Host niche,genotype, and field location shape the diversity and composition of the soybean microbiome

Plant-associated microbes represent a key determinant of plant fitness through acquiring nutrients, promoting growth, and resisting to abiotic and biotic stresses. However, an extensive characterization of the bacterial and fungal microbiomes present in different plant compartments of soybean in field conditions has remained elusive. In this study, we investigated the effects of four niches (roots, stems, leaves, and pods), four genotypes (Andou 203, Hedou 12, Sanning 16, and Zhonghuang 13), and three field locations (Jining, Suzhou, and Xuzhou) on the diversity and composition of bacterial and fungal communities in soybean using 16S and internal transcribed spacer rRNA amplicon sequencing, respectively. The soybean microbiome significantly differed across organs. Host genotypes explained more variation in stem bacterial community composition and leaf fungal community composition. Field location significantly affected the composition of bacterial communities in all compartments and the effects were stronger in the root and stem than in the leaf and pod, whereas field location explained more variation in stem and leaf fungal community composition than in the root and pod. The relative abundances of potential soybean fungal pathogens also differed among host organs and genotypes, reflecting the niches of these microbes in the host and probably their compatibility to the host genotypes. Systematic profiling of the microbiome composition and diversity will aid the development of plant protection technologies to benefit soybean health.