Inhibitory Effect and Mechanism of Dryocrassin ABBA Against Fusarium oxysporum

Abstract

Potato Fusarium dry rot and wilt are the most important soil- and seed-borne diseases in potatoes. They cause high economic losses during potato growth and storage across the world. Previous observations have shown that dryocrassin ABBA can induce resistance in potatoes. However, little is known about whether dryocrassin ABBA can suppress Fusarium oxysporum. In this research, we determined that exogenous dryocrassin ABBA significantly inhibited the mycelial growth, changed the cell ultrastructure, increased the MDA content, and decreased the antioxidant enzyme activity of F. oxysporum. The transcriptome analysis of F. oxysporum with or without dryocrassin ABBA indicated that 1244 differentially expressed genes (DEGs) were identified, of which 594 were upregulated and 650 were downregulated. GO term analysis showed that the DEGs were mostly related to biological processes. The KEGG pathway was mainly related to carbohydrate, amino acid, and lipid metabolism. Moreover, most of the expressions of PCWDEs, HSPs, and MFS were downregulated, decreasing the stress capacity and weakening the pathogenicity of F. oxysporum with dryocrassin ABBA treatment. These findings contribute to a new understanding of the direct functions of dryocrassin ABBA on F. oxysporum and provide a potential ecofriendly biocontrol approach for potato Fusarium dry rot and wilt.

Keywords: Fusarium oxysporum; dryocrassin ABBA; molecular mechanisms; potato.

Figure 1

Dryocrassin ABBA’s inhibition effect on F. oxysporum growth. (a) Mycelial phenotypes of F. oxysporum grown on a PDA medium at different concentrations for 7 d, with distilled water as the control. (b) Rate of dryocrassin ABBA inhibition on the pathogenic ability of F. oxysporum (different lowercase letters indicate p < 0.01). (c) The morphology of F. oxysporum hyphae treated with water, as observed using scanning electron microscopy (SEM). (d) The morphology of F. oxysporum hyphae treated with dryocrassin ABBA, as observed using SEM.

Figure 2

The results of the malondialdehyde content and antioxidant enzyme activity of F. oxysporum mycelium after dryocrassin ABBA treatment. (a) Malondialdehyde (MDA) content of F. oxysporum mycelium. (b) Catalase (CAT) content of F. oxysporum mycelium. (c) Peroxidase (POD) activity of F. oxysporum mycelium. (d) Superoxide dismutase (SOD) activity of F. oxysporum mycelium. (e) Glutathione reductase (GR) activity of F. oxysporum mycelium after dryocrassin ABBA treatment. (Different lowercase letters indicate p < 0.01).

Figure 3

Analysis of the transcriptome data of F. oxysporum treated with or without dryocrassin ABBA. (a) Number of significant up/downregulated genes. (b) Scatter diagram of enriched GO terms. (c) Top 20 enriched KEGG pathways.

Figure 4

Validation results of the Illumina RNA-Seq, relative expression of 10 DEGs without or with the treatment of dryocrassin ABBA (a–j). Note: The error bars represent the standard deviation of the mean relative expression value. The left Y-axis represents the relative expression level of different expression genes, and the right Y-axis represents the FPKM value of transcriptome sequencing. The heatmap at the top of the bar chart represents the expression of Illumina RNA-Seq results. Significant differences from the control are denoted as asterisks (*) at p < 0.05.

Figure 4

Validation results of the Illumina RNA-Seq, relative expression of 10 DEGs without or with the treatment of dryocrassin ABBA (a–j). Note: The error bars represent the standard deviation of the mean relative expression value. The left Y-axis represents the relative expression level of different expression genes, and the right Y-axis represents the FPKM value of transcriptome sequencing. The heatmap at the top of the bar chart represents the expression of Illumina RNA-Seq results. Significant differences from the control are denoted as asterisks (*) at p < 0.05.

Figure 5

Dryocrassin ABBA can inhibit some KEGG pathways involved in lipid, amino acid, and carbohydrate metabolism in F. oxysporum.