Identification Of Several Translocation Lines Derived From Wheat And Different Inbred Rye Lines By Molecular And Cytogenetical Methods

Wheat(Triticum aestivum L.) is one of the most important food crops and possesses about 8000 years of cultivation history. Breeders around the world have conducted in-depth study on wheat and have made remarkable achievements in wheat breeding and genetic improvement. Due to long-term directional selection in breeding, artificially bred varieties of large scale and single cultivation, genetic base of wheat is more and more narrow, genetic diversity is losing gradually and an harmful consequences in wheat production is that wheat is more sensitive to the stress of the outside, especially the resistance to pests and diseases declined significantly.Rye is one of wheat relative species and possesses extensive genetic variation. Rye is important genetic resources to modify disease resistance, quality and yield of wheat. Transfering excellent genes from rye into wheat background is the most effective method to improve wheat. The wheat-rye 1BL.1RS translocation chromosomes have been used widely around the world in commercial wheat(Triticum aestivum L.) production because of the presence of several disease resistance genes and a yield enhancement factor on the rye(Secale cereale L.) chromosome 1R. However the recent reports of the loss of complete effectiveness of the disease resistance genes on the most commonly used 1BL.1RS chromosome have highlighted the need to seek and deploy additional sources of disease resistance genes.In this paper, BC2F5 progeny derived from cross between common wheat MY 11 and rye inbred lines R12 and R3 were studied by molecular cytogenetics methods, including chromosome count, C-banding, genomic in situ hybridization (GISH), A-PAGE and molecular markers. Results are as follows:1. All the root tip cells of wheat lines contained 42 chromosomes. This result indicates that these materials are cytogenetically stable.2. Giemsa C-banding analysis indicated that wheat lines 95I-219-4 and 95I-115 contained one pair of 1RS/1BL translocation chromosomes.3. With rye centromere specific primer cen-2 for molecular identification, specific band were amplified in the translocation lines. This shows that wheat lines 951-219-4 and 951-115 are whole arm translocation with centromere.4. The result of genomic in situ hybridization (GISH) revealed that there were strong fluorescence signals in the same cells after the Giemsa C-banding analysis in wheat lines 951-219-4 and 951-115. Meanwhile the cells had no fluorescence signals in the other wheat lines. The result is consistent with Giemsa C-banding.Therefore,identification of the centromere, GISH analysis, and Giemsa C-banding analysis have proven wheat lines 951-219-4 and 951-115 contain the complete IRS chromosome arm.5. Identification of A-PAGE, the seeds of 1RS/1BL translocation lines 951-219-4 and 951-115 had specific bands of Alkali. This suggests gene Sec-1 expresses in normal.6. Resistance identification showed that the disease resistance of the distant hybridization progenies had changed greatly during the fifteen years after these materials were bred. The 1RS/1BL translocation lines 951-219-4 and 951-115 had developped high sense from highly resistant to stripe rust. The result indicates that continuously developping new wheat heterologous translocations is essential to the keeping of good resistance.7. The results of agronomic traits assessment indicated that, there were obvious differences between wheat lines derived from rye inbred lines R3 and the parent material MY 11,and new characters were produced. This suggests all the 17 wheat lines contain exogenous chromatin. The paper discusses the method to further identification for these exogenous DNA of the possible translocations.