Genetic modification of rosa pinna (Clerodendrum philippinum Schauer) with gai mutant gene for improved plant architecture

Abstract

Rosa pinna (Clerodendrum philippinum Schauer), is a shrub with attractive and fragrant flowers. However, the tall and spread architecture and high leaf to flower ratio hinder its use as an ornamental plant. Hence, changing the level of acceptance of C. philippinum by incorporating a dwarfing gene to the plant is considered useful. A study was conducted to find a suitable regeneration medium and ultimately to modify the plant architecture through transformation of the gibberellic acid inhibitor (gai) mutant dwarfing gene by particle bombardment. Effects of different concentrations of thidiazuron (TDZ:Nphenyl N’ 1,2,3-thidiazol-5-yl urea) on callus initiation and regeneration of shoots and the effects of microcareer flying distance in gene transformation of C. philippinum were investigated. The regenerated shoots were first cultured on hormone free MS medium and transferred to a MS medium with 0.5 mg/L indole butyric acid for rooting after four weeks. The shortest duration for callus initiation, the largest callus volume (28 days after establishment) and the highest number of shoots (75 days after establishment) were observed in 1.5 mg/L TDZ in the MS medium. Results of transferring the gai mutant gene to in vitro leaves of C. philippinum revealed that both the shortest time duration and the highest plant regeneration were at 9 cm micro-carrier flying distance. Leaf tissues of regenerated plants, which carry the gai mutant gene, positively responded for the beta-glucuronidase (GUS) assay. The regenerated shoots were rooted and successfully acclimatized.