水稻白叶枯病菌菌落类型及致病力变异研究

Studies on colony types and variation of the virulenceof Xanthomonas campestris pv. oryzae.

在1983～1988年间从182个菲律宾水稻白叶枯病菌菌株和97个中国菌株中获得2万多个单菌落,根据菌落特征(形态,大小,色泽)及在鉴别品种上致病性测定的结果,供试菌株可区分为野生型,突变型和中间型三个类型,野生型代表菌株的原始致病力;突变型不但在菌落特征上有别于野生型,且致病力接近于无毒菌;中间型菌落的特征和致病力均不稳定,多糖体的产生量与病菌菌株的菌落特征及致病力间无明显的规律性可循,突变型菌落的出现频率与致病力有一定关系,但因菌而异,采用低温和冰冻真空干燥保存法、减少移植次数、延长移植间隔时期、选用适宜的培养基有减少突变型菌落而延缓致病力下降的作用。

During 1983~1988,more than 20 thousands of monocolonies of X.campestrls pv.oryzae were obtained from 279 isolates of the Philippines and China,and differentated into 3 types.Wild type-was a normalftype with the original virulence of the isolates.Mutant type with small colonies was derived from wild type due to unfavorable conditions and was almost avirulent.Intermediate typo was also derived from wild type but was unstable in [morphology and virulence.Production of slime polysaccharide of the strains was not significantly related to the colony characters and the virulence among the above 3 types.Mutant colonies gradually increased when the isolates were maintained or subcultured for!|long period of time.Their frequency in the population was related to the virulence but widely varied with the isolates.It suggests that lyophilization,storage in the deeper freezer,shortening the subculture times,prolonging the interval period and using the appropriate medium would have some effect in reducing the amount of mutant colonies and the attenuation of virulence of the isolates.