Genetic Analysis of Kentucky Bluegrass and Their Offtypes.

Kentucky bluegrass (Poa pratensis L.) is an economically and agronomically important turfgrass in cool season climates. In addition, Kentucky bluegrass is a facultative apomict, and through apomixis, is able to propagate odd ploidy levels that result in many genetically distinct phenotypes. One of these phenotypes results from (poly)haploids generated from reduced egg cells through parthenogenesis. Flow cytometry of somatic tissue was performed to identify polyhaploids among a set of Kentucky bluegrass crosses from different maternal and paternal backgrounds. The frequency of polyhaploids varied depending on the maternal background. It was observed that the polyhaploids were usually, but not always in some maternal backgrounds, slow growing and weak as compared to parents and apomictic siblings. The frequency of polyhaploids was also correlated to the number of other apomictic offtypes (such as B_II hybrids) that may be useful in Mendelian selection.