丛枝菌根真菌多样性对植物群落构建和稀有种维持的研究进展

Insight into recent studies on the diversity of arbuscular mycorrhizal fungi in shaping plant community assembly and maintaining rare species

丛枝菌根(AM)是植物与微生物联系中最为古老的共生体,全球范围内约80%的陆生植物与AM真菌共生形成丛枝菌根。这一共生关系在气候稳定和土壤磷贫瘠的热带、亚热带森林中更为普遍。以往的研究表明AM真菌通过提高植物对磷的吸收促进植物生长和定植,即产生植物-土壤正反馈。植物-土壤正反馈可降低由土壤病原菌引起的植物-土壤负反馈,进而降低植物-土壤负反馈维持植物多样性的能力,这与热带、亚热带森林中极高的植物多样性以及占比惊人的稀有种相悖。随着对热带、亚热带森林中AM真菌多样性研究的不断深入,越来越多的研究发现AM真菌多样性在不同的生境条件下以及不同的宿主植物间存在较大差异,这些差异可引起植物适合度的不同,进而影响植物群落构建。该文整合了AM真菌在宿主植物群落构建、宿主植物共存及稀有种维持等方面的研究进展,以期为验证“稀有种优势”假说提出新的研究思路,进而更有效地保护稀有植物。

Arbuscular mycorrhiza(AM)is one of the oldest symbionts between plants and soil microorganisms,and about 80%terrestrial plant species can associate with AM fungi on earth.Because of the stable climate and poor soil phosphorus content in tropical and subtropical forests,this mutualistic symbiosis is much more common there.Previous studies have extensively investigated the diversity of AM fungi in tropical and subtropical forests,and have shown that AM fungi can promote plant recruitment and growth.However,this positive effect of AM fungi on plants(i.e.,the positive plant-soil feedback)can weaken the contribution of the negative plant-soil feedback(caused by soil-borne pathogens)to maintaining tree species diversity,which appears to contradict with the surprisingly high tree diversity and high proportion of rare tree species in tropical and subtropical forests.Recently,a mounting number of empirical studies have found that the diversity of AM fungi varies significantly in different habitats and AM colonization depends on the identity of host species,thereby affecting the fitness of plants and further shaping the plant community structure.Through synthesizing the current research about the diversity of AM fungi in promoting plant coexistence and maintaining community diversity,we expect to put forward a promising study direction for testing the“rare species advantage”hypothesis,therefore improving the conservation of rare plant species.