Genetic Characterization of the Apple Germplasm Collection in Central Italy: The Value of Local Varieties.

Gianpiero Marconi,Emidio Albertini,Luigi Russi,Fabio Veronesi,Luciano Concezzi,Nicoletta Ferradini

doi:10.3389/fpls.2018.01460

Gianpiero Marconi, Emidio Albertini + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2018.01460

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Abstract

In the last 50 years, intensive farming systems have been boosted by modern agricultural techniques and newly bred cultivars. The massive use of few and related cultivars has dramatically reduced the apple genetic diversity of local varieties, confined to marginal areas. In Central Italy a limited spread of intensive fruit orchards has made it possible to preserve much of the local genetic diversity, but at the same time the coexistence of both modern and ancient varieties has generated some confusion. The characterization and clarification of possible synonyms, homonyms, and/or labeling errors in old local genetic resources is an issue in the conservation and management of living collections. 175 accessions provided by 10 apple collections, mainly local varieties, some of unknown origin, and well-known modern and ancient varieties, were studied by using 19 SSRs, analyzed by STRUCTURE, Ward’s clustering and parentage analysis. We were able to identify 25 duplicates, 9 synonyms, and 9 homonyms. As many as 37 unknown accession were assigned to well known local or commercial varieties. Polyploids made up 20%. Some markers were found to be significantly correlated with morphological traits and the loci associated with the fruit over color were related to QTLs for resistance to biotic stresses, aroma compounds, stiffness, and acidity. In conclusion the gene pool of Central Italy seems to be rather consistent and highly differentiated compared with other European studies (FST = 0.147). The importance of safeguarding this diversity and the impact on the management of the germplasm living collection is discussed.

Highlights

Apple (Malus × domestica Borkh., family Rosaceae, tribe Pyreae, 2n = 2x = 34) is one of the most ancient and widespread fruit crops in temperate regions
The thousands of cultivars distributed throughout the world and the world-wide breeding programs, mainly based on organoleptic traits, aesthetic standards and disease resistance, the size of the genetic resources used by breeders has been limited and reduced to a few varieties such as ‘Cox’s Orange Pippin,’ ‘Golden Delicious,’ ‘Jonathan,’ ‘Red Delicious,’ and ‘McIntosh’ (Noiton and Alspach, 1996)
The most important variety is Golden Delicious with 2.546 million metric tons, followed, by Gala with 1.331 million metric tons and Idared with 1.111 million metric tons (Food and Agricultural Organization of the United Nation [FAO], 2016; WAPA, 2017). This massive use of limited and related cultivars, combined with vegetative practices based on cuttings and grafting, has dramatically reduced apple genetic diversity and, many interesting and well adapted traditional and local varieties, considered obsolete, were no longer cultivated and have been partly lost (Hammer et al, 2003)

Summary

Introduction

The most important variety is Golden Delicious with 2.546 million metric tons, followed, by Gala with 1.331 million metric tons and Idared with 1.111 million metric tons (Food and Agricultural Organization of the United Nation [FAO], 2016; WAPA, 2017). This massive use of limited and related cultivars, combined with vegetative practices based on cuttings and grafting, has dramatically reduced apple genetic diversity and, many interesting and well adapted traditional and local varieties, considered obsolete, were no longer cultivated and have been partly lost (Hammer et al, 2003)

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