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Grapevine trunk diseases constitute a significant phytopathological concern in Egyptian viticulture, with ongoing debates regarding their origin and transmission dynamics. These complexities are attributed to the heterogeneous manifestation of symptoms and the involvement of multiple wood-associated pathogens, both suspected and confirmed. This study investigates the mycological aspects of grapevine trunk diseases, focusing on Lasiodiplodia theobromae as a causal agent. The pathogen was associated with vascular cankers, dark brown trunk discoloration, pycnidia formation on necrotic tissues, and grapevine dieback. Identification of L. theobromae was achieved through morphological characteristics and molecular analysis targeting the β-tubulin gene and Internal Transcribed Spacer (ITS) region. Pathogenicity tests were conducted by inoculating detached canes, leaves, petioles, and entire branches with mycelial plugs of L. theobromae . The resulting symptoms closely resembled those observed in naturally infected grapevines in the field. The pathogen was then re-isolated and identified, confirming Koch’s postulates. A disease index (DI) ranging from 60 to 100% provided strong evidence of the high pathogenic potential of L. theobromae under experimental conditions.

Mango is widely grown in Taiwan and anthracnose is one of the most important diseases of this crop. The aim of this study was to investigate Colletotrichum species associated with mango and the pathogenicity of these fungal species. From 2006 to 2017, mango tissue from 33 mango orchards were collected. Eighty-seven isolates associated with mango were analyzed preliminarily by comparing partial glyceraldehyde-3-phosphate dehydrogenase sequences. Four species belonging to C. gloeosporioides complex were preliminarily identified, namely C. asianum (68 isolates), C. fructicola (four isolates), C. siamense (eight isolates) and C. tropicale (two isolates). The other five isolates were identified as belonging to the C. acutatum complex. Ten isolates, belonging to different Colletotrichum species according to glyceraldehyde-3-phosphate dehydrogenase sequences prediction, were used for further morphology and multi-gene phylogenetic analysis. Five species were identified, namely C. asianum, C. fructicola, C. siamense, C. tropicale and C. scovillei. All five species showed pathogenicity on fruit, and C. asianum isolates C-1076 and C-1646 as well as C. siamense isolate C-526 caused larger lesions than the other isolates. On mango leaves, C. asianum, C. fructicola, C. siamense and C. scovillei isolates were pathogenic, while C. tropicale isolates, C-141 and C-303, failed to cause significant foliar lesions. In addition, C. siamense isolates C-526 and C-848 caused significantly larger lesions on leaves than other isolates. This study reports the identification and pathogenicity of Colletotrichum species related to mango anthracnose in Taiwan.

Marek’s disease virus (MDV) is a highly contagious tumor virus that causes detrimental outbreaks in poultry. Since its initial description, the virus’s virulence and acuteness have progressively increased. During this study, we investigated suspected tumorigenic cases of MDV-1 infection among different avian species (chicken, ducks, and turkey) in various Egyptian governorates, including Al-Sharqia, Gharbia, Dakahlia, Port Said, Damietta, and Fayoum, between 2020 and 2023. A molecular study targeting the virulent oncogenic Meq gene revealed that the tumorigenic masses in chicken and duck tissues were identified as virulent MDV-1, but turkeys with cauliflower-like ovarian tumors showed negative results. The isolated MDV-1 strain of chicken origin was given the designation YLE2021 and the sequence was submitted to GenBank with accession number PQ59985. Sequence analysis revealed a partial Meq open reading frame encoding 296 amino acids and contains seven proline motifs, three of them are interrupted (187 PLQPP 191, 195 PAPP198, 224 PPQPP 228). Experimental infection of one-day-old specific-pathogen-free (SPF) chickens with a strain recovered from a chicken tumor resulted in 40% of infected birds showing the classical neural form of MDV infection. No parenchymal tumors were observed, and the virus could be molecularly detected in the peripheral blood mononuclear cells (PMNCs) of infected and neighboring uninfected SPF birds. In conclusion, this is the first report to identify the presence of MDV-1 in Egyptian ducks. Further investigations are recommended to detect the main cause of the turkeys’ tumor. Continuous molecular monitoring of circulating field viruses is crucial to investigate the mechanisms behind the increase in virus evolution, which could lead to increased virus virulence and allow the virus to evade vaccine protection.

Leaf spot disease is commonly found on leaves of avocado plants in avocado orchards in Taiwan. Needle-like spots with yellow halos appear on diseased avocado leaves at the incipient stage, and these spots gradually enlarge and become brown lesions with black-brown centers. The causal agent of this disease is unknown. A Pseudoplagiostoma species was isolated from these leaf spots. Evaluation of morphological traits and phylogenetic analysis using the ribosomal DNA internal transcribed spacer operon, β-tubulin, and partial large subunit of ribosomal DNA markers identified this fungal species as a novel species, Pseudoplagiostoma perseae sp. nov. A pathogenicity test was conducted on three avocado cultivars, ‘Choquette’, ‘Hall’, and ‘Hung Shin Yuan’. After 2 weeks of inoculation, needle-like leaf spots appeared on all three cultivars, and P. perseae was re-isolated from the spots of all inoculated leaves, fulfilling Koch’s postulates. This is the first report describing the novel species P. perseae, which was validated as the causal agent of avocado leaf spot disease.

Gnomoniopsis castaneae has become an important pathogen of European chestnut (Castanea sativa), affecting fruits and colonizing shoots and branches, as well as galls caused by the oriental chestnut gall wasp (Dryocosmus kuriphilus). On apparently asymptomatic fruits, G. castaneae can colonize the endosperms, causing quality issues, especially in post-harvest. Given the alarming spread of G. castaneae infections in Italy and the current knowledge gaps regarding aspects of G. castaneae biogeography and virulence, research was addressed to: 1) evaluate occurrence of G. castaneae in chestnut nuts and branches in different Italian regions; 2) study occurrence and distribution of the two known G. castaneae haplotypes throughout Italy; and 3) evaluate their virulence on chestnut under different water regimes. Fungal isolation from representative chestnut branch and nut samples consistently yielded colonies that were morphologically consistent with G. castaneae, the identity of which was confirmed by analysis of ITS sequences. Analysis of β-tubulin sequences confirmed the presence of two distinct genetic lineages (Gc-haplotypes A and B). To assess pathogenicity, G. castaneae isolates were inoculated onto chestnuts, chestnut cuttings and 3-year-old young plants grown under two water regimes. All assessed isolates were pathogenic on chestnut, and water-stressed plants exhibited more extensive necrosis than well-watered plants when inoculated with the Gc-haplotype A, highlighting the influence of environmental conditions on disease expression. This study expands current knowledge on the distribution, genetic diversity, and effects of water stress on the pathogenic potential of G. castaneae on chestnut.

Aeromonas veronii is an important pathogen causing freshwater fish sepsis and ulcer syndrome. An increasing number of cases have demonstrated its significance as an aquatic zoonotic agent. The purpose of this study was to ensure the safety of freshwater products by evaluating the infection status of edible freshwater fish. In this experiment, we isolated A. veronii from several species of apparently healthy freshwater fish, including Carassius auratus, Cyprinus carpio, Ctenopharyngodon idella, and Silurus asotus. A. veronii was identified through bacterial staining, culture characteristics, and 16S rDNA gene sequence. In addition, polymerase chain reaction (PCR) was used to investigate the distribution of seven major virulence genes, including aerolysin (aer: 88.51%), cytotoxic enterotoxin (act: 71.26%), serine proteinase (ser: 54.02%), adhesin (Aha: 40.23%), phospholipase (lip: 45.98%), nuclease (exu: 51.72%), and quorum sensing-controlled virulence factor (LuxS: 59.77%). In total, 496 strains of Aeromonas were isolated, including 87 strains of A. veronii. The isolates of A. veronii were Gram-negative, rod-shaped bacteria, and the colonies are yellow on Rimler-Shotts (RS) medium and showed greater than 99% homology with A. veronii ATCC35624 according to analyses of the 16S rDNA sequence. Nearly 50% of the A. veronii isolates carried at least four or more virulence genes, 25% of the isolates carried at least five types of virulence genes, and 59.77% isolates carried the LuxS gene, and the isolates carrying more virulence genes were found to be more virulent. These results are of great significance for further improving the food safety assessment of freshwater aquatic products.

Background Diseases on Prunus spp. have been associated with a large number of phylogenetically different pathovars and species within the P. syringae species complex. Despite their economic significance, there is a severe lack of genomic information of these pathogens. The high phylogenetic diversity observed within strains causing disease on Prunus spp. in nature, raised the question whether other strains or species within the P. syringae species complex were potentially pathogenic on Prunus spp. Results To gain insight into the genomic potential of adaptation and virulence in Prunus spp., a total of twelve de novo whole genome sequences of P. syringae pathovars and species found in association with diseases on cherry (sweet, sour and ornamental-cherry) and peach were sequenced. Strains sequenced in this study covered three phylogroups and four clades. These strains were screened in vitro for pathogenicity on Prunus spp. together with additional genome sequenced strains thus covering nine out of thirteen of the currently defined P. syringae phylogroups. Pathogenicity tests revealed that most of the strains caused symptoms in vitro and no obvious link was found between presence of known virulence factors and the observed pathogenicity pattern based on comparative genomics. Non-pathogenic strains were displaying a two to three times higher generation time when grown in rich medium. Conclusion In this study, the first set of complete genomes of cherry associated P. syringae strains as well as the draft genome of the quarantine peach pathogen P. syringae pv. persicae were generated. The obtained genomic data were matched with phenotypic data in order to determine factors related to pathogenicity to Prunus spp. Results of this study suggest that the inability to cause disease on Prunus spp. in vitro is not the result of host specialization but rather linked to metabolic impairments of individual strains.

Brown leaf spot disease caused by Alternaria spp. is among the most common diseases of potato crops. Typical brown spot symptoms were observed in commercial potato-cultivation areas of northern Korea from June to August 2020–2021. In total, 68 isolates were collected, and based on sequence analysis of the internal transcribed spacer (ITS) region, the collected isolates were identified as Alternaria spp. (80.9%). Phylogenetic analysis revealed that a majority of these isolates clustered within a clade that included A. alternata. Additionally, the ITS region and rpb2 yielded the most informative sequences for the identification of A. alternata. Pathogenicity tests confirmed that the collected pathogens elicited symptoms identical to those observed in the field. In pathogenicity tests performed on seven commercial cultivars, the pathogens exhibited strong virulence in both wound and non-wound inoculations. Among the cultivars tested, Arirang-1ho, Arirang-2ho, and Golden Ball were resistant to the pathogens. Furthermore, among the fungicides tested in vitro, mancozeb and difenoconazole were found to be effective for inhibiting mycelial growth. In summary, our findings suggest that A. alternata plays a critical role in leaf disease in potato-growing regions and emphasise the necessity of continuous monitoring and management to protect against this disease in Korea.

Anthracnose disease caused by Colletotrichum spp. is a limiting factor in avocado production worldwide. In Taiwan, Colletotrichum spp. cause post-harvest disease on avocado and greatly reduce the shelf life of the fruit. The aim of this study was to identify the species causing avocado anthracnose in Taiwan and characterize their pathogenicity. In this study, mature avocado fruits with brown lesions were collected from 13 orchards in avocado production areas in Taiwan from 2008 to 2010 and from 2019 to 2020. Eighty-seven Colletotrichum isolates were isolated from the lesions of avocado fruits. Eighty-six isolates were assigned to the Colletotrichum gloeosporioides species complex according to the Apn2-Mat1-2 intergenic spacer and partial mating type (Mat1-2) gene (ApMat) sequence. A preliminary phylogenetic analysis based on ApMat sequences indicated that the 86 isolates formed four clades, C1 to C4. A multi-gene phylogeny based on partial actin, calmodulin, chitin synthase (CHS), GAPDH, ribosomal internal transcribed spacer, and beta-tubulin (TUB) sequences further confirmed the species in the four clades, namely Colletotrichum fructicola (C1), Colletotrichum siamense (C2 and C4), and Colletotrichum tropicale (C3). One isolate, Col-735, was identified to be Colletotrichum eriobotryae according to a phylogenetic tree constructed with the CHS, GAPDH, and TUB sequences. Pathogenicity tests on wounded ‘Choquette’ and ‘Zhongpu green peel’ avocado fruits showed the above four Colletotrichum species were pathogenic on these fruits. This is the first report studying Colletotrichum species and their pathogenicity on avocado in Taiwan, and C. eriobotryae is reported as an avocado fruit pathogen for the first time.