Factors affecting in vitro plant regeneration from cotyledonary node explant of Senna sophera (L.) Roxb. A highly medicinal legume

Abstract

An efficient in vitro regeneration protocol has been developed for a medicinal legume Senna sophera (L.) Roxb. using Cotyledonary Node (CN) explants. The plant exhibits high medicinal potential and is being used in several traditional and homeopathy system of medicine. The present study described an in vitro regeneration protocol, where different factors were optimized for maximum multiplication and propagation. The age of the explant, plant growth regulators, basal medium, pH of the medium and sucrose concentrations markedly influenced in vitro propagation of S. sophera. Among 14, 21 and 28 day-old CN explants, 21 day-old explants were found to be the most responsive. A maximum of 19.50 ± 0.51 shoots/explant were produced from 21 day-old seedling explants, having an average shoot length of 5.23 ± 0.14 cm in 86.00 ± 2.08% cultures after 6 weeks of incubation on Murashige and Skoog (MS) medium supplemented with benzyl adenine (BA) (5.0 µM) + naphthalene acetic acid (NAA) (1.0 µM) and containing 3% sucrose with pH value adjusted at 5.8. The highest rooting frequency (96.00 ± 2.08%) with maximum of 7.63 ± 0.23 roots/shoot having an average root length of 4.86 ± 0.35 cm was obtained on half-strength MS medium with 1.0 µM indole-3-butyric acid (IBA) and solidified with 0.25% phytagel. The plantlets were acclimatized in sterile soilrite under controlled conditions, hardened and successfully transferred to soil in natural conditions with 90% survival rate. The regenerated plants showed no morphological variations in terms of leaf shape, flower shape, pod size, number of seeds etc., when compared with the naturally grown plants in the field.   Key words: Senna sophera, fabaceae, cotyledonary node, in vitro shoot regeneration, rooting, acclimatization.