Browsing by Author "Guarnaccia, Vladimiro"

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    High diversity of Diaporthe species associated with dieback diseases in China, with twelve new species described
    (Pensoft Publishers, 2018-09-17) Yang, Qin; Fan, Xin-Lei; Guarnaccia, Vladimiro; Tian, Cheng-Ming
    Diaporthe species have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although several Diaporthe species have been recorded in China, little is known about species able to infect forest trees. Therefore, extensive surveys were recently conducted in Beijing, Heilongjiang, Jiangsu, Jiangxi, Shaanxi and Zhejiang Provinces. The current results emphasised on 15 species from 42 representative isolates involving 16 host genera using comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions, as well as their morphological features. Three known species, D. biguttulata, D. eres and D. unshiuensis, were identified. In addition, twelve novel taxa were collected and are described as D. acerigena, D. alangii, D. betulina, D. caryae, D. cercidis, D. chensiensis, D. cinnamomi, D. conica, D. fraxinicola, D. kadsurae, D. padina and D. ukurunduensis. The current study improves the understanding of species causing diebacks on ecological and economic forest trees and provides useful information for the effective disease management of these hosts in China.
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    Liberomyces pistaciae sp. nov., the causal agent of pistachio cankers and decline in Italy
    (Pensoft Publishers, 2018) Vitale, Salvatore; Aiello, Dalia; Guarnaccia, Vladimiro; Luongo, Laura; Galli, Massimo; Crous, Pedro W.; Polizzi, Giancarlo; Belisario, Alessandra; Voglmayr, Hermann
    A new canker and decline disease of pistachio (Pistacia vera) is described from Sicily (Italy). Observations of the disease and sampling of the causal agent started in spring 2010, in the area where this crop is typically cultivated, Bronte and Adrano (Catania province) and later extended to the Agrigento and Caltanissetta provinces. Isolations from the margins of twig, branch and stem cankers of declining plants resulted in fungal colonies with the same morphology. Pathogenicity tests on 5-year-old potted plants of Pistacia vera grafted on P. terebinthus reproduced similar symptoms to those observed in nature and the pathogen was confirmed to be a coloniser of woody plant tissue. Comparison of our isolates with the type of the apparently similar Asteromella pistaciarum showed that our isolates are morphologically and ecologically different from A. pistaciarum, the latter being a typical member of Mycosphaerellaceae. Asteromella pistaciarum is lectotypified, described and illustrated and it is considered to represent a spermatial morph of Septoria pistaciarum. Multi-locus phylogenies based on two (ITS and LSU rDNA) and three (ITS, rpb2 and tub2) genomic loci revealed isolates of the canker pathogen to represent a new species of Liberomyces within the Delonicicolaceae (Xylariales), which is here described as Liberomyces pistaciae sp. nov. (Delonicicolaceae, Xylariales). The presence of this fungus in asymptomatic plants with apparently healthy woody tissues indicates that it also has a latent growth phase. This study improves the understanding of pistachio decline, but further studies are needed for planning effective disease management strategies and ensuring that the pathogen is not introduced into new areas with apparently healthy, but infected plants.
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    Phyllosticta citricarpa and sister species of global importance to Citrus
    (British Society for Plant Pathology, 2020) Guarnaccia, Vladimiro; Gehrmann, Thies; Silva-Junior, Geraldo J.; Fourie, Paul H.; Haridas, Sajeet; Vu, Duong; Spatafora, Joseph; Martin, Francis M.; Robert, Vincent; Grigoriev, Igor V.; Groenewald, Johannes Z.; Crous, Pedro W.
    Several Phyllosticta species are known as pathogens of Citrus spp., and are responsible for various disease symptoms including leaf and fruit spots. One of the most important species is P. citricarpa, which causes a foliar and fruit disease called citrus black spot. The Phyllosticta species occurring on citrus can most effectively be distinguished from P. citricarpa by means of multilocus DNA sequence data. Recent studies also demonstrated P. citricarpa to be heterothallic, and reported successful mating in the laboratory. Since the domestication of citrus, different clones of P. citricarpa have escaped Asia to other continents via trade routes, with obvious disease management consequences. This pathogen profile represents a comprehensive literature review of this pathogen and allied taxa associated with citrus, focusing on identification, distribution, genomics, epidemiology and disease management. This review also considers the knowledge emerging from seven genomes of Phyllosticta spp., demonstrating unknown aspects of these species, including their mating behaviour.
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    Species of Diaporthe on Camellia and Citrus in the Azores Islands
    (Firenze University Press, 2018) Guarnaccia, Vladimiro; Crous, Pedro W.
    Species of Diaporthe are important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Species such as D. citri are well-known on Citrus, as agents of pre- or post-harvest infections, causing dieback, melanose and stem-end rot on fruit. In this study we explored the occurrence and diversity of Diaporthe associated with tropical and sub-tropical plants. In particular, species of Camellia and Citrus were sampled. Surveys were carried out during 2017 in the Azores Islands, Portugal. Ten Diaporthe strains were isolated from symptomatic twigs and leaves. Five representative isolates were subjected to morphological characterization and multi-locus phylogeny based on five genomic loci (ITS, tef1, cal, his3 and tub2). Diaporthe citri was found associated with shoot blight on Citrus reticulata, which represents a new record for Europe. A new species, Diaporthe portugallica sp. nov. was isolated and described from leaf spots on Camellia sinensis.