Paper Reviewed
El Kelish, A., Zhao, F., Heller, W., Durner, J., Winkler, J.B., Behrendt, H., Traidl-Hoffmann, C., Horres, R., Pfeifer, M., Frank, U. and Ernst, D. 2014. Ragweed (Ambrosia artemisiifolia) pollen allergenicity: SuperSAGE transcriptomic analysis upon elevated CO2 and drought stress. BMC Plant Biology 14: 10.1186/1471-2229-14-176.

Noting that the pollen of common ragweed (Ambrosia artemisiifolia) is one of the main causes of allergic diseases in North America, and that it is also in the process of spreading throughout Europe, a team of eleven scientists (El Kelish et al., 2014) took it upon themselves to determine if this unfortunate development was being helped along by the ongoing rise in the air's CO2 content. This they did by growing ragweed plants in a greenhouse under both ambient (380 ppm) and elevated (700 ppm) atmospheric CO2 concentrations, both with and without a drought treatment, while generating SuperSAGE (a substantially improved variant of serial analysis of gene expression) libraries, which they derived from the plants' RNA and used to identify different expressed sequence tags or ESTs in the ragweed's transcriptome.

This work revealed, in the words of El Kelish et al., that "under global change scenarios the pollen transcriptome was altered," and they say that the change "impacts the allergenic potential of ragweed pollen," as they note has also been found to be the case by Singer et al. (2005). However, they say they "cannot exclude the possibility that the increased 'Amb a' transcript level will also reflect the corresponding allergenic protein level, as an incongruent expression between transcripts and proteins is well described in the literature," citing Gygi et al. (1999), Perco et al. (2010) and Sanchez-Pons et al. (2011). In addition, they indicate that "transcript homologies to other plant allergens were found that might modulate the 'Amb a' allergenic response," which possibility, as they see it, "requires to be tested in suitable model systems."

Consequently, and like the pollen itself, we must consider this situation to still be "up in the air," as it were, while we await the results of additional and more definitive studies.

References
Gygi, S.P., Rochon, Y., Franza, B.R. and Aebersold, R. 1999. Correlation between protein and mRNA abundance in yeast. Molecular and Cellular Biology 19: 1720-1730.

Perco, P., Muhlberger, I., Mayer, G., Oberbauer, R., Lukas, A. and Mayer, B. 2010. Linking transcriptomic and proteomic data on the level of protein interaction networks. Electrophoresis 31: 1780-1789.

Sanchez-Pons, N., Irar, S., Garcia-Muniz, N. and Vicient, C.M. 2011. Transcriptomic and proteomic profiling of maize embryos exposed to camptothecin. BMC Plant Biology 11: 10.1186/1471-2229-11-91.

Singer, B.D., Ziska, L.H., Frenz, D.A., Gebhard, D.E. and Straka, J.G. 2005. Increasing Amb a l content in common ragweed (Ambrosia artemisiifolia) pollen as a function of rising atmospheric CO2 concentration. Functional Plant Biology 32: 667-670.