Metagenomic evidence of stronger effect of stylo (legume) than bahiagrass (grass) on taxonomic and functional profiles of the soil microbial community

Plants are key determinants of soil microbial community (SMC). Legumes and grasses are distinct groups in various ecosystems; however, how they differentially shape SMC structure and functioning has yet to be explored. Here, we investigate SMC in soils grown with stylo (legume) or bahiagrass (grass). Soil metagenomic sequencing indicates that Archaea was more abundant in unplanted soils than in planted soils, and that stylo selected higher abundance of fungi than bahiagrass. When the stylo soils enriched Streptomyces, Frankia, Mycobacterium and Amycolatopsis, the bahiagrass soils enriched Sphingomonas and Sphingobium. NMDS reveals that the legume shaped SMC more greatly than the grass (P < 0.004). SMC functional profiles (KEGG and CAZy) were also greatly altered by plants with the legume being more effective (P < 0.000 and P < 0.000). The abundant microbial taxa contributed to the main community functions, with Conexibacter, Sphingomonas, and Burkholderia showing multifunctionality. Moreover, soil chemical property showed much higher direct effect on SMC structure and functional profiles than soil extracts, although the soil total nitrogen and some compounds (e.g. heptadecane, 1-pentadecyne and nonanoic acid) in soil extracts were best correlated with SMC structure and functional profiles. These findings are the first to suggest that legume species shape SMC more greatly than grass species.