In Vitro Regeneration of Trichosanthes from Shoot Tips
The morphogenetic potential of parval or pointed gourd (Trichosanthes dioica Roxb.) shoot-tip explants was investigated to establish this species as a model tissue culture system. An effective multiple-shoot propagation method is described. Ten-millimeter shoot tips from young branches of greehouse-grown plants served as explants. They were initiated on a MS basal medium. Multiple shoots were encouraged by transferring established explants to a proliferation medium consisting of MSB + 1 mg BAP/liter, because lower concentrations of BAP (0.1 to 0.5 mg–liter–1) inhibited multiple shoot formation; however, the same concentrations promoted rooting in explants. Medium supplemented with 1 mg BAP/liter and 100 mg PVP/liter caused the best proliferation of shoot tips. Upon transferring to fresh medium of the same composition, these shoot tips elongated 24 cm with three to five nodes in 4 weeks of culturing. Shoot multiplication cultures were maintained by transferring segments of multiple-shoot clusters to medium containing 1 mg BAP/liter and 0.5 mg GA3/liter. Medium supplemented with TDZ inhibited the number of regenerating explants but enhanced the number of shoot buds. Eighty percent of these plantlets were successfully rooted on MS medium supplemented with 1 mg NAA/liter. Plantlets survived in potting soil and exhibited normal growth under mist in the greenhouse.