Molecular Cytogenetic Identification Of Wheat-Thinopyrum Intermedium Hybrid Offspring 14-520

Common wheat (Triticum aestivum L. AABBDD,2n=6x=42) is one of the most important food crops in the world, and the improvement of common wheat is the key factor for the production of wheat. However, the genetic base of wheat in recent years has become more and more narrow along with the development of breeding, the increase of yield and quality of wheat has become difficult. On the other hand, the related species of wheat, Thinopyrum intermedium, has many excellent characters for wheat improvement, the distant hybridization between wheat and Th. intermedium not only enrich the genetic variability of wheat, but also creates a number of intermediate materials and for wheat breeding.The wheat line 14-520 was a stable material derived from the progeny of common wheat cultivar CM107 and Th.intermedium. The works of agricultural traits, chromosome number, chromosome structure in line 14-520 were carried out by cytological observation, genomic in situ hybridization, fluorescence in situ hybridization and plug marker and field agronomic trait analysis. The main results are as follows:1. Agricultural traits:The results of the field survey between line 14-520 and its recurrent parent CM107 indicated the effective tiller number and spikelet number of line 14-520 were more than those of CM 107, numerical values are more than 0.3 and 3. While the plant height, spike lengh and thousand kernel weight of line 14-520 were very different from those of CM 107.2. Chromosome number:Root-tip chromosome count showed that line 14-520 contained 2n=44 chromosomes, which suggested the chromosome number had changed, this line might be an alien addition line. The chromosome pairing observation using pollen mother cell at meiosis found that the 22 bivalents and no univalent were observed in meiotic metaphase I, which shows that the t line 14-520 was a genetic stable material.3. The chromosome structure:The genomic in situ hybridization (GISH) analysis using total DNA of Thinopyrum intermedium as probe indicated that there are two pairs of Th. intermedium chromosomes in line 14-520, of which one pair chromsomes is longer than the other pair. The GISH result using Pseudoroegneria spicata as probe further identified suggested that the pair of long chromosomes was St-Js chromosomes, and another pair of shorter chromosome was J chromosomes. The shorter Th. intermedium chromosomes were a pair of telocentric chromosome by centromeric repeats CCS1 probe analysis. The sequential fluorescence in situ hybridization (sequential in situ hybridization) were analysed the lines 14-520 chromosome structure using repeat sequence, pTa535 and pSc 119.2, as probes showed that one pair of 4D chromsomes in line 14-520 was absent. These results indicated one pair of Th. intermedium chromosomes substituted the 4D wheat chromosomes in line 14-520, and line 14-520 was a wheat-Th. intermedium substitution addition line.4. PLUG analysis:PLUG (PCR-based landmark unique gene) analysis was carried out on order to acertain which pair of Th. intermedium chromosomes substituted the 4D chromsomes. Only two PLUG primers, TNAC1403 and TNAC 1398 can amplified same band among line 14-520, Th. Intermedium and Ps. Spicata or Th. Bessarabicum and different band compared with the wheat caontrols. PLUG markers TNAC 1403 which located in 4DL12-0.71-0.86 did not amplify the specific fragments of wheat 4D chromosome, but the same specific segments of line 14-520, Th. intermedium, Ps. spicata and Th. Bessarabicum were produced. The specific fragments of 4D were also absent with PLUG markers TNAC1398 which located in 4DL12-0.71-0.86, however, a same fragments among line 14-520, Ps. Spicata and Th. Intermedium were produced. These results demonstrated that the 4D chromosomes of line 14-520 were substituted by Th. Intermedium telocentric chromosomes and the telocentric chromosomes were 4JL. Therefore, line 14-520 was a substitution addition line whose a pair of 4D chromosomes was substitued by a pair of 4JL telocentric chromosomes and one pair of St-Js chromosomes was added.