Relación genómica entre citotipos diploides de Paspalum simplex y P. procurrens (Poaceae: Paniceae)

FRANCISCO ESPINOZA; QUARIN, C. L.

DARWINIANA

INSTITUTO DE BOTÁNICA DARWINION

Lugar: Buenos Aires; Año: 1998 vol. 36 p. 59 - 63

0011-6793

Interspecific crossing was conducted between diploid cytotypes of two Paspalum species of the subgenus Anachyris in order to investigate their genomic relationship and to evaluate the possibilities of gene exchange between these species as a tool for their genetic improvement. Paspalum simplex was the female parent. The F1 hybrids showed stoloniferous growth habit which is characteristic of the male parent, P. procurrens. Regular meiotic behavior in the F1 hybrids demonstrated that both species have significant homology in their genomes. Embryological studies and seed production analysis under self- and cross-pollinated conditions demonstrated that the hybrids, like their parents, are sexual and self-sterile but cross-compatible. Both, the high level of crossabitity of the parents and the degree of fertility observed in F1 hybrids and in backcross progenies, indicated the feasibility of gene exchange between these species. Morphologically, P. simplex and P. procurrens are easily recognized as different species. Notwithstanding, the high crossability and the high level of fertility observed in hybrids and backcrossed progenies contrast with the lack of intermediate forms observed in herbaria and during field trips. Diploid cytotypes of both species seem to be restricted to western areas of the phytogeographic Chaco province, from Bolivia to Argentina. However, divergent evolution likely occurred in correlation with latitude and specific soil requirements. Diploid P. simplex was found in the southwestern Chaco province on clayey soil while P. procurrens was collected in the northwest of the province, growing on sandy soil.