亚热带酸雨区不同林型中马尾松外生菌根的根尖真菌群落特征

Characteristics of Root Tip Fungal Community of Pinus massoniana Ectomycorrhizal in Different Forest Types in Subtropical Acid Rain Area

【目的】揭示亚热带酸雨区不同林型中马尾松(Pinus massoniana)外生菌根(ectomycorrhizal,ECM)根尖的真菌群落多样性、结构和组成的差异,探讨ECM根尖真菌群落的多样性与功能群落分布特征。【方法】对重庆铁山坪林场的马尾松纯林(Pi)、马尾松−香樟(Camphora officinarum)混交林(Pi_Ca)以及马尾松−木荷(Schima superba)混交林(Pi_Sc),采用样地调查和分子生态学相结合的方法,全面揭示不同林型马尾松ECM根尖的真菌群落特征。【结果】1)3种林型的马尾松ECM根尖样品中共获得3737个OTUs,隶属于15门60纲338科770属。2)不同林型马尾松ECM根尖真菌群落多样性比较均态化,Pi纯林丰富度最高;真菌群落结构差异显著。3)在Pi纯林和Pi_Sc混交林中较多的产酸菌青霉属、Meliniomyces、Glutinomyces均与土壤pH值呈显著负相关,可能会加速土壤酸化;且Meliniomyces和Glutinomyces与土壤TP、TK含量显著负相关,会加剧磷钾限制;在Pi_Ca混交林中丰度较高的有益菌陶氏菌属和假小垫革菌属与土壤pH值、交换性Ca、TP含量以及(Ca+Mg)/Al呈显著正相关,可能有利于缓解土壤酸化。4)Pi纯林改造为Pi_Sc混交林后,共生营养型真菌减少,腐生营养型和病理营养型真菌丰度增加,感病风险上升;Pi纯林改造为Pi_Ca混交林后,共生营养型真菌增加,利于植物生长。【结论】研究结果表明Pi_Sc混交林会加剧土壤酸化以及土壤磷钾限制,增加林木感病风险;而Pi_Ca混交林的ECM根尖真菌群落有益于缓解土壤酸化,研究结果能为酸雨区森林生态系统健康的可持续经营提供科学依据。

【Objective】The aim of this study is to reveal the fungal ecological characteristics of Pinus massoniana ectomycorrhizal(ECM)root-tip under different forest types in subtropical acid rain area and explore the diversity and distribution characteristics of ECM root-tip fungal communities.【Method】P.massoniana ECM root-tips were collected from pure P.massoniana stands(Pi),mixed plantations with Camphora officinarum(Pi_Ca)or Schima superba forest(Pi_Sc),and then the fungal communities at the root tips of P.massoniana ECM were detected by Illumina miseq sequencing.【Result】1)A total of 3737 fungi OTUs were obtained from all the samples,belonging to 15 phyla,60 classes,338 families and 770 genera.2)The diversity of ECM root tip fungal community in different forest types of P.massoniana was homogenized,and the richness of Pi was the highest.There are significant differences in fungal community structure.3)In Pi and Pi_Sc,higher abundances of acid-producing fungi such as Penicillium,Meliniomyces,and Glutinomyces were significantly negatively correlated with soil pH-value,potentially accelerating soil acidification.Additionally,Meliniomyces and Glutinomyces were significantly negatively correlated with soil total phosphorus(TP)and total potassium(TK)content,which would further exacerbate P and K limitations.In Pi_Ca,the higher abundant beneficial fungi like Tausonia and Pseudotomentella showed significant positive correlations with soil pH-value,exchangeable calcium(Ca)and TP content,and the(Ca+Mg)/Al ratio,potentially helping to mitigate soil acidification.4)Transformation from Pi to Pi_Sc decreased the relative abundance of symbiotrophic fungi,and increased saprotrophic and pathotrophic fungi,which would elevate the risk of plant diseases.Conversely,plantation with C.officinarum could increase symbiotrophic fungi,which was beneficial for plant growth.【Conclusion】The results showed that Pi_Sc would aggravate soil acidification and soil P and K limitation,and also increase the risk of forest diseases.However,the fungal community of ECM root tip from Pi_Ca was beneficial to alleviate soil acidification.The research results could provide scientific basis for the sustainable management of forest ecosystem in acid rain area.