs) and receptor-like cytoplasmic kinases (RLCKs). Our project aims to elucidate the interactions between RLK/RLCK proteins and upstream and downstream regulatory steps that are important for understanding the evolution and the molecular mechanisms of RLCKs in AM symbiosis signaling in the context of the CSSP in land plants. We plan to compare the liverwort Marchantia paleacea, which forms AM symbiosis, with the evolutionarily distant aquatic and terrestrial alga Zygnema, which belongs to the extant sister group of land plants. We expect to gain significant insight into the evolution of AM symbiosis regulation and the integration of phosphate sensing and signaling. Our project will complement other proposals within MAdLand on integrating sensing of environmental cues, downstream cellular signaling and transcriptional responses underlying complex adaptive traits for life on land.