Genetic variability and gene flow in hybrid and wild populations of peach palm accessed with RAPD markers

Abstract

The hybrid populations of peach palm (Bactris gasipaes Kunth) have accumulated genetic variability from adjacent landraces, which is expected to increase their variability. To test this hypothesis, 176 plants maintained in the peach palm Germplasm Bank at INPA, including four hybrid populations [Belém (n=26); Manaus (n=38); Iquitos, Peru (n=41); Yurimáguas, Peru (n=41)], two wild populations (B. gasipaes variety chichagui) types 1 (n=21) and 3 (n=7), and two samples of a related species, B. riparia, were genotyped with RAPD markers and compared to adjacent landraces reported in other studies. Eight RAPD primers generated 88 polymorphic and 11 monomorphic markers. The replicability test presented a Dice similarity of 0.67, considered acceptable. The average heterozygosity of the hybrid populations was 0.34 and the polymorphism was 87.9%, greater than in the wild populations (0.31; 74.7%). The dendrogram of Dice similarities did not present groups that clearly correspond to the hybrid populations. The gene flow between Iquitos and Yurimáguas (Nm=12.75), and between Iquitos and Manaus (Nm=9.47) was high, while between Belém and Manaus it was lower than expected (Nm=7.72), probably due to the influence of the Solimões landrace near Manaus. The high value of heterozygosity in Manaus seems to be the result of the union of two dispersals after domestication: the western Amazonian dispersal, with Iquitos and Yurimáguas, and the eastern Amazonian, with Belém, joining in Manaus. However, these hybrid populations did not present an accumulation of genetic variability expressive enough to differentiate them from the landraces.