Ancient origin of bicolor fruit in Cucurbita moschata Duchesne

Bicolor fruits have been well studied in Cucurbita pepo but are also known to occur in Cucurbita maxima and Cucurbita argyrosperma. It is not clear whether they share the same inheritance as C. pepo, that is, a precocious yellow pigment gene, designated B, along with multiple alleles and other modifying genes. Bicolor is expressed in the ovary prior to anthesis and throughout much of fruit development but often fades early in post-harvest fruits. Lesser known among commercial squash cultivars are bicolor Cucurbita moschata fruit. An artificial interspecific cross was made between a bicolor C. pepo and C. moschata that was backcrossed to C. moschata, which introduced the B gene into C. moschata. However, landraces of bicolor C. moschata were known to exist prior to this. The pre-Columbian Moche society along northern coastal Peru is noted for its high art in ceramics realistically depicting everyday aspects of life, including cultivated Cucurbita fruits, even some painted ceramics depicting bicolor fruits. 'Abobora Brasileirinha' is a popular bicolor C. moschata in Brazil today, consumed both immature and mature stage. There are landraces of bicolor fruits native to South America, particularly Peru and Ecuador, as well as Brazil. The bicolor fruits range in shape from spherical to pyriform and warty crookneck, just as they do in the Moche ceramics. Bicolor is not just phenotypically expressed in the fruit but also in vegetative parts of the plant, such as variegated yellow leaves. The bicolor fruit range from half yellow and half green to completely yellow or even with various banding patterns. The gene in C. pepo has been widely used in breeding for increased carotene content of the fruit flesh and in creating new ornamentals. Comparable breeding programs could be undertaken for making improvements in C. moschata.