Existence of Genetic Differences in Pellicle Peelability in Japanese Chestnut (Castanea crenata Sieb. et Zucc.) Cultivars and Selections with Difficult-peeling Pellicles

The pellicle of the Japanese chestnut (Castanea crenata Sieb. et Zucc.) is difficult to peel, with the exception of the recently developed 'Porotan', whose pellicle peelability (PP) is high and controlled by a single major gene. The objective of the present study was to identify any genetic differences in PP in Japanese chestnuts with difficult-peeling pellicles. We detected a significant genetic difference in PP (evaluated as the nut surface area that peeled away without scraping with a hand knife after deep frying in cooking oil) among five Japanese chestnut cultivars grown in Tsukuba, Japan, using two trees in 2 years, and among three cultivars grown in five locations using a single tree in 1 year. We evaluated the PP of 32 Japanese chestnut cultivars/selections and one wild clone (Shibaguri-37) using a single tree in 3 years to quantify the variation. The broad-sense heritability of mean values over the 3 years was estimated as 0.67. Shibaguri-37 had the highest PP. The suggested new genes controlling the variation in PP have high potential in terms of breeding strategy for easy-peeling pellicles as an alternative to the major gene of 'Porotan', the use of which is likely to result in inbreeding.