Abstract: To study the population structures of Xanthomonas oryzae pv.oryzae and understand the virulence variation and pathotypic diversity of pathogen in indica and japonica rice in Southwest China,218 strains were tested using 6 near-isogenic rice lines each containing a single resistance gene to provide effective strategies on breeding resistance genes and resistant varieties application.Our main results were as following The tested strains were diversified and it includes 18 pathotypes;The population structures of Xanthomonas oryzae pv.oryzae in different cultivar types were distinction.The number of pathotypes of Xoo in japonica rice was more than those in indica rice.Richness index,Shannon index and evenness index kept at low level in indica rice and showed significant differences between strains isolated from japionica and indica rice.We found the virulence of strains in different cultivar types were very different when we analyzed the number of resistance genes defeated and the average lesion length of rice lines infected by strains.The virulence of strains isolated from indica rice were higher than those from japonica rice.All strains tested were similar to each other at a level of 60% similarity,18 pathotypes of strains were constituted four clusters.Strains belonging to clustersⅠwith weak virulence were mainly isolated from japonica rice,while strains of cluster Ⅳ with strong virulence were mainly isolated from indica rice.As far as the layout of the breed is concerned,the rice cultivar containing more resistance genes should be used in indica rice planted region,while a programme of alternating genes for forestalling the pathogen variation should be worked out in japonica rice planted region for the purpose of disease reduction.

Key words: Bacterial blight, Virulence, Indica rice, Japonica rice, Resistance gene, Pathotype-abundance analysis

CLC Number: 

• S435.111.41