The Analysis Of Repeat Sequences And Development Of Specific Molecular Markers For Chromosome 1St Of Thinopyrum Intermedium Ssp. Trichophorum

Thinopyrum intermedium(2n=6x=42, JJJsJsStSt), is a very important wild relative species of Triticum. As the third gene pool for wheat, it is a quite valuable donor for quality improvement, since it has many valuable genes and high ability to adapt to the stressful environment. Compaired with common Th. intermedium species, Thinopyrum intermedium ssp. trichophorum is a new subspecies. Except the performance of hairs covering the panicle and leaf in Th. intermedium ssp. trichophorum, it also has a very significant difference on chromesome bands in the heterochromatin of chromosome. Besides, it is immune to rusts and can also be resistant to fusarium head blight.The object of this paper focused on two aspects. Firstly, we attempted to investigate the composition and distribution character of tandem repeats in the chromosome 1St genome of Th. intermedium ssp. trichophorum by analyzing parts of the genomic sequences obtained by high-throughput sequencing. Secondly, we developed some molecular markers for deteting specific 1St chromosome or arms in wheat background.The detailed contents and results in this study were as follows:1 Total 1,390 microsatellite repeat sequences and 435 minisatellite repeat sequences were identified in the chromosome 1St genome of Th. intermedium ssp. trichophorum.2 In microsatellite repeats, the dinucleotides were the most rich type, the following type was trinucleotides, mononucleotides, tetranucleotides, pentanucleotides and hexanucleotides. In mononucleotides repeat type, the A repeat class was the dominant repeat class. The repeat number of the AT repeat class was the most rich in dinucleotides repeat type, the following repeat classes were the AC and AG. The AAT repeat class was the dominant repeat class in trinucleotides repeat type. The frequency distribution character of the dinucleotide repeats was centralized in a middle-leaning-left position. It was similar to the normal distribution.3 The most rich type of repeats were trinucleotides and tetranucleotides in minisatellite repeats, accounting for 90.7% of total minisatellite repeat numbers. The fourteen-nucleotides was the most common type in minisatellite repeats. All of minisatellite repeats were rich of A/T repeat class. The length of repeat units was between 7bp and 36 bp, mainly between 7bp and 25 bp. We also found that the number of repeat sequences was degressive mainly, following the increase of the copy numbers of the repeat unit.4 We developed 359 specific fragments of chromosome 1St from Th. intermedium ssp. trichophorum using SLAF-seq technique, and randomly selected 114 fragments to design specific primers. Futhermore, we amplified them by polymerase chain reaction(PCR). And then, we detected PCR products by non-denaturing polyacrylamide gel electrophoresis. Finally 37 1St arms-specific molecular markers were obtained, with the efficiency up to 32.46%. All the newly developed molecular markers could amplify the specific bands in different lines derived from wheat-Th. intermedium ssp. trichophorum progenies.