Molecules 2012, 17(2), 1159-1176; doi:10.3390/molecules17021159
Article

Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels

email and * email
Received: 14 November 2011; in revised form: 16 December 2011 / Accepted: 19 December 2011 / Published: 27 January 2012
Download PDF [239 KB, uploaded 18 June 2014]
Abstract: The resource availability hypothesis predicts an increase in the allocation to secondary metabolites when carbon gain is improved relative to nutrient availability, which normally occurs during periods of low irradiance. The present work was carried out to confirm this hypothesis by investigating the effects of decreasing irradiance on the production of plant secondary metabolites (flavonoids and phenolics) in the herbal plant Orthosiphon stamineus, and to characterize this production by carbohydrate, H2O2, and malondialdehyde (MDA) levels, net photosynthesis, leaf chlorophyll content and carbon to nitrogen ratio (C/N). Four levels of irradiance (225, 500, 625 and 900 µmol/m2/s) were imposed onto two-week old seedlings for 12 weeks in a randomized complete block design experiment. Peak production of total flavonoids, phenolics, soluble sugar, starch and total non-structural carbohydrate ocurred under low irradiance of 225 µmol/m2/s, and decreased with increasing irradiance. The up-regulation of secondary metabolites could be explained by the concomitant increases in H2O2 and MDA activities under low irradiance. This condition also resulted in enhanced C/N ratio signifying a reduction in nitrogen levels, which had established significant negative correlations with net photosynthesis, total biomass and total chlorophyll content, indicating the possible existence of a trade-off between growth and secondary metabolism under low irradiance with reduced nitrogen content. The competition between total chlorophyll and secondary metabolites production, as exhibited by the negative correlation coefficient under low irradiance, also suggests a sign of gradual switch of investment from chlorophyll to polyphenols production.
Keywords: light intensity; total non-structural carbohydrate; carbon-based secondary metabolites; lipid peroxidation; total soluble sugar; protein competition model; C/N ratio
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Export to BibTeX |
EndNote


MDPI and ACS Style

Ibrahim, M.H.; Jaafar, H.Z.E. Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels. Molecules 2012, 17, 1159-1176.

AMA Style

Ibrahim MH, Jaafar HZE. Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels. Molecules. 2012; 17(2):1159-1176.

Chicago/Turabian Style

Ibrahim, Mohd Hafiz; Jaafar, Hawa Z. E. 2012. "Primary, Secondary Metabolites, H2O2, Malondialdehyde and Photosynthetic Responses of Orthosiphon stimaneus Benth. to Different Irradiance Levels." Molecules 17, no. 2: 1159-1176.


Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert