Genotypic diversity and population structure of the apricot landraces of the Campania region (Southern Italy) based on fluorescent SSRs

Apricot (Prunus armeniaca L.) is a cosmopolitan, major stone fruit species cultivated for its delicious drupes. Strong concerns about loss of diversity in apricot have been recently put forward mainly because of the enduring transition from local to globalized varieties more suitable for intensive agriculture. Italy, one of the top producing countries in the world, has arguably one of the richest apricot germplasms, with the Campania region being a traditional and leading area of cultivation since Roman times. This work aimed to study the molecular diversity of an ex-situ collection of local apricot varieties. They once flourished in conventional cropping systems, but are nowadays neglected, surviving in family farms, and sold only in local markets. We investigated the level of genetic and genotypic diversity, assessed clonality in the population, and verified the presence of genetic structure and differentiation in 73 apricot varieties by using fluorescent SSR markers resolved in capillary electrophoresis (SSR-CE). The analysis indicated a high level of genetic diversity (with little locus-specific differences) and of genotypic assortment, with few possible synonyms. Moreover, the investigation of relatedness among apricot landraces and the negligible within-landraces differentiation are consistent with a common origin of the germplasm, a likely result of an adaptive diversification that is mainly due to similar environmental and agricultural factors. This work highlights the value of the traditional germplasm where crops thrived. Moreover, it provides support for studying the possible mechanisms of evolution and adaptation and for implementing measures for the exploitation, regeneration, and on-farm promotion of the apricot landraces.