Inheritance of the easy-peeling pellicle trait of Japanese chestnut cultivar Porotan.

摘要

Porotan is a Japanese chestnut cultivar that was selected from offspring of the cross 550-40 x Tanzawa and released in 2006. Its nut is distinguished by a pellicle that is easy to peel after roasting; previously, all Japanese chestnut cultivars were thought to have a pellicle that was difficult to peel. Both 550-40 and Tanzawa are Japanese chestnuts, and 550-40 is a selection descended from Tanzawa. Both 550-40 and Tanzawa have a pellicle that is difficult to peel. Among 59 offspring of a cross of 550-40 x Tanzawa, 12 had an easy-peeling pellicle and 47 had a difficult-peeling pellicle; this ratio is not significantly different from the 1:3 expected ratio for monogenic inheritance based on a chi-square test at P = 0.05. A half-diallel cross without selfings was made among Porotan, Tanzawa and Tsukuba. All the offspring from Tanzawa x Tsukuba and from Tsukuba x Porotan had a difficult-peeling pellicle; in contrast, 39 offspring from Tanzawa x Porotan segregated in a ratio of 19 difficult-peeling pellicle to 20 easy-peeling pellicle, which is not significantly different from the expected 1:1 ratio for monogenic segregation based on a chi-square test at P = 0.05. Results suggested that the easy-peeling pellicle trait of Porotan is controlled by a major recessive gene at a single locus. The pellicle peelability locus was designated as P/p. According to this model, the Tsukuba genotype is homozygous-dominant (PP), the Tanzawa genotype is heterozygous (Pp) and the Porotan genotype is homozygous-recessive (pp).