Development of High-Density Genetic Linkage Maps and Identification of Loci for Chestnut Gall Wasp Resistance in Castanea spp.

Daniela Torello Marinoni,Nadia Valentini,Ezio Portis,Kenta Shirasawa,Roberto Botta,Emile Cavalet-Giorsa,Alberto Alma,Vera Pavese,Sogo Nishio,Alberto Acquadro,Aziz Akkak

doi:10.3390/plants9081048

Abstract

Castanea sativa is an important multipurpose species in Europe for nut and timber production as well as for its role in the landscape and in the forest ecosystem. This species has low tolerance to chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu), which is a pest that was accidentally introduced into Europe in early 2000 and devastated forest and orchard trees. Resistance to the gall wasp was found in the hybrid cultivar ‘Bouche de Bétizac’ (C. sativa × C. crenata) and studied by developing genetic linkage maps using a population derived from a cross between ‘Bouche de Bétizac’ and the susceptible cultivar ‘Madonna’ (C. sativa). The high-density genetic maps were constructed using double-digest restriction site-associated DNA-seq and simple sequence repeat markers. The map of ‘Bouche de Bétizac’ consisted of 1459 loci and spanned 809.6 cM; the map of ‘Madonna’ consisted of 1089 loci and spanned 753.3 cM. In both maps, 12 linkage groups were identified. A single major QTL was recognized on the ‘Bouche de Bétizac’ map, explaining up to 67–69% of the phenotypic variance of the resistance trait (Rdk1). The Rdk1 quantitative trait loci (QTL) region included 11 scaffolds and two candidate genes putatively involved in the resistance response were identified. This study will contribute to C. sativa breeding programs and to the study of Rdk1 genes.

Highlights

Chestnut belongs to the genus Castanea, in the Fagaceae family, which includes Quercus, Fagus, and Castanopsis
A progeny produced by crossing a resistant hybrid of C. sativa × C. crenata and a susceptible cultivar of C. sativa was used to evaluate the response to gall wasp
Euro-Japanese F1 hybrids cultivars in Europe were obtained by INRA Bordeaux to increase the resistance of cultivated chestnuts to ink disease and canker blight

Summary

Introduction

Chestnut belongs to the genus Castanea, in the Fagaceae family, which includes Quercus, Fagus, and Castanopsis. C. sativa is distributed along the Mediterranean basin and Asia Minor, and it is a multipurpose species used for nut and wood production, and for its contribution to the landscape in mountainous areas. This species has very good nut quality, especially the ‘Marrone’. Plants 2020, 9, 1048 type, which is known for the fine taste and the easy-to-remove pellicle [1] This species is susceptible to two main diseases, ink disease (Phytophthora cinnamomi Rands) and canker blight (Cryphonectria parasitica Murr.) [2]. Most of the C. sativa cultivars are susceptible to chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu)

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