The Resistance Study of Xanthomonas oryzae pv.oryzicola in Southwest China to Streptomycin Sulfate
For the analysis of streptomycin resistance of X.oryzae pv.oryzicola in Southwest,the establishment of streptomycin-sensitive baseline,screening resistant mutant strains.The strains of X.oryzae pv.oryzicola which from Yunnan,Guizhou and Sichuan provinces were used to examined the sensitivities of streptomycin sulfate in vitro.UV mutagenesis and pharmaceutical tame approach were used to induced the streptomycin resistant mutant strains.We also detected the mutation site of streptomycin resistance gene (rpsL gene).The results showed that there were sensitivity differences among the strains; The EC50 values of streptomycin sulfate to all tested strains ranged from 0.165 ~ 1.532 μg/mL with the average of 0.667 μg/mL; The average EC50 0.667 μg/mL was the baselinesensitivity of X.oryzae pv.oryzicola from Yunnan,Guizhou and Sichuan provinces to streptomycin sulfate; A resistant mutant strain 30-U-3 was induced by UV mutagenesis; The EC50 values of 30-U-3 was 57.544 μg/mL,which resistance increased 138.661 times; The mutation site was the first 43 amino of rpsL gene; The acid lysine (AAG) was mutated to arginine (AGG) on this site.This research showed that:although there were no natural streptomycin resistant mutant strains in Southwest currently,but a high resistant strain has been found in Chuxiong city,so the use of streptomycin in Chuxiong should be attract our attention.