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Advisor(s)
Abstract(s)
Previous studies have shown that elevated levels of carbon dioxide [CO2] may increase, decrease, or have
no effect on the concentrations of phenolic compounds in plants. The underlying causes of these variations
in responses remain poorly understood. In the present study, it was hypothesized that different plant
responses come mainly from the duration of exposure to the gas, growing conditions, and sampling procedures. A two-year field study was conducted in open-top chambers (375 vs. 550 mmol CO2mol−1 air) using
a japonica rice variety (Oryza sativa L. cv. Ariete) as the test crop, with plants grown under elevated [CO2]
during their entire life cycle. Leaf, stem and root samples were collected at five different growth stages,
and submitted to a series of physiological and biochemical measurements. The carbon:nitrogen ratio and
total non-structural carbohydrates were increased by elevated [CO2] in all plant tissues. Data showed that
under elevated [CO2], there was a reduction in the total phenolic and total flavonoid contents measured
during the seedling, tillering, elongation, and flowering stages in all plant organs, probably resulting
from a relaxation of the antioxidative system during seed germination. By contrast, the total phenolic
and flavonoid contents increased under elevated [CO2] at maturity, a change in response which coincided with acclimation of photosynthesis. The same trends were observed for sixteen individual phenolic
compounds, including the allelopathic tricin, the phytoalexin sakuranetin and several O-glycosylated
flavonoids of ecological importance. Overall, the results indicated that during the early stages of plant
development, photosynthates were mainly used to synthesize proteins and meet the growth demand
of the plant. Growth reduction at maturity made more resources available for the synthesis of phenolic
compounds.
Description
Keywords
Carbon dioxide Tricin Rice Phenolic acids Flavonoids Photosynthetic acclimation
Citation
Goufo P., Pereira J., Moutinho-Pereira J., Correia C.M., Figueiredo N., Carranca C., Rosa E.A.S., Trindade H., 2014. Rice (Oryza sativa L.) phenolic compounds under elevated carbon dioxide (CO2) concentration. Environmental and Experimental Botany 99, 28-37.
Publisher
Elsevier