Another study used GeoChip 2.0 to examine microbial communities in Zn-and Cd-contaminated soil microcosms with or without Thlaspi caerulescens, a Cd and Zn hyperaccumulator plant (Epelde et al., 2010) . Higher numbers of functional genes were detected in the contaminated samples than in uncontaminated samples and in planted samples compared to unplanted. Thirty-five to forty-seven percent of the variation in community structure observed was explained by metal concentrations. All of the Cd and/or Zn resistance genes (12) were detected in the contaminated, planted samples while only 7 were detected in the contaminated/unplanted samples. Substrate-induced respiration, K concentration, and nitrate concentration were the most important environmental variables in determining the functional community structure.