Research of Juglans regia provenances by molecular, morphological and biochemical markers: a case study in Italy

In the current climate change scenarios, the choice of seed sources is one of the main factors affecting the establishment and productivity of plantations of forest trees. Juglans regia L. (walnut) is one of the more valuable hardwood species since it could provide high quality timber and fruits. The aim of this study was to search peculiar Italian walnut provenances as putative biodiversity sources for seed orchards and to establish new hardwood plantations. A multidisciplinary approach, integrating molecular markers (ISSR), seed morphological traits (equatorial and polar diameter, shape, dry weight) and fruit composition (total oil, fatty acids, tocopherol) was applied to analyze samples collected in ten sites (three in Campania and seven in Abruzzo regions) and samples of four varieties (two from Southern and two from Northern Italy). Eleven selected ISSR primers exhibited a strong ability to discriminate walnut provenances. The Principal Coordinate Analysis performed on the ?PT values divided all germplasm in four distinct groups. The genotyping results were partially confirmed by the morphological and biochemical analysis of fruits. The provenances Montella, collected in a hilly plateau of Campania region, and Pescasseroli, sampled in mountainous zone of Abruzzo,, resulted differentiated for genetic, morphological and biochemical characters. They can be two promising source of seed for nurseries and hardwood plantations.