Gene flow between wild trees and cultivated varieties shapes the genetic structure of sweet chestnut (Castanea sativa Mill.) populations

The sweet chestnut orchards (<em>Castanea sativa</em> Mill.) are traditionally planted in the northern Adriatic region. This study investigates their population structure, as well as the genetic background of three toponymous clonal varieties. Six genomic simple sequence repeat (gSSR) and nine EST-derived SSR (EST-SSR) loci were utilized in this study. We have identified five closely related clones, which represent a singular, polyclonal marron variety, found in all three cultivation areas, acompanied by many hybrids, resulting from the breeding between cultivated and wild chestnuts.