Skip to main content
Log in

The 5-oxoprolinase is required for conidiation, sexual reproduction, virulence and deoxynivalenol production of Fusarium graminearum

Current Genetics Aims and scope Submit manuscript

Abstract

In eukaryotic organisms, the 5-oxoprolinase is one of the six key enzymes in the γ-glutamyl cycle that is involved in the biosynthetic pathway of glutathione (GSH, an antioxidative tripeptide counteracting the oxidative stress). To date, little is known about the biological functions of the 5-oxoprolinase in filamentous phytopathogenic fungi. In this study, we investigated the 5-oxoprolinase in Fusarium graminearum for the first time. In F. graminearum, two paralogous genes (FgOXP1 and FgOXP2) were identified to encode the 5-oxoprolinase while only one homologous gene encoding the 5-oxoprolinase could be found in other filamentous phytopathogenic fungi or Saccharomyces cerevisiae. Deletion of FgOXP1 or FgOXP2 in F. graminearum led to significant defects in its virulence on wheat. This is likely caused by an observed decreased deoxynivalenol (DON, a mycotoxin) production in the gene deletion mutant strains as DON is one of the best characterized virulence factors of F. graminearum. The FgOXP2 deletion mutant strains were also defective in conidiation and sexual reproduction while the FgOXP1 deletion mutant strains were normal for those phenotypes. Double deletion of FgOXP1 and FgOXP2 led to more severe defects in conidiation, DON production and virulence on plants, suggesting that both FgOXP1 and FgOXP2 play a role in fungal development and plant colonization. Although transformation of MoOXP1into ΔFgoxp1 was able to complement ΔFgoxp1, transformation of MoOXP1 into ΔFgoxp2 failed to restore its defects in sexual development, DON production and pathogenicity. Taken together, these results suggest that FgOXP1 and FgOXP2 are likely to have been functionally diversified and play significant roles in fungal development and full virulence in F. graminearum.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

References

Download references

Acknowledgements

This work was supported by the National Natural Science Foundation of China under Grant no. 31670142 and the China Postdoctoral Science Foundation under Grant 2016M590587. We thank Drs. Xu Zhao, Guanghui Wang, Lianhu Zhang, Huawei Zheng and Yi Lou for fruitful discussions and suggestions.

Author information

Authors and Affiliations

Authors

Corresponding authors

Correspondence to Zonghua Wang or Wenhui Zheng.

Additional information

Communicated by M. Kupiec.

Electronic supplementary material

Below is the link to the electronic supplementary material.

294_2017_747_MOESM1_ESM.docx

Fig. S1 Sequence comparison of 5-oxoprolinase from different species. ClustalW (Thompson, et al. 1994)assisted multiple sequence alignments of 5-oxoprolinase of NcOxp1 (N. crassa), SmOxp1 (S. macrospora), MoOxp1 (M. oryzae), FfOxp1 (F. fujikuroi), FoOxp1 (F. oxysporum), FvOxp1 (F. verticillioides), FgOxp1 (F. graminearum), TrOxp1 (T. reesei), BcOxp1 (B. cinerea), ScOxp1 (S. cerevisiae), CgOxp1 (C. gloeosporioides), TrOxp2 (T. reesei), FfOxp2 (F. fujikuroi), FoOxp2 (F. oxysporum), FvOxp2 (F. verticillioides), FgOxp2 (F. graminearum), CgOxp2 (C. gloeosporioides), AtOxp1 (A. thaliana), HsOxp1 (H. sapiens). Box shade was used for graphical rendering and presentation. Residues that are the same in all four sequences are boxed in red. Fig. S2 Relative mycelial growth rate, hyphal tip growth and branching patterns of each strain of F. graminearum. Images of each strain were registered after 3 days of incubation at 25°C on CMII plates (9 cm in diameter). Scale bar = 100 μm. Fig. S3 Conidial morphology of each strain of F. graminearum. Conidia of each strain were stained with CFW to visualize the cell wall and septa and with DAPI to visualize the cell nucleus. Conidia were observed via differential interference contrast (DIC, left) and fluorescence microscopy (UV, middle). MERGE images were constructed by the microscopic software of “NIS-Elements” (right). Scale bar = 10μm. Fig. S4 Conidiation without or with 0.5mM GSH of each strain of F. graminearum. Fresh mycelia of each strain were inoculated in liquid CMC culture without or with 0.5mM GSH and shaking at 28°C at 180 rpm for 3 days, 6 days, 9 days and 15 days, respectively. Means and standard deviations were calculated from data of three biological replicates. The experiment was repeated three times with similar results. Asterisk indicates a significant difference of conidiation between the mutant strain and the wild-type (PH-1) (P≤0.05, Duncan’s test). Fig. S5 DON production without or with 0.5mM GSH of each strain of F. graminearum. DON production (μg g−1 dry weight) was tested for each strain incubated in LTB liquid culture for 7 days at 28 °C in the dark without shaking. The blank control for DON quantification was 0. Error bars denote the standard deviation of three biological replicates. The experiment was repeated three times with similar results. Asterisk indicates a significant difference of DON production between the mutant strain and the wild-type (PH-1) (P≤0.05, Duncan’s test). Table. S1 Wild-type and mutant strains used in this study. Table. S2 PCR Primers used in this study. Supplementary material 1 (DOCX 10909 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yang, P., Chen, Y., Wu, H. et al. The 5-oxoprolinase is required for conidiation, sexual reproduction, virulence and deoxynivalenol production of Fusarium graminearum . Curr Genet 64, 285–301 (2018). https://doi.org/10.1007/s00294-017-0747-y

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00294-017-0747-y

Keywords

Navigation