Crop-dependent root-microbe-soil interactions induce contrasting natural attenuation of organochlorine lindane in soils.

Plant-specific root-microbe-soil interactions play an indisputable role in microbial adaptation to environmental stresses. However, the assembly of plant rhizosphere microbiomes and their feedbacks in modification of pollution alleviation under organochlorine stress condition is far less clear. This study examined the response of root-associated bacterial microbiomes to lindane pollution and compared the dissipation of lindane in maize-cultivated dry soils and rice-cultivated flooded soils. Results showed that lindane pollution dramatically altered the microbial structure in the rhizosphere soil of maize but had less influence on the microbial composition in flooded treatments regardless of rice growth, when the reductive dechlorination of lindane was actively coupled with natural redox processes under anaerobic conditions. After 30 days of plant growth, lindane residues dissipated much faster in anaerobic than in aerobic environments, with only 1.08 mg kg lindane remaining in flooded control compared to 12.79 mg kg in dry control soils. Compared to the corresponding unplanted control, maize growth significantly increased, but rice growth slightly decreased the dissipation of lindane. Our study suggests that opposite impacts would lead to the self-purification of polluted soils during the growth of xerophytic maize and hygrocolous rice. This was attributed to the contrasting belowground micro-ecological processes regarding protection of root tissues and thereby assembly of rhizosphere microbiomes shaped by the xerophytic and hygrocolous crops under different water managements, in response to lindane pollution.