Identifying And Evaluation Of Resistance To Stripe Rust In Wheat Germplasm And Current Wheat Cultivars From Inoculum Overwintering Region In Sichuan Basin

Stripe rust of wheat(Triticum aestivum L.) has been considered one of the mostdamaging for wheat production in China. Stripe rust can complete its year-round cycle inChina where is considered the largest independent epidemic region in the world. Growingresistant cultivars is considered the most effective, low-cost, and environmentally safeapproach to control stripe rust. Hence, it is very important that search for new resistancesources in breeding for disease resistance and identifying of resistance of stripe rust in currentwheat cultivars from epidemic regions in china.A total of1980wheat landraces and foreign germplasms, which have not been widelyused in China, were evaluated for resistance to stripe rust at seedling stage under greenhouseand at adult plants in field conditions respectivrly during2008-2011, and the selectedresistant sourcrs were detected with the known DNA markers linked to rust resistance genesYr5,Yr9,Yr10, Yr15,Yr26/24and Yr18. A selection of50resistant entries were screened withinboth artifical nusery with mixed races at Yangling and natural nersery at Tianshui, including8entries have seedling resistance and42entries have adult plant resistance. Combined with theresistance spectra and the detection of Yr gene markers,we found, in the resistant50entries,6entries possibly carry Yr9;2entries possibly contain Yr10;21entries possibly contain Yr18;There was no indication of Yr5, Yr15and Yr26in any selected resistant entries. The landraces,Pindong34and Qingchun39displayed high or very high levels of resistance,which maybecarried undiscovered Yr-genes, and18of these showed full compatibility at the seedling stagewere resistant to all races and were identified as a new rust resistance source. A system ofidentification and evoluation for resistance to stripe rust has been established and six seedlingresistant sources and13adult plant resistant sources with broad spectrum resistance havebeen identified.Stripe rust of wheat has been considered to overwinter in Sichuan basin. To verify theresistance levels and the distribution of the resistance genes of the wheat cultivars in theregion, which is very important to prevent the spread of stripe rust. In this research,67wheatcultivars from Sichuan (23are current major cultivars) were evaluated for stripe rustresistance of the seeding and adult plant stages, and were detected Yr26related genes by molecular marker and analysis of pedigree or resistance spectrum. The results showed thatthere were10cultivars that had all stage resistance;22cultivars had adult plant resistance;35cultivars were susceptible; more than60%of current major cultivars lost their resistance.19cultivars possibly carried Yr26;7cultivars possibly carried Yr26+?. The resistance of27cultivars declined because of the appearance of the pathogenic types which were toxic to Yr26;For the10major cultivars, the disappearance of the resistance was related to the abuse ofYr26. The research showed that the resistance levels of cultivars from Sichuan to stripe rustwere very low and the probability of outbreak of stripe rust was increasing after the arisen ofthe pathogenic types which were toxic to Yr26in Sichuan basin.