Evolutionary and ecological forces shape woody plant-symbiont nutrient strategies across biomes

The associations of arbuscular mycorrhizal (AM) or ectomycorrhiza (EcM) fungi with plants have sequentially evolved and played vital roles in enhancing plant nutrition. Nonetheless, how evolutionary and ecological forces drive nutrient acquisition strategies of AM and EcM plants remains poorly understood. Our global analysis of woody species revealed that, over divergence time, AM plants evolved faster nitrogen mineralization rates without changes in nitrogen resorption. However, EcM plants exhibited an increase in nitrogen mineralization but a decrease in nitrogen resorption, indicating a shift towards a more inorganic nutrient economy. Despite this alteration, when considering species under modern climates, AM plants display faster nitrogen mineralization rates and lower nitrogen resorption than EcM plants. This inorganic nutrient economy allows AM plants to thrive in warm environments with a faster litter decomposition rate. Overall, our study suggests that the interplay between phylogeny and climate has shaped nutrient acquisition strategies of AM and EcM plants.

丛枝菌根（arbuscular mycorrhizal, AM）真菌与外生菌根（ectomycorrhiza, EcM）真菌和植物的共生关系经逐步演化而来，在提升植物营养获取能力方面发挥着至关重要的作用。然而，演化与生态驱动力如何调控AM与EcM植物的营养获取策略，目前仍有待深入解析。我们针对全球木本植物开展的分析显示，随着物种分化时间的推移，AM植物演化出了更快的氮矿化（nitrogen mineralization）速率，且氮重吸收（nitrogen resorption）效率未发生显著变化。与之相对，EcM植物的氮矿化速率有所提升，但氮重吸收效率出现下降，表明其营养策略正向更偏向无机营养的方向转变。尽管存在上述策略差异，在现代气候环境下的物种对比中，AM植物的氮矿化速率仍高于EcM植物，而氮重吸收效率则更低。这种无机营养策略使得AM植物能够在温暖、凋落物分解（litter decomposition）速率更快的生境中茁壮生长。总体而言，本研究表明系统发育（phylogeny）与气候的交互作用塑造了AM与EcM植物的营养获取策略。