Stable soil moisture altered the rhizosphere microbial community structure via affecting their host plant

Abstract

Abstract Temporal variation of soil moisture is one of the influencing factors affecting crop water use efficiency (WUE). Compared with fluctuating soil moisture (FSM), stable soil moisture (SSM) with weaker temporal variance has the potential to improve the WUE of crops. However, response of crop rhizosphere microbiome to soil moisture temporal variation remains unclear. In this study, we performed pot experiments on romaine lettuce (Lactuca sativa L. var. longifolia) to compare the effects of different soil moisture temporal variation on plant growth, yield, water use efficiency (WUE), and rhizosphere bacterial and fungal community structures, via manual irrigation and negative pressure irrigation to create FSM and SSM conditions, respectively. The results indicate that SSM improved the growth and WUE of romaine lettuce. Moreover, the rhizosphere microbial community composition of romaine lettuce differed under SSM and FSM conditions. Under SSM, bacterial Bacillus, fungal Aspergillus and Chaetomium were enriched in the romaine lettuce rhizosphere, whereas some taxa such as bacterial Devosia, Lysobacter, Blastococus and Bacillus, fungal Alternaria were reduced; these taxa could therefore be biomarkers in future research. Partial least squares path model (PLS-PM) analysis revealed that rhizosphere microbial communities were indirectly affected by the soil moisture temporal variation, as evidenced by the improvement in plant growth. Our results suggest that the rhizosphere microbial communities of romaine lettuce primarily respond to changes in the soil moisture temporal variation through the plant-microbiome interaction but are not directly affected by soil moisture.