Association Among Triadimefon Sensitivity, Temperature Tolerance, Virulence And Genetic Diversity Of Blumeria Graminis F.sp. Tritici Isolates In2012

The pressure of abiotic factors and the natural environment play an important role in theevolution of biological genome and phenotypic diversity which can affect the virulence, invasiveness,fecundity of biological traits and further affecting the prevalence of disease. In this study, the sensitivityof Blumeria graminis f.sp.tritici to triadimefon was detected. Furthermore, the relationships amongtriadimefon sensitivity, temperature sensitivity, virulence diversity and genetic diversity were alsocarried out.One hundred and twenty nine Blumeria graminis f. sp. tritici isolates were collected from9provinces/cities in2012, and the sensitivity of the isolates to triadimefon was tested by seed treatmentand detached leaf segment methods. The results showed that median EC50of isolates to triadimefonwas109.97mg/L,the coeffective of EC50was107.2，the mean resistance factor (RF) was52.62.Theresistant frequency of all isolates to triadimefon was up to99.21%. The mean resistant factor of B.graminis f. sp. tritici from Beijing was higher compared with the other eight provinces.The isolates were also inoculated onto31differential wheat lines of powdery mildew to test thevirulence. Virulence diversity of B. graminis f. sp. tritici isolates from Sichuan Province was highestwith the index of virulence gene diversity0.2241. The virulence gene diversity of isolates fromZhejiang was lowest with the index0.0968.Analysis of genetic diversity of B. graminis f. sp. tritici isolates using SSR method showed thatthe genetic diversity of isolates sampled from Henan Province was the highest, and the index of geneticdiversity was0.2708, while isolates sampled from Qinghai had the lowest genetic diversity. Clusteringanalysis of genetic distance by Popgen showed that genetic diversity of isolates sampled from Gansuand Qinghai, Sichuan and Yunnan were similar,respectively, there was significant relationship betweengenetic distance and geographic distance, which indicated that the genetic similarity was higher whenthe sites were closer.The association among triadimefon-sensitivity, temperature sensitivity and virulence diversity ofB. graminis f. sp. tritici isolates showed that there was no significant correlation among median EC50,variation coefficient of EC50and virulence diversity. However, there is a logarithmic function (r=0.2404,P=0.0096) relationship between EC50and numbers of virulence genes of129Blumeria graminis f. sp.tritici isolates. What’s more, there was a negative correlation between temperature sensitivity andvirulence diversity. These results may provide a reference for reasonable utilization of resistancevarieties, as well as the use of triazole fungicides.