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Fountain grass, Cenchrus setaceus (Forssk.) Chiov. (syn. Pennisetum setaceum) is an invasive plant with high impact on insular environments such as the Canary Islands. Although there are no mentions on C. setaceus phytopathogens, plant communities with symptoms of withering, yellowing and decay have been found in Canary Islands. Our project aims to find autochthonous potential biological control agents for C. setaceus. Herein, we present a workflow in which we tested fast and cost-effective methods to screen a high number of fungal strains, aiming features like fast colonizers as well as competitive saprophytes and facultative pathogens with ability to cause infection. Affected plants were collected from the islands of Gran Canaria, Tenerife, La Gomera, La Palma and Lanzarote and 243 fungal strains belonging to 38 genera were isolated. First screening was performed on adult plants with pooled multiple species strains - spores suspensions of 10 random strains per pool, each strain representing a genus or a morphotype (n = 83). No symptoms of disease were observed. Most isolated genera in this study were Alternaria and Fusarium, known as cosmopolite phytopathogens. Next screening methods were focused accordingly. Two in vitro single-strain screening methods were employed by using mycelium-inoculated sectioned and entire leaves, to observe the ability of tissue colonization. First screening on sectioned leaves was performed with high amount of inoculum, to increase the chances of colonization and to determine the ability of fungi to use the plant material as substrate. The method was not effective in significantly reducing the number of candidates as most strains had abundant growth. To detect differences in fungal strains acting as facultative pathogens or phytopathogens, the 2nd single-strain screening was performed on physiologically-stressed (pelargonic acid, a desiccant molecule to induce turgor loss) and not pre-treated leaves using less inoculum. Six strains were selected and subsequently evaluated in the last in vivo screening in the presence and absence of the desiccant. Finally, we detected strain 967 Fusarium clavum as able to colonize and reproduce at the crown of the young plants. In view of our experimental process, we propose a workflow for the cost-effective search for potential BCAs in similar situations. [ABSTRACT FROM AUTHOR]

Microbial volatile compounds (MVCs) significantly influence the growth of plants and phytopathogens. However, the practical application of MVCs at the field level is limited by the fact that the concentrations at which these compounds antagonize the pathogens are often toxic for the plants. In this study, we investigated the effect of dimethyl disulfide (DMDS), one of the MVCs produced by microorganisms, on the fitness of tomato plants and its fungicidal potential against a fungal phytopathogen, Sclerotinia minor. DMDS showed strong fungicidal and plant growth promoting activities with regard to the inhibition of mycelial growth, sclerotia formation, and germination, and reduction of disease symptoms in tomato plants infected with S. minor. DMDS exposure significantly upregulated the expression of genes related to growth and defense against the pathogen in tomato. Especially, the overexpression of PR1 and PR5 suggested the involvement of the salicylic acid pathway in the induction of systemic resistance. Several morphological and ultrastructural changes were observed in the cell membrane of S. minor and the expression of ergosterol biosynthesis gene was significantly downregulated, suggesting that DMDS damaged the membrane, thereby affecting the growth and pathogenicity of the fungus. In conclusion, the tripartite interaction studies among pathogenic fungus, DMDS, and tomato revealed that DMDS played roles in antagonizing pathogen as well as improving the growth and disease resistance of tomato. Our findings provide new insights into the potential of volatile DMDS as an effective tool against sclerotial rot disease. [ABSTRACT FROM AUTHOR]

Abstract The perennial wild rice Zizania latifolia is confined in the swampy habitat and wetland of the Indo-Burma biodiversity hotspot of India and infection by the biotrophic fungus Ustilago esculenta is hallmarked by swellings that develop to form localized smut-gall at the topmost internodal region. The cellular and proteomic events involved in the non-systemic colonization of Z. latifolia by U. esculenta leading to smut-gall formation is poorly understood. Proteins were extracted from the smut-gall region at the topmost internodal region below the apical meristematic tissue from the infected and uninfected parts of Z. latifolia. By combining transmission electron microscopy (TEM) and fluorescent microscopy (FM), we showed that U. esculenta hyphal morphological transitions and movement occurred both intercellularly and intracellularly while sporulation occurred intracellularly in selective cells. Following proteome profiling using two dimensional SDS-PAGE at different phenological phases of smut-gall development and U. esculenta infection, differentially expressed proteins bands and their relative abundance were detected and subjected to liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Importantly, the fungus explores at least 7 metabolic pathways and 5 major biological processes to subdue the host defense and thrive successfully on Z. latifolia. The fungus U. esculenta produces proteases and energy acquisition proteins those enhance it's defensive and survival mode in the host. The identified differentially regulated proteins shed-light into why inflorescence is being replaced by bulbous smut-gall at late stages of the disease, as well as the development of resistance in some Z. latifolia plants against U. esculenta infection. Highlights • Cellular events in Z. latifolia – U. esculenta interaction triggering smut-gall formation. • 2DE and SDS-PAGE was used to profile the proteomes in interaction. • Differentially expressed proteins identified by LC-MS/MS analysis. • U. esculenta produces diverse functional proteins and discretely alters the host biological processes. [ABSTRACT FROM AUTHOR]

Summary: Austropuccinia psidii is a biotrophic rust fungus that affects species from the Myrtaceae family. In Mexico, Myrtaceae is widely distributed in temperate, tropical and semi‐arid ecosystems, and includes 20 genera and 192 endemic and exotic species. Austropuccinia psidii has been present in Mexico for the last four decades; however, little is known about the distribution of this rust or the vulnerability of native and exotic Myrtaceae to infection. In this study, we used global occurrence records for the pandemic biotype of myrtle rust to model its current and future suitable habitat using a species distribution model, Maxent. We identified regions that are highly suitable for myrtle rust establishment, now and in the future (2050). Additionally, we identified the Myrtaceae species known to be susceptible to rust infection and that are currently distributed in areas with high rust habitat suitability. Thirty‐six susceptible plant species and 142 untested species are distributed within areas of suitable rust habitat and are considered potentially at risk of rust infection. Current suitable habitat is mainly restricted to the east coast of Mexico, with Veracruz, Puebla, Chiapas, Tabasco and Oaxaca being the most vulnerable regions to the rust under current and future climates. We encourage monitoring within these regions by surveying locations where the rust occurs and within areas with high suitable habitat to determine the threat to native ecosystems and industries reliant on Myrtaceae. We also recommend screening to test the susceptibility of Myrtaceae species with no known susceptibility rating. [ABSTRACT FROM AUTHOR]

The invasive pathogen Cryphonectria parasitica causes one of the most destructive chestnut blight diseases on Castanea sativa stands. in Bulgaria, the disease was observed for first time at the end of 1980s in pure and mixed chestnut stands in Belasitsa mt. and the eastern rhodopes. over the last decades, the disease has affect negatively the vitality of C. sativa populations throughout the country, leading to the loss of an important chestnut stands production and the progressive death of the trees. in 2018, the incidence of the pathogen, its distribution and strain diversity were surveyed in a network of permanent sample plots established on the northern slopes of Belasitsa mountain, southwest Bulgaria and in the eastern rhodopes. the sample trees were visually assessed for the presence of pathogen's reproductive structure and dieback in crowns. the severity of chestnut blight disease was evaluated according to the number of cankers on stems and degree of defoliation compared between the different sample plots and regions. at lower altitude (400-600 m), the outbreak of disease leaded to destruction of the stands and degradation for a longer period, the stands were assessed as degraded. new records for C. parasitica spreading on a chestnut mature plantation planted in the region of state Forests Kirkovo and Krumovgrad, the eastern rhodopes, were established. isolation of 86 pathogen strains were carried out at the laboratory, among them, 25% revealed whitish colour. current knowledge of the spreading and severity of the disease is an important circumstanse for the implementation of timely and effective management control strategies. [ABSTRACT FROM AUTHOR]

Summary: Root‐colonizing fungi can form mycorrhizal or endophytic associations with plant roots, the type of association depending on the host. We investigated the differences and similarities of the fungal communities of three boreal ericoid plants and one coniferous tree, and identified the community structure of fungi utilizing photosynthates from the plants studied. The fungal communities of roots and soils of Vaccinium myrtillus, Vaccinium vitis‐idaea, Calluna vulgaris and Pinus sylvestris were studied in an 18‐month‐long experiment where the plants were grown individually in natural substrate. Photosynthates utilizing fungi were detected with DNA stable‐isotope probing using 13CO2 (13C‐DNA‐SIP). The results indicated that the plants studied provide different ecological niches preferred by different fungal species. Those fungi which dominated the community in washed roots had also the highest 13C‐uptake. In addition, a common root endophyte without confirmed mycorrhizal status also obtained 13C from all the plants, indicating close plant‐association of this fungal species. We detect several fungal species inhabiting the roots of both ericoid mycorrhizal and ectomycorrhizal plants. Our results highlight that the ecological role of co‐occurrence of fungi with different life styles (e.g. mycorrhizal or endophytic) in plant root systems should be further investigated. [ABSTRACT FROM AUTHOR]

The Panel on Plant Health performed a pest categorisation of the fungus Apiosporina morbosa, the causal agent of black knot, for the EU. The identity of the pest is well established and reliable methods exist for its detection/identification. The pest is listed in Annex IIAI of Directive 2000/29/EC and is not known to occur in the EU. Apiosporina morbosa is present in Alaska, Canada, Mexico and the continental states of the USA. The major hosts of A. morbosa are Prunus domestica and Prunus cerasus; the host status of other Prunus species and hybrids is uncertain because of contradictory reports or lack of information. The pest could potentially enter the EU on host plants for planting and plant parts originating in infested third countries. Wood of Prunus spp. is also a pathway of entry, but of minor importance. The current pest distribution and climate matching suggest that the pest could establish and spread in the EU wherever the hosts are grown. In the infested areas, the pest causes girdling of twigs and occasionally of larger branches, whereas trees with multiple infections loose vigour, bloom poorly, and become unproductive, stunted and susceptible to winter injury and infection by other pathogens. The presence of black knots makes trees unsuitable for timber production. It is expected that the pest introduction and spread in the EU would impact host production. Uncertainty exists on whether the agricultural practices and chemical control methods applied in the EU could prevent the establishment and spread of A. morbosa. A. morbosa meets all the criteria assessed by EFSA for consideration as potential Union quarantine pest. As the pest is not known to occur in the EU, this criterion to consider it as Union regulated non-quarantine pest is not met. [ABSTRACT FROM AUTHOR]

The article discusses research which examined whether thalli infected with lichenicolous fungus Plectocarpon lichenum have lower synthesis of lichen produce carbon-based secondary compounds (CBSC). Topics discussed include the reduction in the total CBSC concentration in healthy thalli with acetone treatment and adverse influence of Plectocarpon lichenum on its lichen host by reducing CBSC and growth.

Many plant-pathogenic fungi are highly host-specific. In most cases, host-specific interactions evolved at the time of speciation of the respective host plants. However, host jumps have occurred quite frequently, and still today the greatest threat for the emergence of new fungal diseases is the acquisition of infection capability of a new host by an existing plant pathogen. Understanding the mechanisms underlying host-switching events requires knowledge of the factors determining host-specificity. In this review, we highlight molecular methods that use a comparative approach for the identification of host-specificity factors. These cover a wide range of experimental set-ups, such as characterization of the pathosystem, genotyping of host-specific strains, comparative genomics, transcriptomics and proteomics, as well as gene prediction and functional gene validation. The methods are described and evaluated in view of their success in the identification of host-specificity factors and the understanding of their functional mechanisms. In addition, potential methods for the future identification of host-specificity factors are discussed. [ABSTRACT FROM AUTHOR]

* Cerato-platanin proteins (CPs), which are secreted by filamentous fungi, are phytotoxic to host plants, but their functions have not been well defined to date. * Here we characterized a CP (SsCP1) from the necrotrophic phytopathogen Sclerotinia sclerotiorum. Sscp1 transcripts accumulated during plant infection, and deletion of Sscp1 significantly reduced virulence. SsCP1 could induce significant cell death when expressed in Nicotiana benthamiana. * Using yeast two-hybrid, GST pull-down, co-immunoprecipitation and bimolecular florescence complementation, we found that SsCP1 interacts with PR1 in the apoplast to facilitate infection by S. sclerotiorum. Overexpressing PR1 enhanced resistance to the wild-type strain, but not to the Sscp1 knockout strain of S. sclerotiorum. Sscp1-expressing transgenic plants showed increased concentrations of salicylic acid (SA) and higher levels of resistance to several plant pathogens (namely Botrytis cinerea, Alternaria brassicicola and Golovinomyces orontii). * Our results suggest that SsCP1 is important for virulence of S. sclerotiorum and that it can be recognized by plants to trigger plant defense responses. Our results also suggest that the SA signaling pathway is involved in CP-mediated plant defense. [ABSTRACT FROM AUTHOR]

Late blight has been the most devastating potato disease worldwide. The causal agent, Phytophthora infestans, is notorious for its capability to rapidly overcome host resistance. Changes in the expression pattern and the encoded protein sequences of effector genes in the pathogen are responsible for the loss of host resistance. Among numerous effector genes, the class of RXLR effector genes is well-known in mediating host genotype-specific resistance. We therefore performed deep sequencing of five genetically diverse P. infestans strains using in planta materials infected with zoospores (12 h post inoculation) and focused on the identification of RXLR effector genes that are conserved in coding sequences, are highly expressed in early stages of plant infection, and have defense suppression activities. In all, 245 RXLR effector genes were expressed in five transcriptomes, with 108 being co-expressed in all five strains, 47 of them comparatively highly expressed. Taking sequence polymorphism into consideration, 18 candidate core RXLR effectors that were conserved in sequence and with higher in planta expression levels were selected for further study. Agrobacterium tumefaciens-mediated transient expression of the selected effector genes in Nicotiana benthamiana and potato demonstrated their potential virulence function, as shown by suppression of PAMP-triggered immunity (PTI) or/and effector-triggered immunity (ETI). The identified collection of core RXLR effectors will be useful in the search for potential durable late blight resistance genes. Analysis of 10 known Avr RXLR genes revealed that the resistance genes R2, Rpi-blb2, Rpi-vnt1, Rpi-Smira1, and Rpi-Smira2 may be effective in potato cultivars. Analysis of 8 SFI (Suppressor of early Flg22-induced Immune response) RXLR effector genes showed that SFI2, SFI3, and SFI4 were highly expressed in all examined strains, suggesting their potentially important function in early stages of pathogen infection. [ABSTRACT FROM AUTHOR]

Endogonales is a lineage of early diverging fungi within Mucoromycota. Many species in this order produce small sporophores ("sporocarps") containing a large number of zygospores, and many species form symbioses with plants. However, due to limited collections, subtle morphological differentiation, difficulties in growing these organisms in vitro, and idiosyncrasies in their rDNA that make PCR amplification difficult, the systematics and character evolution of these fungi have been challenging to resolve. To overcome these challenges we generated a multigene phylogeny of Endogonales using sporophores collected over the past three decades from four continents. Our results show that Endogonales harbour significant undescribed diversity and form two deeply divergent and well-supported phylogenetic clades, which we delimit as the families Endogonaceae and Densosporaceae fam. nov. The family Densosporaceae consists of the genus Densospora,Sphaerocreas pubescens, and many diverse lineages known only from environmental DNA sequences of plant-endosymbiotic fungi. Within Endogonaceae there are two clades. One corresponds to Endogone and includes the type species, E. pisiformis. Species of Endogone are characterized by above- and below-ground sporophores, a hollow and infolded sporophore form, a loose zygosporangial hyphal mantle, homogeneous gametangia, and an enigmatic trophic mode with no evidence of ectomycorrhizal association for most species. For the other clade we introduce a new generic name, Jimgerdemannia gen. nov. Members of that genus (J. flammicorona and J. lactiflua species complexes, and an undescribed species) are characterized by hypogeous sporophores with a solid gleba, a well-developed zygosporangial hyphal mantle, heterogeneous gametangia, and an ectomycorrhizal trophic mode. Future studies on Densosporaceae and Endogonaceae will be important for understanding fungal innovations including evolution of macroscopic sporophores and symbioses with plants. [ABSTRACT FROM AUTHOR]

Honey fungus (Armillaria spp.) root rot is the disease most frequently inquired about by U.K. gardeners to the Royal Horticultural Society. Armillaria epidemiology has been studied within forestry and agriculture, but data are lacking within gardens, which have greater host plant diversity than orchards and vineyards and greater disturbance than woodlands. Which Armillaria species are responsible for garden disease, and how the broad range of susceptible ornamentals are differentially affected is not known. To address this, isolates of Armillaria were obtained from dead and dying plants from across the U.K. over a 4-year period (2004 to 2007). Species were identified by PCR-RFLP for 1GS, and further verified by species specific PCR for EF-1α. Of the seven species known in the U.K., three were identified: A. mellea (83.1%), A. gallica (15.8%), and A. osloyae (1.1%). Armillaria was isolated from trees, shrubs, and nonwoody plants including bulbs and vegetables, with newly recorded hosts listed herein. A. mellea was associated with infections of multiple hosts, and with all infections of the most common host, Ligustrwn. In sites where more than one Armillaria species was found, the combination was of A. mellea and A. gallica, raising questions regarding the interactions of these species in U.K. gardens. [ABSTRACT FROM AUTHOR]

In the Asian citrus psyllid (Diaphorina citri Kuwayama), learning facilitates host recognition and mate preference; however, it is unclear whether induced female oviposition preference occurs in this species. We investigated the influence of natal host experience on adult oviposition preference when reared on either 'Valencia' orange (Citrus x sinesis) or orange jasmine (Murraya paniculata). Psyllids reared on 'Valencia' orange preferred 'Valencia' orange as an oviposition host compared with orange jasmine, whereas there was no difference in oviposition between the two hosts in orange jasmine reared psyllids. Nymphs transferred from 'Valencia' orange to orange jasmine were smaller in adult size and required more time for development. These findings were reversed in orange jasmine reared psyllids, which increased in size and displayed shorter development times when transferred from orange jasmine to 'Valencia' orange. However, mortality increased in nymphs transferred to the non-natal host species in both treatment groups compared with nymphs transferred to the same host. These results indicate an association between host plant preference and performance in this species. Maternal host experience appeared to influence the oviposition preference in this species. Juvenile psyllid performance appeared negatively affected by orange jasmine plants such that fitness was reduced, suggesting benefits for maternal host fidelity in those insects not acclimated to feeding on orange jasmine. Induced oviposition preference may provide an important mechanism of adaptive plasticity in D. citri reproductive strategies, allowing females to discriminate among potential host species in favor of those to which her offspring are best adapted. [ABSTRACT FROM AUTHOR]

Fomitopsis pinicola is a species of Polyporales frequently encountered in Nordic temperate and boreal forests. In nature, the fungus causes destructive brown rot in wood, colonizing tree trunks often occupied by other Basidiomycota species. We mimicked these species-species interactions by introducing F. pinicola to five white rot species, all common saprotrophs of Norway spruce. Hyphal interactions and mycelial growth in various combinations were recorded, while activities of lignocellulose-acting CAZymes and oxidoreductases were followed in co-cultures on two different carbon-source media. Of the species, Phlebia radiata and Trichaptum abietinum were the strongest producers of lignin-modifying oxidoreductases (laccase, manganese peroxidase) when evaluated alone, as well as in co-cultures, on the two different growth media (low-nitrogen liquid medium containing ground coniferous wood, and malt extract broth). F. pinicola was an outstanding producer of oxalic acid (up to 61 mM), whereas presence of P. radiata prevented acidification of the growth environment in the liquid malt-extract cultures. When enzyme profiles of the species combinations were clustered, time-dependent changes were observed on wood-supplemented medium during the eight weeks of growth. End-point acidity and production of mycelium, oxalic acid and oxidoreductase activities, in turn clustered the fungal combinations into three distinct functional groups, determined by the presence of F. pinicola and P. radiata, by principal component analysis. Our findings indicate that combinations of wood-decay fungi have dramatic dynamic effects on the production of lignocellulose-active enzymes, which may lead to divergent degradative processes of dead wood and forest litter. [ABSTRACT FROM AUTHOR]

Background: Pseudostellaria heterophylla (P. heterophylla), a herbaceous perennial, belongs to Caryophyllaceae family and is one of the Chinese herbal medicine with high pharmacodynamic value. It can be used to treat the spleen deficiency, anorexia, weakness after illness and spontaneous perspiration symptoms. Our previous study found that consecutive monoculture of Pseudostellaria heterophylla could lead to the deterioration of the rhizosphere microenvironment. The specialized forms of pathogenic fungus Fusarium oxysporum f.Sp. heterophylla (F. oxysporum) in rhizosphere soils of P. heterophylla plays an important role in the consecutive monoculture of P. heterophylla. Results: In this study, F. oxysporum was used to infect the tissue culture plantlets of P. heterophylla to study the responding process at three different infection stages by using RNA-sequencing. We obtained 127,725 transcripts and 47,655 distinct unigenes by de novo assembly and obtained annotated information in details for 25,882 unigenes. The Kyoto Encyclopedia of Genes and Genomes pathway analysis and the real-time quantitative PCR results suggest that the calcium signal system and WRKY transcription factor in the plant-pathogen interaction pathway may play an important role in the response process, and all of the WRKY transcription factor genes were divided into three different types. Moreover, we also found that the stimulation of F. oxysporum may result in the accumulation of some phenolics in the plantlets and the programmed cell death of the plantlets. Conclusions: This study has partly revealed the possible molecular mechanism of the population explosion of F. oxysporum in rhizosphere soils and signal response process, which can be helpful in unraveling the role of F. oxysporum in consecutive monoculture problems of P. heterophylla. [ABSTRACT FROM AUTHOR]

The anisotropic nature of the surface of highly elongated cereal leaves means that longitudinally and transversely oriented germinating conidia of phytopathogenic fungi could have different biological properties. We measured the angles between the long axis of the conidium, the axis of the plant leaf and the direction of the appressorial germ tube of the powdery mildew fungus Blumeria graminis f. sp. tritici on wheat leaves. Two main distribution patterns were observed. Normal appressorial germ tubes were associated with the longitudinal microrelief of the wheat leaves, whereas abnormal germ tubes tended to have a random distribution. The increased rotational mobility of these abnormal germ tubes may result from a reduction in their adhesion to the surface of plant cells. [ABSTRACT FROM AUTHOR]

Ralstonia solanacearum a phytopathogenic bacterium produces virulence factor via production of extracellular polysaccharides (EPS). We have isolated EPS from R. solanacearum and characterized this by AFM, SEM, FTIR, LC-MS and NMR spectroscopy. Interestingly, the result showed pore size distribution, topology, rheological and pseudoplastic behaviour of EPS and three major monosaccharides, glucuronic acid, N -acetylglucosamine and glucose associated with EPS. Eggplant treated with intact crude EPS showed a significant 51% decrease in bacterial wilt incidence for both in vitro and greenhouse conditions. In eggplant cultivars EPS induces significant up-regulation of guaiacol peroxidase and ascorbate peroxidase defense genes, providing screen resistance against bacterial wilt. [ABSTRACT FROM AUTHOR]

Plant pathogenic bacteria attack numerous agricultural crops, causing devastating effects on plant productivity and yield. They survive in diverse environments, both in plants, as pathogens, and also outside their hosts as saprophytes. Hence, they are confronted with numerous changing environmental parameters. During infection, plant pathogens have to deal with stressful conditions, such as acidic, oxidative and osmotic stresses; anaerobiosis; plant defenses; and contact with antimicrobial compounds. These adverse conditions can reduce bacterial survival and compromise disease initiation and propagation. Successful bacterial plant pathogens must detect potential hosts and also coordinate their possibly conflicting programs for survival and virulence. Consequently, these bacteria have a strong and finely tuned capacity for sensing and responding to environmental and plant stimuli. This review summarizes our current knowledge of the signals and genetic circuits that affect survival and virulence factor expression in three important and well-studied plant pathogenic bacteria with wide host ranges and the capacity for long-term environmental survival. These are: Ralstonia solanacerarum, a vascular pathogen that causes wilt disease; Agrobacterium tumefaciens, a biotrophic tumorigenic pathogen responsible for crown gall disease and Dickeya, a brute force apoplastic pathogen responsible for soft-rot disease. [ABSTRACT FROM AUTHOR]

Many phytopathogenic fungi use infection structures (IFSs, i.e., appressoria and infection cushions) to penetrate host cuticles. However, the conserved mechanisms that mediate initiation of IFS formation in divergent pathogens upon sensing the presence of host plants remain obscure. Here, we demonstrate that a conserved septin gene SEP4 plays crucial roles in this process. Disruption of SEP4 in the plant grey mould fungus Botrytis cinerea completely blocked IFS formation and abolished the virulence of Δ Bcsep4 mutants on unwounded hosts. During IFS formation, mutants lacking SEP4 could produce reactive oxygen species (ROS) normally. Inhibition of ROS production in strains harbouring the SEP4 gene resulted in disordered assembly of Sep4 and the subsequent failure to form infection cushions, suggesting that proper Sep4 assembly regulated by ROS is required for initiation of IFS formation and infection. Moreover, loss of SEP4 severely impaired mutant conidiation, melanin and chitin accumulation in hyphal tips and lesion expansion on wounded hosts, but significantly promoted germ tube elongation and sclerotium production. SEP4-mediated fungal pathogenic development, including IFS formation, was validated in the hemibiotroph Magnaporthe oryzae. Our findings indicate that Sep4 plays pleiotropic roles in B. cinerea development and specifically facilities host infection by mediating initiation of IFS formation in divergent plant fungal pathogens in response to ROS signaling. [ABSTRACT FROM AUTHOR]

During the infection of host plants, pathogens can deliver virulence-associated 'effector' proteins to promote plant susceptibility. However, little is known about effector function in the obligate biotrophic pathogen Puccinia striiformis f. sp. tritici ( Pst) that is an important fungal pathogen in wheat production worldwide. Here, they report their findings on an in planta highly induced candidate effector from Pst, PSTha5a23. The PSTha5a23 gene is unique to Pst and shows a low level of intra-species polymorphism. It has a functional N-terminal signal peptide and is translocated to the host cytoplasm after infection. Overexpression of PSTha5a23 in Nicotiana benthamiana was found to suppress the programmed cell death triggered by BAX, PAMP-INF1 and two resistance-related mitogen-activated protein kinases (MKK1 and NPK1). Overexpression of PSTha5a23 in wheat also suppressed pattern-triggered immunity (PTI)-associated callose deposition. In addition, silencing of PSTha5a23 did not change Pst virulence phenotypes; however, overexpression of PSTha5a23 significantly enhanced Pst virulence in wheat. These results indicate that the Pst candidate effector PSTha5a23 plays an important role in plant defense suppression and rust pathogenicity, and also highlight the utility of gene overexpression in plants as a tool for studying effectors from obligate biotrophic pathogens. [ABSTRACT FROM AUTHOR]

Elucidating interactions of above-ground and below-ground communities in different habitat types is essential for understanding biodiversity maintenance and ecosystem functioning., Using 454 pyrosequencing of ITS2 sequences we examined the relationship between subtropical mountain forest soil fungal communities, abiotic conditions, and plant communities using correlation and partial models., Ridge and valley habitats with differing fungal communities were delineated. Total, saprotrophic and pathogenic fungal richness were significantly correlated with plant species richness and/or soil nutrients and moisture in the ridge habitat, but with habitat convexity or basal area of Castanopsis eyrei in the valley habitat. Ectomycorrhizal ( EM) fungal richness was significantly correlated with basal area of C. eyrei and total EM plants in the ridge and valley habitats, respectively. Total, saprotrophic, pathogenic and EM fungal compositions were significantly correlated with plant species composition and geographic distance in the ridge habitat, but with various combinations of plant species composition, plant species richness, soil C : N ratio and pH or no variables in the valley habitat., Our findings suggest that mechanisms influencing soil fungal diversity and community composition differ between ridge and valley habitats, and relationships between fungal and woody plant assemblages depend on habitat types in the subtropical forest ecosystem. [ABSTRACT FROM AUTHOR]

Endophytic fungi and ectomycorrhizal fungi co-exist in the mycorrhizal root tips of boreal forest trees. However, very little is known about the functional role they play in their host's biology. The activity of enzymes responsible for important biochemical processes is used to determine the functional role of root-associated mycorrhizal fungi. However, enzyme activity is never studied in the presence of endophytic fungi in-planta. The aims of this study were to investigate the effect of Scots pine ( Pinus sylvestris L.) root-isolated fungal endophytes on the host plant root morphology, to determine their functional effects using host root-excreted enzyme activity measurements, and to compare them with roots colonized by decomposer and ectomycorrhizal fungal strains and noncolonised Scots pine root tips. Our results show that endophytic fungi did not damage the pine roots in contrast to the decomposer fungi. The endophytic fungi penetrated the cortical cells of the host plant. The roots colonised by endophytic fungi produce different exo-enzymes compared with those produced by roots colonized by other fungal groups or noncolonized control root tips. Our results indicate that endophytic fungi are clearly a distinctive ecological group of fungi that have functional traits different from those of ectomycorrhizal and decomposer fungi. [ABSTRACT FROM AUTHOR]

Symbiotic ectomycorrhizal fungi mobilize nutrients from both organic and inorganic substrates and supply them to their host plants. Their role in mobilizing base cations and phosphorus from mineral substrates through weathering has received increasing attention in recent years but the processes involved remain to be elucidated. We grew selected ectomycorrhizal and nonmycorrhizal fungi in axenic systems containing mineral and organic substrates and examined their capacity to fractionate and assimilate stable isotopes of magnesium. The mycorrhizal fungi were significantly depleted in heavy isotopes with the lowest Δ26Mg values (the difference between δ26Mg in fungal tissue and δ26Mg in the substrate) compared with nonmycorrhizal fungi, when grown on mineral substrates containing granite particles. The ectomycorrhizal fungi accumulated significantly higher concentrations of Mg, K and P than the nonmycorrhizal fungi. There was a highly significant statistical relationship between δ26Mg tissue signature and mycelial concentration of Mg, with a clear separation between most ectomycorrhizal fungi and the nonmycorrhizal fungi. These results are consistent with the idea that ectomycorrhizal fungi have evolved efficient mechanisms to mobilize, transport and store Mg within their mycelia. [ABSTRACT FROM AUTHOR]

The current investigationwas carried outto evaluate the effect of collar rot fungus Macrophomina phaseolina (Tassi) Goid. on germination, growth and physiology of Capsicum frutescens L. Two commercial varieties DY1143 California hybrid and DY1143 were used for the experiment. The experiment was designed as completely randomized (CRD) with three replicates per treatment in Petri plates and pots. In Petri plate experiment considerable decline in germination rate, germination percentage, seed vigor, length and weight was observed in 10-days old seedling ofboth the tested varieties of C. frutescens. Physiological parameters i.e. protein content, proline content, sugar content and chlorophyll content also significantly suppressed under M. phaseolina stress. The present investigation concluded that DY1143 California hybrid variety of C. frutescensis more sensitive as compared to DY1143 variety. [ABSTRACT FROM AUTHOR]

Didymella pinodes is the principal causal agent of ascochyta blight, one of the most important fungal diseases of pea (Pisum sativum) worldwide. Understanding its host specificity has crucial implications in epidemiology and management; however, this has not been clearly delineated yet. In this study we attempt to clarify the host range of D. pinodes and to compare it with that of other close Didymella spp. D. pinodes was very virulent on pea accessions, although differences in virulence were identified among isolates. On the contrary, studied isolates of D. fabae, D. rabiei, and D. lentil showed a reduced ability to infect pea not causing macroscopically visible symptoms on any of the pea accessions tested. D. pinodes isolates were also infective to some extend on almost all species tested including species such as Hedysarum coronarium, Lathyrus sativus, Lupinus albus, Medicago spp., Trifolium spp., Trigonella foenum-graecum, and Vicia articulata which were not mentioned before as hosts of D. pinodes. On the contrary, D. lentil and D. rabiei were more specific, infecting only lentil and chickpea, respectively. D. fabae was intermediate, infecting mainly faba bean, but also slightly other species such as Glycine max, Phaseolus vulgaris, Trifolium spp., Vicia sativa, and V. articulata. DNA sequence analysis of the nuclear ribosomal internal transcribed spacer region (ITS) was performed to confirm identity of the isolates studies and to determine phylogenetic relationship among the Didymella species, revealing the presence of two clearly distinct clades. Clade one was represented by two supported subclusters including D. fabae isolates as well as D. rabiei with D. lentil isolates. Clade two was the largest and included all the D. pinodes isolates as well as Phoma medicaginis var. pinodella. Genetic distance between D. pinodes and the other Didymella spp. isolates was not correlated with overall differences in pathogenicity. Based on evidences presented here, D. pinodes is not specialized on pea and its host range is larger than that of D. fabae, D. lentil, and D. rabiei. This has relevant implications in epidemiology and control as these species might act as alternative hosts for D. pinodes. [ABSTRACT FROM AUTHOR]

The molecular characterization of a novel single-stranded RNA virus, obtained by next generation sequencing using Illumina platform, in a field grapevine isolate of the plant pathogenic fungus Botrytis , is reported in this work. The sequence comparison of this virus against the NCBI database showed a strong identity with RNA dependent RNA polymerases (RdRps) of plant pathogenic viruses belonging to the genus Ourmiavirus , therefore, this novel virus was named Botrytis ourmia-like virus (BOLV). BOLV has one open reading frame of 2169 nucleotides, which encodes a protein of 722 amino acids showing conserved domains of plant RNA viruses RdRps such as the most conserved GDD active domain. Our analyses showed that BOLV is phylogenetically closer to the fungal Narnavirus and the plant Ourmiavirus than to Mitovirus of the family Narnaviridae . Hence, we proposed that BOLV might represent the link between fungal viruses of the family Narnaviridae and the plant ourmiaviruses. [ABSTRACT FROM AUTHOR]

The importance of phyllosphere fungi to ecosystem functioning via soil processes has aroused increasing interest during the last decade. Here, we briefly review the current knowledge of how the foliar endophytic fungi and nutrient cycling interact. Recent findings suggest that endophytes may affect plant litter quality, organisms that control litter decomposition and the availability of nutrients in plant communities. However, the results obtained so far are highly variable. We attempt to integrate these observations with the knowledge of ecology and life-history strategies of endophytic fungi, and highlight general rules and gaps in our knowledge. Finally, we suggest testable hypotheses for future studies. [ABSTRACT FROM AUTHOR]

Clavicipitaceous fungi producing ergot alkaloids were recently discovered to be epibiotically associated with peltate glandular trichomes of Ipomoea asarifolia and Turbina corymbosa, dicotyledonous plants of the family Convolvulaceae. Mediators of the close association between fungi and trichomes may be sesquiterpenes, main components in the volatile oil of different convolvulaceous plants. Molecular biological studies and microscopic investigations led to the observation that the trichomes do not only secrete sesquiterpenes and palmitic acid but also seem to absorb ergot alkaloids from the epibiotic fungal species of the genus Periglandula. Thus, the trichomes are likely to have a dual and key function in a metabolic dialogue between fungus and host plant. [ABSTRACT FROM AUTHOR]

Pathogen adaptation to different hosts can lead to specialization and, when coupled with reproductive isolation, genome-wide differentiation and ecological speciation. We tested the hypothesis of host specialization among California populations of Eutypa lata (causal fungus of Eutypa dieback of grapevine and apricot), which is reported from >90 species. Genetic analyses of nine microsatellite loci in 182 isolates from three hosts (grapevine, apricot, and willow) at three locations were complemented by cross-inoculations on cultivated hosts grapevine and apricot to reveal patterns of host specialization. The cultivated hosts are likely more important sources of inoculum than the wild host willow, based on our findings of higher pathogen prevalence and allelic richness in grapevine and apricot. High levels of gene flow among all three hosts and locations, and no grouping by clustering analyses, suggest neither host nor geographic differentiation. Cross-inoculations revealed diversified phenotypes harboring various performance levels in grapevine and apricot, with no apparent correlation with their host of origin. Such phenotypic diversity may enable this pathogen to persist and reproduce as a generalist. Regular genetic reshuffling through sexual recombination, frequent immigration among hosts, and the lack of habitat choice in this passively dispersed fungus may prevent fixation of alleles controlling host specialization. [ABSTRACT FROM AUTHOR]

Ampelomyces quisqualis is a mycoparasite of a diverse range of phytopathogenic fungi associated with the powdery mildew disease. Among them are several Erysiphaceae species with great economic impact on high-value crops such as grape. Due to its ability to parasitize and prevent the spread of powdery mildews, A. quisqualis has received considerable attention for its biocontrol potential. However, and in sharp contrast to the extensively studied biocontrol species belonging to the genus Trichoderma, little is known about the biology of A. quisqualis at the molecular and genetic levels. We present the first genome-wide transcription profiling in A. quisqualis during host-induced germination. A total of 1,536 putative genes showed significant changes in transcription during the germination of A. quisqualis. This finding denotes an extensive transcriptional reprogramming of A. quisqualis induced by the presence of the host. Several upregulated genes were predicted to encode for putative mycoparasitism-related proteins such as secreted proteases, virulence factors, and proteins related to toxin biosynthesis. Our data provide the most comprehensive sequence resource currently available for A. quisqualis in addition to offering valuable insights into the biology of A. quisqualis and its mycoparasitic lifestyle. Eventually, this may improve the biocontrol capacity of this mycoparasite. [ABSTRACT FROM AUTHOR]

The plant pathogenic rust fungi colonize leaf tissue and feed off their host plants without killing them. Certain economically important species of different genera such as Melampsora, Phakopsora, Puccinia, or Uromyces are extensively studied for resolving the mechanisms of the obligate biotrophy. As obligate parasites rust fungi only can complete their life cycle on living hosts where they grow through the leaf tissue by developing an extended network of intercellular hyphae from which intracellular haustoria are differentiated. Haustoria are involved in key functions of the obligate biotrophic lifestyle: suppressing host defense responses and acquiring nutrients. This review provides a survey of rust fungi nitrogen nutrition with special emphasis on amino acid uptake. A variety of sequences of amino acid transporter genes of rust fungi have been published; however, transport activity of only three in planta highly up-regulated amino acid permeases have been characterized. Functional and immunohistochemical investigations have shown the specificity and localization of these transporters. Sequence data of various genome projects allowed identification of numerous rust amino acid transporter genes. An in silico analysis reveals that these genes can be classified into different transporter families. In addition, genetic and molecular data of amino acid transporters have provided new insights in the corresponding metabolic pathways. [ABSTRACT FROM AUTHOR]

The lavendin (Lavandula hybrida Reverchon) and the lavender (Lavandula officinalis Chaix ex Villars) are used in the pharmaceutical, cosmetic, and veterinary industries. The lavendin is the species with the most extended production area for its high yield of good quality essential oil and dried flowers. In 2012, in the south of Buenos Aires province (Argentina), L.hybrida plants with dark and necrotic lesions on leaves and stems, with death of the most affected plants, were observed in the field. This problem justified the present study to identify the cause of the damage observed. Segments of symptomatic tissues of twenty plants, chosen from a total of forty plants examined, were disinfected and placed into Petri dishes with potato dextrose agar (APG 2%). Fungal colonies developed on all the tissue segments.The isolates were identified as Phomopsis lavandulae (Gabotto) Cif. & Vegni), Fusarium oxysporum Schltdl, Selenophoma Maire, and Pestalotiopsis maculans (Corda) Nag Raj.Pathogenecity of each fungus was separately examined by inoculating leaves and stem of ten healthy plants with the fungal suspension using a hypodermic syringe; the control was inoculated with sterile distilled water. This material was cultured in Petri dishes with PGA. In this test, only the material inoculated with Selenophom reproduced the symptoms observed in the field. Between 24-48 h after inoculation, all the tissues developed browning and necrosis. The pathogen was then reisolated from leaves and stems fulfilling Koch's postulates. The controls remained symptomless. This is the first report of Selenophoma as the causal agent of browning and necrosis in Lavandula hybrida in Argentina. [ABSTRACT FROM AUTHOR]

Lasiodiplodia theobromae is the causal agent of numerous plant diseases in a wide variety of hosts. Fruit and vegetable crops are particularly susceptible to infection by this fungus. Although in Mexico, L. theobromae is associated with dieback and fruit rot in fruits such as mango, grapes, papaya, rambutan, sapote mamey and citrus fruit, the number of reports of this fungus related to diseases in different plant species is still few. The taxonomy of L. theobromae has shown important progress, with the characterization of the intergenic spacer regions and the elongation factor 1 alpha, phylogenetic location and cryptic species differentiation have been clarified and an increase of reports in new plant hosts has been made. Thus, the objective of this review is to present the status of L. theobromae in Mexico. [ABSTRACT FROM AUTHOR]

For plant pathogenic fungi, such as powdery mildews, that survive only on a limited number of host plant species, it is a matter of vital importance that their spores sense that they landed on the right spot to initiate germination as quickly as possible. We investigated a barley (Hordeum vulgare) mutant with reduced epicuticular leaf waxes on which spores of adapted and nonadapted powdery mildew fungi showed reduced germination. The barley gene responsible for the mutant wax phenotype was cloned in a forward genetic screen and identified to encode a 3-KETOACYL-CoA SYNTHASE (HvKCS6), a protein participating in fatty acid elongation and required for synthesis of epicuticular waxes. Gas chromatography-mass spectrometry analysis revealed that the mutant has significantly fewer aliphatic wax constituents with a chain length above C-24. Complementation of the mutant restored wild-type wax and overcame germination penalty, indicating that wax constituents less present on the mutant are a crucial clue for spore germination. Investigation of Arabidopsis (Arabidopsis thaliana) transgenic plants with sense silencing of Arabidopsis REQUIRED FOR CUTICULAR WAX PRODUCTION1, the HvKCS6 ortholog, revealed the same germination phenotype against adapted and nonadapted powdery mildew fungi. Our findings hint to an evolutionary conserved mechanism for sensing of plant surfaces among distantly related powdery mildews that is based on KCS6-derived wax components. Perception of such a signal must have been evolved before the monocot-dicot split took place approximately 150 million years ago. [ABSTRACT FROM AUTHOR]

Puccinia psidii has long been considered a significant threat to Australian plant industries and ecosystems. In April 2010, P. psidii was detected for the first time in Australia on the central coast of New South Wales (NSW). The fungus spread rapidly along the east coast and in December 2010 was found in Queensland (Qld) followed by Victoria a year later. Puccinia psidii was initially restricted to the southeastern part of Qld but spread as far north as Mossman. In Qld, 48 species of Myrtaceae are considered highly or extremely susceptible to the disease. The impact of P. psidii on individual trees and shrubs has ranged from minor leaf spots, foliage, stem and branch dieback to reduced fecundity. Tree death, as a result of repeated infection, has been recorded for Rhodomyrtus psidioides. Rust infection has also been recorded on flower buds, flowers and fruits of 28 host species. Morphological and molecular characteristics were used to confirm the identification of P. psidii from a range of Myrtaceae in Qld and compared with isolates from NSW and overseas. A reconstructed phylogeny based on the LSU and SSU regions of rDNA did not resolve the familial placement of P. psidii, but indicated that it does not belong to the Pucciniaceae. Uredo rangelii was found to be con-specific with all isolates of P. psidii in morphology, ITS and LSU sequence data, and host range. [ABSTRACT FROM AUTHOR]

In Japan, since black root rot of cucurbitaceous crops was found more than 30 years ago, the disease has caused severe economic losses to the cucurbit crop industry. Subsequent to the pathogen being correctly identified as Diaporthe sclerotioides based on morphology and DNA sequence, knowledge about DNA sequences has developed making technical tools to detect and quantify the pathogen in natural samples of plants and soils available. In addition to chemical soil disinfectants, solarization and biological soil disinfestation have been developed as environment-friendly methods to effectively control this disease. Although it is difficult to apply such temperature-dependent methods in open-fields especially under cool climate conditions, an alternative approach, which changes soil pH to weak alkaline with amending steel converter slag, has also proved effective against the disease. In this mini-review, the process of D. sclerotioides identification, detection and quantification methods developed for this fungus, host specificity, and disease control measures available and practiced in Japan are discussed concisely. [ABSTRACT FROM AUTHOR]

Ensuring a sustainable yield is essential for continued survival of a natural resource, however over-exploitation can easily occur. Therefore, understanding how increasing the harvesting rate affects the yield is vital. Harvesting of infected hosts in a host-pathogen system, for example the fungal pathogen Cordyceps sinensis which is harvested for medicinal use, has not been explored mathematically in the literature. We present a generalized host-pathogen model in which the infected host is harvested. Two strategies are explored; proportional harvesting at a constant rate and in an open-closed setting (a repeating cycle of a period of harvest followed by a period where the resource is left to recover). We present yield-effort curves for both strategies and find that open-closed harvesting affects the traditional yield-effort curve, with the system able to support a greater range of harvesting rates. Furthermore, host-pathogen systems may exhibit more complex population dynamics than single equation/species models, depending on the eigenvalues of the linearised system. In the open-closed setting we find that if there are complex eigenvalues in the absence of harvesting although small changes in the length of open season have little impact on the maximum sustainable yield, it can dramatically change the harvesting rate needed to achieve this. For proportional harvesting in a constant setting our model shows that if there are real eigenvalues in the absence of harvesting, then resilience-harvest relationship agrees with accepted theory, where as yield initially increases so too does the return time (a measure of the long-term resilience). However, when there are complex eigenvalues we see, counter to intuition, that the return time initially decreases whilst still providing increased yield. We also study the transient (short-term) reactivity, which shows that in both cases harvesting can initially decrease the reactivity. These results show that harvesting can in some instances enhance the ability of host-pathogen systems to respond to perturbations in both the short- and long-term. [ABSTRACT FROM AUTHOR]

The basidiomycete smut fungus Ustilago hordei was previously shown to comprise isolates that are avirulent on various barley host cultivars. Through genetic crosses we had revealed that a dominant avirulence locus UhAvr1 which triggers immunity in barley cultivar Hannchen harboring resistance gene Ruh1, resided within an 80-kb region. DNA sequence analysis of this genetically delimited region uncovered the presence of 7 candidate secreted effector proteins. Sequence comparison of their coding sequences among virulent and avirulent parental and field isolates could not distinguish UhAvr1 candidates. Systematic deletion and complementation analyses revealed that UhAvr1 is UHOR_10022 which codes for a small effector protein of 171 amino acids with a predicted 19 amino acid signal peptide. Virulence in the parental isolate is caused by the insertion of a fragment of 5.5 kb with similarity to a common U. hordei transposable element (TE), interrupting the promoter of UhAvr1 and thereby changing expression and hence recognition of UhAVR1p. This rearrangement is likely caused by activities of TEs and variation is seen among isolates. Using GFP-chimeric constructs we show that UhAvr1 is induced only in mated dikaryotic hyphae upon sensing and infecting barley coleoptile cells. When infecting Hannchen, UhAVR1p causes local callose deposition and the production of reactive oxygen species and necrosis indicative of the immune response. UhAvr1 does not contribute significantly to overall virulence. UhAvr1 is located in a cluster of ten effectors with several paralogs and over 50% of TEs. This cluster is syntenous with clusters in closely-related U. maydis and Sporisorium reilianum. In these corn-infecting species, these clusters harbor however more and further diversified homologous effector families but very few TEs. This increased variability may have resulted from past selection pressure by resistance genes since U. maydis is not known to trigger immunity in its corn host. [ABSTRACT FROM AUTHOR]

Studies on the use of Pochonia chlamydosporia isolates as biological control agents of root-knot nematodes (RKN, Meloidogyne spp.), showed that their efficacy relies on selected key factors such as fungal proliferation in soil, establishment in the rhizosphere, and ability to parasitize RKN eggs. A pot experiment was conducted to evaluate the performance of a Portuguese P. chlamydosporia isolate (Pc2) and of a non-native isolate (Pc10) against M. chitwoodi in a potato-maize-potato-potato crop rotation. The growth of P. chlamydosporia in soil and roots was monitored throughout the experiment by assessing the numbers of colony forming units (cfu). The prevalence in M. chitwoodi eggs and nematode reproduction was measured at the end of each crop. The cfu/g of soil varied over time and was particularly low for both isolates during the spring and summer 2009, when temperatures above 30ºC were registered. Native isolate Pc2 was more effective in establishing in soil than Pc10. Growth and survival of the fungus did not seem to depend on the presence of nematode or host plant species. Establishment of P. chlamydosporia in soil was slow and was only achieved after the full cropping sequence. The two P. chlamydosporia isolates revealed subtle differences in host preference, plant compatibility, or tolerance to abiotic conditions that may affect their efficacy as biocontrol agents in a long-lasting management programme. [ABSTRACT FROM AUTHOR]

Potato plants can be colonized by various viruses and by symbiotic, saprophytic and pathogenic fungi. However, the significance of interactions of viral infection and fungal colonization is hardly known. This work presents a model experiment in which the influence of three different types of fungal associations on the growth and physiology of the potato variety Pirol was tested individually or in combination with infection by PVY. It was hypothesized that simultaneous viral and fungal infections increase the biotic stress of the host plant, but mutualistic plant-fungal associations can mask the impact of viral infection. In the present study, a symbiotic arbsucular mycorrhizal fungus, Glomus intraradices, significantly stimulated the growth of plants infected with PVY. In contrast, two saprophytic Trichoderma spp. strains either did not influence or even inhibited the growth of PVY-infected plants. Also, inoculation of PVY-infected potato plants with a pathogenic strain of Colletotrichum coccodes did not inhibit the plant growth. Growth of the PVY-free potato plants was not promoted by the symbiotic fungus, whereas T. viride, T. harzianum and C. coccodes had an evident inhibitory effect. The strongest growth inhibition and highest concentration of H2O2, as an indicator of biotic stress, was observed in PVY-free potato plants inoculated with T. harzianum and C. coccodes strains. Surprisingly, ultrastructural analysis of PVY-infected plant roots colonized by G. intraradices showed virus-like structures in the arbuscules. This pointed to the possibility of mycorrhizal-mediated transmission of virus particles and has to be further examined by testing with immunoassays and real transmission to uninfected plants. In conclusion, although mycorrhiza formation might decrease the impact of PVY infection on plants, a possible role of mycorrhizal fungi as virus vectors is discussed. [ABSTRACT FROM AUTHOR]

Adopting the currently used concept for the genus Peltaster, the sooty blotch fungus Peltaster cerophilus is newly described from the cuticle of ripening or ripe apples. It forms a punctate phenotype consisting of superficially formed pycnothyria and a superficial mycelial mat consisting of a net of brown or brownish black hyphae. The pycnothyria are olivaceous brown to brown but have a spot in the center that is less strongly pigmented. Pycnothyria on the holotype of P. fructicola are homogeneously pigmented. On synthetic nutrient-poor agar, P. cerophilus is largely indistinguishable from P. fructicola. It forms delicate, spreading hyphae and intercalary conidiogenous cells with short, lateral, apically thick-walled conidiogenous necks forming blastic, unpigmented, one-celled conidia in basipetal succession. Conidia can swell and become one-septate. The species has microcyclical conidiation in proximate parts of colonies. DNA sequence analyses based on the ITS and the partial nuclear small and large subunit ribosomal RNA genes, the partial mitochondrial small subunit rRNA gene and the partial translation elongation factor 1-α gene support the distinction of the European P. cerophilus from P. fructicola, which is known from North America and Europe. The nuclear small ribosomal RNA subunit gene sequences of P. cerophilus contain two group I introns at locations known to accommodate introns in certain other, unrelated taxa. One of these, for which the code "SSU-1506 intron" was adopted, is 1459 base pairs long and located between the universal primer sites ITS5 and ITS1. Similar or positional-differing introns were encountered also in three currently undescribed Peltaster species. Representative strains of Peltaster fructicola did not accommodate introns in the nuclear small subunit ribosomal RNA gene. [ABSTRACT FROM AUTHOR]

The generally positive relationship between biodiversity of groups of directly or indirectly interacting organisms is one of the most important ecological concepts (Gaston, 2000 Nature, 405, 220-227; Scherber C, Eisenhauer N, Weisser WW et al., 2010 Nature, 468, 553-556). In a recent issue of Molecular Ecology, Gao C, Shi N-N, Liu Y-X et al. (2013: 22, 3403-3414) reported that the richness of plants and ectomycorrhizal fungi is positively correlated both at local and at global scales. Here, we challenge these findings by re-analysis of data and ascribe the reported results to sampling effect and poor data compilation. [ABSTRACT FROM AUTHOR]

Exploring the relationships between the biodiversity of groups of interacting organisms yields insight into ecosystem stability and function (Hooper et al. ; Wardle ). We demonstrated positive relationships between host plant richness and ectomycorrhizal ( EM) fungal diversity both in a field study in subtropical China (Gutianshan) and in a meta-analysis of temperate and tropical studies (Gao et al. ). However, based on re-evaluation of our data sets, Tedersoo et al. () argue that the observed positive correlation between EM fungal richness and EM plant richness at Gutianshan and also in our metastudies was based mainly from (i) a sampling design with inconsistent species pool and (ii) poor data compilation for the meta-analysis. Accordingly, we checked our data sets and repeated the analysis performed by Tedersoo et al. (). In contrast to Tedersoo et al. (), our re-analysis still confirms a positive effect of plant richness on EM fungal diversity in Gutianshan, temperate and tropical ecosystems, respectively. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) symbiosis confers numerous benefits to host plants, including improved plant growth and nutrient acquisition efficiency. An experiment was conducted to evaluate the effect of AM fungi {Glomus intraradices and G. mosseae) in the presence of humic acid (HA) spray treatments (0, 100, 400, and 1000 mgL-1) on nutrient (N, P, K, Fe, and Zn) uptake, visual quality and chlorophyll content, root growth and architecture, and colonization of perennial ryegrass {Lolium perenne L.) Speedygreen mixture. The results revealed that HA did not affect plant growth significantly; instead arbuscular mycorrhizal fungal (AMF) colonization improved dry and fresh weights. Mycorrhizal inoculations significantly increased visual quality (13 and 15% in inoculated plants compared to non-inoculated ones) that might be at least partly due to elevated total chlorophyll content. The AM inoculation and HA treatment resulted in improved root architecture rather than root biomass production. Neither HA treatments nor mycorrhizal inoculation affected N and Fe contents of the leaves; however P, K, and Zn concentrations improved by AM inoculation. More roots were colonized by G. intraradices than by G. mosseae. These results suggest that AM inoculation is beneficial in enhancing uptake of some nutrients and root development of ryegrass possibly leading to less fertilizer input and more drought resistance. [ABSTRACT FROM AUTHOR]

Soybean rust, caused by the fungus Phakopsora pachyrhizi, is an economically important disease of soybean with potential to cause severe epidemics resulting in significant yield losses. Host resistance is one of the management tools to control this disease. This study compared soybean genotypes exhibiting immunity, complete and incomplete resistance. and susceptibility to an isolate of P. pachyrhizi based on visual assessment of reaction type, other visual traits such as sporulation, quantitative measurements of the amount of fungal DNA (FDNA) present in leaf tissues, and data on infection and colonization levels. Soybean genotype UG5 (immune), and plant introduction (PI) 567102B and PI 567104B (complete resistance) had lower quantities of uredinia and FDNA than tour other genotypes with incomplete resistance. Based on microscopic observations, early events of spore germination, appressorium formation, and fungal penetration of the epidermis occurred within 24 h postinoculation and were similar among the tested soybean genotypes. Differences in infection among the genotypes were evident once the hyphae penetrated into the intercellular spaces between the mesophyll cells. At 2 days after inoculation (dai), soybean genotype Williams 82 had a significantly (P < 0.05) higher percentage of hyphae in the mesophyll tissue than other soybean genotypes, with UG5 having significantly (P < 0.05) lower percentages than all of the other soybean genotypes at 3, 4, and 5 dai. The percentage of interaction sites with mesophyll cell death was significantly (P < 0.05) higher in UG5 than other genotypes at 3, 4, and 5 dai. There was a significant positive correlation (r = 0.30, P < 0.001) between quantities of hyphae in the mesophyll cells and FDNA. These results demonstrated that incompatible soybean-P, pachyrhizi interaction results in restricted hyphal development in mesophyll cell tissue, likely due to hypersensitive apoptosis. [ABSTRACT FROM AUTHOR]

The fungus Phytophthora parasitica Dast., produces crown and root rot and has a wide circle of host plants, mostly horticultural crops. The fungus once installed can cause significant damage, leading even to the point of crop loss. Although this fungus has been described in earlier works, it has not been reported in recent years, but the climatic conditions of the year 2014 were favorable to the appearance and evolution of the micromycetes in the Pythiaceae family. In the last decade the pathogen Phytophthora parasitica Dast. Has been reported only sporadically. Also the increase in imports of horticultural material in the past few years favors the risk of transmission and spread of the fungus. In the crops of Petunia hybrida Hort. from the Municipality Greenhouses of Iasi and the Botanical Garden of Iasi, in the month of April 2014, there have been established a number of plants attacked by the pathogen agent Phytophthora parasitica Dast. Within this paper observations were made both in the field and in the laboratory. Measurements were made based on the symptoms of attack, the fungal morphological characters and the reference monographs. [ABSTRACT FROM AUTHOR]

The mutualistic symbiont Piriformospora indica exhibits a great potential in agriculture. The interaction between P. indica and Chinese cabbage (Brassica campestris cv. Chinensis) results in growth and biomass promotion of the host plant and in particular in root hair development. The resulting highly bushy root phenotype of colonized Chinese cabbage seedlings differs substantially from reports of other plant species, which prompted the more detailed study of this symbiosis. A large-scale expressed sequence tag (EST) data set was obtained from a double-subtractive EST library, by subtracting the cDNAs of Chinese cabbage root tissue and of P. indica mycelium from those of P. indica-colonized root tissue. The analysis revealed ~700 unique genes rooted in 141 clusters and 559 singles. A total of 66% of the sequences could be annotated in the NCBI GenBank. Genes which are stimulated by P. indica are involved in various types of transport, carbohydrate metabolism, auxin signalling, cell wall metabolism, and root development, including the root hair-forming phosphoinositide phosphatase 4. For 20 key genes, induction by fungal colonization was confirmed kinetically during the interaction by real-time reverse transcription–PCR. Moreover, the auxin concentration increases transiently after exposure of the roots to P. indica. Microscopic analyses demonstrated that the development of the root maturation zone is the major target of P. indica in Chinese cabbage. Taken together, the symbiotic interaction between Chinese cabbage and P. indica is a novel model to study root growth promotion which, in turn, is important for agriculture and plant biotechnology. [ABSTRACT FROM AUTHOR]

The article discusses decrease in reproduction of plant-parasitic nematode Radopholus simili by the fungi Rhizophagus irregularis MUCL 41833 in the banana cultivar Yangambi km 5 dessert banana. It mentions that Rhizophagus irregularis MUCL 41833 forms a symbiotic relation with banana plants. It informs that the fungi provides nutrition to banana plants and on the other hand decreases nematode infestation.

Burgundy truffles ( Tuber aestivum syn. Tuber uncinatum) are the highly prized fruit bodies of subterranean fungi always occurring in ectomycorrhizal symbiosis with host plants. Successful cultivation can be achieved through artificial mycorrhization and outplanting of mostly oaks and hazel on suitable terrain. Here, we review ecological requirements, the influence of environmental factors, and the importance of molecular techniques for a successful cultivation of T. aestivum across Europe. The historical background and current knowledge of T. aestivum cultivation are discussed in light of its socioeconomic relevance. [ABSTRACT FROM AUTHOR]