IBONE   05434
INSTITUTO DE BOTANICA DEL NORDESTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Reproductive behavior of interespecific hybrids among two forage species of the Plicatula group of Paspalum.
Autor/es:
AGUILERA PM; GALDEANO F; ORTIZ, J. P. A.; QUARIN CL; ESPINOZA, F
Lugar:
Buenos Aires
Reunión:
Simposio; The 6th International Symposium on the Molecular Breeding of Forage and Turf; 2010
Resumen:
Plicatula group is an informal subgeneric taxonomic rank that includes approximately 35 species morphologically related to P. plicatulum. Available information indicates that diploid and tetraploid cytotypes usually occur in species of this group.  Tetraploids are apomictic (4xA) and diploid counterparts reproduce sexually (2xS). The different ploidy levels and the absence of sexual plants among apomictic tetraploid populations make sexual×apomictic crosses a difficult task in breeding programms. Our research team recently obtained 4x sexual plants (4xS) by chromosome doubling in diploid sexual genotypes of P. plicatulum. The objectives of this study were: to perform interspecific crosses between the induced 4xS plant (female parent) and 4xA (male parent) of P. guenoarum; to establish whether the F1 progeny produces seed; and to determinate the reproductive mode by flow cytometric seed screens (FCSS) for each hybrid. The results indicated that all F1 hybrids set seed, and hence all were fertile. Twenty to seventy seeds were analyzed by FCSS taking bulks of 5 for each one of 117 F1 hybrids. Eighty individuals showed exclusively 2:3 embryo/endosperm ratios and were classified as sexual, while 37 yielded seeds mainly with 2:5 embryo/endosperm ratio and reproduced by apomixis. The degree of apomixis was determined by flow cytometry of single seeds in the 37 apomictic F1 hybrids, and ranged from 88.5 to100%. These 37 interspecific P. plicatulum × P. guenoarum hybrids have two important agronomic qualities: all are fertile and all are highly apomictic. Both species have good forage potential and now selection may be conducted among these 37 hybrids in order to add forage quality, seed production and apomictic reproduction as a key for genetic stability.