Cucurbit Genetics Cooperative Report 3:9 (article 5) 1980
P.E. Grimbly
Glasshouse Crops Research Institute, Littlehampton, BN16 3PU, United Kingdom
A sterile plant with misshapen fruit was found in a crop of ‘Butchers Disease Resisting’ grown at the Rothamsted Experimental Station, Harpeden, Herts, U.K. Plants obtained from cuttings were grown under glass at this institute for observation and test crossing.
The stems and leaves of the mutant were normal but the flowers and fruit were abnormal. The corolla of both staminate and pistillate flowers was reduced to a whorl of five green, reflexed appendages identical to sepals. The flowers, therefore, appeared to have ten sepals in two whorls of five.
The staminate flowers never matured and usually fell off while they were still small. The pistillate flowers developed to their usual size and, if left unpollinated, produced parthenocarpic fruit, as is usual in the parental cultivar.
The ovaries of the pistillate flowers were inferior but the usual narrow attachment between the base of the sepal and the ovary was absent. In this respect, the flowers resembled hermaphrodite flowers, but there were no anthers and the ovary was of a normal length. The base of the ovary was usually tri-locular but the number of locules increased to four, five, or sometimes six at stigmatic end and resulted in a club-shaped ovary with irregular ribbing.
Pollinations were made using pollen from normal plants of ‘Butchers Disease Resisting.’ Since all the “sepals” were reflexed from a very young stage, the immature stigma was exposed and it was difficult to judge when it was receptive to pollen; thus , pollination was repeated on several successive days when ovary size and stigma appearance suggested that the latter might be receptive.
F1 seed was obtained from the cross mutant x wild type. All the F1 plants were normal. In the F2 family 14 plants were normal and five showed all the characters of the original mutant. It seems that the character is controlled by a single recessive allele. The name apetalous and the symbol ap are suggested.