Investigation Of Wheat Leaf Rust Resistance In Aegilops Tauschii

Wheat leaf rust is an important disease in the production of wheat.Screening and breeding for resistance cultivars are considered to be the most economical,environmental, and effective appropriate strategy to reduce the disease damages.It is a long and important task to study,discover,and mark constantly the leaf rust resistance genes.Diploid wild relatives which are the accessions of the wheat genome,normally are the source of wheat leaf rust resistance genes,and are valuable in wheat resistance breeding.The resistance characters and resistance genes to wheat leaf rust in the six Aegilops tauschii were detected and identifiied by means of detached leaves identifying method, resistance gene postulation according to the infection types and molecular markers.SSR markers for Y192 were developed and RGA was carried out at genomic DNA level.The main results were as follows:1.Twenty five wheat leaf rust pathotypes were used to investigate the wheat leaf rust resistance in 6 Aegilops tauschii at seedling stage.Aegilops tauschii Y192 and Y201 were immunity,high resistance to 23 isolates of the 25 inoculated Puccinia triticina isolates. 4254-Y206 and 4255-Y212 were immunity,or high resistance to 22 isolates of 25.Y2272 and 4841-Y2263 were high susceptible to 23 isolates of 25.This indicated that Y192,Y201, 4254-Y206 and 4255-Y212 were resistant to most of isolates used in this test,and had a broad applied prospect in wheat resistance breeding.2.Resistance genes against wheat leaf rust in Aegilops tauschii were detected by comparing the infection-types of 18 races of Puccinia triticina previously characterized for detecting avirulence or virulence gene combination on 4 diploid varieties on detached leaves with 44 Near Isogenic Lines with different resistance genes.Marker-assisted selection for leaf rust resistance in Aegilops tauschii Y192,Y201,4254-Y206 and 4255-Y212 was approached by using STS or SCAR markers.The results showed that other leaf rust resistance genes which haven't been used in this test were postulated to be present in Aegilops tauschii 4254-Y206.Lr1 or other leaf rust resistance genes which haven't been used in this test or new wheat leaf rust resistance genes may be present in Aegilops tauschii 4255-Y212.Lr41,other leaf rust resistance genes which haven't been used in this test may be present in Aegilops tauschii Y192.Other leaf rust resistance genes which haven't been used in this test were probed to be present in Aegilops tauschii Y201.3.RGA technique was used to find the resistance gene analogys in Y192.It produced a band of 530bp with primer pairs NLRR Rev and S1-INV,the sequence of band had not be found any homology sequences in GenBank.This indicated that it maybe a new sequence.4.Microsatellite markers technique was used to target the wheat leaf rust resistance genes in Y192.Puccinia triticina isolate(04-5-192)was used to score the resistance in F₃ generation derived from cross of Y192 and Y2272.DNA samples extracted from the F₃ individuals were pooled into two separate groups(resistance and susceptible)for Bulked Segregant Analysis(BSA)to identify the molecular markers linked to the resistance genes. 122 pairs of microsatellite primers were screened between the parents and progenies.Three SSR markers wmc245,xgwm296,and xgwm261 located on 2D chromosome of wheat generated about 130bp,210bp and 180bp specific bands between the resistant pool and the susceptible ones.Their distance to the resistant genes were 5.4 cM,26.1cM and 27.8cM respectively.