No abstract

No abstract

Eckol, a major phenolic compound isolated from brown seaweed significantly enhanced the bulb size and bioactive compounds in greenhouse-grown Eucomis autumnalis. We investigated the effect of eckol and phloroglucinol (PG) (phenolic compounds) isolated from the brown seaweed, Ecklonia maxima (Osbeck) Papenfuss on the growth, phytochemical and auxin content in Eucomis autumnalis (Mill.) Chitt. The model plant is a popular medicinal species with increasing conservation concern. Eckol and PG were tested at 10(-5), 10(-6) and 10(-7) M using soil drench applications. After 4 months, growth parameters, phytochemical and auxin content were recorded. When compared to the control, eckol (10(-6) M) significantly improved bulb size, fresh weight and root production while the application of PG (10(-6) M) significantly increased the bulb numbers. However, both compounds had no significant stimulatory effect on aerial organs. Bioactive phytochemicals such as p-hydroxybenzoic and ferulic acids were significantly increased in eckol (10(-5) M) and PG (10(-6) M) treatments, compared to the control. Aerial (1,357 pmol/g DW) and underground (1,474 pmol/g DW) parts of eckol-treated (10(-5) M) plants yielded the highest concentration of indole-3-acetic acid. Overall, eckol and PG elicited a significant influence on the growth and physiological response in E. autumnalis. Considering the medicinal importance of E. autumnalis and the increasing strains on its wild populations, these compounds are potential tools to enhance their cultivation and growth.

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.

No abstract