广西香蕉根系内生真菌的群落组成与多样性

本研究对广西香蕉主产区的香蕉根系样本进行内生真菌分离,采用形态学与ITS序列分析相结合的方法进行菌株鉴定,开展其物种组成与多样性分析,对了解广西香蕉与其根部内生真菌间的关系以及探索其内生真菌功能具有重要意义。从168个香蕉根段中共分离获得352株内生真菌,分别归属于5纲17目34科43属62个分类单元,不同分类单元的代表菌株中,有41株菌株能够产生分生孢子(66.13%)。其中,优势纲为粪壳菌纲(Sordariomycetes)和散囊菌纲(Eurotiomycetes),相对频率(RF)分别为66.19%和20.45%;优势目为肉座菌目(Hypocreales)、散囊菌目(Eurotiales)和格孢腔菌目(Pleosporales),相对频率分别为55.4%、17.61%和9.66%;优势属为镰刀菌属(Fusarium)、青霉属(Penicillium)、木霉属(Trichoderma)、未鉴定属3、帚枝霉属(Sarocladium)、未鉴定属2、弯孢属(Curvularia)和突脐蠕孢属(Exserohilum),相对频率分别为32.39%、15.06%、13.35%、5.11%、3.98%、3.41%、3.13%和2.84%,后5个属的相对频率未超过10%,其优势不明显。多样性指数和均匀度系数结果表明,南宁地区坛洛镇TL2样地和锣圩镇LX样地的香蕉根系内生真菌种群多样性较丰富,群落分布较均匀。相似度系数分析显示,钦州地区大成镇2个样地(DC1、DC2)间香蕉根系内生真菌种群组成相似度最高(C_s=0.67)。不同采样点的地理环境和气候条件给香蕉提供了不同的生境,是影响香蕉根系内生真菌种类组成及多样性差异的主要因素之一。

Community Composition and Diversity of Endophytic Fungi in Banana Root in Guangxi

Endophytic fungi were isolated from banana roots in main banana producing areas of Guangxi using the routine tissue isolation method.The endophytic fungi strains were identified based on morphology combined with phylogenetic analysis of ITS sequence.The analysis of composition and diversity of endophytic fungi associated with banana roots in Guangxi is of great significance in studying symbiotic relationship between banana and endophytic fungi and exploring function development of endophytic fungi in banana roots.A total of 352 isolates of culturable endophytic fungi were obtained from 168 tissues of banana roots collected from 7 sampling sites,and they were classified as 62taxa.The identifiable taxa belonged to 3 phylums (Ascomycota,Basidiomycota and Zygomycota) with 5 classes,represented by 17 orders with 43 genera.Observation of colony morphology and diameter of 62 representative fungi showed that most of them grew rapidly on CMMY medium in a week while some of them grew slowly.The color of the fungi colonies was different.Light-colored fungi colonies were generally white,light yellow or pink while dark colonies were generally brown,gray,gray-black or black.The colonies of a few strains were slightly purple or red.The colonies of some strains appeared to be light-colored in the early stage of growth and became dark gradually,which might be caused by the production of a large number of conidia or chlamydospores.In addition,a tiny minority of strains produced yellow or red pigments on CMMY medium.41 representative fungi showed reproductive structures (66.13%).Among the endophytic fungi,the dominant classes were Sordariomycetes and Eurotiomycetes and the relative frequency (RF) was66.19%and 20.45%respectively.The dominant orders were Hypocreales (RF=55.4%),Eurotiales (RF=17.61%) and Pleosporales (RF=9.66%) with the dominant genera Fusarium (RF=32.39%),Penicillium (RF=15.06%),Trichoderma(RF=13.35%),unidentifiable genus 3 (RF=5.11%),Sarocladium (RF=3.98%),unidentifiable genus 2 (RF=3.41%),Curvularia (RF=3.13%) and Exserohilum (RF=2.84%).Many endophytic fungi isolated from the banana roots in the study were common plant pathogenic fungi,such as Fusarium,Colletotrichum,Cladosporium,etc.The change law of Shannon-Wiener,Simpson’Diversity and Evenness indicated that the endophytic fungi communities in Tanluo Town(TL2) and Luoxu Town (LX) of Nanning City were abundant and well-proportioned.The endophytic fungal communities from two locations of Dacheng Town (DC1 and DC2) of Qinzhou City showed the maximum similarity coefficients(Sorenson’s similarit coefficiens,C_s=0.67).Habitats with different geographical conditions and climates are the main factors influencing the community composition and diversity of endophytic fungi in the roots of banana.