Plant Regeneration of Periwinkle (Catharanthus roseus) via Organogenesis

Abstract

Two periwinkle cultivars, Pacific Coral (P1) and Sunstorm Rose (P2), were used for development of a plant regeneration system. Leaf and internodal explants collected from in vitro plants were plated onto woody plant medium (WPM) using a factorial arrangement of 6-benzyladeine (BA) and 1-naphthalene acetic acid (NAA). Shoots were successfully regenerated. Shoot production from leaf tissues was minimal for all cultivars, whereas internodal tissues showed variable rates of regeneration depending on the hormone combination. Cultivar P1 showed the maximum regeneration rate (73.3%) when internodal explants, 4 to 6 mm in length, were placed on WPM containing 5 μm BA and 5 μm NAA. Cultivar P2 showed a regeneration rate of 56.7% with a combination of 20 μm BA and 10 μm NAA. Shoot regeneration rate increased as the internodal explant size increased for P2; however, the regeneration rate decreased when the explant size was greater than 7 mm for P1. The shoot regeneration rate decreased as the period of the dark treatment of internodal explants increased in both P1 and P2. The antibiotics carbenicillin (Carb) and cefotaxime (Cef) had little effect on shoot regeneration. There was a slightly higher rate observed for P1 when Cef was added into the medium, whereas P2 showed a decrease with the addition of Cef. Carb showed no significant effect on shoot regeneration for both cultivars. Addition of both Carb and Cef to the medium slightly inhibited shoot regeneration.