Cucurbit Genetics Cooperative Report 10:90 (article 48) 1987

Inheritance of Internal Fruit Color in an Interspecific Cross

R. W. Robinson and J. W. Shail

Horticultural Sciences Department, New York State Agricultural Experiment Station, Geneva, New York

Cucurbita ecuadorensis, which has white flesh color, was crossed with C. maxima cv. Buttercup, which has deep orange flesh due primarily to [beta]- carotene. Fruit of the interspecific hybrid had yellow flesh.

Acetone extracts of samples from fruit of the parents, F₁, and F₂ generations of this cross were scanned with a Beckman DB spectrophotometer at 440µ, the wave length absorbing [beta] -carotene. 'Buttercup' was high in carotenoids, with readings of 0.98 and above, whereas C. ecuadorensis showed absorbance readings of 0.03 or less. The F₁ was intermediate, ranging from 0.22 to 0.30. Low concentration of [beta] -carotene appears to be incompletely dominant.

Transgressive segregation occurred in the F₂ . Two of 69 F₂ plants had readings of 1.50, higher than any parental plant. Continuous variation for flesh color occurred in the F₂ not only within the ranges of the parents and F₁, but also in the intervening ranges and beyond. Approximately three-fourths of the F₂ population (49 of 69 plants) had color intensity similar to the F₁ or less, and very few plants had as much [beta] -carotene as 'Buttercup'. Thus, large populations in segregating generations will be required to combine the high level of [beta] -carotene of C. maxima with the multiple virus resistance of C. ecuadorensis.