Ultraviolet–B induced flavonoid production in in vitro cultures of shallot (Allium cepa var. Aggregatum g. Don cv Batanes)

Abstract

© 2017, International Society for Southeast Asian Agricultural Sciences. All rights reserved. Onions are a rich source of health-enhancing flavonols, however research in enhancing the levels of these compounds, especially in shallots, is limited. This study was undertaken to investigate the relationship between flavonol production and UV-B exposure in shallots in an in vitro system and at the greenhouse. The experiment was conducted from January 2006 to April 2007 at the Plant Tissue Culture Laboratory, Institute of Crop Science, College of Agriculture and Food Science, UPLB. UV-B was used as an elicitor of flavonol production at two different stages of shallot tissue culture. In vitro established plantlets of shallots (cv Batanes) were subjected to UV-B (~290 nm) at 0, 3, and 6 h per day for 7 and 14 days at shoot induction and bulbing stages. Bulb diameter and total flavonol content was measured and the profiles of the three predominant flavonoids: quercetin, myricetin, and kaempferol, were described using paper chromatography. These were grown in vivo under greenhouse conditions. UV-B exposure did not affect bulb diameter of in vitro-grown plantlets but had increased total flavonols. Cultures at the bulbing stage had higher total flavonol than in the shoot induction stage. Flavonoid accumulation tends to increase with prolonged exposure to UV-B but could not be generalized for the different growth stages. There were no differences in flavonol accumulation regardless of the duration or exposure to UV-B. Percent survival was highest among plants that did not receive UV-B treatment. Bulb weight, diameter, plant height, and flavonol accumulation were not affected by UV-B treatments. Quercetin was found to be the most abundant flavonol followed by myricetin and kaempferol in in vitro cultures and among plants grown in the greenhouse.

Source or Periodical Title

Journal of the International Society for Southeast Asian Agricultural Sciences

ISSN

8593132

Page

146-157

Document Type

Article

Subject

Flavonol, Kaempferol, Myrcetin, Quercetin

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