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

Abstract

Passifl ora edulis f. fl avicarpa is a perennial vine mainly grown in tropical countries which has agricultural and horti cultural importance. Yet, the unavailability of an effi cient micropropagati on technique is a major obstacle to overcome. Diff erent surface sterilizati on methods were tested for the stem and leaf explants. To determine the best plant growth regulator concentrati ons for callus inducti on, diff erent combinati ons 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 eff ecti ve surface sterilizati on 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 opti mal for callus inducti on from leaves under light and dark conditi ons with calli inducti on rates of 33.33% and 16.67%, respecti vely. For stems best results were obtained for 0.3 mg/L NAA; and 2 mg/L BAP with a 66.67% calli inducti on rate in light conditi ons and 33.33% in dark conditi ons. Calli were obtained from both explants within an average of 38.5 days and 44 days in light and dark conditi ons respecti vely. 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, vitrifi cati on and contaminati on underscore the need for refi nements on this protocol.