Table 1.
Fusarium strains used in this study.
Figure 1.
Effects of Fusarium mycovirus infections on F. graminearum strain PH-1.
PH-1/FgV1, PH-1/FgV2, PH-1/FgV3, and PH-1/FgV4 indicate the PH-1 strain infected with FgV1, FgV2, FgV3, and FgV4, respectively. (A) Colony morphology of Fusarium strains used in this study. PH-1 strains infected with FgV1–FgV4 were obtained by protoplast fusion. DK21 and 98-8-60 are FgV1 and FgV2-infected strains, respectively, whereas DK3 is an FgV3/4-coinfected strain. Cultures were photographed after 5 days on PDA. (B) Viral dsRNAs were extracted from mycelia using CF-11 cellulose chromatography. The presence of dsRNAs was confirmed by 5% polyacrylamide gel; the gels were stained with EtBr and visualized with a UV-transilluminator. (C) Sexual development of each strain. The strains were incubated on carrot agar medium for 7 days (upper row) and then treated with a Tween-60 solution to induce sexual reproduction (middle row). Cultures were examined for perithecia after 7 days under UV light. Scale bar = 200 µm. (D) Fusarium head blight symptoms caused by PH-1 (WT) or mycovirus-infected strains PH-1/FgV1–4. (E) Disease severity was evaluated 14 days after inoculation. (F) Trichothecene production. Conidial suspensions were grown in minimal medium containing 5 mM agmatine. After 7 days, trichothecenes in the culture filtrates were quantified by GC-MS. For (E) and (F), data were analyzed by the General Lineal Model (GLM) using IBM SPSS statistics 20 for Windows software. Error bars indicate standard deviations. Different letters above the bars indicate significant differences at p = 0.05.
Table 2.
Phenotypic characteristics of F. graminearum PH-1 when infected by FgV1, 2, 3, or 4.
Table 3.
Vertical transmission of Fusarium mycoviruses.
Figure 2.
F. graminearum genes that were differentially expressed in response to four mycoviruses and that were identified by RNA-Seq.
(A) Volcano plot of RNA-Seq data using log2fold change and log10p-value. X and Y axes represent log2-converted fold change and log10-converted p-value. (B) The number of DEGs. Orange, yellow, and green colors indicate number of DEGs for up-regulated, down-regulated, and total of up- and down-regulated genes, respectively. (C) Venn diagrams illustrating the number of genes that were differentially expressed in subsets of the four virus-infected strains. Total, down, and up indicate total numbers of DEGs, the numbers of up-regulated DEGs, and the numbers of down-regulated DEGs, respectively.
Table 4.
The 12 DEGs commonly identified in response to four different mycovirus infections by RNA-Seq.
Figure 3.
Fusarium graminearum transcription factors that were differentially expressed in response to mycovirus infection.
The number of TFs (A) and the number of TF families (B) that were differentially expressed in response to infection by the four mycoviruses. (C) Venn diagrams illustrating the numbers of TFs that were differentially expressed in subsets of the four virus-infected strains. Total, up, and down indicate the total numbers of DEGs, the numbers of up-regulated DEGs, and the numbers of down-regulated DEGs, respectively. (D) The number of differentially expressed TFs belonging to 15 representative TF families. Red indicates that the number of differentially up-regulated genes was greater than the number of down-regulated genes; green indicates the opposite. (F) The percentage of TF families in all identified differentially expressed TFs.
Figure 4.
Validation of RNA-Seq data by real-time RT-PCR.
The expression of eight selected genes (A) and five genes involved in RNAi silencing (B) was examined by real-time RT-PCR. Up-regulation and down-regulation of selected genes were indicated by red and green bars with corresponding fold changes, respectively.