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Some Basidiomycete fungi are important plant pathogens, and certain species have been associated with the grapevine trunk disease esca. We present the genomes of 4 species associated with esca: Fomitiporia mediterranea, Fomitiporia polymorpha, Tropicoporus texanus, and Inonotus vitis. We generated high-quality phased genome assemblies using long-read sequencing. The genomic and functional comparisons identified potential virulence factors, suggesting their roles in disease development. Similar to other white-rot fungi known for their ability to degrade lignocellulosic substrates, these 4 genomes encoded a variety of lignin peroxidases and carbohydrate-active enzymes (CAZymes) such as CBM1, AA9, and AA2. The analysis of gene family expansion and contraction revealed dynamic evolutionary patterns, particularly in genes related to secondary metabolite production, plant cell wall decomposition, and xenobiotic degradation. The availability of these genomes will serve as a reference for further studies of diversity and evolution of virulence factors and their roles in esca symptoms and host resistance.

Laccases from white-rot fungi catalyze lignin depolymerization, a critical first step to upgrading lignin to valuable biodiesel fuels and chemicals. In this study, a wildtype laccase from the basidiomycete Fomitiporia mediterranea (Fom_lac) and a variant engineered to have a carbohydrate-binding module (Fom_CBM) were studied for their ability to catalyze cleavage of β-O-4 ether and C-C bonds in phenolic and non-phenolic lignin dimers using a nanostructure-initiator mass spectrometry-based assay. Fom_lac and Fom_CBM catalyze β-O-4 ether and C-C bond breaking, with higher activity under acidic conditions (pH < 6). The potential of Fom_lac and Fom_CBM to enhance saccharification yields from untreated and ionic liquid pretreated pine was also investigated. Adding Fom_CBM to mixtures of cellulases and hemicellulases improved sugar yields by 140% on untreated pine and 32% on cholinium lysinate pretreated pine when compared to the inclusion of Fom_lac to the same mixtures. Adding either Fom_lac or Fom_CBM to mixtures of cellulases and hemicellulases effectively accelerates enzymatic hydrolysis, demonstrating its potential applications for lignocellulose valorization. We postulate that additional increases in sugar yields for the Fom_CBM enzyme mixtures were due to Fom_CBM being brought more proximal to lignin through binding to either cellulose or lignin itself.

Recently, in several locations in the province of Trapani (Sicily, Italy), olive growers have reported cases of decaying olive trees of cv. 'Nocellara del Belice', showing symptoms of defoliation, branch drying, xylem browning, and reduced production. Internal symptoms include white and brown wood rot, starting from the base of the trunk. These alterations have been observed in trees irrigated using a pipe system at the trunk with spray sprinklers. To identify the causal agents of decay, some trees were eradicated and dissected, and woody samples were processed to isolate and identify the associated fungal micro-organisms. The most common colonies were identified using morphological (macro- and microscopical observation) and molecular (PCR amplification of the rDNA-ITS region) analyses. Nine fungal taxa were identified, of which four were associated with this decay syndrome (Coriolopsis gallica, Fomitiporia mediterranea, Kirschsteiniothelia sp., and Pleurostoma richardsiae), three were considered ubiquitous and opportunistic fungi (Alternaria spp., Aspergillus amstelodami, and Trichoderma sp.), and the other two were mycelia sterilia. Artificial inoculation satisfied Koch's postulates, confirming the pathogenicity of the aforementioned fungi, even though the infections in the fields seem to be related to the irrigation system. This hypothesis would seem to be confirmed by the progression of decay over time in the trees subjected to the irrigation system described but not reported in olive groves differently managed. It is therefore considered appropriate to conduct further and more in-depth investigations aimed at studying the correlation between the irrigation system, presence of fungal agents, and manifestation of the syndrome. A further ongoing investigation is aimed at the use of biostimulants (Agrusaver, Savory Sun, VA LLC) on symptomatic trees, with the aim of both improving the vegetative performance of the host and limiting the symptoms detected in the field. [ABSTRACT FROM AUTHOR]

Some Basidiomycete fungi are important plant pathogens, and certain species have been associated with the grapevine trunk disease esca. We present the genomes of 4 species associated with esca: Fomitiporia mediterranea , Fomitiporia polymorpha , Tropicoporus texanus , and Inonotus vitis. We generated high-quality phased genome assemblies using long-read sequencing. The genomic and functional comparisons identified potential virulence factors, suggesting their roles in disease development. Similar to other white-rot fungi known for their ability to degrade lignocellulosic substrates, these 4 genomes encoded a variety of lignin peroxidases and carbohydrate-active enzymes (CAZymes) such as CBM1, AA9, and AA2. The analysis of gene family expansion and contraction revealed dynamic evolutionary patterns, particularly in genes related to secondary metabolite production, plant cell wall decomposition, and xenobiotic degradation. The availability of these genomes will serve as a reference for further studies of diversity and evolution of virulence factors and their roles in esca symptoms and host resistance. [ABSTRACT FROM AUTHOR]

Recently, in several locations in the province of Trapani (Sicily, Italy), olive growers have reported cases of decaying olive trees of cv. ‘Nocellara del Belice’, showing symptoms of defoliation, branch drying, xylem browning, and reduced production. Internal symptoms include white and brown wood rot, starting from the base of the trunk. These alterations have been observed in trees irrigated using a pipe system at the trunk with spray sprinklers. To identify the causal agents of decay, some trees were eradicated and dissected, and woody samples were processed to isolate and identify the associated fungal micro-organisms. The most common colonies were identified using morphological (macro- and microscopical observation) and molecular (PCR amplification of the rDNA-ITS region) analyses. Nine fungal taxa were identified, of which four were associated with this decay syndrome (Coriolopsis gallica, Fomitiporia mediterranea, Kirschsteiniothelia sp., and Pleurostoma richardsiae), three were considered ubiquitous and opportunistic fungi (Alternaria spp., Aspergillus amstelodami, and Trichoderma sp.), and the other two were mycelia sterilia. Artificial inoculation satisfied Koch’s postulates, confirming the pathogenicity of the aforementioned fungi, even though the infections in the fields seem to be related to the irrigation system. This hypothesis would seem to be confirmed by the progression of decay over time in the trees subjected to the irrigation system described but not reported in olive groves differently managed. It is therefore considered appropriate to conduct further and more in-depth investigations aimed at studying the correlation between the irrigation system, presence of fungal agents, and manifestation of the syndrome. A further ongoing investigation is aimed at the use of biostimulants (Agrusaver, Savory Sun, VA LLC) on symptomatic trees, with the aim of both improving the vegetative performance of the host and limiting the symptoms detected in the field.

A comprehensive study was conducted on the prevalence of grapevine trunk diseases in Greece, focusing specifically on contamination of grapevine propagation material by Phaeomoniella chlamydospora and black foot disease‐related species. Additionally, detection of esca pathogen Fomitiporia mediterranea, causing white rot in grapevine and other woody hosts, was assessed using a new PCR‐based assay that distinguishes F. mediterranea from F. punctata. Development of a nested PCR assay, combined with a cost‐effective DNA extraction protocol, revealed a high percentage of infection by P. chlamydospora (51%) and Ilyonectria species associated with black foot disease (28%) in different types of grapevine propagation material (dormant cuttings, field‐rooted benchgrafts and green‐growing plants). Interestingly, black foot disease‐related pathogens were more prevalent in nursery plants grown in the field for 6 months (57%) than in other types of propagation material and compared with P. chlamydospora (43%), indicating increased infection of propagation material during growth in the nursery field. The cost‐effective molecular method developed in this study could be used in mass inspections of propagation material for phytosanitary purposes. Finally, using primers specific for F. mediterranea and F. puncata developed in this study, combined with the universal ITS4 primer, a collection of Fomitiporia isolates from mature grapevine and other woody hosts from Greece and Italy (southern Europe) were characterized as F. mediterranea, whereas German and Swedish isolates from forest plants (central Europe) were classified as F. punctata. The developed primers can discriminate between the two Fomitiporia species, which are indistinguishable based on culture and morphological characteristics alone. [ABSTRACT FROM AUTHOR]

Fomitiporia mediterranea M. Fischer (Fmed) is a white-rot wood-decaying fungus associated with one of the most important and challenging diseases in vineyards: Esca. To relieve microbial degradation, woody plants, including Vitis vinifera, use structural and chemical weapons. Lignin is the most recalcitrant of the wood cell wall structural compounds and contributes to wood durability. Extractives are constitutive or de novo synthesized specialized metabolites that are not covalently bound to wood cell walls and are often associated with antimicrobial properties. Fmed is able to mineralize lignin and detoxify toxic wood extractives, thanks to enzymes such as laccases and peroxidases. Grapevine wood's chemical composition could be involved in Fmed's adaptation to its substrate. This study aimed at deciphering if Fmed uses specific mechanisms to degrade grapevine wood structure and extractives. Three different wood species, grapevine, beech, and oak. were exposed to fungal degradation by two Fmed strains. The well-studied white-rot fungus Trametes versicolor (Tver) was used as a comparison model. A simultaneous degradation pattern was shown for Fmed in the three degraded wood species. Wood mass loss after 7 months for the two fungal species was the highest with low-density oak wood. For the latter wood species, radical differences in initial wood density were observed. No differences between grapevine or beech wood degradation rates were observed after degradation by Fmed or by Tver. Contrary to the Tver secretome, one manganese peroxidase isoform (MnP2l, jgi protein ID 145801) was the most abundant in the Fmed secretome on grapevine wood only. Non-targeted metabolomic analysis was conducted on wood and mycelium samples, using metabolomic networking and public databases (GNPS, MS-DIAL) for metabolite annotations. Chemical differences between non-degraded and degraded woods, and between mycelia grown on different wood species, are discussed. This study highlights Fmed physiological, proteomic and metabolomic traits during wood degradation and thus contributes to a better understanding of its wood degradation mechanisms. [ABSTRACT FROM AUTHOR]

Wood colonizing fungi are specialists that exploit the lignocellulose of cell wall components in host wood cylinders as a carbon sources. Some of these specialized fungi, including Fomitiporia mediterranea (Fmed) and Phaeomoniella chlamydospora (Pch), cause the disease Esca of grapevine. This disease complex includes grapevine leaf stripe disease (GLSD) of canopies and white rot and black wood streaking in trunks. The present study gained insights into the activity of Esca pathogens in host xylem of the trunk tissues at an anatomical level. Lesions with white rot and brown wood streaking were microscopically analyzed, and the structures of affected tissues were compared with intact xylem. In trunks with white rot, demarcation zones separated intact tissues from the lesions. Immediately adjacent to the demarcation zones, cell wall decomposition initiated in the xylem. At this initial stage, cavities appeared in the secondary cell walls of libriform fibres, which expanded and closely resembled the degradation pattern of soft rot. In the advanced stage, the fibre cell walls were completely decomposed, and the vessels were attacked with a degradation pattern similar to white rot. Only remnants of the xylem elements remained, forming amorphous matrices. These decomposition patterns occurred in field samples and in wood cores artificially infected with Fmed. The obvious compartmentalization of the tissue affected by Fmed indicated a defense reaction in the xylem, according to the CODIT model. In contrast, brown wood streaking affected only small groups of vessels, adjacent libriform fibres and parenchyma. Dark inclusions in cells and tyloses in vessels indicate a defense reaction against the pathogens causing brown wood streaking. Artificial inoculation of sterile wood cores with Pch confirmed the contribution of this pathogen to brown wood streaking. This research provides insights into the structural and functional anatomy of intact and infected tissues of grapevines, which clarify the etiology of Esca, and provide new knowledge for developing new approaches to control of this disease complex. [ABSTRACT FROM AUTHOR]

Fomitiporia mediterranea (Fmed) is one of the main fungal species found in grapevine wood rot, also called "amadou," one of the most typical symptoms of grapevine trunk disease Esca. This fungus is functionally classified as a white-rot, able to degrade all wood structure polymers, i.e., hemicelluloses, cellulose, and the most recalcitrant component, lignin. Specific enzymes are secreted by the fungus to degrade those components, namely carbohydrate active enzymes for hemicelluloses and cellulose, which can be highly specific for given polysaccharide, and peroxidases, which enable white-rot to degrade lignin, with specificities relating to lignin composition as well. Furthermore, besides polymers, a highly diverse set of metabolites often associated with antifungal activities is found in wood, this set differing among the various wood species. Wood decayers possess the ability to detoxify these specific extractives and this ability could reflect the adaptation of these fungi to their specific environment. The aim of this study is to better understand the molecular mechanisms used by Fmed to degrade wood structure, and in particular its potential adaptation to grapevine wood. To do so, Fmed was cultivated on sawdust from different origins: grapevine, beech, and spruce. Carbon mineralization rate, mass loss, wood structure polymers contents, targeted metabolites (extractives) and secreted proteins were measured. We used the well-known white-rot model Trametes versicolor for comparison. Whereas no significant degradation was observed with spruce, a higher mass loss was measured on Fmed grapevine culture compared to beech culture. Moreover, on both substrates, a simultaneous degradation pattern was demonstrated, and proteomic analysis identified a relative overproduction of oxidoreductases involved in lignin and extractive degradation on grapevine cultures, and only few differences in carbohydrate active enzymes. These results could explain at least partially the adaptation of Fmed to grapevine wood structural composition compared to other wood species, and suggest that other biotic and abiotic factors should be considered to fully understand the potential adaptation of Fmed to its ecological niche. Proteomics data are available via ProteomeXchange with identifier PXD036889. [ABSTRACT FROM AUTHOR]

Fomitiporia mediterranea (Fmed) is one of the main fungal species found in grapevine wood rot, also called “amadou,” one of the most typical symptoms of grapevine trunk disease Esca. This fungus is functionally classified as a white-rot, able to degrade all wood structure polymers, i.e., hemicelluloses, cellulose, and the most recalcitrant component, lignin. Specific enzymes are secreted by the fungus to degrade those components, namely carbohydrate active enzymes for hemicelluloses and cellulose, which can be highly specific for given polysaccharide, and peroxidases, which enable white-rot to degrade lignin, with specificities relating to lignin composition as well. Furthermore, besides polymers, a highly diverse set of metabolites often associated with antifungal activities is found in wood, this set differing among the various wood species. Wood decayers possess the ability to detoxify these specific extractives and this ability could reflect the adaptation of these fungi to their specific environment. The aim of this study is to better understand the molecular mechanisms used by Fmed to degrade wood structure, and in particular its potential adaptation to grapevine wood. To do so, Fmed was cultivated on sawdust from different origins: grapevine, beech, and spruce. Carbon mineralization rate, mass loss, wood structure polymers contents, targeted metabolites (extractives) and secreted proteins were measured. We used the well-known white-rot model Trametes versicolor for comparison. Whereas no significant degradation was observed with spruce, a higher mass loss was measured on Fmed grapevine culture compared to beech culture. Moreover, on both substrates, a simultaneous degradation pattern was demonstrated, and proteomic analysis identified a relative overproduction of oxidoreductases involved in lignin and extractive degradation on grapevine cultures, and only few differences in carbohydrate active enzymes. These results could explain at least partially the adaptation of Fmed to grapevine wood structural composition compared to other wood species, and suggest that other biotic and abiotic factors should be considered to fully understand the potential adaptation of Fmed to its ecological niche. Proteomics data are available via ProteomeXchange with identifier PXD036889.

A peculiar symptom that may develop in grapevines affected by wood pathogens involved in the esca complex of diseases is the leaf stripe symptom, which also gives the name to the Grapevine Leaf Stripe Disease. Multiple studies have revealed strong links between fungal presence, wood symptomatology and expression of the leaf stripe symptom. However, numerous other factors have been shown to play roles in symptom onset, incidence, severity and yearly fluctuation of this disease. While the factors triggering the leaf stripe symptom are still under investigation, three control strategies have been proven effective for substantially reducing its expression, namely trunk surgery, and applications of sodium arsenite or a fertilizer mixture. These control strategies are examined here, including their (putative or confirmed) modes of action, and how they may influence the leaf stripe symptom development. In this article, we also propose the ‘edge’ hypothesis to tentatively explain symptoms onset, keeping in consideration past knowledge and recent advances in the understanding of the esca leaf stripe symptom. Ultimately, it is our intention to offer food-for-thought and stimulate debate within the phytopathological community.

Leaf samples were obtained from Vitis vinifera ‘Malvasia Fina’ plants with well-characterized esca complex disease symptoms (n = 18) and from healthy uninfected plants (n = 6). Leaves from diseased plants were divided into three groups: asymptomatic (ASY), chlorotic (SY1), and scorched leaves (SY2). The metabolic profile of these leaves was then examined using an ultrahigh performance liquid chromatography system coupled to a Q-Exactive Hybrid Quadrupole-Orbitrap high resolution/accurate mass spectrometer interfaced with a heated electrospray ionization source. The number of small molecules measured in a sample was increased by varying the reconstitution solvent, chromatographic column, and ionization source. Data on accurate masses, peak areas, and relative levels of several metabolites were documented for each leaf sample, using the abovementioned approach. In this paper, data on 235 metabolites of known structural identity are reported, along with the biochemical pathways to which the metabolites belong. The remaining data related to lipid species and with a different focus of the research question are reported elsewhere. The broad coverage of metabolites reported here resulted in a greater coverage of the biochemical pathways involved in grapevine metabolism, which could provide a better understanding of the biochemical changes occurring during the onset and progression of foliar symptoms after invasion of woods by esca-associated pathogens. To determine which metabolites varied according to the study design, the detected ion features were processed using different statistical methods, including mean and median values, fold changes, Welch's two-sample t-test, false discovery rate, and quartiles represented by box and whisker plots. The goal of this statistical evaluation was to assess the responses of healthy, asymptomatic, and symptomatic leaf groups using a pairwise comparison, thus providing an opportunity for detecting statistically significant compounds and uncovering the dynamic metabolic models underlying disease latency and symptom expression.

Esca is a major grapevine trunk disease that heavily affects vineyards in the Northern hemisphere. The etiology and epidemiology of this disease have been subject of dispute ever since the earliest disease reports. The reason behind such debate is the presence of multiple internal and external symptoms, as well as several putative and confirmed wood pathogens. While the role of pathogenic fungi, as causal agents of wood symptoms, has been thoroughly assessed, their role in the expression of leaf symptoms remains to be fully elucidated. In this review, we analyzed etiological and epidemiological data, with a special focus on the microbiological aspect of esca and the involvement of Hymenochaetales (Basidiomycota). Vineyard studies have associated leaf symptoms with the presence of white rot, most frequently caused by Fomitiporia mediterranea (Hymenochaetales), while tracheomycotic fungi are commonly found, with similar abundance, in symptomatic and asymptomatic vines. Pathogenicity trials have excluded a direct effect of Hymenochaetales species in triggering leaf symptoms, while the data concerning the role of tracheomycotic fungi remains controversial. Recent microbiome studies confirmed that F. mediterranea is more abundant in leaf- symptomatic vines, and treatments that effectively control leaf symptoms, such as sodium arsenite spray and trunk surgery, act directly on the abundance of F. mediterranea or on the presence of white rot. This suggest that the simultaneous presence of Hymenochaetales and tracheomycotic fungi is a pre-requisite for leaf symptoms; however, the relation among fungal pathogens, grapevine and other biotic and abiotic factors needs further investigation. [ABSTRACT FROM AUTHOR]

In the last few years, trunk surgery has gained increasing attention as a method to reduce foliar symptoms typical of some of the Esca complex diseases. The technique relies on the mechanical removal of decayed wood by a chainsaw. A study on a 14-year-old Cabernet Sauvignon vineyard was carried out to validate the efficacy of trunk surgery and explore possible explanations behind it. Three levels of treatment were applied to three of the most characteristic symptoms associated with some diseases of the Esca complex, such as leaf stripe symptoms (LS), wilted shoots (WS) and apoplexy (APP). The most promising results were obtained by complete trunk surgery, where the larger decay removal allowed lower symptom re-expression. According to the wood types analyzed (decay, medium and sound wood), different changes in microbiota were observed. Alpha-diversity generally decreased for bacteria and increased for fungi. More specifically, main changes were observed for Fomitiporia mediterranea abundance that decreased considerably after trunk surgery. A possible explanation for LS symptom reduction after trunk surgery could be the microbiota shifting caused by the technique itself affecting a microbic-shared biochemical pathway involved in symptom expression. [ABSTRACT FROM AUTHOR]

Although sodium arsenite was widely used in Europe until its ban in 2003, its effects on microorganisms is not clearly understood. To improve our understanding of sodium arsenite curative effect on GTDs, grapevines displaying esca-foliar symptoms from different French regions (Alsace, Champagne, Languedoc) were treated or not with sodium arsenite, and analyzed for their wood microbiota. Using metabarcoding, we identified the fungal and bacterial taxa composition of microbiota colonizing woody trunk tissues. Large differences in fungal microbiota composition between treated and untreated grapevines were observed while no major impacts were observed on bacteria microbiota. The main fungal species detected in untreated necrotic woody tissues was Fomitiporia mediterranea (63–94%), a fungal pathogen associated with esca. The relative abundance of this fungal species significantly decreased after sodium arsenite treatment in the three vineyards, in particular in white-rot necrotic tissues and their borders (−90%). F. mediterranea was the most sensitive to sodium arsenite among fungi from grapevine woody tissues. These results strongly suggest that the effect of sodium arsenite on GTDs is due to its ability to efficiently and almost specifically eliminate F. mediterranea from white-rot necrotic tissues, allowing saprobic fungi to colonize the tissues previously occupied by this pathogenic fungus. [ABSTRACT FROM AUTHOR]

In this study, berry samples were collected from healthy (control) and symptomatic vines of the white varieties Viosinho and Malvasia-fina. Symptomatic vines showed two different degrees of severity at harvest, namely chlorotic and scorched leaves (severity level 1) and tiger stripe leaves (severity level 2). The total fatty acid content was reduced in both varieties and the total organic acid content was unchanged. The total free sugar content increased with symptom progression in Viosinho but remained unchanged in Malvasia-fina. Varietal differences were observed in the response of amino acids, whose levels increased in Malvasia-fina and decreased in Viosinho.

جدایه‌هایی از یک بازیدیومیست از نارون‌های آلوده به پوسیدگی قهوه‌ای عمق چوب در استان فارس به دست آمد. مشاهدات ریخت‏شناختی نشان داد که جدایه‏ها دارای پرگنه‏هایی با رنگ زرد و حاشیه‏ سفید بوده و رنگدانه‏ها‏یی با طیف رنگی قرمز-قهوه‏ای روی هر دو محیط‏ کشت تولید کردند. میانگین عرض ریسه‏های قارچی 8/3-4/2 میکرومتر، دیواره سلولی قهو‏ه‏ای رنگ و ریسه‏ها فاقد پل ارتباط بودند. ریسه‏های هوایی در هیچ‏ یک از جدایه‏ها ملاحظه نگردید و میانگین رشد روزانه در 25 درجه سلسیوس 35/1 میلی‏متر در روز بود. هیچ‏ گونه اندام جنسی پس از شش ماه نگهداری در 25 درجه سلسیوس مشاهده نشد. علاوه بر مشاهدات اولیه‏ ریخت‏شناختی، پس از فزون‌سازی، خالص‌سازی و توالی‌سنجی جدایه‏های به دست آمده، واکاوی‏های فیلوژنتیک توالی‏های فاصله ترانویسی ‌شده داخلی دی.‏اِن.‏اِی ریبوزومی (آی.‏تی.‏اِس) به روش پیوست همسایه‌ها نشان داد که جدایه‏ها مربوط به بازیدیومیست مولد پوسیدگی چوبFomitiporiamediterranea هستند. این نخستین گزارش از وجود قارچ مذکور برای میکوبیوتای ایران است. نمونه بررسی شده: استان فارس، شیراز، باجگاه، جدایه EN1 ازFomitiporiamediterranea، جدا شده از نارون، موجود در مجموعه قارچ‌های بخش گیاه‌پزشکی دانشکده کشاورزی دانشگاه شیراز (FT01.15.01).

Wood decay caused primarily by Fomitiporia mediterranea is considered to be an emerging disease for citrus and olive trees in Mediterranean countries. The pathogen cannot be currently controlled by chemicals whereas there is no available information about the source and level of resistance even for the most important cultivars where the global citrus and olive industries are based on. In the present study, five of the most significant Greek olive cultivars (Amfissis, Chalkidikis, Kalamon, Koroneiki and Mastoidis) were evaluated for their resistance to F. mediterranea by conducting artificial inoculation experiments. Disease reactions were evaluated by measuring the length of bark and wood lesions, 33 months post inoculation. Trunk sections scanning and image pixel analysis were employed to estimate the total discoloration and decay area of infected wood, whereas positive re-isolation ratio of F. mediterranea was also taken into account in resistance evaluation. Data on symptom development along with wood tissue colonization by the pathogen indicated that the resistance of olive cultivars to F. mediterranea varied significantly. Based on the cumulative stress response index (CSRI), 'Kalamon' and 'Koroneiki' were classified as resistant, 'Chalkidikis' and 'Mastoidis' as intermediately resistant, whereas 'Amfissis' was susceptible. Determination of lignin in trunk wood showed that the resistance of olive cultivars to F. mediterranea could be associated with their lignin content. This is the first experimental evidence of differential susceptibility responses of olive cultivars against F. mediterranea, and reveals for the first time the potential exploitation of host resistance as a promising approach in the effort to control wood decay disease of olive in practice. [ABSTRACT FROM AUTHOR]

FmEG from Fomitiporia mediterranea is a non-modular endoglucanase composed of a 24-amino acids extension and 13-amino acids linker-like peptide at the N-terminus and a 312-amino acids GH5 catalytic domain (CD) at the C-terminus. In this study, six FmEG derivatives with deletion of N-terminal fragments or fusion with an extra family 1 carbohydrate-binding module (CBM1) was constructed in order to evaluate the contribution of CBM1 to FmEG processivity and catalytic activity. FmEG showed a weak processivity and released cellobiose (G2) and cellotriose (G3) as main end products, and cellotriose (G4) as minor end product from filter paper (FP), but more amount of G4 was released from regenerated amorphous cellulose (RAC). All derivatives had similar activity on carboxymethylcellulose (CMC) with the same optimal pH (7.0) and temperature (50 °C). However, fusing an extra CBM1 to FmEG△24 or FmEG△37 with flexible peptide significantly improved its processivity and catalytic activity to FP and RAC. Overall, 1.79- and 1.84-fold increases in the soluble/insoluble product ratio on FP, and 1.38- and 1.39-fold increases on RAC, compared to FmEG△24, were recorded for CBM1-FmEG△24 and CBM1-linker-FmEG△24, respectively. Meanwhile, they displayed 2.64- and 2.67-fold more activity on RAC, and 1.68- and 1.77-fold on FP, respectively. Similar improvement was also obtained for CBM1-linker-FmEG△37 as compared with FmEG△37. Interestingly, fusion of an extra CBM1 with FmEG also caused an alteration of cleavage pattern on insoluble celluloses. Our results suggest that such improvements in processivity and catalytic activity may arise from CBM1 binding affinity. The N-terminal 24- or 37-amino acids may serve as linker for sufficient spatial separation of the two domains required for processivity and catalytic activity. In addition, deletion of the N-terminal 24- or 37-amino acids led to significant reduction in thermostability but not the enzymatic activity. [ABSTRACT FROM AUTHOR]

A number of stilbene polyphenols, dimers, trimers and tetramers of resveratrol (viniferins), which are typical Vitaceae metabolites, were extracted from asymptomatic wood (AW) and symptomatic brown-reddiscoloured wood (BRW) of Vitis vinifera cv. Sangiovese affected by “esca proper”, the trunk disease caused by the fungal complex Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Fomitiporia mediterranea. Resveratrol and the same types of viniferins were found in both AW and BRW, with the exception of α-viniferin, which was only detected in AW, and ampelopsin B, only in BRW. The total concentration of stilbene polyphenols was higher in symptomatic wood (3.7% in BRW vs 1.2% in AW). The absolute variationsin molar concentrations of each stilbene polyphenol (i) between BRW and AW (Δi = CiBRW - CiAW), were higherfor ε-viniferin and resveratrol than the other compounds, while the relative variations (Δi/CiAW), were lower for ampelopsin H and isohopeaphenol, and higher for ampelopsin B, hopeaphenol, ampelopsin A, leachianol F and G, pallidol and ε-viniferin (in descending order), than the relative variation for resveratrol. Aspects relating to the biosynthesis of stilbene polyphenols and their role in the host-esca pathogen interaction are discussed.

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Esca is a grapevine disease occurring in all vine-growing areas, including Italy. Multiple fungi that have been associated with esca spread by releasing aerial spores that infect pruning cuts and wounds. The aim of the study was to determine the occurrence of the most common fungi associated with esca in Umbria (central Italy) and to find under what weather conditions they release their spores. Disease incidence was also determined in the summers of 2006 and 2007 on ten grapevine cultivars (Cabernet Sauvignon, Grechetto, Sangiovese, Trebbiano toscano, Pinot bianco, Trebbiano spoletino, Ciliegiolo, Montepulciano, Chardonnay and Merlot) growing together in the same vineyard. Visual inspection of the vines showed that all cultivars were susceptible to esca, but that esca incidence differed in intensity between cultivars. In both years, esca incidence was higher with Cabernet Sauvignon, Sangiovese and Trebbiano toscano, and lower with Montepulciano and Merlot. Disease incidence went up in summer. Phaeomoniella chlamydospora was isolated from vine samples showing dark wood streaking, and Fomitiporia mediterranea from samples with white rot, confirming that these fungi are involved in esca. Spores of P. chlamydospora were trapped from March to December 2007. Spore release was affected by weather parameters (rain and temperature). [ABSTRACT FROM AUTHOR]

Abstract: Secondary metabolites and host defense compounds were shown to occur in xylem sap, and leaves of Vitis vinifera cv. Italia and cv. Matilde naturally infected by the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme). Samples of xylem sap and leaves were collected from healthy vines and from vines showing severe symptoms of brown wood-streaking caused by Pch and Tmi, or from vines with symptoms of both brown wood-streaking and white rot caused by Fme. Xylem sap collection was carried out during the early spring of 2003 and 2004, corresponding to the phenological phases: (A) cotton bud; (B) green tip; (C) leaves out; (D) stretched out leaves; and (E) visible clusters. In the present work we have studied the accumulation of biomolecules (pentaketides and α-glucans), host defense compounds (benzaldehydes, benzoic acid and cinnamic acid derivatives, flavonols, flavanols, flavan-3-ol derivatives and stilbenes) at different stages of grapevine development. Accumulation and changes in total phenolics and recurring phenolics, and of three phytotoxic secondary metabolites (scytalone, isosclerone and pullulan) were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that phenolic concentrations are strongly related to the cv. [Copyright &y& Elsevier]

Abstract: Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) produced scytalone, isosclerone and pullulans in liquid cultures, as well as in calli. Secondary metabolites and host defense compounds were shown to occur in calli of Vitis vinifera cv. Italia and cv. Matilde infected by the esca-associated fungi Pch, Tmi and Fomitiporia mediterranea (Fme). Calli of both cvs. were grown as dual cultures with Pch, Tmi and Fme. The fungi grew well in the presence of calli of both cvs., but callus growth was reduced. Accumulation and changes of total phenolics and recurring phenolics, and of two phytotoxic pentaketides and pullulans were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that concentrations of phenolics are strongly related to the cv. The paper discusses the possible relationship between melanin biosynthesis in Pch and Tmi, which utilize pentaketide metabolites as intermediates and their pathogenicity related to phytotoxity of scytalone and isosclerone. [Copyright &y& Elsevier]

Abstract: When the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme) were grown in liquid stationary cultures, it was seen that they were able to live in media containing resveratrol (RES) or tannic acid (TA) as the sole carbon source and that the fungi were able to convert both compounds. Particular attention is paid here to detecting RES and TA conversion. Pch, Tmi and Fme were partially inhibited by RES or TA. Pch, Tmi and Fme produced extracellular tannase, laccase and peroxidase enzymes in liquid or agarized cultures, whether glucose was present or not. When colonies of Pch, Tmi and Fme were confronted, they showed spatially and temporally heterogeneous patterns of laccase and peroxidase activity. The results indicate the non-synergistic, competitive association of Pch and Tmi and the inhibition of Fme growth. Muconic acid, a well-known intermediate in a large number of lignin and phenol oxidative processes, can partly or completely inhibit the lignolytic agent Fme, but is tolerated by Pch and Tmi. An explanation for wood pigmentation patterns by Pch, Tmi and Fme is given. [Copyright &y& Elsevier]