Effects of consecutive monoculture of Pseudostellaria heterophylla on soil fungal community as determined by pyrosequencing

Under consecutive monoculture, the biomass and quality of Pseudostellaria heterophylla declines significantly. In this study, a three-year field experiment was conducted to identify typical growth inhibition effects caused by extended monoculturing of P. heterophylla . Deep pyrosequencing was used to examine changes in the structure and composition of soil fungal community along a three-year gradient of monoculture. The results revealed a distinct separation between the newly planted plot and the two-year, three-year monocultured plots. The Shannon and Simpson diversity indices were significantly higher in the two-year and three-year monoculture soils than in the newly planted soil. Consecutive monoculture of this plant led to a significant increase in relative abundance of Fusarium , Trichocladium and Myrothecium and Simplicillium , etc., but a significant decrease in the relative abundance of Penicillium . Quantitative PCR analysis confirmed a significant increase in Fusarium oxysporum , an agent known to cause wilt and rot disease of P. heterophylla . Furthermore, phenolic acid mixture at a ratio similar to that found in the rhizosphere could promote mycelial growth of pathogenic F. oxysporum . Overall, this study demonstrated that consecutive monoculture of P. heterophylla can alter the fungal community in the rhizosphere, including enrichment of host-specific pathogenic fungi at the expense of plant-beneficial fungi.