The Fungal-Specific Transcription Factor VpFSTF1 Is Required for Virulence in Valsa pyri

Abstract

Valsa pyri is the causal agent of pear canker disease, which leads to enormous losses of pear production in eastern Asian, especially China. In this study, we identified a fungal-specific transcription factor 1 (termed as VpFSTF1) from V. pyri, which is highly conserved in fungi. To characterize its functions, we generated mutant and complementation strains in V. pyri and found that VpFSTF1 mutants lost the ability to form fruiting bodies along with the reduced virulence. The radial growth of VpFSTF1 mutant was sensitive to increasing concentrations of hydrogen peroxide (H 2 O 2) and salicylic acid (SA). Moreover, RNA-sequencing (RNA-Seq) analysis of wild-type (WT) and VpFSTF1 mutant strains was performed, and the results revealed 1,993 upregulated, and 2006 downregulated differentially expressed genes (DEGs) in the mutant. The DEGs were corresponding to the genes that are involved in amino acid metabolism, starch, and sucrose metabolism, gluconeogenesis, citrate cycle, and carbon metabolism. Interestingly, pathogen host interaction (PHI) analysis showed that 69 downregulated genes were related to virulence, suggesting that they might function downstream of VpFSTF1. Nine DEGs were further validated by quantitative reverse transcriptionpolymerase chain reaction (qRT-PCR), and the results were consistent with RNA-seq analysis. Furthermore, promoter regions were predicted, and VpFSTF1 binding activity was assessed. We demonstrated that five promoters are directly or indirectly targeted by VpFSTF1, including catalase-related peroxidase (VPIG_01209) and P450 family genes. Taken together, these findings indicate that VpFSTF1 is crucial for the virulence of V. pyri via direct or indirect regulation of downstream genes expression and lay an important foundation for understanding the molecular mechanism of V. pyri infection.

The Transcription Factor VpxlnR Is Required for the Growth, Development, and Virulence of the Fungal Pathogen Valsa pyri

“…Furthermore, all protein sequences were submitted to the pfam database 2 by researching the protein domain, and later, the domains were drawn according to the research results. The transcript levels were evaluated as described previously ( Kange et al, 2020 ).…”

“…The resulting PCR product was constructed into XhoI-digested pFL2 through an one-step clone kit (Vazyme, Nanjing, China), and the recombinant vector was then transformed into Escherichia coli (DH5a cells). Later, the vector was extracted using a method described by a previous study ( Kange et al, 2020 ). The plasmids were assessed by sequencing (GenScript, Nanjing, China), and the correct plasmids were used for further study.…”

“…Pathogenicity assays were performed according to a previous study ( Kange et al, 2019 ). Lesion development on inoculated leaves was observed daily, and images were captured at 3 and 5 days post-inoculation (dpi).…”

“…Mycelial growth on PDA under H 2 O 2 and SA stresses was used to assess the sensitivity of the mutants to host mimic stresses. The protocol used was similar to that used in a previous study ( Kange et al, 2020 ). Colony sizes were measured at 36 h, and images were captured at the same time.…”

Antifungal Mechanism of Dipicolinic Acid and Its Efficacy for the Biocontrol of Pear Valsa Canker

“…pyri, also known as V. pyri, is an aggressive canker pathogen that causes pear and apple canker disease on many continents, including Asia. This fungus invades host tissue wounded by injury in the bark (He et al, 2016;Kange et al, 2020). The pathogen can invade the phloem, resulting in vascular tissue necrosis, which can result in the death of the pear tree (Yin et al, 2015;Li et al, 2016).…”