湖北省烟草赤星病菌生物学特性研究

Study on Biological Characteristics of Pathogenic Bacteria Causing Tobacco Brown Spot Disease in Hubei Province

对湖北省烟草赤星病细极链格孢(Alternaria tenuissima)、链格孢(Alternaria alternata)、长柄链格孢(Alternaria longipes)和鸭梨链格孢(Alternaria yaliinficiens)4种链格孢属致病菌的代表性菌株进行了生物学特性分析,并分析了不同温度和保湿时间对长柄链格孢菌致病力的影响。结果表明,4种链格孢菌最适宜的生长温度为25～30℃;长柄链格孢最适宜的pH为5～6,其他种的最适宜生长pH为6～8。在不同碳源中,以甘露醇和半乳糖作为碳源时鸭梨链格孢生长最快,乳糖、葡萄糖等5种碳源最适宜链格孢生长,长柄链格孢在各种碳源下均生长最慢。在不同氮源中,除长柄链格孢的最适氮源为氯化铵外,其他3种链格孢在蛋白胨作为氮源时生长最快。不同种的链格孢属致病菌的致病力存在差异,除鸭梨链格孢菌株表现为弱致病力外,其他3种链格孢均存在强致病力菌株。不同温度及保湿时间对长柄链格孢菌致病力具有显著影响,最适发病温度为25～30℃,保湿时间与病害严重度呈正相关。

Biological characteristics of representative strains of four Alternaria spp.(Alternaria tenuissima,Alternaria alternata,Alternaria longipes,Alternaria yaliinficiens)and the effects of temperature and wetness duration on pathogenicity of Alternaria longipes were studied.The results showed that the most suitable temperature for Alternaria spp.growth was 25~30℃.The most suitable pH for the growth of Alternaria longipes and the other three species were 5~6 and 6~8,respectively.When mannitol and galactose were used as carbon sources,Alternaria yaliinficiens grew fastest;And other five carbon sources,such as lactose and glucose were most suitable for the growth of Alternaria alternata;Alternaria longipes grew most slowly under all carbon sources.The effect of different nitrogen sources on the growth showed that the Alternaria longipes grew fastest when ammonium chloride was used as nitrogen source,and the other three species grew fastest when peptone was used as nitrogen source.Virulence of four species was tested,and the results showed that the virulence of four species of Alternaria spp.were different.Among them,Alternaria tenuissima,Alternaria alternata and Alternaria longipes had strong virulence strains,while the strains of Alternaria yaliinficiens showed weak virulence.Different temperatures and wetness duration had significantly influence on the virulence of Alternaria longipes.The optimal temperature for disease was 25~30℃,and wetness duration was positively correlated with disease severity.