Abstract: Several factors affected attenuation of virulence and colony variation on artificial media. The results showed that nutritional factor was more important than storage of the culture in attenuation of virulence. NA and PSA medium supported least loss of virulence among 6 media. Shorter interval period and more frequent subculture on artificial media also affected attenuation of virulence The sensitivity to lower concentration of oxygen may vary with strains. It also suggest that lyophilization and keeping in deeper freezer be the appropriate methods for storage of this bacterium to have least attenuation of virulence. The experimental data revealed that there was no correlation between production of slime polysaccharide and virulence.

Key words: Xanthomonas campestris pv.oryzae, Artificial media, Virulence

摘要： 稻白叶枯病菌在人工培养基上毒性降低受多种因素的影响。试验结果表明,营养因素对菌的毒性降低比菌的不同保存方法更为明显,在供试的6种常用培养基中,NA 和 PSA 培养基对菌的毒性降低影响较小。较短的移植间隔期和频繁的移植次数也会影响菌的毒性降低。菌对低浓度氧的敏感性可因菌系而有差异。因此认为冰冻真空干燥和低温保存对抑制菌的毒性降低是较为理想的保存办法。试验还表明粘多糖的产生与菌的毒性之间不存在一定的相关性。

关键词: 稻白叶枯病菌, 人工培养基, 毒性