Association Between Temperature Tolerance And Genetic Diversity Of Blumeria Graminis F.sp. Tritici In2012

Temperature sensitivity of139Blumeria graminis f. sp. tritici isolates, collectedfrom Sichuan, Beijing, Gansu, Henan, Zhejiang, Shaanxi, Qinghai, Shandong,Xinjiang and Yunnan, to was studied in incubator setted at18℃,22℃,23℃and24℃,25℃and26℃using in vitro leaf inoculation method. The results showed thatthe average ET50of the139isolates was23.14℃with the highest and lowest ET50at24.46℃and21.34℃, respectively.58.76%of the isolates’ ET50were between23℃and24℃, and only2.03%of the isolates’ ET50were above24℃. The frequencydistribution of the temperature sensitivity of the isolates was not normally distributedshowed that isolates of B. graminis f. sp. tritici in natural environment were influncedby temperature. The results could be used to understand and predict the global climatewarming to wheat powdery mildew occurrence trend so as to provide basis for a longtime.The results of the genetic diversity of B. graminis f. sp. tritici isolates collectedfrom nine provinces (city) showed that there were differences of genetic diversityparameters of isolates collected from different provinces (city). The percentage ofpolymorphic loci (P%) was between48.81%and81.22%for different provinces (city),where the highest was in Gansu, followed by Henan, Shandong, Beijing, Sichuan,Qinghai, Shaanxi, Yunnan and Zhejiang. The genetic diversity indexes (H) wereranged from0.2892to0.1951, where the highest was in Gansu, followed byShandong, Qinghai, Yunnan, Sichuan, Beijing, Henan, Shaanxi and Zhejiang. As aresult, the population genetic diversity of of B. graminis f. sp. tritici isolates in Gansuwas at high level while the isolates in Zhejiang was at low level.Genetic similaritycoefficient among groups was ranged from0.8769to0.9783, and the genetic distancewas between0.0271to0.1313. Isolates from Henan and Shanxi had the largestgenetic correlation coefficient (0.9783) and the lowest genetic distance (0.0271)which indicated that they had the closest relationship.The study of the relationship between temperature sensitivity and number ofvirulence genes of the isolates showed that as ET50increase, the number of virulencegenes showed a trend of decrease. The number of virulence genes was18.25when the22.5℃below ET50. The number of virulence genes was17.51when the ET50below23.5℃and above23℃. The number of virulence genes was17.47when the ET50above23.5℃. The number of virulence genes was17.33when the ET50below23℃ and above22.5℃. There was no significant correlation between the number ofvirulence genes and the ET50.The relations among ET50, coefficient of variation of ET50, number of virulencegenes and genetic diversity of the isolates were studied. The results showed that therewas significant positive relation between number of virulence genes and geneticdiversity Nei index with the correlation coefficient0.7125(P=0.0312). Thecorrelation coefficient between ET50and genetic diversity Nei index was-0.6483although not reached at significant level. There were no significant relations betweennumber of virulence genes and ET50, between number of virulence genes andcoefficient of variation of ET50, between genetic diversity Nei index and coefficientof variation of ET50.