The evolutionary ecology of plant-fungal interactions

植物和真菌之间的相互作用是自然界中最古老的共生关系之一，在4亿多年前进化而来。几乎所有的植物都被土壤真菌定植，植物与丛枝菌根（AM）真菌之间的共生关系尤其普遍，影响着几乎所有的植物谱系，包括大多数作物物种，如何感知和响应它们的环境。从历史上看，这种共生关系被认为是一种互惠互利，因为每个伙伴都可以从互动中受益。AM真菌从土壤中为植物提供养分，植物从光合作用中为AM真菌提供糖。然而，比较调查表明，这种益处的大小是可变的，许多植物物种的生长在共生体的存在下受到抑制。本研究将通过实验测试植物与AM真菌之间的共生关系在自然界中变化的原因，以及它如何影响植物群落的组装。首先，我们将确定共生是否可以在自然种群中进化，并通过实验确定有利于植物更大生长利益的自然选择的生态原因。其次，我们将测试根系功能如何影响植物从真菌伙伴关系中获得的利益程度。第三，我们将确定植物对AM真菌的生长反应的进化变化是否会影响它们与其他植物竞争有限资源的能力。这种认识将产生三个主要影响。首先，它可以解释共生中的变异性是如何进化的，并预测其对未来环境变化的反应。其次，了解根系对养分的吸收如何影响共生关系，可以为作物育种工作提供信息，以最大限度地从共生关系中获得植物利益。第三，了解共生关系如何影响植物竞争能力可以提高对植物群落聚集机制的理解，从而有助于旨在生态恢复的管理实践。

The interaction between plants and fungi is one of the most ancient symbioses in nature, evolving more than 400 million years ago. Nearly all plants are colonized by soil fungi, and the symbiosis between plants and arbuscular mycorrhizal (AM) fungi is particularly common, influencing how nearly all plant lineages, including a majority of crop species, perceive and respond to their environment. Historically, this symbiosis was considered to be a mutualism because each partner can benefit from the interaction. AM fungi provide plants with nutrients from soil and plants provide AM fungi with sugars from photosynthesis. However, comparative surveys indicate that the magnitude of the benefit is variable and the growth of many plant species is suppressed in the presence of the symbiont. The proposed research will experimentally test why the symbiosis between plants and AM fungi varies in nature, and how it can impact the assembly of plant communities. First, we will determine whether the symbiosis can evolve in natural populations and experimentally identify the ecological causes of natural selection that favour greater growth benefits to plants. Second, we will test how root function influences the degree of benefit plants gain from the fungal partnership. Third, we will determine whether evolutionary change in the growth response of plants to AM fungi influences their ability to compete with other plants for limited resources. This knowledge will have three primary impacts. First, it can explain how variability in the symbiosis evolved and predict its evolution in response to future environmental changes. Second, knowledge of how root absorption of nutrients influences the symbiosis can inform crop breeding efforts designed to maximize plant benefits from the symbiosis. Third, knowledge of how the symbiosis influences plant competitive ability can improve understanding of the mechanisms of plant community assembly and thus contribute to management practices aimed at ecological restoration.