p-Coumaric Acid Influenced Cucumber Rhizosphere Soil Microbial Communities and the Growth of Fusarium oxysporum f.sp. cucumerinum Owen

Abstract

BackgroundAutotoxicity of cucumber root exudates or decaying residues may be the cause of the soil sickness of cucumber. However, how autotoxins affect soil microbial communities is not yet fully understood.Methodology/Principal FindingsThe aims of this study were to study the effects of an artificially applied autotoxin of cucumber, p-coumaric acid, on cucumber seedling growth, rhizosphere soil microbial communities, and Fusarium oxysporum f.sp. cucumerinum Owen (a soil-borne pathogen of cucumber) growth. Abundance, structure and composition of rhizosphere bacterial and fungal communities were analyzed with real-time PCR, PCR-denaturing gradient gel electrophoresis (DGGE) and clone library methods. Soil dehydrogenase activity and microbial biomass C (MBC) were determined to indicate the activity and size of the soil microflora. Results showed that p-coumaric acid (0.1–1.0 µmol/g soil) decreased cucumber leaf area, and increased soil dehydrogenase activity, MBC and rhizosphere bacterial and fungal community abundances. p-Coumaric acid also changed the structure and composition of rhizosphere bacterial and fungal communities, with increases in the relative abundances of bacterial taxa Firmicutes, Betaproteobacteria, Gammaproteobacteria and fungal taxa Sordariomycete, Zygomycota, and decreases in the relative abundances of bacterial taxa Bacteroidetes, Deltaproteobacteria, Planctomycetes, Verrucomicrobia and fungal taxon Pezizomycete. In addition, p-coumaric acid increased Fusarium oxysporum population densities in soil.Conclusions/SignificanceThese results indicate that p-coumaric acid may play a role in the autotoxicity of cucumber via influencing soil microbial communities.

Allelopathic effects of humus forest soil of Hippophae rhamnoides, Caragana korshinskii and Amorpha fruticosa on medicinal plants

“…This is similar with the findings of several previous studies, in which they showed that certain phenolic acids which were identified in plant root exudates can be active allelochemicals and can cause detrimental effects on the growth of their neighbor plants by changing the distribution of the hormone or water balance (Hao et al, 2010;Zhang et al, 2010;Zhou et al, 2012). However, differences are that humus soil of C. korshinskii increased the shoot dry weigh of B. chinense by 85.9%, which contributed to the total dry weigh; but soil of A. fruticosa performanced inversely.…”

Functional Soil Microbiome: Belowground Solutions to an Aboveground Problem

“…The specific role of root exudates in the shaping of the rhizosphere is further confirmed by showing different groups of natural compounds derived from plant root exudates synergistically modifying the root microbiome (Badri et al, 2013b). The known components of cucumber (Cucumis sativus) root exudates p-coumaric acid and vanillic acid showed differential effects on the soil microbiome: p-coumaric acid increased the pathogenic fungal taxa that degrades the p-coumaric acid (Zhou and Wu, 2012), while vanillic acid promoted the plant growthpromoting rhizobacteria Bacillus spp. (Zhou and Wu, 2013).…”

The components of rice and watermelon root exudates and their effects on pathogenic fungus and watermelon defense

“…cucumerinum in the rhizosphere of Cucumis sativus (L.). 33 Higher levels of CA were secreted by resistant cultivars than by susceptible cultivars of Arachis hypogaea (L.). 34 Rice root exudates had an allelopathic effect on the root growth of Sagittaria montevidensis (arrowhead) plants.…”