Abstract

Background: Saurauia punduana Wallich (Actinidiaceae) is a therapeutically important threatened plant species. Habitat destruction due to anthropogenic activities and over-collection for medicinal purpose has reduced the natural population. Present communication reports successful somatic embryogenesis and plant regeneration from in vitro cotyledonary leaves.

Method: Saurauia punduana seeds were extracted from 5-7 weeks old fruits and cultured on MS medium fortified BA (2μM) for germination. The cotyledonary leaves were harvested from in vitro raised seedlings and cultured on MS fortified medium. Embryogenic callus was maintained on MS medium fortified with sucrose (3%), NAA (1.5 μM) and BA (4 μM) for callus proliferation. The callus was subsequently maintained for embryo development and maturation.

Results: About 68% of the leaf pieces formed embryogenic callus on MS medium fortified with sucrose (3%, w/v), NAA (1.5 μM) and BA (4 μM). The embryogenic cultures registered ~348% proliferation of inoculum callus after four weeks on subsequent subculture onto proliferation medium. The proembryos converted into cotyledonary embryos and torpedo shaped embryos when transferred onto MS medium fortified with sucrose (4%) and BA (4 μM); ~62% globular embryos converted to cotyledonary embryos. In addition as many as 38 embryos per 200 mg of embryogenic cultures were formed. The somatic embryos germinated on the conversion medium accompanied by secondary somatic embryo formation. The germinated embryos could be easily separated from the clump and transferred to potting mix and maintained in a polyhouse for 5-6 weeks, where ~75% seedlings survived after 6 weeks in the potting mix.

Conclusion: This is a reproducible protocol for somatic embryogenesis and secondary embryogenesis of Saurauia punduana and their conversion into embling. The protocol developed will help in production of clonal planting materials and propagation of this species.

Keywords: Cotyledonary leaves, medicinal plant, plant regeneration, secondary somatic embryos, somatic embryogenesis, Suarauia punduana.

Graphical Abstract