Identification Of Erysiphe Graminis F.sp. Tritici Races In Nanjing And Screening Of Low Phosphorus Telorant New Wheat Germplasms

Powdery mildew is an economically important disease of wheat in all of the wheat-producing area in China. The survey of virulence frequency will aids the application ofpowdery mildew resistance genes in breeding. In this research, samples of conidia ofBlumeria graminis f. sp. tritici (Bgt) were collected from naturally infected field plants inNanjing, single-spore isolates from the samples were characterized with different varietiescarrying known resistance genes, and frequencies of virulent genes of Bgt population inNanjing were analyzed with these isolates. In the end, we evaluated the resistance spectrumof the diploid and tetraploid wheat germplasms in our lab with these isolates.A total of twenty-one different Bgt races, each carrying different numbers of knownvirulent genes ranging from 5 to 14, were obtained from 33 sing-spore isolates, amongwhich Bgt1 was prevailing with a occurence frequency of 12.1ï¼…. Among the resistantgenes evaluated, Pm3c and Pm5 had lost their resistance completely while Pm4a, Pm19,Pm21 and Pm23 are still valuable in breeding program in Nanjing.Among the 31 germplams evalued with all the isolates, 30 were resistant to Bgt, whichpossessed different reaction patterns from the known resistant genes'.In order to identify new germplasms tolerant to low phosphate environment, theresponses of all the collected 48 wheat land races to low phosphate supply were preliminarily evaluated, and the three lines of 231104, 231106 and 231122 were tolerant tolow phosphate environment.The study of the difference in relative biomass and characters of root of these wheatvarieties under P-deficiency stress and P-adequate conditions demonstrated some of lowphosphate tolerance mechanisms of wheat. The results showed that the low phosphate-tolerant genotype, 231104, 231106 and 231122, had more than 80ï¼…relative biomass,especially 231122 with relative biomass reaching to 100ï¼…, which were significantly higherfrom those of sensitive genotypes moreover, the root dry weight and the ratio of root/shootof 231122 had increased under P-deficiency stress compared with under P-adequate supply,which indicating that the low-phosphate tolerance genotype is able to ensure the growth ofroot preferentially to absorb more nutrition for growth requirement. In addition, 231104,231106 and 231122 had longer and more dense root hairs, incontrast to 231105 and 231111,which maybe another factor contributing to their high effectiveness in phosphate-absorbing.