The reproductive mode of tetraploid Paspalum malacophyllum and its incidence in breeding programs

HOJSGAARD DH; MARTÍNEZ EJ; QUARIN CL

Buenos Aires

Simposio; The 6th International Symposium on the Molecular Breeding of Forage and Turf; 2010

Instituto Nacional de Tecnología Agropecuaria

Analysis about the mode of reproduction in tetraploid material of Paspalum malacophyllum have used different tools, and clasified this species in a contrary way as sexual or apomictic, obligate or facultative with different levels of expression. The aims of this work were examine the degree of sexual reproduction in five genotypes of P. malacophyllum. Three different tools were used in the analysis to assess the level of sexuality on three stages for character expression. The cytoembryologic observation of mature ovules show a 40% average in the proportion of sexual embryo sacs (haploid) on five genotypes, with a great variation (10 folds) ranging between 7.2% and 73%. This variation was practicaly absent on mature seeds analysis using flow cytometry, in which reduced values of sexual seeds -respect to that expected according the cytoembryologic data- ranging between 9.6% and 11.7% were found for all genotypes of P. malacophyllum. Finally, in fifty individuals obtained through free pollination seeds for each of the five genotypes, molecular genetic pattern by AFLP analysis show none of the progenie materials were product of a sexual event. These results correlate to other embriological and reproductive parameters, and indicate that aposporic embryo sacs in tetraploid races of P. malacophyllum are more efficient than meiotic ones, accentuating this tendency on progeny. It seems like a strongh selective presure again the sexual reproductive way is acting on this species to avoid generation of new recombinant individuals. This data are discussed considering previous studies and through his implications on the characterization of sexual materials in breeding programms.