Multiple structural aberrations and physical mapping of rye chromosome 2R introgressed into wheat

Abstract

Multiple structural aberrations produced by chromosome breakage and reunion not only provide new germplasm for enriching genetic diversity but are also helpful for physical mapping of alien chromosomes introgressed into wheat. In this study, mass structural aberrations of rye chromosome 2R were induced by means of spontaneous breakage and reunion, gametocidal chromosome action and irradiation. A total of 88 chromosome 2R aberrations were identified in 65 plants. From the self-pollinated progenies of plants carrying these aberrations, 19 stable lines with different segments of chromosome 2R which included seven whole arm, six small segmental and three large segmental translocations, one deletion and two ditelosomic additions, were subsequently identified and characterized using cytogenetic and molecular markers. Based on these lines, 88 markers specific for chromosome 2R were physically mapped to 13 different blocks of 2R with three in arm 2RS and 10 in arm 2RL. The powdery mildew resistance gene PmJZHM2RL was located to a region corresponding to the block 2RL-7. A total of eighteen 2R-specific EST markers were located in the same block where ten were derived from genes that were up-regulated during powdery mildew infection. Potential use of these stable aberrations and the colinearity of chromosome 2R with corresponding chromosomes in the other model monocot species were discussed.