Pectobacterium carotovorum subsp. brasiliense is a broad host range bacterial pathogen, which causes blackleg of potatoes and bacterial soft rot of vegetables worldwide. Production of plant cell wall degrading enzymes is usually critical for Pectobacterium infection. However, other virulence factors and the mechanisms of genetic adaptation still need to be studied in detail. In this study, the complete genome of P. carotovorum subsp. brasiliense strain SX309 isolated from cucumber was compared with eight other pathogenic bacteria belonging to the Pectobacterium genus, which were isolated from various host plants. Genome comparison revealed that most virulence genes are highly conserved in the Pectobacterium strains, especially for the key virulence determinants involved in the biosynthesis of extracellular enzymes and others including the type II and III secretion systems, quorum sensing system, flagellar and chemotactic genes. Nevertheless, some variable regions of the T6SS and the CRISP-Cas immune system are unique for P. carotovorum subsp. brasiliense. The extensive comparative genomics analysis revealed highly conserved virulence genes in the Pectobacterium strains. However, several variable regions of type VI secretion system and two subtype Cas mechanism-Cas immune systems possibly contribute to the process of Pectobacterium infection and adaptive immunity.

Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) belongs to the genus of Parthenocissus and Vitaceae family, which is very common in vineyards and where wild grape occurs (Bergh et al., ...

Grape ripe rot, a globally significant fungal disease caused by Colletotrichum spp., severely threatens grape yield and quality. This study systematically investigated the pathogen species, biological characteristics, and fungicide sensitivity through multiregional sampling (2022 to 2024, covering seven districts across four provinces), morphological analysis, molecular identification, and EC ₅₀ assays. The results revealed that 125 isolates were obtained and classified into five species, namely, Colletotrichum aenigma, C. conoides, C. viniferum, C. gloeosporioides, and C. fructicola, based on morphological traits and multilocus phylogenetic analysis (ITS, CHS, GAPDH, TUB2, and ACT). Among these, C. viniferum was identified as the dominant species responsible for grape ripe rot, with an isolation rate of 74.4%, and C. conoides represents a new species isolated from grape ripe rot in China. Biological assays revealed that the optimal temperature and pH for mycelial growth on PDA were 25 to 30°C and pH 5 to 6, respectively, and the pathogenicity significantly increased at 30°C following wound inoculation. Fungicide sensitivity tests indicated that prochloraz exhibited the highest inhibitory efficacy against all the species (EC ₅₀ ≤ 0.03 mg/liter). This study elucidates the geographical distribution patterns of Colletotrichum spp. in China and their differential responses to fungicides, providing critical theoretical and practical insights for optimizing integrated management strategies against grape ripe rot.

The acetylation of histone lysine residues regulates multiple life processes, including growth, conidiation, and pathogenicity in filamentous pathogenic fungi. However, the specific function of each lysine residue at the N-terminus of histone H3 in phytopathogenic fungi remains unclear. In this study, we mutated the N-terminal lysine residues of histone H3 in Fusarium pseudograminearum, the main causal agent of Fusarium crown rot of wheat in China, which also produces deoxynivalenol (DON) toxins harmful to humans and animals. Our findings reveal that all the FpH3^K9R, FpH3^K14R, FpH3^K18R, and FpH3^K23R mutants are vital for vegetative growth and conidiation. Additionally, FpH3K14 regulates the pathogen’s sensitivity to various stresses and fungicides. Despite the slowed growth of the FpH3^K9R and FpH3^K23R mutants, their pathogenicity towards wheat stems and heads remains unchanged. However, the FpH3^K9R mutant produces more DON. Furthermore, the FpH3^K14R and FpH3^K18R mutants exhibit significantly reduced virulence, with the FpH3^K18R mutant producing minimal DON. In the FpH3^K9R, FpH3^K14R, FpH3^K18R, and FpH3^K23R mutants, there are 1863, 1400, 1688, and 1806 downregulated genes, respectively, compared to the wild type. These downregulated genes include many that are crucial for growth, conidiation, pathogenicity, and DON production, as well as some essential genes. Gene ontology (GO) enrichment analysis indicates that genes downregulated in the FpH3^K14R and FpH3^K18R mutants are enriched for ribosome biogenesis, rRNA processing, and rRNA metabolic process. This suggests that the translation machinery is abnormal in the FpH3^K14R and FpH3^K18R mutants. Overall, our findings suggest that H3 N-terminal lysine residues are involved in regulating the expression of genes with important functions and are critical for fungal development and pathogenicity.

Coniella vitis is a dominant phytopathogen of grape white rot in China, significantly impacting grape yield and quality. Previous studies showed that the growth and pathogenicity of C. vitis were affected by the environmental pH. Arrestin-like protein PalF plays a key role in mediating the activation of an intracellular-signaling cascade in response to alkaline ambient. However, it remains unclear whether palF affects the growth, development, and virulence of C. vitis during the sensing of environmental pH changes. In this study, we identified a homologous gene of PalF/Rim8 in C. vitis and constructed CvpalF-silenced strains via RNA interference. CvpalF-silenced strains exhibited impaired fungal growth at neutral/alkaline pH, accompanied by reduced pathogenicity compared to the wild-type (WT) and empty vector control (CK) strains. The distance between the hyphal branches was significantly increased in the CvpalF-silenced strains. Additionally, CvpalF-silenced strains showed increased sensitivity to NaCl, H₂O₂, and Congo red, and decreased sensitive to CaSO₄. RT-qPCR analysis demonstrated that the expression level of genes related to pectinase and cellulase were significantly down-regulated in CvpalF-silenced strains compared to WT and CK strains. Moreover, the expression of PacC, PalA/B/C/F/H/I was directly or indirectly affected by silencing CvpalF. Additionally, the expression of genes related to plant cell wall-degrading enzymes, which are key virulence factors for plant pathogenic fungi, was regulated by CvpalF. Our results indicate the important roles of CvpalF in growth, osmotolerance, and pathogenicity in C. vitis.

Grape white rot, primarily caused by Coniella diplodiella and Coniella vitis, is a major fungal disease threatening grape production worldwide, with C. vitis more prevalent in China. Temperature is a critical environmental factor influencing pathogen development and disease outbreaks, but how temperature influences the biological characteristics, pathogenicity, and fungicide sensitivity of these two pathogens remains limited. This study aimed to evaluate the effects of temperature on mycelial growth, conidial germination, extracellular enzyme activity, pathogenicity, and fungicide sensitivity of C. diplodiella 2019 and C. vitis GP1. The growth, conidial germination, extracellular enzyme production, pathogenicity, and fungicide control efficacy against the two pathogens were systematically evaluated under different temperature conditions (5, 15, 25, 35, and 45 °C). Results showed temperature significantly affected all investigated traits in both species. Optimal mycelial growth, conidial germination, and pathogenicity occurred at moderate temperatures (25 °C), whereas extreme temperatures (5 °C and 45 °C) significantly markedly inhibited fungal development and disease severity. C. vitis GP1 showed greater adaptability and consistently higher pathogenicity than C. diplodiella 2019 across the tested temperature range. Fungicide sensitivity also differed between the two species, and the inhibitory activity of difenoconazole was significantly reduced under temperature extremes, indicating that fungicide performance is influenced by environmental temperature. These findings demonstrate that temperature regulates both fungal development and fungicide efficacy, providing new insights into the temperature-dependent epidemiology of grape white rot and a scientific basis for optimizing disease management under changing environmental conditions.