Identification of cucumber bacterial gummosis pathogens in Baiyin city,Gansu province
In order to clarify the pathogen of cucumber bacterial gummosis in Gansu province,the samples collected from Baiyin city with typical gummosis symptoms were isolated by tissue separation method,and the pathogenicity was veri-fied by Koch's postulate.Then morphological characteristics and molecular biology methods were used for identification.The results showed that four isolates were obtained from the diseased cucumber stems,named hxb 1,hxb 2,hxb 3 and hxb 4,respectively.It was verified by Koch's postulate that hxb 1 was the pathogen causing cucumber gummosis,and its colonies on NA medium were milky white or translucent,round or nearly round,with smooth edges.The cell size was(0.253-0.511)μm×(0.783-2.290)μm,which was short straight rod and gram-negative.Using 16S rRNA and gyrB genes sequence analysis,it was found that hxb 1 was clustered with Pseudomonas fluorescens,and the homology was 100％.Combined with morphological characteristics,the strain hxbl was identified as Pseudomonas fluorescens.The research re-sults provide a theoretical basis for the diagnosis and comprehensive prevention of cucumber bacterial gummosis.
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