Identification Of Wheat-Thinopyrum Intermedium Germplasms Resistant To Powdery Mildew Using In Situ Hybridization And IT Markers

Thinopyrum intermedium?2n=6x=42,JJJ^SJ^SStSt?E^eE^eE^bE^b StSt?is one of the most widely-used species in wheat genetic improvement due to its tolerance to drought,cold,salt and alkali,and resistance to various wheat diseases.Based on field investigation and powdery mildew resistance evaluation,nine wheat-Thinopyrum intermedium germplasms were developed and selected from the cross and backcross progenies?BC₂F₆?of Th.intermedium with common wheat Yannong 15.The chromosome compositions and variation characteristics of them were analyzed by in situ hybridization and molecular markers,which can facilitate their further utilization in wheat breeding.The main results are as follows:1.Disease testing showed that germplasm lines B2017003-2,B2017004-3,B2017005-1,B2017062-5,B2017011-1,B2017017-2,B2017018-1,B2017063-17 and B2017064-39 were nearly immune to powdery mildew at adult stage.After infected with the strain E20 at seedling stage,eight of them were immune or highly resistant except B2017004-3 showed moderate resistance.2.Genomic in situ hybridization?GISH?was carried out on lines B2017003-2,B2017004-3,B2017005-1 and B2017062-5,using genomic DNA of Thinopyrum intermedium as a probe and genomic DNA of Yannong 15 as a blockade.No genetic material of Th.intermedium was detected.Further identification by fluorescence in situ hybridization?FISH?based on complex oligonucleotide probe sets[AFA-3,AFA-4,pAs1-1,pAs1-3,pAs1-4,pAs1-6,pSc119.2-1,and?GAA?₁₀]showed that chromosomes 5A,5D,6B,7B of B2017003-2,7B of B2017004-3,5A and 6B of B2017005-1 and 5A and 6A of B2017062-5were different from those of Yannong15.Intron tatgeting PCR?IT-PCR?showed that 4,8,11 and 12 pairs of IT primers originating from the chromosome homologous group two could amplify specific band of Th.intermedium in B2017003-2,B2017004-3,B2017005-1 and B2017062-5,respectively,indicating that these four lines were the introgressive lines of wheat-Thinopyrum intermedium,and all of them contained genetic materials derived from chromosome homologous group two of Th.intermedium.3.GISH using the genomic DNA of the Pseudowroegneria strigosa as a probe and genomic DNA of Yannong 15 as a blockade showed that B2017011-1,B2017017-2,B2017018-1 and B2017018-1 contained 40 wheat chromosomes and 2 J-genomic chromosomes of Th.intermedium,while B2017064-39 contained 42 wheat chromosomes and2 J-genomic chromosomes of Th.Intermedium.FISH results showed that chromosoems 2D,6B and 7A of B2017011-1,1A,2D and 6B of B2017017-2,2D and 6B of B2017018-1,1A,2D and 6B of B2017063-17,1B,2A,2B,2D,6A and 6B of B2017064-39 were different from those of Yannong 15.IT-PCR analysis showed that 9,9,11,16 and 17 pairs of IT primers derived from chromosome homologous group two could amplify specific bands of Th.intermedium in the five materials mentioned above,respectively,indicating that the J genome chromosomes were 2J.The above results showed that B2017011-1,B2017017-2,B2017018-1and B2017063-17 were different 2J?2A?disomic substitution lines,and B2017064-39 was a2J disomic addition line.