Shortening the biennial life span of Swertia puniced by using tissue culture to obtain season-free inflorescences.

Abstract

Tissue segments from stalked second-year-plants of the biennial Swertia punicea induced calli when they were cultured on the LS gelrite media containing 1μM NAA and 1μM BA, or 1μM NAA and 10μM BA, or 1μM 2, 4-D and 1μM BA, in combination. Those calli were rapidly propagated on the LS gelrite medium containing 0.5μM NAA or 2, 4-D at 25°C at a relative humidity of 65% under an illumination of 2, 000 lux for 12hr. After approximately 60 days of the callus culture in the LS gelrite medium containing 0.5μM IAA and 0.5μM BA, they began to produce numerous adventitious buds which later regenerated plantlets. Those plantlets were chromosomally rather stable clones with the stable karyotype of 26 median-centromeric chromosomes at mitotic metaphase. Large enough plantlets having several leaves of 7-8cm long and many roots were transplanted in pots in vivo and acclimated in environment at above 15°C and relative humidity above 65% for a week. After about three months at any season if cultivated at above 15°C, they usually bolted stems and produced inflorescences. Thus, this culture system shortened the biennial life-span of Swertia punicea.