Search

Cucurbita pepoL. (squash, pumpkin) is a highly polymorphic vegetable species of major importance. Our study characterized a spectrum of C. pepogermplasm for the ability to regenerate in vitroby direct organogenesis from cotyledon explants. Cultivars tested included both cultivated subspecies, texanaand pepo, and nearly all of their respective cultivar-groups. Direct shoot regeneration occurred in all accessions, and was generally high (56–94%), with a single exception of 22% (‘Bolognese’). There was no significant difference between the percentage regeneration of the two subspecies. Shoot regeneration per responding explant was uniform (1.2–1.6 shoots per explant). Only ‘True French’ produced statistically more shoots (3.9 per explant) than other accessions. The morphology of regeneration varied. Most cultivars produced long shoots, often fasciated, amid a few small buds. Some subspecies pepocultivars (Beirut, Yugoslavia 7, Ma’yan and True French) produced short, massive, hollow shoots, sometimes accompanied by shoots that were more normal. Two subspecies texanacultivars (Creamy Straightneck and Small Bicolor) produced single (sometimes double) shoots without other buds. The production of chimeric (mixoploid) regenerants varied and there was a tendency to regenerate chimeric plants from the widest-fruited accessions (i.e. lowest length-to-width ratio) in each subspecies. Subspecies pepoPumpkin Group ‘Tondo di Nizza’ showed significantly greater production of chimeric regenerants. In comparison with the great range of variation observed in fruit shape, the variation of in vitroresponses (mostly less than 2-fold in regeneration and shoot production) was less than expected.Cucurbita pepoL. (squash, pumpkin) is a highly polymorphic vegetable species of major importance. Our study characterized a spectrum of C. pepogermplasm for the ability to regenerate in vitroby direct organogenesis from cotyledon explants. Cultivars tested included both cultivated subspecies, texanaand pepo, and nearly all of their respective cultivar-groups. Direct shoot regeneration occurred in all accessions, and was generally high (56–94%), with a single exception of 22% (‘Bolognese’). There was no significant difference between the percentage regeneration of the two subspecies. Shoot regeneration per responding explant was uniform (1.2–1.6 shoots per explant). Only ‘True French’ produced statistically more shoots (3.9 per explant) than other accessions. The morphology of regeneration varied. Most cultivars produced long shoots, often fasciated, amid a few small buds. Some subspecies pepocultivars (Beirut, Yugoslavia 7, Ma’yan and True French) produced short, massive, hollow shoots, sometimes accompanied by shoots that were more normal. Two subspecies texanacultivars (Creamy Straightneck and Small Bicolor) produced single (sometimes double) shoots without other buds. The production of chimeric (mixoploid) regenerants varied and there was a tendency to regenerate chimeric plants from the widest-fruited accessions (i.e. lowest length-to-width ratio) in each subspecies. Subspecies pepoPumpkin Group ‘Tondo di Nizza’ showed significantly greater production of chimeric regenerants. In comparison with the great range of variation observed in fruit shape, the variation of in vitroresponses (mostly less than 2-fold in regeneration and shoot production) was less than expected.