What was done
Potato plantlets inoculated with Glomus intraradices were grown at various light intensities and atmospheric CO2 concentrations for approximately one month to determine the interactive effects of these variables on the relationship between this arbuscular mycorrhizal fungus and its host plantlets.

What was learned
Exposure to super-elevated atmospheric CO2 concentrations of approximately 10,000 ppm stimulated root colonization by the fungus to a much greater extent than is characteristic of ambient CO2 concentrations, regardless of light intensity.  However, dry matter production in CO2-enriched inoculated plantlets significantly increased only when grown at high light intensity.  In addition, comparison of dry matter production and some photosynthetic parameters suggested that the degree of photosynthetic down regulation observed in CO2-enriched plantlets was less severe in the presence, rather than in the absence, of the fungal symbiont.

What it means
As the CO2 content of the air rises, potato plantlets will likely exhibit greater degrees of root colonization by mycorrhizal fungi.  This phenomenon should not only increase dry matter production and final yields in potato, but should also effectively increase their sink strength, thereby reducing the likelihood of inducing photosynthetic acclimation.