How does rising atmospheric CO2 affect marine organisms?

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Microevolutionary Responses to Atmospheric CO2 Enrichment
Rae, A.M., Tricker, P.J., Bunn, S.M. and Taylor, G. 2007. Adaptation of tree growth to elevated CO2: quantitative trait loci for biomass in Populus. New Phytologist 175: 59-69.

The authors state that various studies "are beginning to identify genes that appear sensitive to elevated CO2 (Gupta et al., 2005; Taylor et al., 2005; Ainsworth et al., 2006)," noting that "leaf growth responses to elevated CO2 have been found in Populus," and that "quantitative trait loci (QTL) for this response [have been] determined (Rae et al., 2006)."

What was done
Working with a three-generation Populus pedigree generated by the hybridization of two contrasting Populus species (P. trichocarpa T.&G. and P. deltoides Marsh.), where two full-siblings (53-242 and 53-246) from the resulting F1 family were crossed to form an F2 family, Rae et al. grew cuttings of the different generations for 152 days in John Innes no. 2 compost (lime-free) in 91-cm-high 15-cm-diameter plastic tubes buried to a depth of 10 cm out-of-doors in open-top chambers maintained at either ambient atmospheric CO2 concentrations or concentrations on the order of 600 ppm, while measuring various plant properties and physiological processes, and determining QTL for above- and below-ground growth and genotype-by-environment interactions.

What was learned
The four UK researchers report that "in the F2 generation, both above- and below-ground growth showed a significant increase in elevated CO2," and that "three areas of the genome on linkage groups I, IX and XII were identified as important in determining above-ground growth response to elevated CO2, while an additional three areas of the genome on linkage groups IV, XVI and XIX appeared important in determining root growth response to elevated CO2."

What it means
Rae et al. say their results "quantify and identify genetic variation in response to elevated CO2 and provide an insight into genomic response to the changing environment." More specifically, they state that the combination of their mapping analysis with other high-throughput technologies now available in systems biology (Taylor et al., 2005) "should lead to an understanding of microevolutionary response to elevated CO2 ... and aid future plant breeding and selection."

Ainsworth, E.A., Rogers, A., Vodkin, L.O., Walter, A. and Schurr, U. 2006. The effects of elevated CO2 concentration on soybean gene expression. An analysis of growing and mature leaves. Plant Physiology 142: 135-147.

Gupta, P., Duplessis, S., White, H., Karnosky, D.F., Martin, F. and Podila, G.K. 2005. Gene expression patterns of trembling aspen trees following long-term exposure to interacting elevated CO2 and tropospheric O3. New Phytologist 167: 129-142.

Rae, A.M., Ferris, R., Tallis, M.J. and Taylor, G. 2006. Elucidating genomic regions determining enhanced leaf growth and delayed senescence in elevated CO2. Plant, Cell & Environment 29: 1730-1741.

Taylor, G., Street, N.R., Tricker, P.J., Sjodin, A., Graham, L., Skogstrom, O., Calfapietra, C., Scarascia-Mugnozza, G. and Jansson, S. 2005. The transcriptome of Populus in elevated CO2. New Phytologist 167: 143-154.

Reviewed 14 November 2007