Differential recruitment of plant growth-promoting bacteria community by soybean rhizosphere in no-tillage and integrated crop-livestock

Abstract

Agricultural practices influence plant-microbe interactions in the rhizosphere and, particularly can drive the recruitment of plant growth-promoting bacteria (PGPB). This study assessed the PGPB community in soil under no-tillage (NT) and in the rhizosphere of maize and grass under integrated cro-livestock (ICL) to evaluate their influence on the recruitment of PGPB in the rhizosphere of soybean. Soil samples from the soybean rhizosphere under NT and ICL were collected and compared to samples collected from bulk soil and the rhizosphere of maize and grass in ICL, using the 16 S rRNA approach. The structure of the PGPB community differed (21.8% of variation) when comparing the rhizosphere of soybean in NT and ICL. The soybean rhizosphere in NT enriched distinct PGPB compared to those observed in ICL. The proportion of specialist PGPB was higher in the rhizosphere of soybean in ICL (33.8%) than in NT (26.5%). Regardless of the agricultural system, the rhizosphere of soybean showed a similar number of nodes, but ICL promoted a higher number of edges in the soybean rhizosphere. Bacillus and Mycobacterium were identified as the main keystone taxa in the rhizosphere of soybean in NT. In contrast, Streptomyces and Sphingomonas were keystone taxa in the rhizosphere of soybean in ICL. This study demonstrated distinct recruitment of PGPB by the rhizosphere of soybean based on agricultural systems, i.e., NT and ICL.