干旱区不同品种苹果树叶片内生真菌群落组成和功能特征

Community composition and functional characteristics of endophytic fungi in leaves of different apple varieties in arid area of Xinjiang

分析新疆典型干旱区轮台国家果树资源圃不同品种苹果树叶片内生真菌的分布特征及差异,为病害防治、品种选育和筛选功能微生物菌株提供参考。利用ITS基因高通量测序技术对6个品种苹果树叶片内生真菌进行测序,并比较其群落组成和功能特性。研究表明,苹果树叶片蕴含着丰富多样的内生真菌资源,共检测到真菌序列566453条,鉴定到5个门、15个纲、30个目、42个科及43个属。不同品种间内生真菌群落多样性存在一定差异,野苹果叶片内生真菌的多样性指数和丰度指数均较高。在门水平上的优势真菌菌群为子囊菌门(85.22%~98.68%),不同品种间差异不大。在纲和属上不同品种间有一定的差异,子囊菌门中的锤舌菌纲和座囊菌纲为优势纲,相对丰度分别在17.48%~69.69%和28.21%~67.59%之间;可归类的优势真菌属包括小粉孢属(17.47%~69.68%)、链格孢属(13.36%~39.35%)、枝孢霉属(2.94%~8.80%)和隐球菌属(0.20%~2.36%)。不同品种苹果树叶片真菌共有属的OTU数有42个,占各样品相对丰度的99%以上,而独有属的丰度各品种均低于1%。由于长期适应干旱区环境,在属水平上可归类的内生真菌多表现出耐盐碱、抗旱等抗逆特性,也具有一定抗病促生、促产活性代谢产物功能。聚类分析表明叶片内生真菌种类和丰度的差异与苹果树品种关系密切。功能分析显示,不同品种间内生真菌功能差异较大,主要集中在病理营养型(17.49%~69.70%)和病理-腐生-共生营养型(14.62%~45.60%)等营养功能类群上。这些研究可为定向研发针对不同苹果品种抑制病害的叶面肥,以及筛选病原菌含量较低、抗病性较好的苹果品种提供参考。

In the typical arid area of Xinjiang,Luntai,the distribution characteristics and differences of endophytic fungi in leaves of different apple varieties were analyzed to provide a reference for disease control,variety selection and screening functional strains.The community composition and functional characteristics were compared using the ITS gene high-throughput sequencing technology.The research showed that endophytic fungi in leaves of different apple varieties were very rich.A total of 566453 fungal sequences were detected,including 5 phyla,15 classes,30 orders,42 families,43 genera.The diversity index and abundance index of endophytic fungi in leaves of different apple varieties were different with the highest values in wild apple in Xinjiang.The dominant fungus at phylum level was Ascomycota(85.22%~98.68%),and there was little difference among different varieties.There were some differences among different varieties in class and genus.The dominant classes were Leotiomycetes and Dothideomycetes of Ascomycetes,with relative abundances of 17.48%~69.69%and 28.21%~67.59%respectively.The dominant fungal genera included Microidium(17.47%~69.68%),Alternaria(13.36%~39.35%),Cladosporium(2.94%~8.80%)and Cryptococcus(0.20%~2.36%).There were 42 OTUs in common genera,accounting for more than 99%of the relative abundance of each sample,while the unique genera were less than 1%.Due to long-term adaptation to the arid environment,most of the classified endophytic fungi at the genus level showed stress resistance characteristics such as salt alkali tolerance and drought resistance,and also had the functions of disease resistance,growth and production promotion of active metabolites.UPGMA analysis found that the differences of species and abundance of endophytic fungi in leaves were closely related to apple varieties.Function analysis of FUNGuild showed that there were great differences among endophytic fungi of different apple varieties.Functional groups of fungi were mainly concentrated in Pathotroph(17.49%~69.70%)and Pathotroph-Saprotroph-Symbiotroph(14.62%~45.60%).This study provides a reference value for targeted research and development of foliar fertilizer for different varieties and disease inhibition,and screening apple varieties with low pathogen content and good disease resistance for production.