An Improved Protocol for Callus Initiation Using Leaf Discs and Stems as Explants from Yellow Passion Fruit (Passifl ora edulis f. fl avicarpa)

Passiflora edulis f. flavicarpa is a perennial vine mainly grown in tropical countries which has agricultural and horti cultural importance. Yet, the unavailability of an efficient micropropagation technique is a major obstacle to overcome. Different surface sterilization methods were tested for the stem and leaf explants. To determine the best plant growth regulator concentrations for callus induction, different combinations of NAA (2 to 5 mg/L) and BAP (0.1 to 0.3 mg/L) were tested. Murashige and Skoog full-strength medium was used as the basal medium for cultures. The use of 10% Clorox™ at 150 rpm for 12 minutes twice, followed by 0.1 g/L AgNO3 for 12 minutes found to be the most effective surface sterilization method for leaves with a 100% survival rate. Results found 0.2 mg/L NAA; 2 mg/L BAP and 0.1 mg/L NAA; 4 mg/L BAP to be optimal for callus induction from leaves under light and dark conditions with calliinduction rates of 33.33% and 16.67%, respectively. For stems best results were obtained for 0.3 mg/L NAA; and 2 mg/L BAP with a 66.67% calli induction rate in light conditions and 33.33% in dark conditions. Calli were obtained from both explants within an average of 38.5 days and 44 days in light and dark conditions respectively. Calli of yellow passion fruit can be obtained using full MS media supplemented with NAA ranging from 0.1 to 0.3 mg/L and BAP ranging from 2 to 4 mg/L. Despite successes, vitrification and contamination underscore the need for refinements on this protocol. Keywords: Yellow passion fruit; callus; micropropa- gati on; NAA; BAP