Cultivar-Groups in Cucurbita maxima Duchesne: Diversity and Possible Domestication Pathways

Abstract

Domesticated Cucurbita has been remarked as one of the plant genera with the highest diversity in color, shape and fruit dimensions. Their economic and cultural values are related to the consumption of the mature or immature fruits, seeds, flowers, and to the use as decoration. The wild ancestor of C. maxima, the ssp. andreana has an actual scattered and disjointed distribution, associated with megafauna seed disperser syndrome. It was domesticated in South America around 9000–7000 years BP. The cultivar-group is a subspecific category for assembling cultivars on the basis of defined similarity. The work describes and pictures nine cultivar-groups for the species, Banana, Turban, Hubbard, Show, Buttercup, Zapallito, Plomo, Zipinka and Nugget. The molecular and a morphological join data analysis scatter biplot showed Turban and Buttercup in a central position, suggesting a first step in the domestication pathway associated with seed and immature fruit consumption; afterward, bigger bearing fruits groups were selected for their mature fruit flesh quality on one hand, and bush type, short day induction and temperate climate adaptation on the other hand. The striking domesticated Brazilian accession MAX24 intermediate between cultigens and ssp. andreana strengthens, in concordance with archeological remains, the possible domestication place of the species more easternward than previously believed.