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

Abstract

Gene flow between cultivated and wild gene pools is common in the contact zone between agricultural lands and natural habitats and can be used to study the development of adaptations and selection of novel varieties. This is likely the case in the northern Adriatic region, where centuries-old cultivated orchards of sweet chestnut (Castanea sativa Mill.) are planted within the natural distribution area of the species. Thus, we investigated the population structure of several orchards of sweet chestnuts. Furthermore, the genetic background of three toponymous clonal varieties was explored. Six genomic simple sequence repeat (gSSR) and nine EST-derived SSR (EST-SSR) loci were utilized in this research, and both grafted and non-grafted individuals were included in this study. Five closely related clones were identified, which represent a singular, polyclonal marron variety, found in all three cultivation areas. Furthermore, many hybrids, a result of breeding between cultivated and wild chestnuts, have been found. Analyzed semi-wild orchards defined by a diverse genetic structure, represent a hotspot for further selection and could result in creation of locally adapted, high-yielding varieties.

Biodiversity protection against anthropogenic climate change: Conservation prioritization of Castanea sativa in the South Caucasus based on genetic and ecological metrics

“…The species was extensively cultivated in southern Europe for nuts and timber since the Roman Empire (Fernández‐López et al, 2021; Krebs et al, 2019; Marinoni et al, 2013; Mattioni et al, 2017). Recent studies revealed significant translocation of germplasm between the Iberian and Apennine peninsulas (Fernández‐López et al, 2021) and a considerable gene flow between cultivated orchards and natural populations in the Adriatic region (Tumpa et al, 2022). However, sweet chestnut is also found isolated in the Caucasus ecoregion, a global biodiversity hotspot (Tarkhnishvili et al, 2012; Zazanashvili et al, 2004).…”

Assessing the Genetic Variability of Sweet Chestnut Varieties from the Tuscan Apennine Mountains (Italy)

“…Among them, the most used and reliable tool is focused on simple sequence repeats (SSRs), which are broadly adopted to also assess the genetic variability of many fruit species [32][33][34][35][36][37][38]. In this context, their application in C. sativa germplasm has already been developed, leading to the genetic characterization of several varieties in the whole of Europe [3,[39][40][41][42][43]. Specifically, SSR markers have been previously used to elucidate the relationships among European and Italian chestnut varieties [5,[44][45][46][47] and assess the genetic diversity of cultivars and accessions across Italy, spanning from the southern to northern regions [15,19,[48][49][50].…”