Species-specific response of glucosinolate content to elevated atmospheric CO2

• Published in: Journal of chemical ecology 1997-11, Vol.23 (11), p.2569-2582
• Main Authors: Karowe, D.N. (Western Michigan University, Kalamazoo, MI.), Seimens, D.H, Mitchell-Olds, T
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; BRASSICA CAMPESTRIS; BRASSICA NAPUS; CARBON; CARBON DIOXIDE; CHEMICAL COMPOSITION; DEFENSE; Ecological effects; Flowers & plants; Fundamental and applied biological sciences. Psychology; GLUCOSINOLATES; LEAVES; NITROGEN; NUTRIENT BALANCE; Nutrient content; NUTRITION PHYSIOLOGY; PLANT DEFENSE; Plant growth; Plants and fungi; RAPHANUS SATIVUS
• ISSN: 0098-0331; 1573-1561
• DOI: 10.1023/B:JOEC.0000006667.81616.18

The carbon/nutrient balance hypothesis has recently been interpreted to predict that plants grown under elevated CO2 environments will allocate excess carbon to defense, resulting in an increase in carbon-based secondary compounds. A related prediction is that, because plant growth will be increasingly nitrogen-limited under elevated CO2 environments, plants will allocate less nitrogen to defense, resulting in decreased levels of nitrogen-containing secondary compounds. We present the first evidence of decreased investment in nitrogen-containing secondary compounds for a plant grown under elevated CO2. We also present evidence that plant response is species-specific and is not correlated with changes in leaf nitrogen content or leaf carbon-nitrogen ratio. When three crucifers were grown at 724 +/- 8 ppm CO2, total foliar glucosinolate content decreased significantly for mustard, but not for radish or turnip. Glucosinolate content of the second and fourth youngest mustard leaves decreased by 45% and 31%, respectively. In contrast, no significant change in total glucosinolate content was observed in turnip or radish leaves, despite significant decreases in leaf nitrogen content. Total glucosinolate content differed significantly among leaves of different age; however, the trend differed among species. For both mustard and turnip, glucosinolate content was significantly higher in older leaves, while the opposite was true for radish. No significant CO2 x leaf age interaction was observed, suggesting that intraplant patterns of allocation to defense will not change for these species. Changes in nitrogen allocation strategy are likely to be species-specific as plants experience increasing atmospheric CO2 levels. The ecological consequences of CO2-induced changes in plant defensive investment remain to be investigated