定殖烟草根结线虫卵和雌虫机会真菌的多样性

机会真菌对根结线虫的生物防治具有巨大潜力。本研究于2010—2011年针对来源于中国7个省份的156份烟草根结线虫样本,分别分离根结线虫游离卵、卵块和雌虫上定殖的机会真菌。应用18S rDNA-ITS片段测序结果结合菌株的形态学观察和培养性状鉴定定殖游离卵、卵块和雌虫上的真菌。根据分离到菌株的培养性状、形态学和rDNA-ITS序列分析,对定殖于南方根结线虫或北方根结线虫的9 839个游离卵、408个卵块和284个雌虫的真菌菌株,明确鉴定出9属13个种,其中定殖根结线虫新记录种5个,即长梗木霉、芬芳镰刀菌、渐狭蜡蚧菌、虫草棒束孢和交枝顶孢。淡紫紫孢菌Purpureocillium lilacinum(原名:淡紫拟青霉)为优势种,分布广泛,在云南、安徽、湖北、贵州和山东省均被分离到。该菌在南方根结线虫和北方根结线虫的游离卵、卵块和雌虫平均分离率分别为0.49%、24.00%和16.90%,说明其地理和生态适应性广泛。不同地区来源的烟草根结线虫卵和雌虫上定殖的机会真菌种类存在明显差异。目前尚无渐狭蜡蚧菌和虫草棒束孢作为线虫病原物的报道,有待于进一步深入研究其对根结线虫的致病性。

Diversity of opportunistic fungi colonizing egg and femaleroot-knot nematodes of tobacco

Suppression of plant parasitic nematodes with nematode predators, parasites or antagonists is a more eco-friendly approach than using nematicides. Opportunistic fungi have been investigated as potential biological control agents for root-knot nematodes. In this study, sequence data for the 18S rDNA-ITS region were used in conjunction with morphological observations to resolve opportunistic fungi taxonomy associated with eggs and female root-knot nematodes of tobacco. Fungal colonization was determined for eggs, egg masses and females of 156 specimens of tobacco root-knot nematodes from 7 provinces in China during 2010-2011. A total of 9 839 eggs, 408 egg masses and 284 females of Meloidogyne incognita and M. hapla were examined. Also 13 species, belonging to 9 genera of fungi, were isolated and identified. The common fungi associated with eggs, egg masses and females were Purpureocillium lilacinum, Fusarium oxysporum, F. solani, Penicillium purpurogenum, Alternaria alternata, Aspergillus unguis, A. niger and Acremonium strictum. The new strains of root-knot nematodes were Isaria farinose, Trichoderma longibrachiatum, Lecanicillium attenuatum, F. redolens and A. implicatum. P. lilacinum was the dominant species, which predominated in egg, egg masses and female root-knot nematodes with average frequencies of 0.49%, 24.00% and 16.90%, respectively. It occupied a wide range of niches in the study area, isolated from Yunnan, Anhui, Hubei, Guizhou, Shandong Provinces. Significant differences existed among fungal species communities isolated from eggs and females from various locations. As there hardly existed any information on the potential importance of I. farinose and L. attenuatum as nematode pathogens, pathogenicity tests were recommended in future studies.