Furthermore, the abundance of specific functional genes involved in C fixation and degradation, N fixation, and sulfite reduction was significantly altered in response to elevated [O3] and wheat cultivars. The ozone-sensitive cultivar appeared to harbor microbial functional communities in the rhizosphere, and was more responsive to elevated [O3] than the ozone-tolerant cultivar (Li et al. 2013). The shifts of functional gene representation in wheat rhizosphere microbial communities under elevated [O3] would have great implications for soil functions. Results from these studies suggest that the impacts of elevated [O3] on below-ground communities are closely related to the sensitivity of crop cultivars.