Effects of simultaneously elevated temperature and CO levels on Nicotiana benthamiana and its infection by different positive-sense RNA viruses are cumulative and virus type-specific.

We have studied how simultaneously elevated temperature and CO levels [climate change-related conditions (CCC) of 30°C, 970 parts-per-million (ppm) of CO vs. standard conditions (SC) of 25°C, ~ 405ppm CO] affect physiochemical properties of Nicotiana benthamiana leaves, and also its infection by several positive-sense RNA viruses. In previous works we had studied effects of elevated temperature, CO levels separately. Under CCC, leaves of healthy plants almost doubled their area relative to SC but contained less protein/unit-of-area, similarly to what we had found under conditions of elevated CO alone. CCC also affected the sizes/numbers of different foliar cell types differently. Under CCC, infection outcomes in titers and symptoms were virus type-specific, broadly similar to those observed under elevated temperature alone. Under either condition, infections did not significantly alter the protein content of leaf discs. Therefore, effects of elevated temperature and CO combined on properties of the pathosystems studied were overall cumulative.