Effects of plant growth regulators on in vitro micropropagation of Ruta chalapensis L.

Micropropagation is a rapid method for in vitro clonal multiplication of elite clones and also helps in dissemination and ex situ conservation of medicinal plants. In the present study, we report a highly efficient and cost effective protocol for high frequency plantlet regeneration from leaf explants of Ruta chalapensis L., commonly known as "Fringed Rue" which is an important medicinal herb. The leaf explants were cultured on Murashige and Skoog (MS) basal medium supplemented with Naphthalene acetic acid (NAA), 2,4-Dichlorophenoxyacetic acid (2,4-D), Indole-3-acetic acid (IAA) and Indole-3-butyric acid (IBA). MS medium supplemented with various concentrations of auxins such as IAA, IBA, NAA and 2,4-D was also tested. Among the various growth regulators used, NAA (1.0 mg/L) showed maximum callus induction (86.77±3.47%) from leaf explants, followed by NAA (2.0 mg/L) (79.34±3.09%). MS medium was fortified with NAA (0.5 mg/L) showed maximum (93.60±3.75%) of direct shoot induction. The concentration of auxins such as NAA increased by 2.0 mg/L produced lower shoot induction (74.10±2.96%). About 89.70±3.59% of roots were obtained when MS medium was amended with NAA (0.5 mg/L) as well as NAA (1.0 mg/L). Combination of NAA (1.5 mg/L) + KIN (2.0 mg/L) produced 77.02±3.08% of roots induction from leaf explants. Maximum green organogenic callus (95.55±3.82%) was observed in MS medium with NAA (0.5 mg/L) + KIN (0.5 mg/L). MS medium amended with IAA (0.5 mg/L) + KIN (0.5 mg/L) showed maximum (89.20±0.74%) of shoot induction from organogenic callus. MS medium amended with IAA (0.5 mg/L) + KIN (1.0 mg/L) showed maximum number (87.10±0.44%) of multiple shoot formation from organogenic callus. Maximum number (87.10±0.20%) of root formation from organogenic callus was obtained when the shoots were transferred to MS medium fortified with IAA (0.5 mg/L) + BAP (1.0 mg/L). The well-rooted plantlets were established on soil with 85% survival.