Quantitative effects of enhanced CO<sub>2</sub> on jasmonic acid induced plant volatiles of lima bean (<em>Phaseolus lunatus</em> L.)


  • D. J. Ballhorn
  • C. Reisdorff
  • H. Pfanz


Globally rising CO2 has been predicted to affect plant biochemistry and in consequence the interaction of plants with multiple associated organisms. While CO2 mediated effects on nutritive compounds and direct anti-herbivore defenses appear to be well studied for many plant species, the importance of altered atmospheric CO2 concentrations on indirect defenses is only little understood. In this study, we analyzed the effects of enhanced CO2 on the release of volatile organic compounds (VOCs) using jasmonic acid (JA) as a natural hormone-like inductor. We cultivated lima bean plants (Phaseolus lunatus L.) under different CO2 concentrations (ambient, 500, 700, and 1000 ppm) and quantified the release of VOCs using GC-MS. The total release of VOCs significantly increased in response to higher CO2 concentrations. However, the quantitative emission of individual compounds was differently affected. Nine out of twelve VOCs were released at significantly higher levels (cis-3-hexenylacetate, cis-ocimene, linalool, cis-3-hexenyl butyrate, methyl salicylate, cis-jasmone, β-caryophyllene, trans-geranylacetone, and methyl jasmonate) at enhanced CO2, whereas two were not affected (2-ethylhexan-1-ol, cis-3-hexenyl isovalerate) and the release of indole decreased. Shifts in VOCs release under elevated CO(2) likely affect efficacy of plants' resistance to herbivores, as a range of the affected compounds are of central importance in defense-associated plant-plant and within-plant signaling. Given the importance of plant-herbivore interactions in terrestrial ecosystems, CO2 mediated changes in defense-associated VOCs might have implications on agricultural and natural ecosystem functions.