Dietary supplementation with plant-derived polyphenolic compounds such as the flavonoids epigallocatechin-3-gallate (EGCG), quercetin and resveratrol can result in a beneficial effect on degenerative disease processes through both radical scavenging and activation of cellular ion channels. Preliminary investigations have shown that extracts from the halophyte species Carpobrotus rossii have high in vitro antioxidant and in vivo low-density-lipoprotein-lowering activities. In this study, we have investigated the environmental conditions responsible for inducing flavonoid production in C. rossii in an attempt to maximise production of these compounds. Both field surveys and controlled glasshouse experiments were conducted. Flavonoid production appears to be related to conditions known to cause oxidative stress in plants such as exposure to excessive light, reduced water availability, and low soil potassium levels. Flavonoid production was minimal under salinity levels optimal for C. rossi growth (around 50 mM NaCl) and increased dramatically at sub- and supra-optimal salinities. Flavonoids were clearly concentrated in metabolically active palisade mesophyll tissue rather than the spongy parenchyma. Non-optimal (outside 50–100 mM range) NaCl levels significantly increased flavonoid concentration on a per leaf basis. However, the reduction in biomass production at sub and supra optimal salinities diminished absolute flavonoid production per plant. As a result, saline conditions favouring optimal plant growth appear to be most suitable for maximising production of flavonoids in C. rossii.

Item Type:	Refereed Article
Keywords:	flavonoid, halophyte, oxidative stress, salinity, potassium, stomata
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Environmentally sustainable plant production
Objective Field:	Environmentally sustainable plant production not elsewhere classified
UTAS Author:	Pirie, A (Mr Adam Pirie)
UTAS Author:	Parsons, D (Dr David Parsons)
UTAS Author:	Renggli, J (Ms Jolanda Renggli)
UTAS Author:	Narkowicz, C (Dr Christian Narkowicz)
UTAS Author:	Jacobson, GA (Associate Professor Glenn Jacobson)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	82118
Year Published:	2013
Web of Science® Times Cited:	15
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2013-01-16
Last Modified:	2014-04-04
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