Assessment of the domestication state of ackee (Blighia sapida K.D. Koenig) in Benin based on AFLP and microsatellite markers

Abstract

Ackee (Blighia sapida) is a native multipurpose species important for the livelihoods of the rural populations in Benin. Trees are found in natural forests or are managed by farmers in different traditional agroforestry systems. Genetic variation at amplified fragment length polymorphism (AFLP) markers, four nuclear microsatellites (nSSRs) and one chloroplast microsatellite (cpSSR) were investigated in 279 individuals from six wild and eight cultivated populations from Benin. The AFLP data revealed moderate levels of diversity of ackee in Benin (mean diversity values are proportion of polymorphic loci = 52.8% and Nei's gene diversity = 0.157, for 375 AFLP fragments). The mean diversity values based on nSSR-markers are expected heterozygosity = 0.286, allelic richness = 2.77. Genetic variation of wild and cultivated populations did not differ markedly. AMOVA revealed that only 7.3 and 5.2% of the variation was partitioned among populations for nSSR-and AFLP-markers, respectively. A Mantel test based on these both markertypes revealed significant correlations between population pairwise geographic distance and genetic differentiation. Differentiation among cultivated populations was higher than among wild populations. The only polymorphic chloroplast microsatellite marker (ccmp7) showed three haplotypes. Cultivated populations from northeastern Benin were fixed on one haplotype which was not observed elsewhere indicating a different origin of these populations possibly from neighboring Nigeria. Farmer-led domestication had an impact on the spatial distribution of genetic variation but did not result in significant losses of diversity within populations. Measures to conserve genetic resources of ackee in each of the three main bioclimatic zones in Benin are proposed.

Genetic Diversity Analysis Reveals Genetic Differentiation and Strong Population Structure in Calotropis Plants

“…Generally, species with a wide distribution, wind dispersal and outcrossing show high genetic diversity 25 , however, based on EST-SSR markers, Calotropis displays a moderate genetic diversity ( H S = 0.245). This level is comparable to the genetic diversity in Blighia sapida , a woody perennial species widespread in tropics and subtropics which had an average genetic diversity of H S = 0.29 26 . It seems that the genetic diversity of Calotropis plants is lower than that of most outcrossing species 25 .…”

The African baobab (Adansonia digitata, Malvaceae): Genetic resources in neglected populations of the Nuba Mountains, Sudan

“…In general, a weak impact of humans on genetic structure within the research area was observed as ‘homestead' and ‘wild' stands were only weakly differentiated. Nonsignificant isolation‐by‐distance patterns for ‘homestead' and ‘wild' stands of baobab also contradicted the idea of human intervention as shown for the on‐farm timber tree Vitex fisheri in Kenya (Lengkeek et al, 2006) or Blighia sapida in Benin (Ekué et al, 2011). However, the long life cycle of baobab, the enhanced genetic diversity due to its tetraploidy level (Gulsen et al, 2009; Pock Tsy et al, 2009), its outcrossing mechanisms (Kyndt et al, 2009), as well as the unknown settlement history and mobility of humans in the surveyed area may prevent a more detailed interpretation.…”

“…These markers allow for the analysis of the genetic diversity of the species, seed‐ and pollen‐mediated gene flow and inbreeding, and may even help to predict consequences of climatic fluctuations on genetic structures (Larsen et al, 2009). The approach is particularly effective in evaluating genetic bottlenecks associated with anthropogenic interventions (Hollingsworth et al, 2005; Larsen et al, 2009; Ekué et al, 2011).…”

“…Agroforestry systems (such as ‘homegardens’) located in human settlements are ideal to study the effects of anthropogenic interventions on genetic and morphological variation in tree species. It is well known that human intervention through selection may reduce the genetic diversity of cultivated species, including indigenous fruit trees (Lengkeek et al, 2006; Ekué et al, 2011). However, increased diversity in planted populations may also occur because of the non‐random admixture of certain genotypes (Stefenon et al, 2008).…”

Morphological and Genetic Diversity of Sea Buckthorn (Hippophae rhamnoides L.) in the Karakoram Mountains of Northern Pakistan

“…Fourth, the genetic setup itself may play a role in phenotypic variation, although to our knowledge no study has so far analyzed this association in sea buckthorn. Fifth, human-induced plant material exchange, overexploitation, and domestication could have negative consequences on population structures leading to genetic bottleneck effects [33][34][35]. For northern Pakistan, the identification and characterization of superior ecotypes and populations with respect to yield, nutritional characteristics, time of ripening, and genetic constitution are important to allow for the collection of berries of higher nutritional quality and other market demanded properties, such as fruit size and color.…”