Genetic variability and gene flow in hybrid and wild populations of peach palm accessed with RAPD markers/Variabilidade genetica e fluxo genico em populacoes hibridas e silvestres de pupunha acessada com marcadores RAPD

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 [Belem (n = 26); Manaus (n = 38); Iquitos, Peru (n = 41); Yurimaguas, 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 Yurimaguas (Nm = 12.75), and between Iquitos and Manaus (Nm = 9.47) was high, while between Belem and Manaus it was lower than expected (Nm = 7.72), probably due to the influence of the Solimoes 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 Yurimaguas, and the eastern Amazonian, with Belem, joining in Manaus. However, these hybrid populations did not present an accumulation of genetic variability expressive enough to differentiate them from the landraces.