INHERITANCE OF PARENTAL GENOMES IN PROGENIES OF POA PRATENSIS L. FROMSEXUAL AND APOMICTIC GENOTYPES AS ASSESSED BY RAPD MARKERS AND FLOW-CYTOMETRY

Moving gene(s) responsible for the apomictic trait into crop plants th at naturally reproduce through a sexual process would open up new area s in plant breeding and agricultural systems. Kentucky bluegrass (Poa pratensis L.) is one of the most important forage and turf grasses in temperate climates. It reproduces through facultative aposporous parth enogenesis, but the reproductive behaviour ranges naturally from nearl y obligate apomixis to complete sexuality. In addition to apomictic re production, sexual hybridization may take place. Selfing may also occu r, and occasionally reduced egg cells may develop through parthenogene sis generating (poly)haploids. The inheritance of parental genomes was assessed in Kentucky bluegrass progenies by employing RAPD markers in combination with flow cytometry (FCM). Nine progenies from different crosses carried out between completely sexual and highly apomictic gen otypes were evaluated in order to probe the reproductive behaviour of the mother plants and to distinguish the different classes of aberrant plants. Not only were maternals and balanced B-II hybrids recorded, b ut so were (poly)triploid B-III hybrids, selfs, and (poly)haploids. Th e application of these techniques demonstrated that FCM analysis accur ately distinguishes the n, 2n, and 3n ploidy levels of progenies, and that RAPD markers unequivocally recognize progenies of apomictic and h ybrid origin. The occurrence of aneusomaty was documented in one of th e selected sexual genotypes, whose crossed progeny plants manifested t wo distinct classes of ploidy. The nomenclature B-I was adopted to ref er to hybrids with a hypodiploid nuclear condition. On the whole, the FCM analysis confirmed most of the RAPD data. The combined evaluation of DNA markers and DNA contents proved to be an efficient screening to ol for scoring maternal plants, assessing the genetic origin of aberra nt plants, and quantifying the inheritance of parental genomes in Kent ucky bluegrass. Hybrid populations from sexual x apomictic matings tha t segregate for the mode of reproduction represent a valuable basis fo r attempting to identify molecular markers linked to the apomixis gene (s).