Characteristics of Regenerated Plants via Protoplast Electrofusion between Melon (Cucumis melo) and Pumpkin (Interspecific Hybrid, Cucurbita maxima*C. moschata).

Abstract

Protoplasts of melon (Cucumis melo L.) and pumpkin (interspecific hybrid pumpkin for grafting, Cucurbita maxima x C. moschata), were fused by electrofusion. Out of 188 calli with leaf regenerated, 33 putative somatic hybrids were selected by electrophoresis band pattern of acid phosphatase. Out of them three plants were grown in a green house. These plants possessed dark green leaves, the shape of the leaf showed variations from a round type to a deep serration type. Isozyme pattern exhibited both parent's band pattern. Chromosome numbers were counted from 24 approximately 48 in one root tip of one plant. The small shape chromosomes with low stainability were observed, which are always found in this pumpkin. With the progress of plant growth, these plants closely resembled melons in traits of leaves and other organs. In the flowering stage, chromosome numbers of root tips from cutting of axillary buds were observed almost 2n = 24. The pumpkin's band was not found in the isozyme pattern. Both the fertility and germination rate of the pollen were high; fruit and seeds were obtained by self-pollination. The traits and taste of the fruit were almost the same as the melon. In the early stage of growth, the traits of the regenerated plants via protolast fusion between melon and pumpkin showed hybridity owing to the introduction of a part of the pumpkin chromosome, but the hybridity disappeared in the late stage of growth. This fact showed the difficulty of transferring genes between the crops belonging to different genus in Cucurbitaceae in the future.