Mixed Phenolic Acids Mediated Proliferation of Pathogens Talaromyces helicus and Kosakonia sacchari in Continuously Monocultured Radix pseudostellariae Rhizosphere Soil

Abstract

Radix pseudostellariae L. is a common and popular Chinese medication. However, continuous monoculture has increased its susceptibility to severe diseases. We identified two pathogenic microorganisms, Talaromyces helicus M. (KU355274) and Kosakonia sacchari W. (KU324465), and their antagonistic bacterium, Bacillus pumilus Z. in rhizosphere soil of continuously monocultured R. pseudostellariae. Nine types of phenolic acids were identified both in the rhizosphere soil and in culture medium under sterile conditions. A syringic acid and phenolic acid mixture significantly promoted the growth of T. helicus and K. sacchari. T. helicus could utilize eight types of phenolic acids, whereas K. sacchari could only use four phenolic acids. K. sacchari produced protocatechuic acid when consuming vanillin. Protocatechuic acid negatively affected the growth of B. pumilus. The 3A-DON toxin produced by T. helicus promoted the growth of K. sacchari and inhibited growth of B. pumilus at low concentrations. These data help explain why phenolic exudates mediate a microflora shift and structure disorder in the rhizosphere soil of continuously monocultured R. pseudostellariae and lead to increased replanting disease incidence.

Diversity of rhizosphere and endophytic fungi in Atractylodes macrocephala during continuous cropping

“…At the genus level, the relative abundance of Talaromyces and Fusarium increased significantly with cropping time. Talaromyces and Fusarium genera fungi contain several potential pathogens, such as Fusarium oxysporum and Talaromyces helices (Wu et al, 2016). Thus, increases in these genera may negatively contribute to A. macrocephala continuous cropping, eventually leading to increased disease pressure.…”

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

“…Pseudostellaria heterophylla is a traditional medicinal plant used in China for over 3,000 years [21,42]. It contains polysaccharides, ginseng saponins, flavonoids, cyclic peptides, amino acids, and trace elements [16,38]. The root tuber of P. heterophylla can be used to treat splenic asthenia, anorexia, lassitude, weakness, and palpitation [19,36].…”

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

“…that have shown strong antagonistic activities against F. oxysporum were used as inocula to fortify organic fertilizer for the purpose of suppressing P. heterophylla Fusarium wilt (Supplementary Figure S1). In addition, our previous studies found that phenolic acids in the root exudates of medicinal plants mediated the increase of soil-borne pathogens (Wu H. et al, 2016; Wu L. et al, 2016). Some Bacillus spp.…”

“…However, consecutive monoculture of this plant has led to a serious decline of biomass and quality of its underground tubers. Fields used for P. heterophylla cultivation can only be replanted once every 4 years (Wu H. et al, 2016; Wu L. et al, 2016). In addition, farmers generally apply a copious amount of pesticides and fertilizers to maintain production levels under this monoculture regime, but such application raises production costs, causes excessive pesticide residues, and leads to environmental pollution.…”