Community Structure of Arbuscular Mycorrhizal Fungi in Roots of Subsequent Soybean After Cultivation of Various Winter Crops.

Arbuscular mycorrhizal (AM) fungi improve the uptake of phosphate from soil through symbiotic associations with plant roots. The introduction of winter crops has been shown to increase nutrient uptake and yield of subsequent crops, and may result from increased AM fungal biomass in the soil. However, there is little information regarding the effects of different winter crops on AM fungal communities of subsequent crop roots. The present study evaluated the impact of various winter crops on AM fungal community structure in the roots of subsequent soybean. A two year field experiment was conducted at Nihon University in Kanagawa, Japan. Replicated plots of winter sown wheat, spring sown wheat, canola and fallow were established in 2007, and wheat, red clover, canola and fallow were established in 2008. After the winter crop, soybean was sown in all plots. AM fungal community structure was characterized on the basis of the D1-D2 region of large subunit ribosomal DNA (LSU rDNA). In the present study, a total of 1938 clones were sequenced. Phylogenetic analysis revealed that 19 AM fungal phylotypes including eleven Glomus, three Gigaspora, two Scutellospora, two Acaulospora, one Diversispora were found in the roots of soybean. The number of phylotype in soybean roots was not difference among various winter crops, but Glomus was dominant in roots of soybean regardless of winter crops. By RDA (Redundancy analysis), the winter crops have a strong effect on the AM fungal communities in the roots of soybean. Thus, choice of winter crop has the potential to change the community structure of AM fungal communities in the roots of soybean.