Tissue culture and organogenesis in the winged bean

Abstract

Seedlings of Psophocarpus tetragonolobus var. TPt2 were grown under sterile conditions on nutrient agar. Hypocotyl sections (0.5 cm) from 2-week-old seedlings were used to initiate callus on solid B5 medium with 0.5 mg/L 2,4-D. Callus was transferred into liquid B5 and MS media also containing 0.5 mg/L 2,4-D. Suspension cultures developed within 6 weeks, but could not be maintained longer than 3 months. However, when suspensions were transferred into medium containing MS salts, iron-EDTA, and the following organic compounds: inositol, thiamine, pyridoxine, nicotinic acid (0.5 mg/L), kinetin (0.3 mg/L), IAA (5.0 mg/L), 2,4-D (1.5 mg/L), and sucrose (40 mg/L), optimal growth resumed and has continued for 2 years with a doubling time of 57.6 h. Chromosome counts of the suspension culture cells show predominantly the diploid chromosome number of 2n = 18. Greening of callus occurred in the absence of exogenous hormones, but efforts to hormonally induce organogenesis from callus have succeeded only in promoting root formation.