[Differential Responses of Rhizospheric and -type Denitrifier Communities to Different Phosphorus Levels in Paddy Soil].

Phosphorus is an essential life element, which can affect the activities and functions of denitrifiers. Both and genes can code nitrite reductase; however, it remains unclear whether - and -containing denitrifers respond differentially to changes in the availability of phosphorus in paddy soil. In this study, P-deficient paddy soil was used to grow rice plants. Three phosphorus levels established by applying P fertilizer at a rate of 0 mg·kg (CK), 15 mg·kg (P1), and 30 mg·kg(P2), respectively. The abundance and community structure of - and - containing denitrifers were determined using quantitative PCR and high-throughput sequencing techniques. Results indicated that - and -containing communities responded differentially to changes in the P levels. The -containing communities are more sensitive to the changes in P in both rhizosphere and bulk soil samples. In addition, the abundance of genes was 2-3 times higher in the P2 treatment than in the CK treatment. Furthermore, the community structure is also clearly differed from the CK treatment. However, P addition only induced partial modification of the community structure and abundance of -containing denitrifiers. Moreover, compared to the bulk soil with each phosphorus level, the community structure in the rhizosphere soil changed significantly; however, only the P2 treatment induced significant increases in the abundance of the gene. In contrast, no significant differences in the abundance and composition of -containing denitrifers were detected between rhizosphere and bulk soils under different phosphorus levels. Collectively, application of phosphate fertilizer in P-deficient paddy soil could significantly increase the abundance of - and -containing denitrifiers, changing their community structures, with -type showing a greater sensitivity than -type denitrifiers. In comparison, the denitrifying communities in the rhizosphere were more sensitive to variable P levels than that in the bulk soil. Compared to bulk soils, rice growth shifted the community structure of - and -containing denitrifiers in rhizosphere soils at each level of P, but failed to induce significant changes in their abundance (except for P2) that could cause a significant increase in abundance. These results could provide a theoretical basis for exploring the effects of fertilization on soil denitrification.