Microsatellites revealed genetic diversity and population structure in Colombian avocado (Persea americana Mill.) germplasm collection and its natural populations

摘要

Avocado (Persea americana Mill.) is one of the most consumed fruits around the world. The species is differentiated into three botanical races: Mexican, Guatemalan and West Indian. A genetic characterization of a Colombian avocado germplasm collection (N = 105) preserved since 2006 and 92 avocado “criollo” trees sampled in Antioquia was made with 12 microsatellites. Colombian avocado exhibits higher genetic diversity (13.9 alleles/locus, Ho = 0.79-0.38, Na =12.3-2.4, Ne= 5.3-1.8, I = 1.87-0.68) than avocados from other germplasms as criollo trees are the product of free crossing (multiple hybridizations). Population structure was found within Antioquian criollo avocados (FST = 0.13, p<0.0001) and in the germplasm collection (FST = 0.068, p<0.0001). Divergence in Antioquia resulted from differences in elevation and climatic conditions. Southwest, East and Altiplano-norte Antioquian sub-regions are genetically close and produce criollo avocados in high elevations where grafting with Hass is likely to be successful. In Colombia, avocado genetic differences were enhanced by the Andean Chain of Mountains. STRUCTURE HARVESTER assignment revealed that germplasm avocados were distributed in K = 2. The first cluster was composed of samples collected from the south of Colombia (Valle del Cauca, Nari?o), the second by samples from the north (Antioquia, Bolivar, Magdalena) and avocados from the rest of the departments were distributed in both. The results obtained are relevant for avocado certification because knowledge of genotypic and phenotypic variation is crucial for crop management and grafting with avocado cultivars such as Hass, which is economically important for Colombian avocado exportation.