红江橙可培养内生真菌生物多样性和种群结构分析

Biodiversity and Community Structure of CulturableEndophytic Fungi in Hongjiang Orange

为探究红江橙内生真菌种群多样性和群落结构,比较红江橙健株和患黄龙病病株内生真菌群落的差异,采用组织块分离法从红江橙的根、茎、叶中分离内生真菌,以形态学结合ITS-rDNA序列分析法进行菌株分类鉴定,根据Shannon-Wiener多样性指数、菌株分离的相对频率和相似性指数分析红江橙内生真菌的菌群分布及多样性。结果表明,从红江橙根、茎、叶中分离得到内生真菌117株,鉴定归属为3纲11目15科18属,其中炭疽菌属(Colletotrichum spp.)、镰刀菌属(Fusarium spp.)、叶点霉属(Phyllosticta spp.)、黑孢霉属(Nigrospora spp.)和青霉菌属(Penicillium spp.)为优势菌群,其相对分离率分别为58.97%、8.55%、8.55%、4.27%、3.42%。植株总体内生真菌Shannon-Wiener多样性指数为1.68,总均匀度指数为0.30,茎与叶、根与叶及根与茎的相似性指数分别为0.48、0.33、0.32。黄龙病病株与健株内生真菌Shannon-Wiener多样性指数有较大差异,健株多样性指数除根部略低于病株外,总多样性指数和茎、叶的多样性指数分别是病株的1.73倍、2.07倍和5.54倍。健株和病株内生真菌菌落相似性指数为0.43,在根、茎、叶部位健病株相似性指数根部较高为0.75,其次是叶为0.44,茎的最低为0.35。分离得到的内生真菌中炭疽菌属在病株茎、叶中的相对分离率为77.78%、92.86%,远高于其在健株中的相对分离率54.05%、54.17%。结果显示红江橙内生真菌属类丰富,但分布不均匀,其内生真菌类群分布具有组织特异性。患黄龙病的红江橙内生真菌群落与健株的显著不同,其内生真菌群落总多样性指数显著低于健株,其中叶部降低最显著,其次为茎部。

To compare the difference of the endophytic fungal diversity and community composition between healthy Hongjiang orange plants and those infected with Candidatus Liberibacter asiaticus,the endophytic fungi were isolated using the method of tissue block culture from roots,stems and leaves.The result showed that the endophytic fungal communities were highly diverse and rich,with the total of 117 strains obtained,and distributed into 3 classes,11 orders,15 families and 18 genera.The dominant members belonged to the geuns Colletotrichum,Fusarium,Phyllosticta,Nigrospora and Penicillium,with relative abundance of 58.97%,8.55%,8.55%,4.27%and 3.42%respectively.The total Shannon-Wiener diversity index(H′)was 1.68,and the total similarity index was 0.30.The similarity index between stem and leaf was 0.48,followed by root and leaf at 0.33 and root and stem at 0.32.The Shannon-Wiener diversity index of endophytic fungi of healthy plants was significantly different from that in diseased plants.The diversity index of the root in healthy plants was slightly lower than that in the diseased plants,while the total diversity index and the diversity index of the stem and leaf were 1.73,2.07 and 5.54 times that of the diseased plants,respectively.The endophytic fungi community similarity index(Cs)between healthy and diseased plants was 0.43,and in the similarity index of the endophytic fungi of healthy and diseased plants in root,stem and leaf,the index of root was higher(Cs=0.75),followed by the index of leaf(Cs=0.44),the index of stem was lowest(Cs=0.35).Colletotrichum species were enriched as dominant populations,with relative abundances of 77.78%and 92.86%in stem and leaves,respectively,which were significantly higher than those in healthy plants(54.05%,54.17%).In summary,the endophytic fungi community of Hongjiang orange were rich at genus level,but its distribution were uneven,exhibiting tissue specificity.The community structure of endophytic fungi in Hongjiang orange infected with Citrus huanglongbing(HLB)differs significantly from that of healthy plants.The diversity index of endophytic fungi in diseased plants was significantly lower than that in healthy plants,especially in leaves and stems.