micrantha, one of the worst invasive weeds in the world, which in turn might enhance its potential allelopathic effect on neighboring native plants if released in bioactive concentrations. These results suggest that elevated atmospheric CO₂ levels may enhance biosynthesis and phytotoxicity of allelochemicals in M. β-Caryophyllene displayed higher phytotoxic effects at 750 ppm than those at 350 ppm CO₂, especially on R. micrantha was dose-dependent and varied with the receptor plants and concentrations of CO₂. Bioassays showed that phytotoxicity of β-caryophyllene against Raphanus sativus, Brassica campestris, Lactuca sativa, and M. micrantha increased when exposed to 750 ppm CO₂. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC) analyses showed that emission levels of β-caryophyllene from leaves of M. micrantha leaves was strongly induced in response to elevated CO₂. Real-time PCR analysis revealed that gene expression of β-caryophyllene synthase in M. β-Caryophyllene synthase catalyses the conversion of farnesyl diphosphate to β-caryophyllene, a volatile sesquiterpene with allelopathic potential. micrantha exposed to CO₂ at 350 and 750 ppm for 6 d, and isolated a novel gene named β-caryophyllene synthase.
To better understand the effect of predicted elevated levels of carbon dioxide (CO₂) on an invasive weed Mikania micrantha, we constructed a suppressive subtractive hybridization (SSH) library from the leaves of M.