Mutataion Affecting Virulence In Puccinia Striiformis Induced By Chemical Mutagen

The studies here were conducted to determine if the chemical mutagen Ethyl MethaneSulphonate (EMS) applied to urediospores could alter the virulence of Puccinia striiformisand if mutants could detect on rust-resistant screening wheat cultivars. The results of thestudies were reported as follows: 1. EMS has extensive biological effects on the viability, pathogencity and reproductionof stripe rust. Germination rate of radiated spores was remarkably reduced, its disposal timeand concentration curve have shown that urediospores of stripe rust were sensitive to lowerdisposal concentration and to longer time. The dose-germination curve were followed MMFand Harris mode in CurveExpert (1.3), they were inverse S shape. Implied its has a optimizedparameter among in the space. On primary leaf of susceptible cultivars inoculated mutatedurediospres, the latent period of rust infection was extended, rust incidence and severity werereduced, reproduction of urediospores of stripe rust decreased, and the host-pathogeninteraction changed into incompatible with low-infection type. All of responses strengthenedwith the increase of disposal dose. An optimized mutagenic system of wheat stripe rusturediospore was designed,The results indicated that when the buffer PH value was7.0 in thenormal temperature conditions, the uredospore of tripe rust disposed 7-8 minutes with0.03mol/L EMS solution the death rate has reached 80% to 90%. This number value adaptedto the selection criterion of the optimum mutagenic dose of the microbe chemical mutagenesisexperience value. 2.Urediospores of patents culture, predominant race CY17-5 and CY31-3 were treatedby EMS, induce mutant were screened on the Chinese differential cultivars and thenear-isogenic lines (NILs) of rust. 11 and 8 mutant isolations were obtained with estimatedmutation rates 10-5～10-6. 5 mutant groups isolate form CY17-5, code 17M1 to 17M5, theyhave 86% similarity with its patents culture. And 4 mutant groups form CY31-3, code 31M1to 31M4, using 92% similarity cut-off point. The virulence of the mutants to a set ofdifferentials used in Chinese race survey was different from all of the known races of striperust. Most mutant isolates kept stable virulence such as 17M2 to Wirgilio, 17M3 to Mentana,17M4 to Mentana,Suwon11 and 17M5 to Abbonanza,Suwon11, 31M1 were virulent onJubilejina 2 and Trigo Eureka. But races in 17M1 were avirlent on Early Premium, races of31M2,31M3 and 31M4 were detected to avirlent on several differential cultivars. Thevirulences of mutants were also surveyed to the near-isogenic lines of stripe rust. From the4 化学诱导小麦条锈菌毒性突变研究relative responses of Chinese cultivars and NILs, the resistant genes of former can beconclusion. 3.The relative parasitic fitness of 16 mutants was evaluated on susceptible cultivars inthis study. The results showed that three primary element attributed to CY17 races adaptability,which represent sporulation capacity, the speed of growth and senescence of colonyrespectively. CY31 was decided by urediospore germination ability, sporulation speed and thesize of uredosporus. According to the principal components analysis, the sequence of CY17fitness was 17F08-1＞17F09-1＞17Mut-1＞17F09-2＞17F15-1＞17F15-3＞17CK, the avirulentmutants, 17F08-1　and　17F09-1 have higher vigor. Otherwise the order of CY31, 31F14-3＞31mutS-3＞31C13-2＞31MutH-1＞31F14-2＞31F14-1＞31CK＞31C17-1＞31MutH-2＞31MutS-2＞31C7-1, 31F14-3 and 31MutS-3 have more energy than the avirulent ones. The results suggested that the technique mutation of wheat stripe rust is feasibility andcredibility. Mutation is important mechanism of virulence variation in asexual population ofrust fungi.