In vitro production of true-to-type plants of Vitex negundo L. from nodal explants

Abstract

An efficient micropropagation protocol, involving axillary bud multiplication, was established to clone Vitex negundo L. plants. An optimum regeneration frequency (97%) and a desirable organogenic response, in the form of multiple shoots, was obtained on Murashige and Skoog (MS) medium augmented with 5.0 μM 6-benzyladenine (BA) in combination with 0.5 μM 1-naphthaleneacetic acid (NAA). Healthy, growing in vitro-raised microshoots rooted efficiently on MS medium supplemented with 1.0 μM indole-3-butyric acid (IBA). Following standard hardening procedures, rooted shoots were transferred to the field with ≥ 90% survival. No morphological variations were detected among the micropropagated plants when compared with the mother plant. Inter-simple sequence repeat (ISSR) markers were used to evaluate the genetic stability of both the in vitro and in vivo propagated plants. All ISSR profiles from micropropagated plants were monomorphic, and similar to those of field-grown control plants. These results suggest that the culture conditions used for axillary bud proliferation are appropriate for clonal propagation of this medicinally important plant as they do not appear to interfere with the genetic integrity of in vitro-regenerated plants (i.e., no somaclonal variation).