scholarly journals Inoculum Sources, Infection Periods, and Effects of Environmental Factors on Alternaria Brown Spot of Mandarin in Mediterranean Climate Conditions

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 409-417 ◽  
Author(s):  
D. D. M. Bassimba ◽  
J. L. Mira ◽  
A. Vicent
Keyword(s):  
Classification Tree ◽  
Disease Onset ◽  
Epidemiological Studies ◽  
Brown Spot ◽  
Morphological Identification ◽  
Weather Factors ◽  
Climate Conditions ◽  
Airborne Inoculum ◽  
Alternaria Brown Spot ◽  
Serious Disease

Alternaria brown spot (ABS), caused by Alternaria alternata, is a serious disease affecting mandarin in humid and in semi-arid regions. The information available from Florida cannot be easily extrapolated to Mediterranean regions; thus, epidemiological studies were conducted during two consecutive years in Spain. Pathogenic isolates were found in the canopy and leaf litter and on weeds of the genus Sonchus. The pathogen survived in fallen immature leaves for up to 76 days, until complete leaf decay. Conidia of Alternaria spp. were captured continuously and pathogenic isolates were detected in all sampling dates. However, the number of pathogenic isolates was not correlated with the total captured, indicating that morphological identification is not sufficient for airborne inoculum monitoring. In contrast to humid areas, infections occurred mainly in spring and autumn. Classification tree analysis indicated that virtually all infections occurred on weeks with rainfall ≥2.5 mm and average temperature ≥12.5°C. Based on regression quantiles, the amount of rainfall, number of rain days, and total wetness duration were considered important factors increasing ABS incidence during infection periods. The development of decision support systems for ABS control in Mediterranean conditions may benefit from the restricted periods of infection and the strong influence of weather factors in disease onset.

scholarly journals Functional Analysis of a Multicopy Host-Selective ACT-Toxin Biosynthesis Gene in the Tangerine Pathotype of Alternaria alternata Using RNA Silencing

2008 ◽  
Vol 21 (12) ◽  
pp. 1591-1599 ◽  
Author(s):  
Y. Miyamoto ◽  
A. Masunaka ◽  
T. Tsuge ◽  
M. Yamamoto ◽  
K. Ohtani ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Rna Silencing ◽  
Toxin Production ◽  
Brown Spot ◽  
Plasmid Construct ◽  
Dispensable Chromosome ◽  
Alternaria Brown Spot ◽  
Multiple Copies ◽  
Commercially Important ◽  
Serious Disease

Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a serious disease of commercially important tangerines and their hybrids. The pathogen produces host-selective ACT toxin, and several genes (named ACTT) responsible for ACT-toxin biosynthesis have been identified. These genes have many paralogs, which are clustered on a small, conditionally dispensable chromosome, making it difficult to disrupt entire functional copies of ACTT genes using homologous recombination-mediated gene disruption. To overcome this problem, we attempted to use RNA silencing, which has never been employed in Alternaria spp., to knock down the functional copies of one ACTT gene with a single silencing event. ACTT2, which encodes a putative hydrolase and is present in multiple copies in the genome, was silenced by transforming the fungus with a plasmid construct expressing hairpin ACTT2 RNAs. The ACTT2 RNA-silenced transformant (S-7-24-2) completely lost ACTT2 transcripts and ACT-toxin production as well as pathogenicity. These results indicated that RNA silencing may be a useful technique for studying the role of ACTT genes responsible for host-selective toxin biosynthesis in A. alternata. Further, this technique may be broadly applicable to the analysis of many genes present in multiple copies in fungal genomes that are difficult to analyze using recombination-mediated knockdowns.

scholarly journals Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation

2014 ◽  
Vol 42 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Florin PĂCURAR ◽  
Ioan ROTAR ◽  
Albert REIF ◽  
Roxana VIDICAN ◽  
Vlad STOIAN ◽  
...  
Keyword(s):  
Vegetation Change ◽  
Compositional Data ◽  
Classification Tree ◽  
Vegetation Period ◽  
Early Years ◽  
Permanent Plots ◽  
Climate Variables ◽  
Vegetation Composition ◽  
Climatic Fluctuations ◽  
Climate Conditions

Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study./span>

First report of Alternaria brown spot of Citrus reticulata cv. ‘Kinnow’ caused by Alternaria arborescens in Pakistan

2019 ◽  
Vol 102 (1) ◽  
pp. 235-236
Author(s):  
Anam Moosa ◽  
Ayaz Farzand ◽  
Muhammad Fahim Abbas ◽  
Shahbaz Talib Sahi ◽  
Sajid Aleem Khan ◽  
...  
Keyword(s):  
Brown Spot ◽  
Citrus Reticulata ◽  
First Report ◽  
Alternaria Arborescens ◽  
Alternaria Brown Spot

scholarly journals Genetically Based Location from Triploid Populations and Gene Ontology of a 3.3-Mb Genome Region Linked to Alternaria Brown Spot Resistance in Citrus Reveal Clusters of Resistance Genes

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e76755 ◽  
Author(s):  
José Cuenca ◽  
Pablo Aleza ◽  
Antonio Vicent ◽  
Dominique Brunel ◽  
Patrick Ollitrault ◽  
...  
Keyword(s):  
Gene Ontology ◽  
Resistance Genes ◽  
Brown Spot ◽  
Genome Region ◽  
Alternaria Brown Spot

scholarly journals Greenhouse Evaluation of Products That Induce Host Resistance for Control of Scab, Melanose, and Alternaria Brown Spot of Citrus

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 69-74 ◽  
Author(s):  
J. P. Agostini ◽  
P. M. Bushong ◽  
L. W. Timmer
Keyword(s):  
Disease Severity ◽  
Host Resistance ◽  
Phosphorous Acid ◽  
Brown Spot ◽  
Bud Break ◽  
Mature Leaves ◽  
Rough Lemon ◽  
Greenhouse Evaluation ◽  
Alternaria Brown Spot ◽  
Integrated Program

Products that induce disease resistance in plants were evaluated on potted seedlings of rough lemon for citrus scab, caused by Elsinoe fawcettii; grapefruit for melanose, caused by Diaporthe citri; and Dancy tangerine for Alternaria brown spot caused by Alternaria alternata pv. citri. Plants were pruned to a single stem with mature leaves and treated at bud break or various times thereafter. New foliage was inoculated and subsequently evaluated for disease severity. Oxycom, Nutriphite, Messenger, Goemar H11, Serenade, ReZist, ProPhyt, Aliette, Actigard, and KeyPlex were evaluated and compared with benomyl or strobilurin fungicides as standards. Most products reduced disease severity compared with the untreated control, but were less effective than standard fungicides. The most generally effective products were ReZist and Actigard, those that contain or produce phosphorous acid (Aliette and Nutriphite), and a bacterial preparation (Serenade). Oxycom and Messenger controlled scab well in some tests. Products that induce host resistance may be useful for disease control in citrus in an integrated program with standard fungicides.

Cinnamomun zeylanicum oil and trans-cinnamaldehyde against Alternaria brown spot in tangerine: direct effects and induced resistance

2019 ◽  
Vol 47 (4) ◽  
pp. 575-589 ◽  
Author(s):  
Fabiano José Perina ◽  
Camila Cristina Lage de Andrade ◽  
Silvino Intra Moreira ◽  
Eduardo Mateus Nery ◽  
Claudio Ogoshi ◽  
...  
Keyword(s):  
Induced Resistance ◽  
Brown Spot ◽  
Direct Effects ◽  
Alternaria Brown Spot

scholarly journals SARS-CoV-2 S1 and N-based serological assays reveal rapid seroconversion and induction of specific antibody response in COVID-19 patients

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abdullah Algaissi ◽  
Mohamed A. Alfaleh ◽  
Sharif Hala ◽  
Turki S. Abujamel ◽  
Sawsan S. Alamri ◽  
...  
Keyword(s):  
Antibody Response ◽  
Specific Antibody ◽  
Large Scale ◽  
Disease Onset ◽  
High Specificity ◽  
Epidemiological Studies ◽  
Cross Reactivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Specificity And Sensitivity ◽  
Human Coronaviruses

Abstract As the Coronavirus Disease 2019 (COVID-19), which is caused by the novel SARS-CoV-2, continues to spread rapidly around the world, there is a need for well validated serological assays that allow the detection of viral specific antibody responses in COVID-19 patients or recovered individuals. In this study, we established and used multiple indirect Enzyme Linked Immunosorbent Assay (ELISA)-based serological assays to study the antibody response in COVID-19 patients. In order to validate the assays we determined the cut off values, sensitivity and specificity of the assays using sera collected from pre-pandemic healthy controls, COVID-19 patients at different time points after disease-onset, and seropositive sera to other human coronaviruses (CoVs). The developed SARS-CoV-2 S1 subunit of the spike glycoprotein and nucleocapsid (N)-based ELISAs not only showed high specificity and sensitivity but also did not show any cross-reactivity with other CoVs. We also show that all RT-PCR confirmed COVID-19 patients tested in our study developed both virus specific IgM and IgG antibodies as early as week one after disease onset. Our data also suggest that the inclusion of both S1 and N in serological testing would capture as many potential SARS-CoV-2 positive cases as possible than using any of them alone. This is specifically important for tracing contacts and cases and conducting large-scale epidemiological studies to understand the true extent of virus spread in populations.

scholarly journals Genealogy of the neurodegenerative diseases based on a meta-analysis of age-stratified incidence data

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniela Gerovska ◽  
Haritz Irizar ◽  
David Otaegi ◽  
Isidre Ferrer ◽  
Adolfo López de Munain ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Meta Analysis ◽  
Disease Onset ◽  
Epidemiological Studies ◽  
Misfolded Proteins ◽  
Mathematical Framework ◽  
Dynamic Adjustment ◽  
Genealogical Tree ◽  
Incidence Data ◽  
Multistep Model

Abstract While the central common feature of the neurodegenerative diseases (NDs) is the accumulation of misfolded proteins, they share other pathogenic mechanisms. However, we miss an explanation for the onset of the NDs. The mechanisms through which genetic mutations, present from conception are expressed only after several decades of life are unknown. We aim to find clues on the complexity of the disease onset trigger of the different NDs expressed in the number of steps of factors related to a disease. We collected brain autopsies on diseased patients with NDs, and found a dynamic increase of the ND multimorbidity with the advance of age. Together with the observation that the NDs accumulate multiple misfolded proteins, and the same misfolded proteins are involved in more than one ND, motivated us to propose a model for a genealogical tree of the NDs. To collect the dynamic data needed to build the tree, we used a Big-data approach that searched automatically epidemiological datasets for age-stratified incidence of NDs. Based on meta-analysis of over 400 datasets, we developed an algorithm that checks whether a ND follows a multistep model, finds the number of steps necessary for the onset of each ND, finds the number of common steps with other NDs and the number of specific steps of each ND, and builds with these findings a parsimony tree of the genealogy of the NDs. The tree discloses three types of NDs: the stem NDs with less than 3 steps; the trunk NDs with 5 to 6 steps; and the crown NDs with more than 7 steps. The tree provides a comprehensive understanding of the relationship across the different NDs, as well as a mathematical framework for dynamic adjustment of the genealogical tree of the NDs with the appearance of new epidemiological studies and the addition of new NDs to the model, thus setting the basis for the search for the identity and order of these steps. Understanding the complexity, or number of steps, of factors related to disease onset trigger is important prior deciding to study single factors for a multiple steps disease.

scholarly journals Role of the Host-Selective ACT-Toxin Synthesis Gene ACTTS2 Encoding an Enoyl-Reductase in Pathogenicity of the Tangerine Pathotype of Alternaria alternata

2010 ◽  
Vol 100 (2) ◽  
pp. 120-126 ◽  
Author(s):  
Naoya Ajiro ◽  
Yoko Miyamoto ◽  
Akira Masunaka ◽  
Takashi Tsuge ◽  
Mikihiro Yamamoto ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Essential Gene ◽  
Toxin Production ◽  
Brown Spot ◽  
Gene Encoding ◽  
Bac Clone ◽  
Biosynthesis Gene Cluster ◽  
Enoyl Reductase ◽  
Alternaria Brown Spot ◽  
Rapid Amplification

The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease of tangerines and tangerine hybrids. Sequence analysis of a genomic BAC clone identified a previously uncharacterized portion of the ACT-toxin biosynthesis gene cluster (ACTT). A 1,034-bp gene encoding a putative enoyl-reductase was identified by using rapid amplification of cDNA ends and polymerase chain reaction and designated ACTTS2. Genomic Southern blots demonstrated that ACTTS2 is present only in ACT-toxin producers and is carried on a 1.9 Mb conditionally dispensable chromosome by the tangerine pathotype. Targeted gene disruption of ACTTS2 led to a reduction in ACT-toxin production and pathogenicity, and transcriptional knockdown of ACTTS2 using RNA silencing resulted in complete loss of ACT-toxin production and pathogenicity. These results indicate that ACTTS2 is an essential gene for ACT-toxin biosynthesis in the tangerine pathotype of A. alternata and is required for pathogenicity of this fungus.

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