Variabilidade genética e fluxo gênico em populações híbridas e silvestres de pupunha acessada com marcadores RAPD

Abstract

RESUMO -As populações híbridas de pupunha (Bactris gasipaesKunth GENETIC VARIABILITY AND GENE FLOW IN HYBRID AND WILD POPULATIONS OF PEACH PALM ACCESSED WITH RAPD MARKERSABSTRACT -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.

Peach palm core collection in Brazilian Amazonia

“…Cristo-Araújo et al (2010) also used the same RAPD markers on another set, and found results similar to those of Silva et al (2003) and Rodrigues et al (2004). Santos et al (2011) assessed the genetic variability of hybrid populations with the same markers and concluded that they are not different from the landraces surrounding them. This analytical process took a decade because the peach palm is not an economically important crop and therefore is not a national priority , which also has implications for the conservation of its genetic resources.…”

“…characterization (Silva et al 2003, Rodrigues et al 2004, Cristo-Araújo et al 2010, Santos et al 2011). …”

“…At the first level, the samples were classified based on the degree of domestication: wild and domesticated. At the second level, the domesticated populations were subdivided into landraces, non-designated populations and hybrid populations, although after the study of Santos et al (2011), which showed that hybrid populations are not different from their surrounding landraces, these samples were incorporated into their landraces. Because there is a significant relationship between gene flow and geographic distance (Rodrigues et al 2004), this stratum represents the eco-geographical distribution of peach palm also.…”

Origin and Dispersal of Domesticated Peach Palm

“…While validation of morphometrically defined landraces has been a preoccupation of the molecular genetic analyses in the Brazilian germplasm bank (Sousa et al, 2001;Clement et al, 2002;Rodrigues et al, 2005;Cristo-Araújo et al, 2010;Santos et al, 2011), these analyses often had insufficient or unbalanced numbers of each population to work with. When sufficient numbers were available, they validated some landraces and did not validate others, specifically the Guatuso and Tuira landraces in Central America, and the Solimões landrace in central-western Amazonia (Rodrigues et al, 2005).…”

Características físicas e químicas de frutos de pupunheira no Estado do Pará

“…A pupunheira (Bactris gasipaes Kunth, Palmae) é uma fruteira nativa da Amazônia que apresenta ampla diversidade genética em suas populações silvestres e domesticadas, devido aos seus diferentes estádios de domesticação, locais de cultivo e por atender a diversas preferências humanas em termos de sabor, uso, processamento e até cor (CLEMENT; SANTOS, 2002;SANTOS et al, 2011).…”