Feeding the World Four Decades from Now
Rosenthal, D.M., Locke, A.M., Khozaei, M., Raines, C.A., Long, S.P. and Ort, D.R. 2011. Over-expressing the C3 photosynthesis cycle enzyme Sedoheptulose-1-7 Bisphosphatase improves photosynthetic carbon gain and yield under fully open air CO2 fumigation (FACE). BMC Plant Biology 11: 123.
Wild type tobacco (Nicotiana tabacum) and "transformed" tobacco that overexpresses the C3 cycle enzyme sedoheptulose-1,7 bisphosphatase (SBPase) were grown in the field at the Soy-FACE facility of the University of Illinois at Urbana-Champaign under ambient (385 ppm) and enriched (585 ppm) atmospheric CO2 concentrations, during which time a number of plant properties and processes were assessed, in order to determine the ultimate impact of the aerial fertilization effect of atmospheric CO2 enrichment on the two types of plants.
The six scientists determined that growth under elevated CO2 stimulated instantaneous net photosynthesis, as well as the diurnal integral of net photosynthesis, more in the transformed plants than in the wild type plants; and although there was some evidence of photosynthetic acclimation in both sets of plants, there was still a greater CO2-induced stimulation of final biomass in the transformed plants than in the wild-type plants (22% vs. 13%).
Noting that their study "demonstrated that transgenic tobacco plants with increased SBPase have the potential for greater stimulation of photosynthesis and biomass production relative to wild type tobacco when grown at elevated CO2," Rosenthal et al. say their results "provide proof of concept that increasing [the] content and activity of a single photosynthesis enzyme can enhance carbon assimilation and yield of C3 crops grown at CO2 concentrations expected by the middle of the 21st century," which productivity boost they feel will be needed in order to adequately feed the world's projected population at that point in time.
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