Identification of male-specific AFLP markers in dioecious Texas bluegrass

Dioecy is a breeding system that promotes cross-pollination in plants. The transfer of this trait into economically important self-pollinated cereal crops would revolutionize the production of hybrids in these species and provide a means for increasing yields because of heterosis. Texas bluegrass (Poa arachnifera Torr.) (2n = 8x = 56) is a polymorphic dioecious species that provides an opportunity to genetically map the dioecy locus. In this study, amplified fragment length polymorphism (AFLP)-based linkage maps were constructed for both the maternal and paternal plants used to develop a mapping population of Texas bluegrass. The maternal map contained 126 single dose restriction fragments (SDRFs), 31 linkage groups, 1744 cM, and an average marker spacing of 13.8 cM. The paternal map contained 210 SDRFs, 46 linkage groups, 2699 cM, and an average marker spacing of 12.9 cM. Approximately 76 to 81% of the Texas bluegrass genome was covered. Two AFLP markers (txbg7 and txbg154) mapped equidistantly (9.5 cM) on opposite sides of the dioecy locus (PDio1) on the paternal map. These markers provide a preliminary tool for studying sex determination and a framework for further characterization of the genomic region conferring dioecy in Texas bluegrass.