Figure 4
The relative changes of the detected genes involved in N cycling at eCO2 compared to aCO2.
A: soil depth of 0–5 cm; B: soil depth of 5–15 cm soil. The signal intensity for each gene detected was normalized by all detected gene sequences using the mean. The percentage of a functional gene in a bracket was the sum of the signal intensity of all detected sequences of this gene divided by the grand sum of signal intensities of the detected N cycling genes and weighted by the fold change of the signal intensity of this gene at eCO2 to that at aCO2. For each functional gene, colors mean that this gene had a higher (blue) or lower (green) signal intensity at eCO2 than at aCO2 with significance at P < 0.05 (*). Gray-colored genes were not targeted by this GeoChip, or not detected in those samples. It remains unknown if nosZ homologues exist in nitrifiers. Genes and their involved functional processes: N2 fixation by nifH encoding nitrogenase; Nitrification by amoA encoding ammonia monooxygenase; Denitrification by narG encoding nitrate reductase, nirS and nirK encoding nitrite reductase, norB encoding nitric oxide reductase and nosZ encoding nitrous oxide reductase; Dissimilatory N reduction to ammonium by napA for nitrate reductase and nrfA for c-type cytochrome nitrite reductase; Ammonification by gdh encoding glutamate dehydrogenase and ure C encoding urease; Assimilatory N reduction, nasA encoding nitrate reductase.
