Genetic Structure of Wild and Domesticated Populations of Capsicum annuum (Solanaceae) from Northwestern Mexico Analyzed by RAPDs

Abstract

Levels of genetic variation and genetic structure of 15 wild populations and three domesticated populations of Capsicum annuum were studied by RAPD markers. A total of 166 bands (all of them polymorphic) and 126 bands (125 of them polymorphic) were amplified in wild and domesticated populations, respectively. Mean percentage of polymorphism was 34.2% in wild populations and 34.7% in domesticated populations. Mean and total genetic diversity were 0.069 and 0.165 for wild populations and 0.081 and 0.131 for domesticated populations. Parameters of genetic diversity estimated from 54 bands with frequencies ‡1 À (3/n) (n = sample size) showed that 56.7% of the total variation was within and 43.3% among wild populations, whereas 67.8% of the variation was within and 32.2% among domesticated populations. AMOVA indicated that total genetic diversity was equally distributed within (48.9 and 50.0%) and among (50.0 and 51.1%) populations in both wild and domesticated samples. Wild and domesticated populations were clearly resolved in a UPGMA dendrogram constructed from Jaccard's distances (average GD = 0.197), as well as by AMOVA (17.2% of variance among populations types, p = 0.001) and by multidimensional scaling analysis. Such differentiation can be associated with domestication as well as different origin of gene pools of the wild (Northwestern Mexico) and cultivated (more probably Central Mexico) samples analyzed. The considerable genetic distances among cultivars (average GD = 0.254) as well as the high number of diagnostic bands per cultivar (33 out of 126 bands), suggest that genetic changes associated with domestication could have resulted from artificial selection intervening in different directions, but the inclusion of more domesticated samples might clarify the nature of distinctions detected here.

Plasticidad fenotípica de poblaciones de chile silvestre ( Capsicum annuum var. glabriusculum ) en respuesta a disponibilidad de luz

“…Debido a que las plantas de estas poblaciones crecieron en condiciones controladas de invernadero, estos resultados indican que la variación observada en ellas posee una base genética. La diferenciación entre las poblaciones observada en este estudio coincide con la elevada variación genética mostrada por estas poblaciones en análisis de isoenzimas, RAPDs y microsatélites (Hernán-dez-Verdugo et al, 2001a;Oyama et al, 2006;PachecoOlvera et al, 202). Las poblaciones silvestres de C. annuum estudiadas mostraron elevados niveles de plasticidad fenotípica en las características analizadas en respuesta a la disponibilidad de luz.…”

“…Los elevados niveles de plasticidad y variación en la plasticidad observados en las poblaciones de Capsicum annuum aquí estudiadas, junto con los altos niveles de variación genética detectada con análisis de isoenzimas (Hernández-Ver-dugo et al, 2001a) y RAPDs (Oyama et al, 2006) en estas mismas poblaciones indican que en C. annuum silvestre la plasticidad fenotípica y la variabilidad genética no son dos medios alternativos (Marshall y Jain,968), sino son dos recursos independientes que esta especie puede utilizar para sobrevivir y adaptarse a ambientes espacial y temporalmente variables. Elevados niveles de plasticidad y variación genéti-ca han sido reportados en otras especies vegetales (Scheiner y Goodnight, 1984;Mcdonald y Chinappa, 1989).…”

“…Estudios con isoenzimas y marcadores moleculares RAPDs y microsatélites (Hernández-Verdugo et al, 2001a;Oyama et al, 2006;Pacheco-Olvera et al, 202) indican que las poblaciones de chile silvestre del noroeste de México mantienen niveles altos de variación genética dentro y entre sus poblaciones. En condiciones naturales, las poblaciones de Capsicum annuum silvestre habitan sitios que difieren en la disponibilidad de luz.…”

Genetic variation among wild and cultivatedAgropyron desertorumpopulations based on total protein profiles and phenotypic traits

“…The high gene flow may have prevented genetic differentiation between cultivated A. desertorum populations and their wild progenitors. Wild relatives of cultivated plants are important reservoirs of genes for improving commercial varieties (Oyama et al 2006).…”

“…The genetic structures of cultivated plant populations have been shaped by many factors in the course of cultivation (HernandezVerdugo et al 2001;Oyama et al 2006). Of importance is the way in which genetic material is passed from one cultivated generation to the next (Miller & Schaal 2006).…”