Growth and phytochemical levels in micropropagated Eucomis autumnalis subspecies autumnalis using different gelling agents, explant source, and plant growth regulators

Abstract

The therapeutic value of Eucomis species is well recognized in African traditional medicine. As a potential approach to improve growth and phytochemical content in Eucomis autumnalis subspecies autumnalis, the effect of agar (Bacteriological Agar No. 1 Oxoid) and gellan gum (GELRITE™) was evaluated using different explant sources and plant growth regulator (PGR) combinations. After 10 wk, the growth parameters were measured and phytochemical levels in 50% methanol (MeOH) extracts of the dried regenerated plantlets were determined using colorimetric methods. The highest mean shoot number (ca. 9 per explant) was observed in gellan gum-solidified media using a benzyladenine (BA) and α-naphthaleneacetic acid (NAA) treatment. Regardless of the gelling agent or PGR applied, the (initial/primary) explant source (LDL = leaf explant derived from primary leaf regenerants and LDB = leaf explant derived from primary bulb regenerants) significantly influenced all the parameters with the exception of shoot length and number of bigger shoots (≥5 mm). In most cases, the regenerants from agar-solidified media contained higher levels of flavonoids and phenolics. In terms of PGRs, the BA + NAA treatment had the highest shoot proliferation (fourfold higher than PGR-free) and number of larger shoots in LDL (gellan gum) and LDB (agar and gellan gum) regenerants. Generally, the evaluated factors (gelling agent, explant source, and PGR) significantly affected the concentrations of all the phytochemicals with the exception of total phenolic content. Taken together, the current study justifies the need to fully evaluate the manner in which in vitro culture conditions/factors affect the overall outcome of micropropagation endeavors.