Assessing the effects of acetochlor on soil fungal communities by DGGE and clone library analysis.

We assessed the potential eco-toxicological risks of the herbicide acetochlor on fungal communities in the microcosm of black soil using 28S rRNA gene-PCR-DGGE and clone library analysis. The acetochlor was applied to black soil at four concentrations (0-control, 50, 150, and 250 mg/kg). The DGGE fingerprint patterns indicated that acetochlor stimulated fungal communities at day 7 after application, after which there was a suppression effect. The fungal communities in acetochlor-treated soil gradually became more like that of the control during the 60-day experimental period. Diversity indices in the 50 and 150 mg/kg acetochlor treatments changed more rapidly than in the 250 mg/kg acetochlor treatment. The cluster analysis indicated a significant change in fungal community structure after application of acetochlor. The impacts were markedly greater in the 150 and 250 mg/kg acetochlor treatments compared with the 50 mg/kg acetochlor treatment. Sequencing of clones showed that acetochlor application resulted in an increase in pathogenic and non-cultivatable fungal populations, which could increase the risk of plant disease outbreaks.