MOLECULAR MAPPING OF SEGREGATION DISTORTION LOCI IN AEGILOPS TAUSCHII

Distorted segregation ratios of genetic markers are often observed in progeny of inter-and intraspecific hybrids and may result from competi tion among gametes or from abortion of the gamete or zygote. In this s tudy, 194 markers mapped in an Aegilops tauschii F-2 population were s urveyed for distorted segregation ratios. Region(s) with skewed segreg ation ratios were detected on chromosomes 1D, 3D, 4D, and 7D. These di storter loci are designated as QSd.ksu-1D, QSd.ksu-3D, QSd.ksu-4D, and QSd.ksu-7D. Three regions of segregation distortion identified on chr omosome 5D were analyzed in two sets of reciprocal backcross populatio ns to analyze the effect of sex and cytoplasm on segregation distortio n. Extreme distortion of marker segregation ratios was observed in pop ulations in which the F-1 was used as the male parent, and ratios were skewed in favor of TA1691 alleles. There was some evidence of differe ntial transmission caused by nucleocytoplasmic interactions. Our resul ts agree with other studies stating that loci affecting gametophyte co mpetition in male gametes are located on 5DL. The distorter loci on 5D L are designated as QSd.ksu-5D.1, QSd.ksu-5D.2, and QSd.ksu-5D.3.