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Grapevine trunk diseases cause substantial economic loss worldwide. Grapevines are susceptible to infection by the causal agents when pruning during dormancy coincides with rainfall. The ascospores of Eutypa lata, the causal agent of the trunk disease Eutypa dieback, are released by fruiting bodies following rainfall and infect fresh wounds in woody tissue. Wound-colonising microbes have the potential to compete with the pathogen but the effect on such microbes of exposure of wounds on grapevines to rainfall has not been investigated. The presence of microbes in grapevine pruning wounds, both exposed to and sheltered from rainfall, was investigated at weekly intervals for one month following pruning. Surface disinfected tissue was cultured and the predominant microbes identified by morphology and by Sanger sequencing. Epicoccum nigrum, Aureobasidium pullulans, Alternaria and Cladosporium spp. were the predominant fungi, E. lata was not isolated and bacteria were isolated only rarely. The number of microbes found in rainfall-exposed wounds was greater than in those protected from rainfall and, of the above-mentioned, Epicoccum nigrum was predominant. Three of these species competed for space with E. lata when co-cultured in vitro. [ABSTRACT FROM AUTHOR]

During a survey from 2004 to 2016, symptoms of grapevine dieback were observed in six vineyards in Serbia. Symptoms initially appeared as small, chlorotic, and necrotic spots along the rim of the leaves, deformation of leafs, and the appearance of shortened shoots, often with the so-called zigzag internodes. Over time, partial or complete dying of the vines developed. Symptomatic samples were collected and submitted to laboratory analysis. Based on the morphological characterization, the isolated fungus was initially identified as belonging to Eutypa species. Pathogenicity tests showed that 47 selected isolates caused tissue necrosis around the site of inoculation, chlorosis, and deformation of the leaves, along with the appearance of tiny, necrotic spots on the periphery of the leaf that fall off over time. Inoculated cuttings were stunted, dwarf-like with zigzag internodes. Molecular identification was done with sequence and phylogenetic analysis of ITS, TUB, and RPB2 genomic regions. Based on the phylogenetic analysis, all isolated fungi were determined as Eutypa lata. [ABSTRACT FROM AUTHOR]

Little is known about effects of salinity and flooding on plant symbionts, including baldcypress trees (Taxodium distichum), the dominant trees in many swamp ecosystems in the southeastern US. In this study, we characterize the culturable fungal and bacterial endophytes in the roots and leaves of baldcypress trees at four sites with varying levels of salinity and flooding regimes in southeastern Louisiana. Both salinity and flooding (water level) contributed to endophytic community composition of leaves and roots. We found that diversity and endophyte isolation frequency were higher in roots than in leaves, with leaf bacteria being almost negligible. Our study demonstrates a connection between environmental variables, plant symbionts, and a key restoration species. This work may help in predicting future outcomes of sea level rise for endophytes communities in baldcypress and other wetland plants. [ABSTRACT FROM AUTHOR]

Cell suspension cultures of Vitis vinifera cv. Dauphine berries were used to study the response to the vascular pathogen, Eutypa lata, in comparison with a biological control agent, Trichoderma atroviride, that was previously shown to be effective in pruning wound protection. The expression of genes coding for enzymes of the phenylpropanoid pathway and pathogenesis-related (PR) proteins was profiled over a 48-h period using quantitative reverse transcriptase PCR. The cell cultures responded to elicitors of both fungi with a hypersensitive-like response that lead to a decrease in cell viability. Similar genes were triggered by both the pathogen and biocontrol agent, but the timing patterns and magnitude of expression was dependent on the specific fungal elicitor. Culture filtrates of both fungi caused upregulation of phenylalanine ammonia-lyase ( PAL), 4-coumaroyl Co-A ligase ( CCo-A) and stilbene synthase ( STS), and a downregulation of chalcone synthase ( CHS) genes. The pathogen filtrate caused a biphasic pattern in the upregulation of PAL and STS genes which was not observed in cells treated with filtrates of the biocontrol agent. Analytical assays showed significantly higher total phenolic content and chitinolytic enzyme activity in the cell cultures treated with the T. atroviride filtrate compared to the pathogen filtrate. These results corresponded well to the higher expression of PAL and chitinase class IV genes. The response of the cell cultures to T. atroviride filtrate provides support for the notion that the wound protection by the biocontrol agent at least partially relies on the induction of grapevine resistance mechanisms. [ABSTRACT FROM AUTHOR]

Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during the spore events. [ABSTRACT FROM AUTHOR]

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Cross sections of woody stems of 309 diseased grapevines collected in France showed two kinds of necrosis typical of esca: a) A central light-colored necrosis of soft consistency, consisting of three zones, preceded by a centrally discolored wood, and b) a sectorial light-colored necrosis composed of two zones preceded by a sectorial brown necrosis. Isolations showed that different microflora was associated with each necrosis. Phaeoacremonium aleophilum and Phaeoacremonium chlamydosporum occurred in the discolored wood and the zones bordering the central decayed wood. Eutypa lata was the main fungus isolated from sectorial brown necrosis and the zones adjoining the decay wood. Phellinus punctatus was isolated from the sectorial and central decayed wood. Stereum hirsutum was present in decayed wood of 15 grapevines with esca symptoms not inhabited by P. punctatus. Wood decay tests and pathogenicity tests showed that S. hirsutum and P. punctatus were responsible for the decayed wood. Phaeoacremonium chlamydosporum and S. hirsutum produced a centrally discolored wood similar to that found in esca-affected vines. Phaeoacremonium aleophilum caused a sectorial brown necrosis of soft texture. From these studies, it was found that esca is a complex disease involving several microorganisms whose role in the process leading to wood degradation is discussed. [ABSTRACT FROM AUTHOR]