Selection And Identification With In Situ Hybridization Of Derivatives Derived From Thinopyrum Ponticum

Thinopyrum ponticum(2n=10x=70,StStStStE~eE~eE~bE~bE~xE~x or JJJJJJJ~SJ~SJ~SJ~S)is one of the most widely used relatives in wheat genetic improvement due to its drought resistance,cold resistance,saline-alkali resistance and resistance to a variety of wheat diseases.Our laboratory created many Trititrigia germplasms with different characteristics from crosses between Th.ponticum and common wheat.On the basis of previous work,twenty-five Trititrigia germplasms were selected in the present study by means of identification of their field phenotype and resistance to powdery mildew.Genomic DNA of Th.ponticum genomic was used as probe,genomic DNA of Yannong 15 was used as blocking for genomic in situ hybridization(GISH)identification,and further fluorescence in situ hybridization(FISH)identification was carried out.In situ hybridization was also used to analyze their chromosomal composition and variations.Those Trititrigia germplasms facilitate the further study and utilization.1.Evaluation of powdery mildew resistance.Infected with the isolate E20 at the seedling stage,B18305-6,B18526-5-1,B18526-8-2 and B18526-8-4 showed nearly immunity,B18526-9-1,B18526-16-1,B18526-28-2,B18526-29-2 showed high resistance,and B18307-6 and B18526-20-2 moderate resistance.At the adult stage,all of the ten Trititrigia germplasms were nearly immunity.At the both stage,the common wheat parents were susceptible while the parent Th.ponticum immune,indicating that resistance in the the ten Trititrigia germplasms may derive from Th.ponticum.2.Identification of an addition line.GISH showed that B18307-6 was a disomic alien addition line.Fluorescence in situ hybridization(FISH),based on oligonucleotide multiplex containing[AFA-3?AFA-4?pAs1-1?pAs1-3?pAs1-4?pAs1-6?pSc119.2-1?(GAA)10],was used to detect chromosomal structure variations.The results showed that some hybridization signals disappeared on some chromosomes of B18307-6 compared with those of the parents Shannong TE20 and Shanong637,such as disappearance of the red signal in the middle of the long arm of chromosome 1A and the red signal at the end of the short arm and near the centromere of chromosome 2A.Structural variation also occurred on the chromosomes 7A and 1D.3.Identification of a substitution line.GISH showed that B18305-6 was a disomic alien substitution line.The further results of FISH showed that a pair of chromosomes 7D were absent.Compared with the parents Shannong TE20 and Shanong637,chromosomal structure of B18305-6 was found to have changed,such as disappearance of the green signal near the centromere of 2A and the red signal at the end of 1DS.4.Identification of translocation lines.GISH and FISH showed that B18526-8-2 and B18526-8-4 were T1BL·1BS-Tp translocation lines(Tp stands for chromosome fragments of Th.ponticum);B18526-9-1 and B18526-29-2 were T3DL·3DS-Tp translocation lines.The FISH results showed that chromosomes 1A,2A,5A,6A,7A,1B,2B,3B,6B,7B,1D,2D and5D of B18526-8-2,5A,6A,1B,2B,3B,6B,1D and 2D of B18526-8-4,1A,2A,7A,1B,2B,6B,7B,1D and 2D of B18526-9-1,1A,2A,6A,7A,1B,2B,6B,7B and 5D of B18526-29-2were different from those of the common wheat parent Yannong15.There were also differences in chromosomal structure variation between the four translocations,so they were different from one another.5.Identification of introgression lines.GISH showed that there was no hybridization signal in 19 germplasms,indicating that they were Trititrigia introgression lines.The FISH results showed that chromosomes 1A,6A,7A,1B,2B,5B,6B and 5D of B18526-5-1,1A,2A,6A,7A,2B and 6B of B18526-16-1,1A,2A,4A,6A,7A,2B,7B,1D and 2D of B18526-20-2,1A,2A,6A,7A,2B and 6B of B18526-28-2 were different from those of their parent Yannong15.Differences of FISH signals and phenotype suggested that they were different one another.