Soil amendments with ethylene precursor alleviate negative impacts of salinity on soil microbial properties and productivity

Some microbes enhance stress tolerance in plants by minimizing plant ethylene levels via degradation of its immediate precursor, 1-aminocyclopropane-1-carboxylate (ACC), in the rhizosphere. In return, ACC is used by these microbes as a source of nitrogen. This mutualistic relationship between plants and microbes may be used to promote soil properties in stressful environments. In this study, we tested the hypothesis that amendments of ACC in soils reshape the structure of soil microbiome and alleviate the negative impacts of salinity on soil properties. We treated non-saline and artificially-developed saline soils with ACC in different concentrations for 14 days. The structure of soil microbiome, soil microbial properties and productivity were examined. Our results revealed that microbial composition of bacteria, archaea and fungi in saline soils was affected by ACC amendments; whereas community composition in non-saline soils was not affected. The amendments of ACC could not fully counteract the negative effects of salinity on soil microbial activities and productivity, but increased the abundance of ACC deaminase-encoding gene (acdS), enhanced soil microbial respiration, enzymatic activity, nitrogen and carbon cycling potentials and Arabidopsis biomass in saline soils. Collectively, our study indicates that ACC amendments in soils could efficiently ameliorate salinity impacts on soil properties and plant biomass production