Identification Of Exotic Germplasm From Wheat-rye Hybrid Descendant By Molecular Cytogenetics

Wheat(Triticum aestivum L.) is the second-largest food crop after the rice, which plays an important role in ensuring Chinese food supply. Stripe rust(yellow rust)is one of the most devastating diseases of wheat in the world. This disease caused great losses whenever it goes out of control. The best strategy to control stripe rust is to breed resistant cultivars. But for a long time, the concentration on using single disease-resistant parent has caused genetic variation of wheat diminish. Thus, there is a very urgent need for introduct choiceness gene into wheat. Rye is one of allied species of wheat. It is an important genetic resource, which is rich in favorable genes to improve wheat. Creating translocation that contains aimed characterized gene by chromosome engineering is the most effective method of using those genetic resources.1RS/1BL translocation plays a significant role in the past. But the advent of new stripe rust isolates cause the resistence of traditional1RS/1BL translocation lost. Therefore, the further use of the genetic resources of rye and developing new lines became the key of wheaten breeding.In this paper, between common wheat cultivar Mianyang11(high susceptible to stripe rust) and an inbred line baili rye (immune to stripe rust),53materials were bred from different vintages. To identify the exotic germplasm in those materials, molecular cytogenetics methods including specific PCR (ASPCR), chromosome count, C-banding, genomic in situ hybridization (GISH), A-PAGE were used. Results are as follows:1. Based on the rye-specific repetitive sequence of pSc20H, a series of PCR primer was designed and used to screen the200single-plant,98-1054-11-9-5-1,98-1054-15-15-1-4,98-1054-09xuan-4-1,98-1054-09xuan-4-2,98-1054-09xuan-7-1were found contain chromosome segments of rye.2. The result of chromosome counts of root-tip cells, all lines except98-1054-09xuan-4-2contained42chromosomes, some of plants of98-1054-09xuan-4-2contained43 chromosomes. This indicate most of materials are cytogenetically stable.98-1054-09xuan-4-2may be monosomic alien addition lines.3. Giemsa C-banding analysis indicated that98-1054-11-9-5-1contained a pair of1RS/1BL translocation chromosomes.98-1054-09xuan-4-2have one more chromos-ome. It may be6R chromosome of rye.4. The result of GISH shows that there were strong fluorescence signals in a pair of short arm of chromosome of98-1054-11-9-5-1. All of the signals were located on one chromosome in98-1054-09xuan-4-2. And, there was strong fluorescence signal in one short arm of chromosome of98-1054-09xuan-4-1.5. Identification of A-PAGE,98-1054-11-9-5-1had specific bands of Alkali, its gene Sec-1expresses in normal.6. By extensive phenotyping in the field, it discovered that MY11was highly susceptible to stripe rust, five materials were immune and residual materials were high resistant to stripe rust. In other cases, there were obvious differences between the parents and53materials. This suggests that all materials contain exogenous chromatin. Two single-plant from98-1054-11-9-5-1were near-isogenic lines possibly.The research showed that98-1054-11-9-5-1is a1RS/1BL translocation, which contains a new gene resistant to stripe rust. It can be used as a good breeding material.98-1054-09xuan-4-2is monosomic alien addition lines.