Genetic Insights into the Historical Attribution of Variety Names of Sweet Chestnut (Castanea sativa Mill.) in Northern Italy

TL;DR

This study uses genetic analysis to explore the historical classification of sweet chestnut varieties in northern Italy, revealing new genetic insights that could aid conservation efforts.

Contribution

The study introduces a genetic perspective to validate and enhance traditional classifications of sweet chestnut varieties in northern Italy.

Findings

Genetic analysis revealed a homogeneous gene cluster not recognized by traditional classification.

Bayesian methods reconstructed possible propagation routes and ancestral relationships of chestnut varieties.

Findings align with palynological data and suggest integrating genetic and cultural heritage for conservation.

Abstract

The sweet chestnut (Castanea sativa Mill.) is subject to the progressive disappearance of its traditional chestnut groves. In the northern part of Italy, where distribution of the sweet chestnut is fragmented, many local varieties continue to be identified mostly by oral tradition. We characterised by SSRs eleven historically recognised varieties of sweet chestnut in the area surrounding Lake Como, with the goal of giving a genetic basis to the traditional classification. We performed classical analysis about differentiation and used Bayesian approaches to detect population structure and to reconstruct demography. The results revealed that historical and genetic classifications are loosely linked when chestnut fruits are just “castagne”, that is, normal fruits, but increasingly overlap where “marroni” (the most prized fruits) are concerned. Bayesian classification allowed us to identify a homogeneous gene cluster not recognised in the traditional assessment of the varieties and to reconstruct possible routes used for the propagation of sweet chestnut. We also reconstructed ancestral relationships between the different gene pools involved and dated ancestral lineages whose results fit with palynological data. We suggest that conservation strategies based on a genetic evaluation of the resource should also rely on traditional cultural heritage, which could reveal new sources of germplasm.

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