拮抗烟草疫霉的枝穗霉菌株筛选

【背景】烟草疫霉(Phytophthora nicotianae)引起的烟草黑胫病(tobacco black shank)是烤烟生产上重要的土传根茎病害之一，生产上防治困难。【目的】筛选对病原菌具有强拮抗能力的有益微生物菌株是开展生物防治的基础。【方法】采用平板对峙法筛选对烟草疫霉具有拮抗作用的枝穗霉菌株。根据枝穗霉在烟草疫霉菌落上的覆盖程度和产孢量，以及对烟草疫霉菌丝、孢囊梗和孢子囊的缠绕情况，将枝穗霉的拮抗能力划分为强、中等、弱和无4个等级。【结果】供试8种65株枝穗霉中，6株具有强拮抗能力、27株具有中等拮抗能力、22株具有弱拮抗能力、10株无拮抗能力；不同枝穗霉菌株对烟草疫霉的抑制率大小为20.0%-86.7%。【结论】粉红枝穗霉(Clonostachys rosea)菌株7901、11361和亚麻生枝穗霉(C. byssicola)5072、6729、7507及条孢枝穗霉(C. grammicospora)6730对烟草疫霉具有强拮抗能力，这为后续盆栽试验及作用机理研究等提供了种质资源。

Screening of Closnostachys strains against Phytophthora nicotianae

Background] Tobacco black shank, induced by Phytophthora nicotianae, is one of the major soil-borne diseases that cause serious stem and root rot in flue-cured tobacco production. Objective] Screening of strong antagonistic strains is the basis of biological control. Methods] In this study, the dual culture assay was used to screen Closnostachys strains against P. nicotianae. Sixty-five strains of Closnostachys belonging to eight species were tested. According to their abilities of sporulation on colony of P. nicotianae and hyphal coilings produced surrounding hyphae, sporangiophores, and sporangia of the pathogen, the antagonism of Closnostachys was classified into four degrees:strong, moderate, weak, and absent. Results] A total of 6 tested strains had strong antagonistic ability, 27 moderate antagonistic ability, 22 weak antagonistic ability, and 10 no antagonistic ability. The inhibition rates of Closnostachys strains tested to P. nicotianae were 20.0%-86.7%. Conclusion] The strains tested with strong antagonistic ability were C. rosea 7901 and 11361, C. byssicola 5072, 6729, and 7507, and C. grammicospora 6730. Their potential as biocontrol resources needs further pot experiment confirmation.