菌根真菌介导下植物对丹霞地貌山顶胁迫环境的适应机制

Adaptation mechanism of plants to the stressful environments of Danxia Landscape mediated by mycorrhizal fungi

植物与菌根真菌的互利共生关系广泛存在于森林群落中,对植物种间竞争、群落结构、演替以及生态系统功能和稳定性均具有重要的调节作用.现有研究通常关注菌根真菌驱动的不同菌根类型植物间生态位分化和植物-土壤反馈作用强度的差异,而忽略了不同生境条件下寄主物种对菌根真菌依赖性的动态变化及其对局域生物多样性的影响.本研究基于广东丹霞山独特的山顶生态效应和土壤胁迫条件,通过对比分析山顶和山谷土壤理化性质、寄主植物根系菌根定殖率、菌根真菌子实体形态特征及多样性等指标,系统比较了同种植物在不同生境中与菌根真菌互作强度的差异.结果发现,山顶林下土壤比山谷生境中更为贫瘠和干旱,分布于山顶生境中的植物个体其根系菌根定殖率显著高于山谷,而山顶菌根真菌子实体的个体大小普遍低于山谷中的同种个体.这些结果表明,森林群落中两种主要的菌根类型树种均表现出在山顶生境中对菌根真菌共生的依赖性高于山谷,进而可以促进植物对氮磷养分及水分的获取能力,并最终提高了寄主植物在山顶胁迫条件下的适合度.本研究揭示了寄主植物可以通过动态调节与菌根真菌的互作强度以适应胁迫生境,为环境异质性条件下的植物生存策略和生物多样性维持机制提供了新的视角.

The mutualistic symbioses between plants and mycorrhizal fungi are widespread in forest communities,playing crucial roles in regulating plant interspecific competition,community structure,succession,as well as ecosystem function and stability.However,previous studies primarily focused on how mycorrhizal fungi regulate the niche differentiation among plants with different mycorrhizal types and the plant-soil feedback effects,while overlooking the dynamic changes in host-mycorrhizal interactions under different habitat conditions.Based on the unique ecological effects and soil stress conditions on the hilltops of Mt.Danxia in Guangdong,this study systematically analyzed the soil physical and chemical properties,the mycorrhizal colonization rates of host roots,the morphological characteristics and diversity of fruiting bodies,to compare the differences in the intensity of plantmycorrhizal interactions between the mountain summit and valley among individuals of the same plant species.We found that the forest soil on summit was significantly more barren and droughty than the valley habitat.The root colonization rates of mycorrhizal fungi in plant individuals distributed in the summit were significantly higher than that in the valley,while the individual sizes of mycorrhizal sporocarps on the summit were generally smaller than those of the same species in the valley.In this forest,both of the two main mycorrhizal types of tree species exhibited higher dependencies on mycorrhizal symbiosis in the summit than in the valley,indicating enhanced ability to acquire soil nutrients and water,ultimately improved fitness for host plants under the stressful conditions on the hilltops.This study reveals that tree species adapt to stressful habitats by dynamically adjusting their interactions with mycorrhizal fungi,providing a new perspective on plant adaptation strategies and biodiversity maintenance mechanisms under environmental heterogeneity.