抗噻枯唑和抗叶枯净的水稻白叶枯病菌株的适应度比较

将水稻白叶枯病噻枯唑抗性菌和叶枯净抗性菌的适应度特性进行了比较。当Ｓａ＾ｒ和Ｐ＾ｒ与敏感菌（Ｓ）的等量混合物在植株上繁殖时,Ｓａ＾ｒ和Ｐ＾ｒ竞争不过Ｓ,但Ｐ＾ｒ竞争能力较Ｓａ＾ｒ强。Ｓａ＾ｒ和Ｐ＾ｒ的致病力与Ｓ的无明显差异。但在离体保存时Ｓａ＾ｒ和Ｐ＾ｒ易于丧失致病力。这种致病力的丧失是由于被保原群体中低致病力的敏感菌比例上升所致,进一步说明Ｓａ＾ｒ和Ｐ＾ｒ的适应度不及Ｓ。结果表明,白叶枯病市民经

THE FITNESS OF SAIKUZUO-RESISTANT STRAINS OF XANTHOMONAS ORYZAE PV ORYZAE IN COMPARISION WITH THOSE OF PHENAZINE OXIDE-RESISTANT ONES

The fitness of saikuzuo-resistant strains (Sar) of Xanthomonas oryzae pv oryzae was compared with those of phenazine oxide-resistant ones(Pr). When the mixture of Sar or Pr and sensitive strains (S) in "proportion of 1 :1" grew in susceptible rice variety the chemical resistant strains (R) could not compete with S. But competitive ability of Pr was stronger than that of Sar. There were no differences between the pathogenicity of R and that of S. But the pathogenicity of R lost easily. The pathogenic-ity loss of R was due to the increase of the proportion of S with low pathogenicity in R population preserved. The results showed the fitness of R was less than those of S. It is suggested that the R population do not set up easily in field conditions. Camparing with Sar, Pr population might more easily set up in field conditions. But the results above do not mean that there is no possibility of R population forming under high selective pressure.