菌根真菌可减少植物的适应性差异,但其共存取决于植物内在菌根反应的差异

Mycorrhizal fungi reduce fitness differences,but coexistence is determined by differences in intrinsic plant mycorrhizal responsiveness

植物-丛枝菌根真菌(AMF)可以调节竞争植物之间的土壤资源,以影响植物资源的捕获和适应性,使AMF成为植物共存的潜在媒介。本研究使用6种菌根状态不同的植物物种,通过生态位和适应性差异评估植物共存。在有或没有AMF的情况下,将15对竞争植物种植在一起。AMF对共存的影响是通过参数化成对的Lotka-Volterra植物竞争模型来确定的。通过比较在没有与AMF竞争的情况下生长的单个植物的枝条生物量与没有AMF的枝条生物量来确定6种植物物种对AMF的响应。研究结果表明,接种AMF减少了竞争者之间的适应度差异,但AMF介导的共存程度取决于竞争植物物种的身份。竞争植物物种之间更大的AMF响应差异减少了生态位重叠并增加了共存。这些结果说明,虽然AMF通常会减少适应性差异,但AMF的均衡效应并不总是足以克服由于生态位重叠导致的竞争不平衡,因此并不总是导致共存。相反,不同植物物种对AMF的内在生长反应可以预测生态位重叠减少,进而导致共存。这表明菌根依赖是一种旨在降低与竞争植物物种的生态位重叠程度,从而实现更多共存的植物策略。

Plant–arbuscular mycorrhizal fungal(AMF)associations can mediate soil resources among competing plants to influence plant resource capture and fitness,making AMF a potential agent of plant coexistence.We assessed plant coexistence,via niche and fitness differences,using six plant species varying in their mycorrhizal status.We grew the species in 15 competitive pairs with or without AMF.Effects of AMF on coexistence were determined by parametrizing pair-wise Lotka–Volterra plant competition models.Responses of the six plant species to AMF were determined by comparing the shoot biomass of single plants grown in the absence of any competition with AMF to the shoot biomass without AMF.The inoculation with AMF reduced the fitness differences between competitors,but the degree of AMF-mediated coexistence depended on the identity of the competing plant species.A greater AMF response difference between competing plant species reduced niche overlap and increased coexistence.These results show that while AMF generally reduce fitness differences,the equalizing effect of AMF is not always strong enough to overcome a competitive imbalance due to niche overlap and thus does not always lead to coexistence.Instead,it is the intrinsic growth response of different plant species to AMF,which can predict reduced niche overlap that in turn leads to coexistence.This implies that mycorrhizal dependence is a plant strategy to reduce niche overlap with competitors,thus allowing for greater coexistence.