炭疽病对油橄榄果实真菌群落结构的影响

Effects of Colletotrichum sp.infection on fungi community of olive fruit

【目的】掌握油橄榄果实感染炭疽病后真菌群落结构特征变化,为油橄榄炭疽病病原学研究和生物防治研究提供基础和科学依据。【方法】以健康油橄榄果实、患炭疽病初期和后期油橄榄果实为研究对象,利用高通量测序对比分析果皮和果肉真菌群落结构及多样性差异。【结果】(1)在97%的相似度水平上,从所有样品中获得1596个真菌非重复可操作分类单元(Operational taxonomic units,OTU),分属于2门9纲17目21科25属,其中,果皮上有939个真菌OTU,果肉中有921个真菌OTU;(2)Chao指数和ACE指数对发病程度均无显著响应(P>0.05);(3)无论是果皮还是果肉,患病果实的真菌多样性均显著少于健康果实(P<0.05);(4)在门、纲、目、科、属、种水平上,排名前5的真菌类群对发病程度均有显著响应(P<0.05);(5)染病后,炭疽病病原菌取代原优势菌群(黑孢霉属和短梗霉属),成为优势菌群。发病初期和后期,病原菌刺盘孢属(Colletotrichum)在果皮上的相对丰度分别为86.97%和70.02%,而果肉中的相对丰度分别为72.31%和91.38%;(6)果皮中的假尾孢属(Pseudocercospora)和核盘菌属(Sclerotinia)及果肉中的黑孢霉属(Nigrospora)和短梗霉属(Aureobasidium)为炭疽病病原菌敏感菌,在染病后数量下降明显,也是健康油橄榄果的标志物种;(7)油橄榄果感染炭疽病后期,果皮中其它病原菌菌属,如Bisifusarium属、汉纳酵母属(Hannaella)、镰刀菌属(Fusarium)明显增加;(8)共生营养型真菌数量在发病后期显著回升,且显著高于健康果实(P<0.05)。【结论】炭疽病感染显著改变了油橄榄果实真菌群落结构,炭疽病病原菌个体数量急剧增长,改变了菌群间相对丰富度,显著降低了群落多样性;同时,染病后期多种病原菌数量的增长,为炭疽病防治提出了综合防治的要求和方向;另外,炭疽病感染后期数量出现明显回升的共生营养型真菌,可作为炭疽病生防菌筛选的潜在对象。

【Objective】The study of the changes of the fungal community structure in olive fruit after infected by anthracnose is great meaning⁃ful for the research on the etiology and biological control of olive anthracnose.【Method】Using Illumina MiSeq platform,the study took healthy olive fruits,mildly anthracnose diseased fruits and severe anthracnose diseased fruits as research objects,and analyzed the differ⁃ences in fungal community structure and diversity in the peel and flesh.【Result】(i)At a similarity level of 97%,1596 non⁃redundant op⁃erational taxonomic units(OTUs)were obtained from all samples,belonging to 2 phyla,9 classes,17 orders,21 families and 25 genera.A⁃mong them,there were 939 OTUs on the peel and 921 OTUs in the flesh;(ii)Chao index and ACE index had no significant response to the degree of infection(P>0.05);(iii)Whether it was the peel or the flesh,the fungal diversity of the diseased fruits was significantly less than that of the healthy fruits(P<0.05);(iv)At the level of phylum,class,order,family,genus and species,the top 5 fungal groups in number all had a significant response to the degree of infection(P<0.05);(v)After infection,Colletotrichum spp.replaced the original dominant group(Nigrospora and Aureobasidium)and became the dominant group,with the relative abundance of Colletotrichum in the peel rose to 86.97%and 70.02%respectively at mildly and severe anthranose stages of infection,while in the flesh,the relative abundance rose to 72.31%and 91.38%;(vi)Pseudocercospora and Sclerotinia in the peel,Nigrospora and Aureobasidium in the flesh were most sensitive to the pathogen.Their number decreased obviously after infection,and were the markers of healthy olive fruits;(vii)At the severe anthrac⁃noselater stage of infection,other pathogenic fungi,such as Bisifusarium,Hannaella and Fusarium,increased significantly in the peel;(vi⁃ii)The number of symbiotic fungi increased significantly,which was significantly higher than that of healthy fruits(P<0.05).【Conclu⁃sion】Anthracnose infection significantly changed the fungal community structure of olive fruits.With the rapidly increase of the pathogenic fungi number,relative abundance between fungi changed significantly,and the diversity of the community was significantly reduced.At the same time,the increase of the number of various pathogens in the severe anthracnose stage of infection proposed the necessity of comprehen⁃sive prevention in the of control of anthracnose.In addition,symbiotic fungi whose number significantly increased at the severe anthracnose stage could be used to screen potential bio⁃control fungi of anthracnose.