Chromosome Identification,Transmission And Comparative Genome Analysis Of Thinopyrum.ponticum In Wheat Background

Thinopyrum ponticum（2n=10x=70,JJJJJJJ^SJ^SJ^SJ^S）is one of the most widely used related species in wheat genetic improvement.It has excellent characters such as cold resistance,salt-alkali tolerance,luxuriant growth,multi-flower and multi-grains,resistance to a variety of wheat diseases（powdery mildew,Fusarium head blight,triple rust,etc.）and high protein.A material used in this study is wheat-Thinopyrum ponticum6J^S（6B）substitution line X005,which is derived from the hybrid progeny of Xiaoyan7430 and common wheat ML-13.It has good resistance to wheat stripe rust at mature stage.Another material is a wheat-Th.ponticum recombinant line A155（6Ae addition line）was provided by Professor Ian Dundas at University of Adelaide,Australia,which contained two genes of resistance to stem rust,Sr B and Sr26.This study mainly used multi-color non-denaturing fluorescecce in situ hybridization（mc-ND-FISH）and molecular markers for precise cytological and molecular identification of the derived progeny of materials X005 and A155,with aim to detect the translocation and transmission of Th.ponticum chromosomes in wheat background.Combined with the survey and statistics of agronomic traits,the application value of these offspring materials in wheat improvement is evaluated.The main results are as follows:1.By using（sequential mc-ND-FISH）,PLUG and IT molecular markers,we established the standard karyotypes for 6J^S and 6Ae by FISH and molecular marker.（1）The FISH signal patterns of the Oligo probes of 6J^S and 6Ae chromosomes were clearly clarified by multiply probes;（2）A total of 86 6J^S-specific and a total of 31 6Ae-specific molecular markers were obtained.Among them,12 pairs of markers showed polymorphism between 6J^S and 6Ae,which laid the foundation for the subsequent identification of chromosomal rearrangements.2.Through mc-ND-FISH and molecular markers,the cytological and molecular marker-assisted identification of the X005-irradiated M₃generation population were carried out,and the variation of chromosomes 6J^S and wheat chromosomes in X005 were calculated.The results showed that:（1）A total 17 types of large-segment translocations,small-segment translocations,whole-arm translocations,and 2 types long or short arm deletions about 6J^S were identified in the X005-irradiated M₃generation;（2）A total of288 wheat chromosomal translocation chromosomes were also identified,a total of 97were different types.These translocation chromosomes cover 7 homologous groups,and the chromosomes of fourth homologous group has the highest translocation frequency,while the chromosomes of first homologous group have the smallest translocation frequency.3.Through mc-ND-FISH,molecular markers,and field agronomic character surveys,two F₃ populations of crosses between X005 and MY11 and Taichang 29 were analyzed.The results showed that:（1）In the F₃ generation of the cross between X005 and MY11,7 types of wheat chromosome variation and 6 types of 6J^S variation types were identified;combined with the survey of agronomic traits,it was found that the translocation line material 6J^SL.6BL was significantly higher than its parent in terms of plant height,seed length,width and thousand-grain weight.（2）In the F₃ generation of the cross between X005 and Taichang 29,only 5 types of rearrangements between wheat chromosomes and4 types of 6J^S mutations were found.4.By mc-ND-FISH,field agronomic traits investigation and character mean correlation analysis of F₁ and part of F₂ generation from the cross between A155 and MY11,six 6Ae variant types were identified.It was found that chromosome 6Ae may carry genes related to plant height,spikelet number,grain width and 1000-grain weight,which can be easily expressed in wheat background.5.Through the statistics of the transmission rates of 6J^S and 6Ae in the above four populations,the results showed that:（1）the frequency of the whole 6J^S appeared in the progeny of X005 radiation was the highest,and the transmission rate of the whole 6J^S in wheat background Taichang 29 was 7.5%higher than that in Mianyang 11.（2）In the F₁generation of hybrid A155 and MY11,the transmission rate of the whole 6Ae chromosome was 44.61%,but the frequency of 6Ae long arm was higher than that of short arm.