Screening and Identification of Harmful and Beneficial Microorganisms Associated with Replanting Disease in Rhizosphere Soil of Pseudostellariae heterophylla

Abstract

Pseudostellariae heterophylla, an important medicinal plant, has been shown to suffer from serious replanting disease that causes significant declines in both yield and quality. The objective of this study was to isolate the soil-born pathogen and antagonistic microorganism for investigation of the relationship between these microorganism and consecutive monoculture problems of P. heterophylla. In this study, we isolated the bacteria with different morphology from P. heterophylla rhizosphere soil, detected the pathogenicity of these bacteria to P. heterophylla plantlet and antagonistic ability to Fusarium of P. heterophylla biotype, identified their species and analyzed their abundance with qRT-PCR in rhizosphere soil of different planting years. We isolated Enterobacter sp1 and Burkholderia sp1 from P. heterophylla rhizosphere soil, and found Enterobacter sp1 possessed the pathogenicity to P. heterophylla plantlet and Burkholderia sp1 was antagonistic for Fusarium of P. heterophylla biotype. However, Burkholderia sp1 was not the antagonistic microorganism to Enterobacter sp1. The growth of Enterobacter sp1 was stimulated by phenolic acids at a certain concentration nearly closed to that in P. heterophylla rhizosphere soil, which increased as planting years of P. heterophylla increased. On the contrary, the phenolic acids had no promoting effect on the growth of Burkholderia sp1. And with the increase of planting years, the abundance of Burkholderia sp1 decreased and abundance of Enterobacter sp1 increased in the P. heterophylla rhizosphere soil. The results indicated that harmful microorganisms increase and beneficial microorganisms decrease, which were mediated by the accumulated autotoxins in rhizosphere soil of consecutively monocultured P. heterophylla, and hence leads to the imbalance of microbial community structure and the degradation of soil ecological function. So several abatement methods, such as crop rotation, specific microbial fertilizer and organic matter, could be used to improve the structure and functional diversity of microbial community, and overcome the obstacles of continuous cropping.

Cucumber (Cucumis sativus L.) Seedling Rhizosphere Trichoderma and Fusarium spp. Communities Altered by Vanillic Acid

“…Autotoxicity is an intraspecific allelopathy process through which plants can inhibit their growth or that of their relatives by releasing toxic chemicals into the environment ( Huang et al, 2013 ), as has been observed in both natural and manipulated ecosystems, particularly agroecosystems. According to previous studies, an imbalance in the microbial community structure and the accumulation of soil-borne pathogens induced by autotoxins are the main causes of soil sickness ( Yu et al, 2000 ; Lin et al, 2015 ; Zhang et al, 2016 ). Cucumber is one of the main vegetable crops among greenhouse plants and is planted in up 40% of the greenhouse vegetable-producing area in China; however, soil sickness problems substantially restrict cucumber production ( Yu et al, 2000 ).…”

Interaction of Pseudostellaria heterophylla with Quorum Sensing and Quorum Quenching Bacteria Mediated by Root Exudates in a Consecutive Monoculture System

“…Wu et al [39] found that a phenolic acid mixture could efficiently promote mycelial growth, sporulation, and toxin production of Fusarium oxysporum, one of the most important fungal pathogens, and lead to increased replanting disease incidence of R. glutinosa. In previous studies, four phenolic acids (benzoic acid, myristic acid, cinnamic acid, and 2-butenoic acid) have been identified as potential autotoxic chemicals, and exhibited partially autotoxic effects of P. heterophylla [21,22]. Furthermore, these phenolic acids released by P. heterophylla root could be utilized efficiently by three specific pathogens (Fusarium oxysporium, Talaromyces helicus, and Kosakonia sacchari) from the soil or tissue of P. heterophylla, which resulted in increased replanting disease incidence [38,42].…”

Insights into the Regulation of Rhizosphere Bacterial Communities by Application of Bio-organic Fertilizer in Pseudostellaria heterophylla Monoculture Regime

“…Our previous studies have demonstrated that the phenolic acids identified in the root exudates of P. heterophylla could significantly inhibit the growth of beneficial Burkholderia sp. but promote the growth of soil-borne F. oxysporum (Lin et al, 2015; Wu L. et al, 2016). However, bio-organic fertilizer, in particular, MT containing antagonistic bacteria could rebalance the beneficial and detrimental microbial residents in soil, leading to relatively more beneficial microorganisms and relatively fewer pathogenic microorganisms ( Figure 8 ; Table 3 ).…”