广东肉桂内生真菌多样性及其抗肉桂枝枯病菌初步研究

本研究从广东省罗定市20年生和1年生肉桂的叶、枝、根和皮等不同器官共分离得到90株内生真菌,通过菌落特征、显微观察和ITS序列分析鉴定为2门3纲10目14科22属,其中拟盘多毛孢属Pestalotiopsis、黑孢霉属Nigrospora和间座壳属Diaporthe为优势属;肉桂内生真菌的分布存在明显的组织特异性和偏好性,叶中内生真菌的分布最多,有49株,分属于19个属,占分离菌株总数的54.44%。叶、枝、根和皮部内生真菌多样性指数分别为2.63、1.86、1.30和1.07,叶部多样性最高。20年生肉桂内生真菌较为丰富(H'=2.39),1年生次之(H'=2.00)。基于罗定市肉桂枝枯病害的病样,采用组织分离法得到疑似病原菌,通过形态学观察,柯赫氏法则验证及ITS、TEF和TUB序列分析,确定该病原菌为假可可毛色二胞菌Lasiodiplodia pseudotheobromae。这是L. pseudotheobromae所致肉桂枝枯病的首次发现。平板对峙法对L. pseudotheobromae的拮抗结果显示,共有9株内生真菌有显著抑菌效果,抑菌率均高于52%,其中Trichoderma sp. DZR-1-2抑菌率最高为68.80%,Hypoxylon vinosopulvinatum DYR-1-7抑菌带距离最大为2.5 mm,为肉桂枝枯病生物防治提供菌种资源。结果表明肉桂内生真菌多样性丰富,部分内生真菌菌株具有较强的抑菌活性,值得进一步深入研究。

Diversity of endophytic fungi from Cinnamomum cassia and their antagonism to the pathogen of C. cassia branch blight in Guangdong,South China

Endophytic fungi from the leaves, branches, roots and barks of 20-year-old and 1-year-old Cinnamomum cassia plants collected from Luoding city, Guangdong Province were investigated. In total, 90 fungal isolates were obtained and identified as 22 genera, 14 families, 10 orders, 3 classes and 2 phyla by colony characteristics, microscopic observation and ITS sequence analysis. Pestalotiopsis, Nigrospora and Diaporthe were the dominant genera. The distribution of endophytic fungi in C. cassia plants had obvious tissue specificity and preference. Endophytic fungi in leaves showed the highest level in diversity, and 49 isolates obtained were referred to 19 genera, accounting for 54.44% of the total number of isolates. The diversity index of endophytic fungi in leaves, branches, roots and barks were 2.63, 1.86, 1.30 and 1.07, respectively. Endophytic fungi were more abundant in 20-year-old (H'=2.39) plants than in 1-year-old plants (H'=2.00). Based on C. cassia branch blight samples in Luoding City, the suspected pathogens were obtained by tissue isolation method, and the pathogen was identified as Lasiodiplodia pseudotheobromae by morphological observation, Koch's rule verification and ITS, TEF and TUB sequence analysis. This is the first discovery of C. cassia branch blight caused by L. pseudotheobromae. The antagonistic effect against L. pseudotheobromae based on plate confrontation observation showed that 9 isolates of endophytic fungi had significant inhibition activity, and the inhibitory rates were all over 52%. Trichoderma sp. DZR-1-2 had the highest inhibitory rate (68.80%), and Hypoxylon vinosopulvinatum DYR-1-7 had the maximum distance of inhibitory zone (2.5 mm). These strains seem useful for biological control of C. cassia branch blight, which are worthy of further study.