Molecular Cytogenetics Analysis of Backcrossing Progenies of the Irradiated Triticum Aestivum-Hordeum Californicum Amphiploid
|School||Nanjing Agricultural College|
|Course||Crop Genetics and Breeding|
|Keywords||H. californicum amphiploid GISH/FISH karyotype Alien Chromosome Lines EST markers Powdery mildew|
H. br achy anther um ssp californicum confers lower Nitrogen tolerance and multiple disease resistances and other useful characters, represents an important resource for wheat improvement. Discrimination of seven pairs of H. californicum chromosomes and development of chromosome-specific markers will be useful for the development of wheat-H, californicum alien chromosome lines for further utilization in wheat improvement. Using genomic DNA of T. aestivum L. cv. Chinese spring (CS)-H. californicum amphiploid, tandem repeat squences 45SrDNA,5SrDNA and rye repetitive pSc119.2 as probes, FISH-based karyotype of H, californicum chromosomes in the T. aestivum L. cv. Chinese spring (CS)-H. californicum amphidiploid was established. A total of 2546 EST-based and 747 SSR primer pairs previously mapped to 7 homoeologous groups of wheat and 243 EST-based primer pairs from barley were used for screening specific markers for H. californicum via amplifying between Chinese spring, CS-H.californicum amphiploid and Yangmai 15. Among them,347 were found to be able to amplify specific bands of H. californicum. Establishment of FISH-based karyotype and development specific molecular markers of H. californicum chromosomes provided the foundation of discrimination and tracing of seven pairs of H. californicum chromosomes in the wheat background.To development Triticum aestivum-H. californicum alien chromosome lines and induction the structural rearrangement between chromosomes of T. aestivum and H. californicum, the pollens of CS-H. californicum amphiploid were irradiated by 60Co-y and crossed to a emasculate elite wheat variety Yangmai 15, then backcrossed and self-fertilized. Among the obtained BC1F2 progenies, alien addition lines and chromosome structural variations involving different H. californicum chromosomes were identified by FISH and molecular markers, i.e.1 disomic addition (DAH4),3 monosomic addition (MAH3; MAH1; MAH4),1 alien translocation line (H7S/1BL), and many multiple addition lines except chromosome H2 and H3.Using the developed alien chromosome lines, specific markers were located on specific H. californicum chromosomes, in which 18 markers were on chromosome H1,10 were on H4 and 8 were on H5. Accordingly, we deduce that H1S belongs to the wheat homoeologous group 4, H1L belongs to the wheat homoeologous group 7; the H4 chromosome belongs to the wheat homoeologous group 6 and could be designated as 6H; H5 belongs to the wheat homoeologous group 3 and could be designated as 3H.The identified alien chromosome lines were evaluated for powdery mildew resistance. The results showed that only alien addition lines DA6H showed improved powdery mildew resistance, indicating that chromosome H4 (6H) might carry the powdery mildew resistance gene of H. califronicum, while chromosome H1,3H, H6 and H7S might not carry the powdery mildew resistance gene or major locus.