|GONG, YINGDI - Huazhong Agricultural University
|FU, YANPING - Huazhong Agricultural University
|XIE, JIATAO - Huazhong Agricultural University
|LI, BO - Huazhong Agricultural University
|CHEN, TAO - Huazhong Agricultural University
|LIN, YANG - Huazhong Agricultural University
|JIANG, DAOHONG - Huazhong Agricultural University
|CHENG, JIASEN - Huazhong Agricultural University
Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2022
Publication Date: 5/20/2022
Citation: Gong, Y., Fu, Y., Xie, J., Li, B., Chen, T., Lin, Y., Chen, W., Jiang, D., Cheng, J. 2022. Sclerotinia sclerotiorum SsCut1 modulates virulence and cutinase activity. The Journal of Fungi. 8. Article 526. https://doi.org/10.3390/jof8050526.
Interpretive Summary: The fungal pathogen Sclerotinia sclerotiorum causes white mold diseases on many broad-leaf plants and significant economical losses every year. Despite intensive studies on this pathogen, its pathogenicity mechanisms are not fully understood. One approach to investigate virulence mechanisms is to study specific genes by deleting the individual genes and examine the effect of the gene deletion. The S. sclerotiorum genome encodes at least eight cutinase genes, and cutin is an important protective layer of plants. In this study, the SsCut1 gene was cloned and analyzed. Analysis of the amino acid sequence showed that SsCut1 contains the conserved cutinase domain and a fungal cellulose binding domain. Deletion of SsCut1 using targeted mutagenesis showed that SsCut1 is not necessary for normal growth and completion of the fungal life cycle, since the deletion mutants had normal growth rate and formed normal sclerotia. However, the SsCut1 deletion mutants showed significantly reduced cutinase activity and pathogenicity, compared with the wild-type strain. Providing the mutant with a normal SsCut1 gene restored cutinase activity and pathogenicity to normal levels. This study demonstrated that the SsCut1 gene promotes the virulence of S. sclerotiorum by enhancing its ability to degrade the protective cutin layer in plants.
Technical Abstract: The plant cuticle is one of the protective layers of the external surface of plant tissues. Plants use the cuticle layer to reduce water loss and resist pathogen infection. Fungi release cell wall degrading enzymes to destroy the epidermis of plants to achieve the purpose of infection. Sclerotinia sclerotiorum secretes a large amount of cutinase to disrupt the cuticle layer of plants during the infection process. In order to further understand the role of cutinase in the pathogenic process of S. sclerotiorum, the SsCut1 gene was cloned and analyzed. The protein SsCut1 contains the conserved cutinase domain and a fungal cellulose binding domain. Targeted deletion of the SsCut1 gene significantly reduced cutinase activity and pathogenicity, compared with the wild-type strain. Complementation with the wildtype SsCut1 allele restored cutinase activity and pathogenicity to wild-type levels. This study demonstrated that the SsCut1 gene promotes the virulence of S. sclerotiorum by enhancing its cutinase activity.