GENETIC-VARIABILITY AND MATING SYSTEM IN 3 SPECIES OF THE GENUS CENTROSEMA

The genus Centrosema includes several species both potentially and cur rently useful as pasture and fodder crops in tropical and subtropical areas, Genetic variability, population genetic structure, and the mati ng systems of three species of this genus, C, acutifolium, C. brasilia num, and C, pubescens have been studied using isozyme (17 loci) and DN A markers (random amplified polymorphic DNA and rDNA intergenic spacer length polymorphism), Both kinds of markers discriminate populations belonging to different species, Outcrossing rates and other experiment al parameters have been determined in populations of an active germpla sm collection outside the species native habitat, Populations of all t hree species showed relatively high polymorphism and heterozygosity, a nd total genetic diversity was higher within than between populations, The mating system parameters indicated that outcrossing was higher th an expected in the three species, previously considered as being predo minantly selfers. The multilocus analysis carried out in C, acutifoliu m provided estimations of the outcrossing rate ranging from 0.27 to 0. 41 among populations; estimations carried out from the fixation index in the other two species also suggested relatively high outcrossing ra tes, These species should be considered species with mixed mating syst ems, and this fact should be taken into consideration in further breed ing programs and germplasm conservation.