Identification and inheritance of a winter squash cultivar (Cucurbita maxima) with low heptachlor epoxide uptake ability

• The F1 cultivar ‘TC2A’ had a low HEPX uptake ability among popular Japanese winter squash cultivars.
• The low HEPX uptake ability of ‘TC2A’ was derived from genes contributed by ‘Hokkai 1’.
• The low HEPX uptake ability was not inherited dominantly, and the inheritance was found to be quantitative.

We aimed to find a cultivar with low Heptachlor exo-epoxide (HEPX) uptake ability among popular winter squash (Cucurbita maxima) cultivars and to reveal the heredity of cultivars with low HEPX uptake ability. The cultivar with low HEPX uptake ability ‘Hokkai 1’ was a pure-line, and the inheritance of low HEPX uptake ability could be investigated using this cultivar. Furthermore, we examined the suitability of ‘Hokkai 1’ as a parental line for F1 lines or as breeding material for low HEPX uptake ability. Heptachlor epoxide uptake ability in the shoots of young winter squash plants was a good indicator to evaluate HEPX uptake ability in the fruit. The F1 cultivar ‘TC2A’ had a low HEPX uptake ability among popular Japanese winter squash cultivars. The low HEPX uptake ability of ‘TC2A’ was derived from genes contributed by ‘Hokkai 1’, a parental line of ‘TC2A’. ‘Hokkai 1’ accumulated less HEPX than ‘TC2A’ or the ancestral cultivars. ‘Hokkai 1’ will be suitable for use as breeding material for the low HEPX uptake trait. The low HEPX uptake ability was not inherited dominantly in the F1, and the inheritance was found to be quantitative after examination of the F2 lines.