Enhanced In Vitro Shoot Regeneration in Oldenlandia umbellata L. by Using Quercetin: A Naturally Occurring Auxin-Transport Inhibitor

An improved micropropagation and ex vitro rooting of a commercially important crop Henna (Lawsonia inermis L.)

An improved micropropagation protocol has been developed for a cosmetically important, dye yielding crop, henna (Lawsonia inermis). Quality of henna product is governed by naphthoquinone based pigment lawsone, thus in vitro multiplication of superior healthy plant to achieve enhanced productivity in terms of dye content and biomass deserve due attention. In the present study, nodal explants collected from an elite plant screened on the basis of superiority in lawsone content was cultured on MS medium supplemented with 0.5 μM benzyl adenine (BA) gave significantly (p < 0.05) high number of shoots (24.33). The explants placed on MS medium augmented with 0.5 μM BA and 2-isopentenyladenine (2-iP) resulted in the formation of maximum number of shoots (43.67) and was elongated (12.57 cm) within 4 weeks of culture period. Enhanced axillary bud proliferation and production of mass number of micro shoots was achieved by the continuous subculture in MS medium containing 0.5 μM BA and 2-iP. In vitro raised micro shoots were dipped in 0.44 mM NAA for 5 min followed by planting in polyethylene pots containing a soil: vermiculite (1:1 v/v) mixture produced rooted plantlets (100%). Different auxin types and its concentrations had significant role rooting of L. inermis. Rooting response of various size shoots of L. inermis treated with 0.44 mM NAA showed 100% rooting in 4.1-5 cm size class shoots. After two months of potting, survived (95%) plants were successfully transferred to medicinal plant garden of the Department. The lawsone content of one-year-old micropropagated plants (23.04 mg/g dw) growing in normal environmental conditions and elite mother plant (22.84 mg/g dw) was almost similar. Through the present study, efficient cloning of superior germplasm of L. inermis was established.

Auxin and nutritional stress coupled somatic embryogenesis in Oldenlandia umbellata L

Somatic embryos were induced from internodal segment derived callus of Oldenlandia umbellata L., in MS medium supplemented with different concentrations of 2,4-Dichlorophenoxy acetic acid (2,4-D). Initially calli were developed from internodes of microshoots inoculated in 2.5 µM NAA supplemented medium. Then calli were transferred to 2,4-D added medium for somatic embryogenesis. Nutritional stress coupled with higher concentration of 2,4-D triggered somatic embryogenesis. Nutritional stress was induced by culturing callus in a fixed amount of medium for a period up to 20 weeks without any external supply of nutrients. Addition of 2.5 µM 2,4-D gave 100% embryogenesis within 16 weeks of incubation. Callus mass bearing somatic embryos were transferred to germination medium facilitated production of in vitro plantlets. MS medium supplemented with 2.5 µM benzyl adenine and 0.5 µM α-naphthalene acetic acid produced 15.33 plants per culture within 4 weeks of culture. Somatic embryo germinated plants were then hardened and transferred to green house.