Abstract
An optimised method for enhanced in vitro shoot multiplication of Rumex vesicarius (Polygonaceae)-a branched succulent herb-was achieved. The in vitro seed pre-treatment with 4% urea was able to show 95% seed germination on MS medium within 2 weeks of culturing. In vitro shoot bud induction from shoot tip explants was best in the presence of 2 mg L(-1) kinetin on Murashige and Skoog medium (MS medium), wherein 8.3 shoots/explants were observed. Shoot elongation was found to be high (3.75 ± 0.5 cm) in 2 mg L(-1) BA comprising medium. The transfer of micro-shoots on to MS medium comprising 1.5 mg L(-1) IBA and 1% activated charcoal (w/v) supported efficiently in vitro rooting (2.5-4.0 cm) in 3-4 weeks. Upon hardening, 70% rooted plants survived under greenhouse conditions. Though friable callus was produced on MS medium-containing 2 mg L(-1) BA followed by 3 mg L(-1) BA, no organogenesis was noticed. The ascorbic acid content of 78.62 ± 0.25 mg 100 g(-1) FW was recorded in callus cultures grown on medium supplemented with 2 mg L(-1) BA, and it is 1.74-fold more compared to normal ex vitro leaves of the same age. In vitro raised plant leaf showed 1.98-fold more ascorbic acid (89.42 ± 0.18 mg 100 g(-1) FW) to that of ex vitro leaves. The total phenolic content was found to be 60 mg in callus as compared to 610 mg (per 100 g GAE FW) of ex vitro leaves. The major phenolic compounds quantified were synergic, chlorogenic, ferulic, and generic acids, respectively. This optimised protocol will facilitate to pursue scale-up studies for in vitro ascorbic acid production and also to further investigate the kinetics of biosynthetic pathway genes involved.