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báo cáo khoa học: " Transmission ratio distortion results in asymmetric introgression in Louisiana Iris"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Transmission ratio distortion results in asymmetric introgression in Louisiana Iris | Tang et al. BMC Plant Biology 2010 10 48 http www.biomedcentral.com 1471-2229 10 48 BMC Plant Biology RESEARCH ARTICLE Open Access Transmission ratio distortion results in asymmetric introgression in Louisiana Iris Shunxue Tang1 2 Rebecca A Okashah1 Steven J Knapp1 Michael L Arnold3 Noland H Martin4 Abstract Background Linkage maps are useful tools for examining both the genetic architecture of quantitative traits and the evolution of reproductive incompatibilities. We describe the generation of two genetic maps using reciprocal interspecific backcross 1 BC1 mapping populations from crosses between Iris brevicaulis and Iris fulva. These maps were constructed using expressed sequence tag EST - derived codominant microsatellite markers. Such a codominant marker system allowed for the ability to link the two reciprocal maps and compare patterns of transmission ratio distortion observed between the two. Results Linkage mapping resulted in markers that coalesced into 21 linkage groups for each of the reciprocal backcross maps presumably corresponding to the 21 haploid chromosomes of I. brevicaulis and I. fulva. The composite map was 1190.0-cM long spanned 81 of the I. brevicaulis and I. fulva genomes and had a mean density of 4.5 cM per locus. Transmission ratio distortion TRD was observed in 138 48.5 loci distributed in 19 of the 21 LGs in BCIB BCIF or both BC1 mapping populations. Of the distorted markers identified I. fulva alleles were detected at consistently higher-than-expected frequencies in both mapping populations. Conclusions The observation that I. fulva alleles are overrepresented in both mapping populations suggests that I. fulva alleles are favored to introgress into I. brevicaulis genetic backgrounds while I. brevicaulis alleles would tend to be prevented from introgressing into I. fulva. These data are consistent with the previously observed patterns of introgression in natural hybrid zones where I. fulva alleles have been consistently shown to .