栗疫菌低毒力菌株dsRNA的分离及转移

ISOLATION AND CONVERSION OF dsRNA FROM HYPOVIRULENT STRAINS OF ENDOTHIA PARASITICA IN CHINA

自云南、广西、江苏、浙江、河北、京郊六个省市的板栗树(Castanea mollissima)溃疡斑上分离了栗疫菌(Endothia parasitica)160株,进行了 dsRNA 的提取及其毒力测定,获得两株含 dsRNA 的低毒力菌株(H),其毒力与带有起源于欧洲的 dsRNA 的低毒力菌株比较相近.比较国内菌株与欧洲低毒力菌株的 dsRNA 电泳谱带,示有共同分子量为5×10~6或6.2×10~6的电泳带。与正常毒力菌株(V)混合接种能显著降低致病力。这是欧美大陆发现低毒力菌株后,亚洲地区的首次报告。以5株具有欧洲 dsRNA 的低毒力菌株作为供体,与云南、江苏、浙江的10株毒力菌株配对,16%(8/50)的毒力菌株发生形态变化,dsRNA 转入后毒力明显降低。结果表明,国内毒力菌株可以接受欧洲低毒力因子——dsRNA 并转变为低毒力菌株。

One hundred sixty strains of the chestnut blight fungus(Endothia parasitica=Cryphon-ectria parasitica)were isolated from natural cankers on Chinese chestnut trees(Castanea mollis-sima)in Yunnan,Guangxi,Zhejiang,Jiangsu,Hebei provinces and thirty counties in China.Their virulence to chestnut trees was tested and the dsRNA from these fungi was characterizedby electrophoresis.Two less virulent(H)strains,EPC32 and EPC140,reduced the rate of ex-pansion of one V strain canker when the H strains were co-inoculated with the V strain.Com-parison of the dsRNA banding patterns between Chinese and European hypovirulent strainsshowed that both strains contain dsRNA with molecular weight about 5×10^(?) to 6×10^(?).Five Hypovirulent strains which carried European cytoplasmic determinants were pairedwith 10 Chinese virulent(V)strains,16% of the pairs resulted in conversion(eight conversionsper 50 pairings).When dsRNA (?)re transferred into the cytoplasm of Chinese virulent strainswhich lacked detectable dsRNA,changes in morphology and virulence of the V strains wereobserved.The discovery of H strains in China,and the transfer of dsRNA to Chinese V strainsresulting in their conversion to H strains,indicates a possibility for biological control of che-stnut blight in China.