Phenotype differentiation of Capsicum annuum var. glabriusculum of three regions in Mexico and its relation to climate

Abstract

Background: Populations of Capsicum annuum var. glabriusculum are found in a wide portion of the Mexican territory, and it is ancestor of many cultivated forms relevant for the Mexican diet.
 Questions: What are the proportions of phenotypic and genetic variation distributed among its sampled regions, populations and within populations. How does the climate correlates to the population’s phenotypic variation.
 Species: Capsicum annuum var. glabriusculum.
 Study sites and years: 24 populations form three regions were sampled: Northwest, states of Sonora and Sinaloa; South: Oaxaca and Southeast Tabasco and Yucatán, in Mexico. The experiment was performed between years 2016 to 2018.
 Methods: Fruits from single plants were collected in wild populations. Plants were grown in a greenhouse. Nested ANOVAS were performed to estimate phenotypic and genetic variance components for different spatial scales. Climate correlation was estimated through univariate and multivariate methods.
 Results: 49.8 % of phenotypic variation was detected within families, 11.1 % among families (within populations), 21.3 % among populations and 17.6 % among regions. The genetic basis of phenotypic variation was 50.1% on average, for this genetic variation 34.2 % was found among regions, 39.4% among populations and 26.3 % within populations. Climate factors generated different patterns of correlations for vegetative, foliar and reproductive traits.
 Conclusions: Northwest plants were shorth, with small leaves and large fruits, Southeast plants were tall, with large leaves and small fruits, South plants developed intermediate phenotypic traits. Climate explained a large proportion of phenotypic differentiation.