Development And Characterization Of Triticum Aestivum-Hordeum Californicum Alien Chromosome Lines

The wheat production is often threatened by various biotic and abiotic stresses. The improvement of the resistances to diseases and pests, and the adaptabilities in various unfavorable environments is among those most important breeding objectives. Hordeum brachyantherum ssp californicum shows high resistences to barely yellow dwarf, powdery mildew and good tolerance to low nitrogen, freeze injury. The development of a set of chromosome addition lines, substitution lines and translocation lines will provide useful materials for localizing and transferring interested genes from H. californicum, as well as comparative genomic analysis between H. californicum and common wheat.On the basis of the obtained materials and results of Kong Fang (2006) and Yuan Jingya (2011), in the present research, by using the progenies from "Chinese spring (CS)/ CS-H. californicum amphiploid//CS" and "Yangmai 15/CS-H. californicum amphiploid (irradiated by 60Co-y rays)//Yangmai 15", Triticum aestivum-H. californicum alien chromosome lines were developed and characterized by using molecular cytogentics analysis、molecular markers analysis and morphological investigations. The main research results obtained were as follows:1. According to the previously established FISH-based karyotype of H. californicum chromosomes, GISH/FISH was used to identify wheat-alien chromosome lines by using the genomic DNA of T. aestivum L. cv. CS-H. californicum amphiploid, tandem repeat DNA squences 45S rDNA、5S rDNA、pSc119.2 and pAsl as probes. Alien addition lines and chromosome structural variations involving different H. californicum chromosomes were identified, including 4 disomic addition lines (DAH1、DAH3、DAH5、DAH6); 2 telosomic addition lines (MtH1S、MtH1L、MtH3S、MtH3L、MtH5S、MtH5L、MtH7L); 2 multiple addition lines involving chromosomes H2 and H7; and 1 disomic substitution line (DSH4). In addition,48 types of chromosome structure aberrants. Among them,14 were translocations between wheat and H. californicum chromosomes,21 were reciprocal translocation of H. californicum chromosomes,6 were alien iso-chromosomes and 7 were chromosomal deletions.2. In order to define the homoeologous relationship between chromosomes of H. californicum and those of wheat, a total of 3,204 EST-based and 747 SSR primer pairs previously mapped to the seven homoeologous groups of wheat and 182 rye SSR primer pairs were used to screen H. californicum chromosome specific markers by amplification in CS, CS-H.californicum amphiploid and Yangmai 15. Among them,482 could amplify H. californicum specific bands.3. Using the developed wheat-H. californicum alien chromosome lines, specific markers were allocated to seven H. californicum chromosomes, in which,47 markers to chromosome H1,50 to H2,45 to H3,49 to H4,21 to H5,51to H6 and 40 to H7, respectively. Chromosome structure aberrants were further characterized using these specific markers. The results indicated that 12 of these aberrants involving chromosome H1, 11 involving H3,4 involving H4,9 involving H5,9 involving H6, and 11 involving H7. By referring to the available location information of these specific molecular makers and the obtained results in the present research, the homoeologous relationship of chromosomes from H. californicum and those from wheat were determined. The chromosome arm H1S belongs to the homoeologous group 4 and could be designated as 4HL, and the chromosome arm H1L belongs to the homoeologous group 7 and could be designated as 7HL; the chromosome H2 belongs to the homoeologous group 5 and could be designated as 5H; the chromosome H3 belongs to the homoeologous group 2 and could be designated as 2H; the chromosome H4 belongs to the homoeologous group 6 and could be designated as 6H; the chromosome H5 belongs to the homoeologous group 3 and could be designated as 3H; the chromosome arm H6S belongs to the homoeologous group 4 and could be designated as 4HS, and the chromosome arm H6L belongs to the homoeologous group 7 and could be designated as 7HS; the chromosome H7 belongs to the homoeologous group 1 and could be designated as 1H.4. The powdery mildew resistance evaluation showed that CS-H. californicum amphiploid was highly resistant to powdery mildew disease, with a average disease score of 2-4 in the seedling stage and 1 in the audult stage. Among those identified alien chromosome lines, lines YJY7-2-7-14-46, PH-19-14-21 and PH-19-14-5, in which chromosomes 6H,2H or 2HL was introduced, showed similar resistance level as the CS-H. californicum amphiploid in both growth stage. This indicated that chromosmes 2H and 6H may carry the powdery mildew resistance genes.