不同渗透压及pH环境对烟草青枯病菌致病力的影响

为探究不同渗透压和pH环境对烟草青枯病菌Ralstonia solanacearum致病力的影响,用Biolog PM 9～10代谢板中96种渗透压和96种pH环境培养烟草青枯病菌,并采用穿刺法接种于烟草离体叶片,测定不同环境下烟草青枯病菌对烟草的致病情况。结果表明,烟草青枯病菌可致病的渗透压范围包括1%～2%氯化钠、2%～3%硫酸钠、5%～20%乙二醇、1%甲酸钠、2%尿素、1%乳酸钠、20～100 mmol/L磷酸钠、10～100 mmol/L硫酸铵、10～100 mmol/L硝酸钠及10～20 mmol/L亚硝酸钠。可致病pH范围为5.0～8.0;当pH 4.5时,烟草青枯病菌在分别与L-正缬氨酸和5-羟色氨酸共培养时均可致病,与其余33种氨基酸共培养时则均不能致病;当pH 9.5时,烟草青枯病菌在与所有35种供试氨基酸共培养时均不能致病;烟草青枯病菌在葡萄糖苷、辛酸盐、半乳糖苷等10种化合物培养下均可致病。表明渗透压和pH环境会严重影响烟草青枯病菌的生长和致病力。

Effects of different osmolity and pH conditions on the pathogenicity of Ralstonia solanacearum in tobacco leaves

In order to investigate the effect of different osmolity and pH conditions on the pathogenicity of Ralstonia solanacearum, the bacterium R. solanacearum was incubated in Biolog PM 9-10 microplates with 96 different osmolity conditions and 96 pH values. The pathogenicity of this pathogen under different osmolity and pH conditions was investigated by stab inoculation on the detached leaves of tobacco. The results showed that the pathogenic osmolity conditions included 1%-2% sodium chloride, 2%-3% sodium sulfate, 5%-20% ethylene glycol, 1% sodium formate, 2% urea, 1% sodium lactate, 20-100 mmol/L sodium phosphate, 10-100 mmol/L ammonium sulfate, 10-100 mmol/L sodium nitrate, and 10-20 mmol/L sodium nitrite. The pH values for pathogenicity ranged from 5.0-8.0. At the pH 4.5, R. solanacearum still exhibited pathogenicity to tobacco leaves when combined with amino acids Lnorvaline and 5-hydroxytryptophan, but no pathogenicity was observed with other 33 amino acids. At the pH 9.5,the pathogen showed no pathogenicity when combined with all 35 amino acids tested. Additionally, R. solanacearum showed pathogenicity when combined with other ten compounds, including glucoside, X-caprylate, galactoside, etc. The results indicated that osmolity and pH conditions could significantly affect the growth and pathogenicity of R. solanacearum.