Impact of Human Management on the Genetic Variation of Wild Pepper, Capsicum annuum var. glabriusculum

Abstract

Management of wild peppers in Mexico has occurred for a long time without clear phenotypic signs of domestication. However, pre-domestication management could have implications for the population's genetic richness. To test this hypothesis we analysed 27 wild (W), let standing (LS) and cultivated (C) populations, plus 7 samples from local markets (LM), with nine polymorphic microsatellite markers. Two hundred and fifty two alleles were identified, averaging 28 per locus. Allele number was higher in W, and 15 and 40% less in LS and C populations, respectively. Genetic variation had a significant population structure. In W populations, structure was associated with ecological and geographic areas according to isolation by distance. When LM and C populations where included in the analysis, differentiation was no longer apparent. Most LM were related to distant populations from Sierra Madre Oriental, which represents their probable origin. Historical demography shows a recent decline in all W populations. Thus, pre-domestication human management is associated with a significant reduction of genetic diversity and with a loss of differentiation suggesting movement among regions by man. Measures to conserve wild and managed populations should be implemented to maintain the source and the architecture of genetic variation in this important crop relative.

Genome‐wide genotyping of a novel Mexican Chile Pepper collection illuminates the history of landrace differentiation after Capsicum annuum L. domestication

“…Although our population was highly structured, we did observe some admixture that can be explained by the large amount of farmers’ seed sharing followed by crossing (González‐Jara et al., ). The pattern shown in Chile de Agua reflects a combination of these two forces: The overall landrace population is structured into different subpopulations genetically, but several of those subpopulations are spread among multiple sites rather than being endemic to one location.…”

Characterization of genetic diversity of native 'Ancho' chilipopulations of Mexico using microsatellite markers

“…In wild chilis (C. annuum var. glabriusculum), González-Jara et al (2011) found greater variation, with 27 alleles per locus. In contrast, with commercial varieties the number of alleles is very low (Kwon et al, 2005), because of their narrow genetic base.…”

“…In general, analyses of genetic diversity of the native chili populations of Mexico have revealed a very high degree of variability (Oyama et al, 2006;González-Jara et al, 2011;Pacheco-Olvera et al, 2012). All of this genetic diversity found in the native and wild chili populations of Mexico must be protected and conserved for future studies and for the identification of alleles of agronomic interest.…”

Genetic diversity and population structure analysis to construct a core collection from a large Capsicum germplasm

“…Previously, Capsicum germplasm collections have been examined for genetic diversity using accessions from Mesoamerica (Central Mexico to northwestern Costa Rica) to survey geographic origin and understand the domestication process [6, 38]. Recently, STRUCTURE analysis was performed in a Capsicum germplasm collection with 1,352 accessions, which was grouped into six distinct clusters based on genetic analysis with six SSR markers [14].…”