scholarly journals Characterization of the brown leaf spots pathosystem in Brazilian pecan orchards: pathogen morphology and molecular identification

2021 ◽  
Vol 64 (1) ◽  
pp. 75-86
Author(s):  
Tales Poletto ◽  
Marlove Fátima Brião Muniz ◽  
Vinícius Spolaor Fantinel ◽  
Laís Da Silva Martello ◽  
Lucas Graciolli Savian ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungus ◽  
Large Subunit ◽  
Southern Brazil ◽  
Leaf Spots ◽  
Comprehensive Information ◽  
Brown Leaf ◽  
The World ◽  
Causal Pathogen

Due to the increase in pecan nuts demand, plantation areas are expanding around the world and more frequent epidemics caused by fungal pathogens may occur in orchards and nurseries. Ragnhildiana diffusa is a pathogenic fungus reported to cause brown leaf spots on pecans in numerous countries. The scarcity of comprehensive information in symptoms on the host and morphology of the fungus lead this disease to be initially incorrectly identified in Brazil. In this study, we employed different approaches to characterize the pathogen morphology and pathogenicity and to molecularly identify the organism causing brown leaf spots in southern Brazil. A phylogenetic analysis based on the internal transcribed spacer (ITS) and the large subunit (LSU) gene sequences confirmed R. diffusa as the causal pathogen of the disease. Inoculation tests on healthy leaflets confirmed pathogenicity isolates, although some variation in their virulence was observed. Variation in the morphology of the asexual stage was observed among and within isolates. This study brought unprecedented morphological, genetic and pathogenic information that aids elucidating the disease. The accurate and prompt identification of the disease may assist in controlling further spread of the pathogen into orchards and nurseries still free of the disease in South America.

scholarly journals Isolation and molecular characterization of ginger soft rot pathogenic fungi in Aizawl district of Mizoram, India

2018 ◽  
Vol 18 (4) ◽  
pp. 111-119
Author(s):  
G. Rosangkima ◽  
Vanramliana ◽  
H. Lalthanzara ◽  
Lalringngheti ◽  
H.C. Lalramnghaki
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Soft Rot ◽  
Management Programme ◽  
Fusarium Spp ◽  
Soft Rot Disease ◽  
The World ◽  
Causative Agents ◽  
Rot Disease

Ginger soft rot disease caused by fungal pathogens have become one of the most serious problems causing reduced production around the world. It has also caused a major problem among farmers of Mizoram state in India resulting in a huge decline in rhizome yield. However, the exact causative agents of this disease have not been identified in the state. Therefore, the present study was undertaken to isolate and characterized the causative agents of ginger soft rot disease from the diseased plants collected from five different villages of Aizawl district, Mizoram. Isolated fungi were cultured and morphological and molecular identification were done using internal transcribed spacer of rDNA. Fusarium oxysporum, F. solani and Plectosphaerella cucumerina were identified in ginger samples from five villages. Fusarium spp. were the most common and seem to be the major causative agents. It is suggested that further investigation is required to explore the diversity of ginger soft rot pathogenic fungi in the whole state which could be helpful in introducing effective and eco-friendly disease management programme.

scholarly journals A New Disease of Parthenium hysterophorus Incited by an Undescribed Species of Cryptosporiopsis

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1151-1151
Author(s):  
P. Sreerama Kumar
Keyword(s):  
Fungal Pathogens ◽  
Southwest Monsoon ◽  
Parthenium Hysterophorus ◽  
Commonwealth Mycological Institute ◽  
Invasive Weed ◽  
Leaf Spots ◽  
Brown Leaf ◽  
Detached Leaves ◽  
Intensive Investigation ◽  
Whole Plants

Fungal pathogens of parthenium (Parthenium hysterophorus L.), an invasive weed in India, have been under intensive investigation at our Directorate since 1996 for development of mycoherbicides. During the southwest monsoon month of August 1997, a severe foliar disease of the weed was observed near Hunsur (12° 16′N; 76° 18′E; 779.37 masl) in Mysore district of Karnataka State. The primary symptoms consisted of circular to irregular, light brown leaf spots with a diameter up to 8 mm and surrounded by a diffuse chlorotic margin. Isolations on potato dextrose agar (PDA) yielded a relatively fast-growing (approximately 11.4 mm/day) white fungus. The same fungus was isolated consistently from diseased leaves but not from symptomless leaves collected from the vicinity. The mycelium of the fungus on PDA was immersed, branched, septate, and hyaline to pale brown. Conidia (approximately 10.50 × 2.75 µm) were hyaline, thin-walled, smooth, straight, and ellipsoid with obtuse apex and base abruptly tapered to a distinct truncate scar. Pathogenicity was assessed by inoculating healthy, surface-sterilized, mature detached leaves and whole plants (40-day-old) with spore (1 × 106 conidia/ml) or mycelial (0.2 g/ml) suspensions. For both kinds of inoculation, 10 replicates each for detached leaves and whole plants were maintained with equal number of uninoculated controls. Inoculated leaves and plants were incubated at ambient temperature (28 ± 2°C) and 48 h of continuous leaf wetness. Lesions resembling symptoms that occurred in the field were observed on all detached leaves and whole plants within 3 weeks of inoculation. The same fungus was recovered from the diseased tissues excised from all the inoculated material, satisfying Koch's postulates. All the controls remained symptomless and were negative for the fungus. A virulent isolate of this fungus was referred to CABI Bioscience, UK Centre (Egham) and was identified as Cryptosporiopsis sp. (IMI 378270). Although there are at least 12 described species of Cryptosporiopsis Bub. & Kabát (1), no species has been described on parthenium. This pathogen is being studied for its usefulness as a mycoherbicide for parthenium. Reference: (1) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, Surrey, England.

scholarly journals Flow-by-flow chemical stratigraphy and evolution of thirteen Serra Geral Group basalt flows from Vista Alegre, southernmost Brazil

2011 ◽  
Vol 83 (2) ◽  
pp. 425-440 ◽  
Author(s):  
Viter M Pinto ◽  
Léo A Hartmann
Keyword(s):  
Chemical Composition ◽  
Horizontal Position ◽  
Southern Brazil ◽  
Native Copper ◽  
Geochemical Characterization ◽  
Economic Significance ◽  
Basaltic Composition ◽  
The World ◽  
World Class

The geochemical characterization of thirteen Serra Geral Group flows in the Vista Alegre region (RS-SC), southern Brazil, displays the homogeneous basaltic composition near 50 wt.% SiO2. Each of the five basal flows (Pitanga-type, high-Ti/Y ~600, TiO2 > 3 wt.%) and eight upper flows (Paranapanema-type, medium Ti/Y ~400, TiO2 > 2 wt.%) can be identified from their chemical composition; sets of flows have parallel variation in chemical composition. The flow-by-flowcorrelation in four sections shows the horizontal position of the flows in three profiles and an approximately 200-m downdrop of the Itapiranga block with respect to the Frederico Westphalen block. The world-class amethyst geode mineralization and the systematic presence of native copper in the basalts make the correlation of great geological and economic significance.

scholarly journals Leaf spots of calibrachoa caused by Nigrospora oryzae

2020 ◽  
Vol 26 (4) ◽  
pp. 591-597
Author(s):  
Nicolás Pablo Borrelli ◽  
Santiago Stancanelli ◽  
Mirta Leonor Papone ◽  
María Virginia Moreno ◽  
Sebastián Stenglein ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Buenos Aires ◽  
First Record ◽  
Fungal Isolate ◽  
Leaf Spot Disease ◽  
Leaf Spots ◽  
Brown Leaf ◽  
The World ◽  
Pathogenicity Tests ◽  
Nigrospora Oryzae

Abstract Calibrachoa hybrida (calibrachoa, million bells) is a flowering ornamental with increasing importance due to the existence of many successful cultivars for growing indoors in containers and planting in the garden and landscape. The outstanding characteristic is a profuse flowering and intense colour. In October 2019, a fungal isolate was obtained from basal calibrachoa leaves with irregular brown leaf spots, in plants cultivated in Buenos Aires, Argentina. The aim of the present study was to identify the cause of the disease in this ornamental genus, to expand knowledge about prevalent pathologies. The isolate was identified using morphological and molecular markers, and the pathogenicity tests were fulfilled. This paper reports that Nigrospora oryzae is pathogenic to calibrachoa, which seems to be the first record of this leaf spot disease in the world.

Enrichment of arsenite oxidizing bacteria under autotrophic conditions and the isolation and characterization of facultative chemolithoautotrophic arsenite oxidizing bacteria for removal of arsenic from groundwater

2012 ◽  
Vol 12 (5) ◽  
pp. 707-714 ◽  
Author(s):  
L. Nguyen Ai ◽  
A. Sato ◽  
D. Inoue ◽  
K. Sei ◽  
S. Soda ◽  
...  
Keyword(s):  
Arsenic Removal ◽  
Enrichment Culture ◽  
Large Subunit ◽  
Cost Effective ◽  
Isolation And Characterization ◽  
The World ◽  
Genes Encoding ◽  
Arsenite Oxidizing Bacteria ◽  
Removal Of Arsenic

Arsenic contamination in groundwater has caused severe health problems throughout the world. Developing cost-effective processes for arsenic removal is an emerging issue. Because As(III) is predominant in groundwater and is more difficult to remove than As(V) is, oxidation of As(III) to As(V) is necessary to improve overall arsenic removal. This study was undertaken to enrich arsenite oxidizing bacteria under autotrophic conditions and to isolate and characterize facultative chemolithoautotrophic arsenite oxidizing bacteria (CAOs) that can oxidize As(III) effectively to As(V). An enrichment culture which adapted wide As(III) concentrations and completely oxidized 12 mM As(III) within 4 days under autotrophic conditions was established and maintained. Among 10 isolated strains, 6 strains, B1, B2, C, D, E1 and E2 belonging to β-Proteobacteria, were facultative CAOs and contained aoxB genes encoding the arsenite oxidase large subunit. Furthermore, they displayed various As(III) oxidation capabilities: B1, B2, E1 and E2 efficiently oxidized 1–10 mM As(III). The others showed efficient oxidation at 1–5 mM As(III), suggesting the coexistence of facultative CAOs with various As(III) oxidation capabilities in the enrichment. These results suggest that constructed enrichment and strains B1, B2, E1 and E2 can be useful for the bioremediation of arsenic-contaminated groundwater.

scholarly journals Characterization of Resistance to Six Chemical Classes of Site-Specific Fungicides Registered for Gray Mold Control on Strawberry in Spain

Plant Disease ◽  
2016 ◽  
Vol 100 (11) ◽  
pp. 2234-2239 ◽  
Author(s):  
Dolores Fernández-Ortuño ◽  
Juan Antonio Torés ◽  
Manuel Chamorro ◽  
Alejandro Pérez-García ◽  
Antonio de Vicente
Keyword(s):  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Management Practices ◽  
Resistance Management ◽  
Gray Mold ◽  
Amino Acid Substitutions ◽  
Site Specific ◽  
Resistance Profile ◽  
The World

Botrytis cinerea, causal agent of the gray mold disease, is one of the most economically important fungal pathogens of strawberry worldwide. In Spain, as in other parts of the world, management of gray mold control primarily involves the application of fungicides. To determine the fungicide resistance of the Spanish strawberry field population, 367 B. cinerea isolates were examined from one organic and 13 conventional strawberry fields in Huelva (Spain) in 2014 and 2015. The sensitivities of these isolates to six fungicides used for gray mold management in Spain were examined using a spore germination assay based on previously published discriminatory doses. The frequency of resistance to pyraclostrobin, boscalid, cyprodinil, fenhexamid, iprodione, and fludioxonil was 74.6, 64.8, 37.0, 23.7, 14.7, and 0.8%, respectively. The majority of isolates (35.1%) were resistant to three different fungicides classes. Within these isolates, the most prevalent resistance profile (55.8%) was resistance to pyraclostrobin, boscalid, and cyprodinil, followed by the resistance profile (30.2%) of resistance to pyraclostrobin, boscalid, and fenhexamid. One isolate collected in 2015 was resistant to all six fungicide classes. Resistance to boscalid, fenhexamid, iprodione, and pyraclostrobin was found to be caused by amino acid substitutions on target proteins, including H272R/Y in SdhB, F412I/S/V in Erg27, I365 N/S in Bos1, and G143A in Cytb, respectively. The presence of multifungicide resistance phenotypes in B. cinerea isolates from strawberry fields in Spain must be considered in the development of future resistance management practices.

Control of Winged Waterprimrose (Jussiaea decurrens) and Northern Jointvetch (Aeschynomene virginica) with Fungal Pathogens

Weed Science ◽  
1979 ◽  
Vol 27 (5) ◽  
pp. 497-501 ◽  
Author(s):  
C. D. Boyette ◽  
G. E. Templeton ◽  
R. J. Smith
Keyword(s):  
Oryza Sativa ◽  
Glycine Max ◽  
Fungal Pathogens ◽  
Liquid Culture ◽  
Field Experiments ◽  
Colletotrichum Gloeosporioides ◽  
Pathogenic Fungus ◽  
Field Tests ◽  
Wide Range ◽  
Growing Region

An indigenous, host-specific, pathogenic fungus that parasitizes winged waterprimrose [Jussiaea decurrens(Walt.) DC.] is endemic in the rice growing region of Arkansas. The fungus was isolated and identified asColletotrichum gloeosporioides(Penz.) Sacc. f.sp. jussiaeae(CGJ). It is highly specific for parasitism of winged waterprimrose and not parasitic on creeping waterprimrose (J. repensL. var.glabrescensKtze.), rice (Oryza sativaL.), soybeans [Glycine max(L.) Merr.], cotton (Gossypium hirsutumL.), or 4 other crops and 13 other weeds. The fungus was physiologically distinct from C.gloeosporioides(Penz.) Sacc. f. sp.aeschynomene(CGA), an endemic anthracnose pathogen of northern jointvetch[Aeschynomene virginica(L.) B.S.P.], as indicated by cross inoculations of both weeds. Culture in the laboratory and inoculation of winged waterprimrose in greenhouse, growth chamber and field experiments indicated that the pathogen was stable, specific, and virulent in a wide range of environments. The pathogen yielded large quantities of spores in liquid culture. It is suitable for control of winged waterprimrose. Winged waterprimrose and northern jointvetch were controlled in greenhouse and field tests by application of spore mixtures of CGJ and CGA at concentrations of 1 to 2 million spores/ml of each fungus in 94 L/ha of water; the fungi did not damage rice or nontarget crops.

Molecular characterization of a novel fusarivirus infecting the plant-pathogenic fungus Botryosphaeria dothidea

2020 ◽  
Vol 165 (4) ◽  
pp. 1033-1037 ◽  
Author(s):  
Wenyi Liu ◽  
Du Hai ◽  
Fan Mu ◽  
Xiaojing Yu ◽  
Yingtong Zhao ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Pathogenic Fungus ◽  
Botryosphaeria Dothidea ◽  
Plant Pathogenic Fungus

Theileria parva ribosomal internal transcribed spacer sequences exhibit extensive polymorphism and mosaic evolution: application to the characterization of parasites from cattle and buffalo

Parasitology ◽  
1999 ◽  
Vol 118 (6) ◽  
pp. 541-551 ◽  
Author(s):  
N. E. COLLINS ◽  
B. A. ALLSOPP
Keyword(s):  
Genetic Recombination ◽  
Large Subunit ◽  
Small Subunit ◽  
Internal Transcribed Spacers ◽  
Rrna Genes ◽  
Gene Pools ◽  
Theileria Parva ◽  
Causative Agents ◽  
Internal Transcribed Spacer Sequences

We sequenced the rRNA genes and internal transcribed spacers (ITS) of several Theileria parva isolates in an attempt to distinguish between the causative agents of East coast fever and Corridor disease. The small subunit (SSU) and large subunit (LSU) rRNA genes from a cloned T. p. lawrencei parasite were sequenced; the former was identical to that of T. p. parva Muguga, and there were minor heterogeneities in the latter. The 5·8S gene sequences of 11 T. parva isolates were identical, but major differences were found in the ITS. Six characterization oligonucleotides were designed to hybridize within the variable ITS1 region; 93·5% of T. p. parva isolates examined were detected by probe TPP1 and 81·8% of T. p. lawrencei isolates were detected by TPL2 and/or TPL3a. There was no absolute distinction between T. p. parva and T. p. lawrencei and the former hybridized with fewer of the probes than did the latter. It therefore seems that a relatively homogenous subpopulation of T. parva has been selected in cattle from a more diverse gene pool in buffalo. The ITSs of both T. p. parva and T. p. lawrencei contained different combinations of identifiable sequence segments, resulting in a mosaic of segments in any one isolate, suggesting that the two populations undergo genetic recombination and that their gene pools are not completely separate.

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