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This study describes the first genome sequence and analysis of Coniella granati, a fungal pathogen with a broad host range, which is responsible for postharvest crown rot, shoot blight, and canker diseases in pomegranates. C. granati is a geographically widespread pathogen which has been reported across Europe, Asia, the Americas, and Africa. Our analysis revealed a 46.8 Mb genome with features characteristic of hemibiotrophic fungi. Approximately one third of its genome was compartmentalised within 'AT-rich' regions exhibiting a low GC content (30 to 45%). These regions primarily comprised transposable elements that are repeated at a high frequency and interspersed throughout the genome. Transcriptome-supported gene annotation of the C. granati genome revealed a streamlined proteome, mirroring similar observations in other pathogens with a latent phase. The genome encoded a relatively compact set of 9568 protein-coding genes with a remarkable 95% having assigned functional annotations. Despite this streamlined nature, a set of 40 cysteine-rich candidate secreted effector-like proteins (CSEPs) was predicted as well as a gene cluster involved in the synthesis of a pomegranate-associated toxin. These potential virulence factors were predominantly located near repeat-rich and AT-rich regions, suggesting that the pathogen evades host defences through Repeat-Induced Point mutation (RIP)-mediated pseudogenisation. Furthermore, 23 of these CSEPs exhibited homology to known effector and pathogenicity genes found in other hemibiotrophic pathogens. The study establishes a foundational resource for the study of the genetic makeup of C. granati, paving the way for future research on its pathogenicity mechanisms and the development of targeted control strategies to safeguard pomegranate production. [ABSTRACT FROM AUTHOR]

Aspergillus carbonarius causes severe decays on berries in vineyards and is among the main fungal species responsible for grape contamination by ochratoxin A (OTA), which is the foremost mycotoxin produced by this fungus. The main goal of this study was to investigate at the transcriptome level the comparative profiles between two table grape varieties (Victoria and Fraoula, the white and red variety, respectively) after their inoculation with a virulent OTA-producing A. carbonarius strain. The two varieties revealed quite different transcriptomic signatures and the expression profiles of the differential expressed genes (DEGs) highlighted distinct and variety-specific responses during the infection period. The significant enrichment of pathways related to the modulation of transcriptional dynamics towards the activation of defence responses, the triggering of the metabolic shunt for the biosynthesis of secondary metabolites, mainly phenylpropanoids, and the upregulation of DEGs encoding phytoalexins, transcription factors, and genes involved in plant–pathogen interaction and immune signaling transduction was revealed in an early time point in Fraoula, whereas, in Victoria, any transcriptional reprogramming was observed after a delay. However, both varieties, to some extent, also showed common expression dynamics for specific DEG families, such as those encoding for laccases and stilbene synthases. Jasmonate (JA) may play a critical modulator role in the defence machinery as various JA-biosynthetic DEGs were upregulated. Along with the broader modulation of the transcriptome that was observed in white grape, expression profiles of specific A. carbonarius genes related to pathogenesis, fungal sporulation, and conidiation highlight the higher susceptibility of Victoria. Furthermore, the A. carbonarius transcriptional patterns directly associated with the regulation of the pathogen OTA-biosynthesis gene cluster were more highly induced in Victoria than in Fraoula. The latter was less contaminated by OTA and showed substantially lower sporulation. These findings contribute to uncovering the interplay beyond this plant–microbe interaction. [ABSTRACT FROM AUTHOR]

Taphrina deformans is the causal agent of leaf curl, a serious peach disease which causes significant losses in peach production worldwide. Nowadays, in order to control plant diseases, it is necessary to adopt novel and low-cost alternatives to conventional chemical fungicides. These promising strategies are targeted at eliciting host defense mechanisms via priming the host through the consecutive application of plant immunity inducers prior to pathogen challenge. In this study, we investigated whether chitosan or yeast cell wall extracts could provide enhanced tolerance against leaf curl in two-season field trials. Furthermore, we addressed the possible molecular mechanisms involved beyond the priming of immune responses by monitoring the induction of key defense-related genes. The efficacy of spraying treatments against peach leaf curl with both inducers was significantly higher compared to the untreated control, showing efficacy in reducing disease severity of up to 62.6% and 73.9% for chitosan and yeast cell wall extracts, respectively. The application of chitosan in combination with copper hydroxide was more efficient in reducing disease incidence and severity, showing efficacy values in the range of 79.5–93.18%. Peach plantlets were also spray-treated with immunity inducers three times prior to leaf inoculation with T. deformans blastospores in their yeast phase. The relative expression levels of nine key defense and priming genes, including those encoding members of pathogenesis-related (PR) proteins and hub genes associated with hormone biosynthesis, were monitored by RT-qPCR across three days after inoculation (dai). The results indicate that pre-treatments with these plant immunity inducers activated the induction of genes involved in salicylic acid (SA) and jasmonate (JA) defense signaling pathways that may offer systemic resistance, coupled with the upregulation of genes conferring direct antimicrobial effects. Our experiments suggest that these two plant immunity inducers could constitute useful components towards the effective control of T. deformans in peach crops. [ABSTRACT FROM AUTHOR]

Pear brown rot and blossom blight caused by Monilinia laxa seriously affect pear production worldwide. Here, we compared the transcriptomic profiles of petals after inoculation with M. laxa using two pear cultivars with different levels of sensitivity to disease (Sissy, a relatively tolerant cultivar, and Kristalli, a highly susceptible cultivar). Physiological indexes were also monitored in the petals of both cultivars at 2 h and 48 h after infection (2 HAI and 48 HAI). RNA-seq data and weighted gene co-expression network analysis (WGCNA) allowed the identification of key genes and pathways involved in immune- and defenserelated responses that were specific for each cultivar in a time-dependent manner. In particular, in the Kristalli cultivar, a significant transcriptome reprogramming occurred early at 2 HAI and was accompanied either by suppression of key differentially expressed genes (DEGs) involved in the modulation of any defense responses or by activation of DEGs acting as sensitivity factors promoting susceptibility. In contrast to the considerably high number of DEGs induced early in the Kristalli cultivar, upregulation of specific DEGs involved in pathogen perception and signal transduction, biosynthesis of secondary and primary metabolism, and other defense-related responses was delayed in the Sissy cultivar, occurring at 48 HAI. The WGCNA highlighted one module that was significantly and highly correlated to the relatively tolerant cultivar. Six hub genes were identified within this module, including three WRKY transcription factor-encoding genes: WRKY 65 (pycom05g27470), WRKY 71 (pycom10g22220), and WRKY28 (pycom17g13130), which may play a crucial role in enhancing the tolerance of pear petals to M. laxa. Our results will provide insights into the interplay of the molecular mechanisms underlying immune responses of petals at the pear–M. laxa pathosystem. [ABSTRACT FROM AUTHOR]

Oxylipins called psi factors have been shown to alter the ratio of asexual to sexual sporulation in the filamentous fungus Aspergillus nidulans. Analysis of the A. nidulans genome has led to the identification of three fatty acid oxygenases (PpoA, PpoB and PpoC) predicted to produce psi factors. Here, it is reported that deletion of ppoB ([DELTA]ppoB) reduced production of the oleic-acid-derived oxylipin psiB[beta] and increased the ratio of asexual to sexual spore development. Generation of the triple mutant [DELTA]ppoA[DELTA]ppoB[DELTA]ppoC resulted in a strain deficient in producing oleic- and linoleic-acid-derived 8'-hydroxy psi factor and caused increased and mis-scheduled activation of sexual development. Changes in asexual to sexual spore development were positively correlated to alterations in the expression of brlA and yeA, respectively. PpoB and/or its products antagonistically mediate the expression levels of ppoA and ppoC, thus revealing regulatory feedback loops among these three genes. Phylogenetic analyses showed that ppo genes are present in both saprophytic and pathogenic Ascomycetes and Basidiomycetes, suggesting a conserved role for Ppo enzymes in the life cycle of fungi.

In this study, the biological activity of selected Greek medicinal and aromatic plants on the phytopathogenic fungus Alternaria alternata was investigated. Biological activity was screened on crude aqueous extracts and their aqueous phase (ap-pt) after further extraction with petroleum ether. All the Lamiaceae species examined were found to enhance significantly the mycelium growth. Melissa officinalis extracts caused the highest stimulation in mycelium growth, (+109.1%) the ap-pt, and (+51.6%) its crude extract. All ap-pt extracts stimulated conidia production, but Melissa officinalis caused the highest effect (+349.3%). Crude extracts of Salvia officinalis stimulated highly conidial production (+65%) whereas Hyssopus. officinalis and Origanum vulgare inhibited conidia production at 33.3% and 50.0% respectively. The differences in biological activity between crude and ap-pt extracts for each plant species were attributed through the calculation of correspondent synergism ratios (SR) to the interaction between volatile and water - soluble. Rosmarinic acid, detected as the most abundant phenolic compound in all extracts analyzed and found to correlate strongly (R= 0.84) with the stimulation effect on spore production of A. alternata. [ABSTRACT FROM AUTHOR]

Aflatoxins are highly toxic fungal secondary metabolites that often contaminate food and feed commodities. An electrochemical immunosensor for the determination of aflatoxin B1 (AFB1) was fabricated by immobilizing monoclonal AFB1 antibodies onto a screen-printed gold electrode that was modified with carbo-methyldextran by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide cross-linking. An electrochemical interfacial modelling of biomolecular recognition was suggested and reasonably interpreted. Impedance technology was employed for the quantitative determination of AFB1. The limit of detection concentration of AFB1 for standard solutions and spiked pistachio samples was 0.5 ng/mL and 1 ng/mL, respectively. The immunosensor was able to successfully determine AFB1 concentrations in the range of 4.56–50.86 ng/mL in unknown pistachio samples. Comparative chromatographic analysis revealed that AFB1 concentrations that were higher than 345 ng/mL were not within the immunosensor's upper limits of detection. Selectivity studies against Ochratoxin A and Aflatoxin M1 demonstrated that the proposed AFB1 immunosensor was able to differentiate between these other fungal mycotoxins. The novel electrochemical immunosensor approach has the potential for rapid sample screening in a portable, disposable format, thus contributing to the requirement for effective prevention and the control of aflatoxin B1 in pistachios. [ABSTRACT FROM AUTHOR]

Olive trees (Olea europaea L.) are among the most important fruit tree crops grown in Albania, covering an estimated 8% of the arable land of this country. The highest amount of olive production in Albania is concentrated in the coastal districts of Fier, Berat, Elbasan, Lezha, Tirana, Kruja and Vlora, all with Mediterranean climate conditions. Anthracnose is the main disease of olive fruit caused by different Colletotrichum spp. primarily belonging to two complexes, C. acutatum sensu lato (s.l.) and C. gloeosporioides s.l. (Cacciola et al. 2012; Schena et al. 2014.). On July 2018, field observations of about 50 olive trees in the Ishull Shengjin Lezhe Region (54% prevalence), 1 km away from the coast showed severe symptoms of mummified olive fruits in about 20 to 40% disease incidence and 30% disease severity of the Italian table olive cv. Frantoio trees resulting in premature fruit drop or mummification. The causal agent was isolated directly from infected fruits on potato dextrose agar and Rose Bengal nutrient media. Microscopic examinations of five single spore isolated fungal colonies showed acervuli with typical conidia of the genus Colletotrichum that were aseptate, straight, hyaline, subcylindrical with rounded ends and 12.3 to 22.1 µm long (mean = 17.4 µm) and 2.5 to 7.3 µm wide (mean = 5.9 µm) (n= 50 conidia) (Damm et al. 2012). To identify the fungal species, DNA from two single-spore isolates (Col-3-ALB and Col-9-ALB) isolated from fruits was extracted, and six genes were amplified ( ITS, GAPDH, CHS-1, HIS3, ACT , and TUB2 ) using the primers reviewed in Damm et al. (2012). PCR products were sequenced, and BLAST analysis showed 100% identity to C. acutatum for both isolates (GenBank accession nos. for Col-9-ALB MT218337 [ITS1-5.8-ITS2], MT274748 [CHS-1], MT274749 [HIS3], MT274750 [GAPDH], MT274751 [TUB2], and MT274752 [ACT]). Phylogenetic analysis using the concatenated sequences of Col-9-ALB, the type species of C. acutatum (112996), a previously identified published Greek C. acutatum isolate (O9) and three C. godetiae strains confirmed the identification of Col-9-ALB as C. acutatum . Pathogenicity tests were performed in the laboratory to confirm the ability of C. acutatum isolates to cause disease on olive drupes. Fruits were surface disinfected with 0.1% NaClO for 3 min and rinsed with ddH2O. Artificial inoculations with the two above isolates were performed by spraying 24 olive fruits per isolate cv. Kalamon (eight olive fruits per replication) with a spore suspension (10 6 conidia/ml). Olive fruits sprayed with sterilized water served as untreated control. After inoculation, olive fruits were placed in closed sterile plastic boxes and kept at 26°C with a 12-h photoperiod. First rot symptoms and formation of acervuli by the pathogen were initiated 3 days after inoculation. Eight days post-inoculation, all treatments exhibited typical anthracnose symptoms similar to those observed in olive orchards (extensive fruit rot). To fulfil Koch's postulates, C. acutatum was re-isolated from 10 random symptomatic olive fruits/isolate and their identity was confirmed from all samples. To our knowledge, this is the first report of C. acutatum causing fruit rot on olive trees in Albania. It is important to further study the epidemiology for the disease under local climate conditions and on different olive cultivars in order to develop effective management strategies for this very destructive disease of olive.