四川西南部小麦白粉菌群体毒性及遗传多样性分析

Virulence and genetic diversity analysis of wheat pow dery m ildew population in Southw estern area of Sichuan

为明确四川西南部白粉菌群体毒性及其遗传变异情况,本文将2011年采自四川西南部的小麦白粉病标样进行单孢子堆分离纯化,共获得48个白粉菌菌株,并将其按采集地划分为4个地理群体。利用28份已知抗白粉病基因材料测定了群体的毒性频率,并运用SRAP分子标记技术探讨了其遗传多样性。毒性测定结果表明,白粉菌群体毒性较强,群体间毒性结构存在差异。供试群体对Pm1、Pm3a、Pm3b、Pm3d、Pm5a、Pm6、Pm19的平均毒性频率达50%以上,而Pm13、Pm XBD、Pm5b、Pm2+6、Pm5+6抗性保持良好,平均毒性频率在10%以下。群体间毒性遗传距离与地理距离之间有一定的相关性,但未达到显著水平。用筛选出的10对SRAP引物共获得160个清晰、稳定的扩增位点,多态性频率为50.63%;白粉菌群体遗传多样度(h)、Shannon信息指数(I)分别为0.198 8、0.322 7,遗传变异主要源于群体内部。群体间基因流数值均在6.50以上,说明四川西南部白粉菌群体间菌源迁移频繁,基因交流较为充分。M antel Test分析表明SRAP标记解释的群体遗传多样性与地理距离、毒性多样性间的相关性未达到显著水平。

To characterize the virulence and genetic variation among Blumeria graminis f. sp. tritici （Bgt） population, 48 single conidial isolates of Bgt were isolated and divided into 4 geographic populations in Southwest Sichuan in 2011. The virulence variation of these isolates was tested based on the 28 wheat lines with known resistance genes against powdery mildew and genetic diversity of the pathogen isolates was analyzed using SRAP. The results showed that the Bgt population in this area had a higher virulence level, existing virulence structure difference among the 4 geographic populations. The mean virulence frequency of the resistance genes Pm1, Pm3a, Pm3b, Pm3d, Pm5a, Pm6 and Pm19 is higher than 50.0%, indicating that these genes have lost their resistant ability in the southwest Sichuan, whereas Pm13, PmXBD, Pm5b, Pm2＋6 and Pm5＋6 still showed higher resistance level with virulence frequency below 10.0%. There was no a certain correlation between geographical location and the genetic distance of pathogen virulence on significant level. Using10 pairs of SRAP primers, 160 polymorphic bands were identified, and the diversity frequency was 50.63%. The Nei’s gene diversity （h） and Shannon’s information index （I） of Bgt was 0.198 8 and 0.322 7 respectively and the genetic variation of Bgt isolates mainly occurred within the population. The gene flow values among geographical populations were above 6.50, which indicated frequent migration of pathogen isolates and the sufficient exchange of genes happened within population in Southwest Sichuan. Mantel test illustrated that the genetic diversity of the population tested with SRAP was not significantly correlated with their geographic locations and virulence diversity.