Molecular And Cytogenetic Identification Of Triticum Aestivum-Leymus Racemosus Translocation Lines Involved In Leymus Racemosus Chromosome 7Lr

Wheat scab(Fusarium head blight, FHB) is one of the most disastrous diseases in the warm and humid wheat-growing areas of the world. Development and utilization of resistant cultivars in wheat production has been considered as the most economical and effective strategy. The scab-resistance resource of wheat in current breeding programs is particularly limited, because only a few resources, such as Sumai 3 and its derivatives. Exploitation of new resistance resources is an urgent task. Leymus racemosus (2n=4x=28) is a wild perennial relative of wheat and is resistant to FHB. The introduction of new resistance genes from Leymus racemosus to wheat will be useful to broad the genetic base for FHB resistance breeding in wheat. Two T.aestivum-L.racemosus disomic addition lines DA7Lr#1 and DA5Lr#1 resistant to FHB were previously developed by the Cytogenetics Institute, Nanjing Agricultural University.The pollen of T.aestivum-L.racemosus monosomic alien addition line MA7Lr#1 was irradiated using 60 Co-y ray to produce various chromosomes structural changes by LS Wang. Based on the materials, molecular cytogenetic analysis was used to detect four T.aestivum-L.racemosus translocation lines, two of them, NAU639 (T2AS-2AL-7Lr#1S) and NAU640 (T7BS-7Lr#1S) with wheat scab resistance.1 NAU639 (T2AS-2AL-7Lr#1S) and NAU640 (T7BS-7Lr#1S) with wheat scab resistance were identified by chromosome FISH-GISH, C-banding, and molecular markers analysis. The evaluation of scab resistance showed that the two translocation lines had higher resistance than susceptible parent C.S, and the resistance was stable in multiple years. So NAU639 (T2AS-2AL-7Lr#1S) and NAU640 (T7BS-7Lr#1S) provide new genetic resources for breeding of the scab-resistance wheat.2 A total of 234 STS primers were designed based on EST sequences distributed on group-7 chromosomes of Triticum aestivum. The PCR results showed that 40 of the 234 primers could amplify polymorphism bands between Triticum aestivum cv. C.S and Leymus racemosus. Among the 40 markers,16 pair of primers (located on the short arm of homoelogous group 7 of wheat) could amplify the same Leymus racemosus-specific bands between DA7Lr#1 and DA5Lr#1. However, only 4 (located on the long arm of homoelogous group 7 of wheat) could amplify the Leymus racemosus-specific bands from the DA7Lr#1. The results suggested that 5Lr could be a translocation chromosome involved the short arm of chromosome 7Lr#land chromosome 5Lr#1 in this study.16 specific EST-STS markers for 7Lr#1S will play an important role in the mapping of the scab resistance gene Fhb3 and molecular assisted selection in the disease resistance breeding.