Nutrient trade-offs mediated by ectomycorrhizal strategies in plants: Evidence from an Abies species in subalpine forest

1.    Ectomycorrhizal (ECM) symbiosis is an evolutionary biological trait of higher plants for effective nutrient uptakes. However, little is known that how the formation and morphological differentiations of ECM roots mediate the nutrients of below- and aboveground plant tissues and the balance among nutrient elements across environmental gradients. Here we investigated the effects of ECM foraging strategies on root and foliar N and P concentrations and N:P ratio Abies faxoniana under variations of climate and soil conditions. 2.    The ECM symbionts preferentially mediated P uptake under both N and P limitations. The uptake efficiency of N and P was primarily associated with the ECM root traits, e.g., ECM root tip density, superficial area of ECM root tips, the ratio of living to dead root tips, and was affected by the ECM proliferations and morphological differentiations. The tissue N and P concentrations were positively associated with the abundance of the contact exploration typ...1. 外生菌根（Ectomycorrhizal, ECM）共生是高等植物实现高效养分吸收的进化生物学性状。然而，目前对ECM根系的形成与形态分化如何调控植物地下与地上组织的养分状态，以及不同环境梯度下养分元素间的平衡机制仍知之甚少。本研究以岷江冷杉（Abies faxoniana）为研究对象，探究了气候与土壤条件变异下，ECM觅食策略对其根系与叶片氮（N）、磷（P）浓度及氮磷比的影响。 2. 研究发现，在氮、磷双限制条件下，ECM共生体优先介导磷的吸收。氮、磷的吸收效率主要与ECM根系性状相关，例如ECM根尖密度、ECM根尖表面积、活根尖与死根尖的比值，并受ECM增殖与形态分化的调控。植物组织的氮、磷浓度与接触型探索类型（contact exploration typ...）的丰度呈正相关。