由核桃疫病果实上分离的一株栖稻假单胞菌YKW14

Pseudomonas oryzihabitans Strain YKW14 Isolated from Walnut Blighted Fruit

【目的】对一株来自云南昆明核桃疫病幼果上的细菌YKW14进行生理生化特性和分子鉴定。【方法】通过传统的细菌显微形态观察,不同培养基生长状况比较,生理生化特性测定,抗药性及冰核活性测试,结合16S-rDNA和gyrB基因序列比对分析,用MEGA7.0构建进化发育树对菌株进行鉴定。【结果】菌株YKW14在LB培养基平板生长良好,在含2%氯化钠的培养基上不能生长,致死温度为55℃。该菌株对石硫合剂、稻瘟灵和戊唑醇有抗性,对壮观霉素、卡那霉素和氨苄青霉素钠也表现出抗性,而对头孢无抗性。菌株的16S-rDNA和gyrB基因序列与NCBI中的栖稻假单胞菌同源性和相似性为100%。结合形态、生理生化特性和基因序列,将菌株YKW14鉴定为栖稻假单胞菌Pseudomonas oryzihabitans。【结论】栖稻假单胞菌为首次在核桃疫病幼果上分离报道。该菌可能为核桃果实疫病的复合侵染病原菌之一,其致病性或在疫病发生中的作用有待进一步验证。

【Objective】Combing physiological,biochemical characteristics with molecular method, the strain YKW14 isolated from walnut blighted young fruit in Kunming was identified in Yunnan province.【Method】The identification methods including traditional microscopy observation, compared on differential cultural medium, physiological and biochemical tests, antibiotics and ice nucleation activity test, 16S-rDNA and gyr B gene sequences alignment and phylogenetic tree constructed by MEGA7.0 software.【Result】The strain YKW14 grew well on LB medium, however, unable to survive on it containing 2 % NaCl,and it’s lethal temperature is 55 ℃.The strain showed resistance to lime-sulfur, isoprothiolane, tebuconazole alcohol, spectinomycin, kanamycin, ampicillin sodium, except for Cephalosporium. The 16S-rDNA and gyr B gene sequences are 100 % in homology and identity with Pseudomonas oryzihabitans from NCBI. Thus, the strain YKW14 was identified as Pseudomonas oryzihabitans based on these characteristics.【Conclusion】This is the first report of the species isolated from diseased walnut blight fruit. The strain might be as one of complex infectious pathogens, and the pathogenicity role in walnut blight need to be clarified furthermore.