水稻条纹病毒不同地区分离物的致病性研究

 利用36个粳稻品种对来自江苏、云南、河北、山东等地的22个水稻条纹病毒(RSV)分离物进行致病性测定,根据各分离物在36个品种上的平均发病率,将参试分离物划分为HV、SH、MV、SL和LV 5个致病类型,致病力强弱为HV > SH > MV > SL > LV,其中MV和SL型占77%,表明RSV对粳稻的致病力中等偏弱。各致病型在地区间和年度间呈随机分布状态,暗示自然条件下特定地区的RSV为混合致病群。根据致病性测定结果同时将36个粳稻品种划分为免疫、抗、中抗、中感、感和高感6个抗感类型,其中中感和感病类型占70%,无高感和免疫类型,显示粳稻对RSV比较敏感但有一定程度的耐受性。根据试验结果筛选出11个具有鉴别能力的水稻品种,可对RSV分离物进行致病型鉴定。研究发现部分抗病品种对一些分离物表现为中抗~中感类型,接种量加大时可转为感病类型,由此提示各地在应用抗病品种防治水稻条纹叶枯病时应根据当地RSV致病型的差异,针对性地选用抗病品种,当灰飞虱超量发生时需及时做好治虫控病工作,并随时监测当地RSV致病型的变化,警惕品种抗性丧失。

Pathogenicity of Rice stripe tenuivirus isolates from different areas

The pathogenicity of 22 Rice stripe tenuivirus(RSV) isolates derived from Jiangsu,Yunnan,Hebei and Shandong provinces of China were tested on 36 japonica rice varieties.According to the average infection rates of each isolate to 36 varieties,the 22 isolates were divided into 5 pathotypes:HV,SH,MV,SL and LV,and the pathogenicity order was HV > SH > MV > SL > LV.MV and SL types being 77% in the total isolates indicated that the pathogenicity of RSV to japonica rice was moderate to low.Random distribution of RSV pathotypes in different areas and years or in the same area and year implied that RSV was a mixed pathotypes naturally.The tested varieties were classified into immune(I),resistant(R),moderate resistant(MR),moderate susceptible(MS),susceptible(S) and high susceptible(HS) types,in which MS and S types being 70% but no I and HS types in the total varieties confirmed that japonica rice was susceptible to RSV but had some tolerance.Eleven japonica varieties were chosen as differential varieties for RSV pathotype identification.Some resistant varieties,which showed moderately resistant or moderately susceptible to some isolates,could easily changed to susceptible when the inoculated amounts of the small brown planthopper(Laodelphax striatellus Fallén,SBPH),the vector of RSV transmission,were increased.It was suggested to choose high resistant varieties to the given isolates on preventing the rice stripe disease,to control SBPH with chemical pesticide in time when the outbreak of SBPH populations happened and to monitor the variation of RSV pathotype at any time so as to avoid the resistance losing of rice variety.