Effect of soil type and soybean genotype on fungal community in soybean rhizosphere during reproductive growth stages

Fungal communities in soybean rhizosphere from reproductive growth stages R(1) (beginning bloom) to R(8) (full maturity) were studied based on the polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) banding patterns of partial rDNA internal transcribed spacer regions (ITS1) and sequencing methods. Pot experiment subjecting three soybean genotypes grown in two soils (Mollisol and Alfisol) indicated that the soil type was the major factor in shaping the fungal communities in the soybean rhizosphere. Field experiment was conducted in an Alfisol field with three soybean genotypes, and both pot and field experiments showed that rhizosphere fungal communities shifted with growth stages, and more diversity of communities was found in early reproductive growth stages than later stages. No major difference among fungal communities of three soybean genotypes was detected at individual growth stage. BLAST search of ITS sequence data generated from excised DGGE bands showed that fungi belonging to Ascomycetes and Basidiomycetes predominantly inhabited in the soybean rhizosphere. In addition, a few bands had low similarity with database sequences inferred that unknown fungal groups existed in soybean rhizosphere.