Screening And Biological Characteristics Of Rice Bacterial Blight Resistant To Flubenoxazole Sulfone

The bacterial leaf blight of rice(BB)is a kind of rice bacterial wilt,which is widely distributed in rice growing areas and is one of the important diseases threatening rice production in China and even the world.The prevention and control of BB is faced with some problems demanding prompt solution at present,such as lack of resources of bactericide,low antibacterial activity and outstanding resistance.Fubianezuofeng and Zhongshengmycin have good control effects against BB,but their risk and molecular mechanism of resistance remain unclear.Therefore,the Fubianezuofeng and Zhongshengmycin resistance of Xanthomonas oryzae pv.oryzae(Xoo)were obtained,and the resistance level and the physiological-biochemical characteristics of the resistant strains were evaluated adequately.This provides a basis for the search for resistance molecular targets of the resistant strain.The Xanthomonas oryzae pv.oryzae was used as the research object and the combination of ultraviolet mutagenesis and drug acclimation was used to screen resistant strain of Fubianezuofeng and Zhongshengmycin.Four strains of F1,F2,F3,and F4 with resistance to Fubianezuofeng and one strain of Z100 with high resistance to Zhongshengmycin were obtained.The EC50 values of Fubianezuofeng against the wild and resistant strains F1,F2,F3 and F4 were 0.38,5.58,5.97,4.23 and 1.35 ?g/m L,respectively,and with the corresponding resistance multiples(average 11.27)of 14.69,15.72,11.12,respectively.Meanwhile,the minimum inhibitory concentrations(MIC)are 10,30,30,20 and 20 ?g/m L,respectively.The resistance of the Fubianezuofeng resistant strain is reduced after 10 generations of subculture.And the Fubianezuofeng has no cross-resistance with bismerthiazol,thiodiazole copper,phenazino-1-carboxylic acid and zhongshengmycin.The EC50 of zhongshengmycin to the wild and the resistant strain Z100 are 0.43 and 122.93 ?g/m L,respectively,the corresponding resistance multiple is 285.88,the minimum inhibitory concentration is 5 and 800 ?g/m L and the resistance of Z100 can be stably inherited.Zhongshengmycin has no cross-resistance with bismerthiazol,thio diazole copper,phenazino-1-carboxylic acid.The differences in growth rate,cell surface,extracellular polysaccharides,pathogenicity,and swimming ability between resistant and wild strains were evaluated.The experimental results showed that the growth trend of the Fubianezuofeng resistant strain was almost the same as that of the wild strains,but the growth rate of F3 was faster than that of others,while the growth trend of the Zhongshengmycin resistant strain Z100 was slower than that of the wild strain,but there was no significant difference in the growth rate.From the change of cell surface,the morphology of the resistant and wild strain was generally full and no obvious shrinkage or rupture were observed.In addition,the extracellular polysaccharide yield,virulence and swimming ability of resistant strains were generally reduced compared to the wild strain.