1,721,072 research outputs found
Colletotrichum species and complexes: geographic distribution, host range and conservation status
Full text linkThe taxonomy of the genus Colletotrichum has undergone tremendous changes over the last decade, with over 200 species being currently recognised and species complexes being informally used to cluster those species. Many of these species are important plant pathogens, some rather polyphagous and others host-specific, but several occur seldomly and some may in fact be ecologically endangered. Based mainly on literature from the past decade, in this work we review the occurrence, geographic distribution and host spectrum of currently recognised Colletotrichum species under phylogenetic, pathological/agronomic and ecological perspectives, providing a list arranged by Colletotrichum species and species complexes. A total of 257 species are listed and grouped into 15 species complexes. In this work we have recorded 1353 unique host species-Colletotrichum species association records from 720 hosts, with the Fabaceae as the family with higher number of hosts (52 host species) but with the Rosaceae as the family with the highest number of host species-Colletotrichum species association records (118 association records). According to occurrence data, 88 species are common in nature, 128 were considered as data deficient and 41 are threatened, some of which are likely extinct from nature and preserved only in culture collections. Several species are relevant plant pathogens, in some cases geographically confined and thus of potential quarantine relevance. Based on the major changes that occurred on Colletotrichum taxonomy over the last decade, this work provides a comprehensive overview of occurrence data of Colletotrichum species, compiling host range and geographical distribution, with relevance for plant pathology and conservation mycology. The current taxonomic framework in Colletotrichum is revealing numerous species but poses challenges to the employment of standard criteria for the evaluation of biological conservation of these fungi. We advocate that conservation mycology and taxonomy should find common routes simultaneously enabling the correct delimitation of species of Colletotrichum and the implementation of feasible criteria for the evaluation of conservation. The employment of new technologies, such whole genome sequencing (WGS), will help and support the description of new species and to gain a better understanding of the genetic bases of speciation processes
Crotti P., Fiorini L., Ferraboli S., Baroncelli R., Sarrocco S., Vannacci G., Gobbi E. (2016) Velvet Complex and Gliotoxin Biosynthesis in Trichoderma afro-harzianum T6776.
No full textAnthracnose of lupins caused by Colletotrichum lupini: A recent disease and a successful worldwide pathogen
No full textLupins are grain legume crops cultivated in several parts of the world, with important roles in the agricultural and natural ecosystems. Recently lupin breeding faced a new and important challenge, a destructive seed- and airborne disease affecting stems and pods, named anthracnose. The current disease outbreak began in the 1980s and rapidly spread worldwide, affecting apparently all lupin species. The pathogen belongs to Colletotrichum lupini, a member of the acutatum species complex, and contrasts with other members of the latter by its host specificity and by its apparent clonality. However, in a matter of a few decades this pathogen managed to cause severe epidemics in lupin crops from diverse species (both of Mediterranean and North and South American origins) throughout the world, whether in humid or in dry climates, frequently causing high yield losses and in many cases leading farmers to replace lupin with other crops. Although several lupin crops rely on rich genetic resources, it proved very difficult to find effective resistance sources. Recent successes in this matter (backed by advances in genome sequencing of some lupin species) are still conditioned by the very narrow range of resistance genes available for breeders, risking a possible overcoming of such resistances if the pathogen finds itself means to create diversity that enables it to overcome resistance. To this end, advances in Colletotrichum genomics, with the forthcoming sequencing of the genome of C. lupini, are of great importance to understand the genetic nature of C. lupini host specificity and reproduction strategies
Genome resources for the endophytic fungus paraphaeosphaeria sporulosa
Full text linkParaphaeosphaeria genus includes plant pathogens or biocontrol agents as well as bioremediators and endophytic fungi. Paraphaeosphaeria sporulosa 10515 was isolated in 2013 as an endophyte of Festuca spp. collected on Mount Etna at 1,832 meters above sea level. Here, we present the first-draft whole-genome sequence of a P. sporulosa endophytic isolate. This data will be useful for future research on understanding the genetic bases of endophytism
IPE and the study of global crises: making sense of complexity in dire times
No full textTo map relevant themes, problems and approaches to the study of system-wide economic turning points, this chapter adopts a backwards timeline, first discussing how the main political actors have responded to the crisis of 2007-2008. Attention is particularly placed on actors, sectors, behaviour and policies (who, what), across governance levels (where, domestic-supra-international), causal mechanism (why) and time (when). The focus is then moved to outcomes and, particularly, logics that have informed political responses at the international level. Elaborating on the link between the (relative degree of) global coordination and post-crisis systemic persistence, the chapter critically reviews the main IPE, CPE and economic academic contributions on the topic, raising the issue of crisis’ endogeneity, on both epistemological and policy grounds. Building on the conceptualization of crises as endogenous variables, the analysis is then moved back in time to the micro- and macro-foundational paths that those literatures have elaborated upon to explain the origins of the 2007-08 crisis and its subsequent developments, during the Great recession. Connecting political causes and responses, the chapter deepens the focus on short and long run priors, first, and political actions-outcomes, then, in two selected cases in US policy (the anti-cyclical response of the US administrations in several macroeconomic and financial policies, respectively, between 2008 and 2013) . The two short probes are used to shed light on the relative goodness of ‘boom-bust’ models advanced in economic, IPE and CPE literatures to study responses to global crises. Discussing the post-crisis missing run against the US dollar, a notable case of non-response to the recent global shock, the analysis further problematizes the exceptionality narrative. Country and region-specific factors (Eurozone weakness, strategic and security priorities of major Emerging Market Economies- hereinafter EMEs), as well as system-wide dynamics (network and node properties of US, European and EMEs financial markets) have concurred to explain the enduring centrality of the US dollar, strengthening the case for methodological pluralism and inter-disciplinary approaches to the study of global crises. To conclude, the chapter indicates where cross-fertilization may bring further progress in the study of coordinated responses to the 2008 crisis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Management of Post-Harvest Anthracnose: Current Approaches and Future Perspectives
Full text linkAnthracnose is a severe disease caused by Colletotrichum spp. on several crop species. Fungal infections can occur both in the field and at the post-harvest stage causing severe lesions on fruits and economic losses. Physical treatments and synthetic fungicides have traditionally been the preferred means to control anthracnose adverse effects; however, the urgent need to decrease the use of toxic chemicals led to the investigation of innovative and sustainable protection techniques. Evidence for the efficacy of biological agents and vegetal derivates has been reported; however, their introduction into actual crop protection strategies requires the solutions of several critical issues. Biotechnology-based approaches have also been explored, revealing the opportunity to develop innovative and safe methods for anthracnose management through genome editing and RNA interference technologies. Nevertheless, besides the number of advantages related to their use, e.g., the putative absence of adverse effects due to their high specificity, a number of aspects remain to be clarified to enable their introduction into Integrated Pest Management (IPM) protocols against Colletotrichum spp. disease
Insights on KP4 Killer Toxin-like Proteins of Fusarium Species in Interspecific Interactions
Full text linkKP4 killer toxins are secreted proteins that inhibit cell growth and induce cell death in target organisms. In Fusarium graminearum, KP4-like (KP4L) proteins contribute to fungal virulence in wheat seedling rot and are expressed during Fusarium head blight development. However, fungal KP4L proteins are also hypothesized to support fungal antagonism by permeabilizing cell walls of competing fungi to enable penetration of toxic compounds. Here, we report the differential expression patterns of F. graminearum KP4L genes (Fgkp4l-1, -2, -3 and -4) in a competitive interaction, using Trichoderma gamsii as the antagonist. The results from dual cultures indicate that Fgkp4l-3 and Fgkp4l-4 could participate in the recognition at the distance of the antagonist, while all Fgkp4l genes were highly activated in the pathogen during the physical interaction of both fungi. Only Fgkp4l-4 was up-regulated during the interaction with T. gamsii in wheat spikes. This suggests the KP4L proteins could participate in supporting F. graminearum interspecific interactions, even in living plant tissues. The distribution of KP4L orthologous within the genus Fusarium revealed they are more represented in species with broad host-plant range than in host-specific species. Phylogeny inferred provides evidence that KP4L genes evolved through gene duplications, gene loss and sequence diversification in the genus Fusarium
Alternaria species causing pomegranate and citrus fruit rots in Albania
Full text linkThe fungal genus Alternaria is a relevant pathogen for several commodities including citrus and pomegranate fruits. On citrus, it mainly causes brown spots on fruits and leaves, whereas on pomegranate, it mostly causes a fruit heart rot. In the present study the presence of Alternaria rots on citrus and pomegranate fruits cultivated in Albania was assessed. Representative fruits were collected from different regions. Nineteen and thirteen Alternaria spp. isolates were obtained from pomegranate and citrus samples, respectively. The isolates were identified at species and morphotype level. Micro and macroscopic features separated isolates into four morphotypes. BLAST and phylogenetic analysis using the SCAR Marker OPA1-3 confirmed the isolate identity. All 32 isolates proved to be Alternaria alternata and belonged mainly to morphotype alternata, followed by limoniasperae and tenuissima. All Alternaria strains proved to possess the pksI gene of alternariol biosynthesis. Citrus isolates were tested for the presence of genes of the biosynthesis of the phytotoxins ACT and ACR, but none of them proved to possess them. Concluding, Alternaria spp. might represent a treat to pomegranate and citrus production in Albania, and thus effective control means are needed
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