Assessing competence for adventitious shoot formation in hypocotyl explant cultures from Catharanthus roseus cultivars

Hypocotyl expiants from 22 cultivars of Catharanthus roseus were cultured on various shoot-inducing media to assess their competence for adventitious shoot formation. The Murashige and Skoog (MS) media had been supplemented with 14 μM zeatin and 2.5 μM indole-3-butyric acid (IBA), 4.5 μM BA and 0.5 μM α-naphthaleneacetic acid (NAA), or 14 μM thidiazuron and 2.5 μM IBA. After eight weeks, the expiants from ‘Cooler Raspberry Red’ showed the greatest frequency of adventitious shoot formation, followed by ‘Cooler Orchid’ and ‘Cooler Treated’. The highest frequency (86.7%) for ‘Cooler Raspberry Red’ was attained on the medium enhanced with 14 μM zeatin and 2.5 μM NAA. Excised adventitious shoots were then readily rooted on a half-strength MS basal medium. Afterward, the regenerated plantlets were transferred to potting soil and grown to maturity in a greenhouse.