In vitro organogenesis of zucchini squash cv. Caserta

Abstract

A protocol for the in vitro culture of Cucurbita pepo cv. Caserta was studied, using a cotyledon segment with an attached hypocotyl fragment as an explant. First, to determine the optimal seedling age, explants were collected from 4 to 6-day-old in vitro germinated seedlings and cultured in MS basal medium supplemented with benzylaminopurine (BAP, 4.5 µM), under a 16-h photoperiod at 27ºC. Based on the results obtained, the explants collected from the 4-day-old seedlings were then cultured in MS basal medium supplemented with different concentrations of BAP (0, 1.1, 2.2, 3.3, 4.5, or 5.5 µM) and incubated under a 16-h photoperiod at 27ºC. In vitro organogenesis was most efficient with explants collected from 4-day-old seedlings cultured in medium supplemented with 4.5 µM of BAP. After 4 weeks of incubation the development of adventitious buds at the cotyledon/hypocotyl junction could be observed. These buds were transferred to elongation and rooting medium and the developed plants were acclimatized to greenhouse conditions. The morphogenic process was characterized using light and scanning electron microscopy analyses to confirm the organogenesis. The results showed that this alternate explant is efficient for in vitro culture of zucchini squash cv. Caserta. The protocol will be further examined for future use in genetic transformation experiments in this species.