scholarly journals Neofusicoccum parvum, a New Agent of Sequoia Canker and Dieback Identified in Geneva, Switzerland

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 434
Author(s):  
Martine Haenzi ◽  
Bastien Cochard ◽  
Romain Chablais ◽  
Julien Crovadore ◽  
François Lefort
Keyword(s):  
Pure Culture ◽  
Lake Area ◽  
Koch’S Postulates ◽  
Neofusicoccum Parvum ◽  
Rdna Sequencing ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum ◽  
Pure Cultures ◽  
Fusicoccum Aesculi ◽  
Koch's Postulates

Fungi were isolated in pure cultures from decaying giant sequoias in Geneva (Switzerland). Isolates were genetically identified by ITS rDNA sequencing. Young giant sequoia trees were artificially infected with a pure culture of Botryosphaeria parva. Henle-Koch’s Postulates demonstrated that Botryosphaeria parva was pathogenic to Sequoiadendron giganteum. When analysing the microorganisms associated to canker and dieback symptoms in a giant sequoias (Sequoiadendron giganteum) in Geneva, the fungus Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, teleomorph Botryosphaeria parva (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, was isolated, whereas such symptoms are commonly associated to Fusicoccum aesculi (teleomorph Botryosphaeria dothidea). These two fungal species belong to the same genus Botryosphaeria of the Botryosphaeriaceae family. Because Neofusicoccum parvum was causing cankers and diebacks in other woody species around the world, we extended the analysis to other trees displaying sequoia dieback symptoms in order to evaluate the involvement of Neofusicoccum parvum in such increasing symptoms in sequoias in Geneva. Dried twigs, trunk, and branch cankers from diseased trees were sampled on several distinct sites. From all samples, isolated fungi in pure cultures showed a phenotype typical of Botryosphaeriaceae species. Isolates were then genetically identified at the species level. Subsequently Neofusicoccum parvum was inoculated to young giant sequoia trees, re-isolated in pure culture from provoked symptoms, and re-identified to fulfil Henle-Koch’s postulates. The identification confirmed that Neofusicoccum parvum was present on all sites, while Fusicoccum aesculi was retrieved only once alone. The inoculation of Neofusicoccum parvum isolates on young sequoias demonstrated for the first time that this fungus was able to develop cankers in Sequoiadendron gigantean. Neofusicoccum parvum could, therefore, be the major cause for dying of giant sequoias in the Geneva Lake area.

scholarly journals First Report of Neofusicoccum nonquaesitum Causing Branch Cankers on Giant Sequoia (Sequoiadendron giganteum) in North America

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 905-905 ◽  
Author(s):  
S. Rooney-Latham ◽  
T. E. Tidwell ◽  
C. L. Blomquist ◽  
K. S. Peek
Keyword(s):  
North America ◽  
Its Region ◽  
Mature Trees ◽  
California Department ◽  
Coast Redwood ◽  
First Report ◽  
Agar Plug ◽  
Rdna Sequencing ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum

Between 2001 and 2007, samples from three California native plants showing canker symptoms were submitted to the California Department of Food and Agriculture's Plant Pest Diagnostics laboratory. Giant sequoia (Sequoiadendron giganteum) and coast redwood (Sequoia sempervirens) showed branch cankers and dieback, whereas tanoak (Lithocarpus densiflora) had bleeding bole cankers. Samples were collected from mature trees in private landscapes in El Dorado, Sacramento, and Alameda counties in California. A fungus was isolated on one-half strength acidified potato dextrose agar (APDA) from the canker margins of all three hosts. Colonies were moderately fast growing, initially white, later turning olivaceous black. Pycnidia developed singly or in small groups and contained conidia that measured 18 to 29 × 6 to 8 μm (average 21.5 × 6.8 μm). Conidia were aseptate, hyaline, and fusiform, with truncate bases. rDNA sequences of the internal transcribed spacer (ITS) region of the isolates (GenBank JQ282157 through JQ282159), amplified using primers ITS1 and ITS4 (2), were 100% identical to the holotype isolate of Neofusicoccum nonquaesitum Inderb., Trouillas, Bostock & Michailides (1) by a BLAST query (GenBank GU251163). Pathogenicity of the N. nonquaesitum isolate from giant sequoia (CDFA4) was tested on five saplings using cultures grown on APDA for 14 days. A single wound was made approximately 2 cm above the soil line on the cambium of each plant using a 3-mm cork borer. One 3-mm colonized agar plug was placed on each wound and secured with Parafilm. Plugs of APDA were placed onto wounds of five plants as controls. All plants were kept in a growth chamber at 23°C with a 12-h photoperiod. After 4 days, Parafilm was removed to reveal dark brown cankers measuring 12 to 43 mm long on the inoculated plants. Fourteen days after inoculation, cankers were black, sunken, and measured 79 to 117 mm (average 91.4 mm) long. Most of the inoculated plants were wilted with chlorotic to necrotic foliage. Mature pycnidia with cirri developed in most of the cankers. N. nonquaesitum was reisolated on APDA from all of the cankers. No symptoms developed on the control plants. The experiment was repeated once with similar results. Botryosphaeria dothidea, also in the Botryosphaeriaceae, has been reported to cause similar cankers on giant sequoia and coast redwood in California (3). However, rDNA sequencing of the ITS region of this isolate obtained from the American Type Culture Collection (ATCC 60344) (GenBank JQ284384) showed it matched the type specimen of Neofusicoccum australe (GenBank GU251219), not our isolate. To our knowledge, this is the first report of N. nonquaesitum as a pathogen of giant sequoia in North America. This study expands the host range of N. nonquaesitum from almond (Prunus dulcis), California bay (Umbellularia californica), and blueberry (Vaccinium spp.) (1) to include giant sequoia, coast redwood, and tanoak, which are economically important trees in California forests and landscapes. References: (1) P. Inderbitzin et al. Mycologia 102:1350, 2010. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (3) J. J. Worrall et al. Plant Dis. 70:757, 1986.

scholarly journals First Report of Azalea Petal Blight Caused by Pestalotiopsis guepini in Argentina

Plant Disease ◽  
2000 ◽  
Vol 84 (1) ◽  
pp. 100-100 ◽  
Author(s):  
M. C. Rivera ◽  
E. R. Wright
Keyword(s):  
Buenos Aires ◽  
Morphological Characteristics ◽  
Potato Dextrose Agar ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Koch’S Postulates ◽  
First Report ◽  
Pure Cultures ◽  
Pathogenicity Testing ◽  
Koch's Postulates

The most important azalea (Rhododendron spp.) growing area in Argentina is located in the outskirts of Buenos Aires. A disease of the azalea flower was detected during surveys conducted during September 1998. Irregular brown spots were uniformly distributed on petals and resulted in a flower blight that did not lead to abscission of petals. Pieces of infected petals were surface-sterilized for 1 min in 2% NaOCl, plated on potato dextrose agar, and incubated at 24 ± 2°C. Pure cultures were identified as Pestalotiopsis guepini (Desmaz.) Steyaert (synamorph P. guepini Desmaz.) based on morphological characteristics (1,2). Inoculation for pathogenicity testing was carried out by spraying a conidial suspension (1 × 106 conidia per ml) on plants with previously punctured petals. Inoculated plants with unwounded flowers, as well as noninoculated controls, were included. Plants were incubated in moist chambers at 24°C. Symptoms appeared on all punctured flowers within 4 to 5 days. Petals were blighted by 9 days after inoculation and were covered with black acervuli by 12 days after inoculation. Unwounded and noninoculated controls remained symptomless. The pathogen was reisolated from inoculated flowers, completing Koch's postulates. Pathogenicity of P. guepini on azalea leaves in Argentina was reported in 1991. This is the first report of P. guepini causing disease on azalea flowers in Argentina. References: (1) J. E. M. Mordue. CMI Descr. Pathog. Fungi Bact. No. 320, 1971. (2) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, England.

First Report of Pathogenicity of Fusarium sporotrichioides and Fusarium acuminatum on Sunflowers in the United States

2010 ◽  
Vol 11 (1) ◽  
pp. 42 ◽  
Author(s):  
F. Mathew ◽  
B. Kirkeide ◽  
T. Gulya ◽  
S. Markell
Keyword(s):  
United States ◽  
Helianthus Annuus ◽  
The United States ◽  
Fusarium Sporotrichioides ◽  
Charcoal Rot ◽  
Koch’S Postulates ◽  
First Report ◽  
Fusarium Acuminatum ◽  
Helianthus Annuus L ◽  
Koch's Postulates

Widespread infection of charcoal rot was observed in a commercial sunflower field in Minnesota in September 2009. Based on morphology, isolates were identified as F. sporotrichioides and F. acuminatum. Koch's postulates demonstrated pathogencity of both species. To our knowledge, this is the first report of F. sporotrichoides and F. acuminatum causing disease on Helianthus annuus L. in the United States. Accepted for publication 23 August 2010. Published 15 September 2010.

scholarly journals Cancer stem cells: Beyond Koch’s postulates

2009 ◽  
Vol 278 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Emmanuel Garcion ◽  
Philippe Naveilhan ◽  
François Berger ◽  
Didier Wion
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Koch’S Postulates ◽  
Koch's Postulates

Koch’s Postulates

2008 ◽  
pp. 2093-2093
Author(s):  
Gary J. Puterka ◽  
D. Michael Glenn ◽  
George Hangay ◽  
Darryl Gwynne ◽  
John B. Heppner ◽  
...  
Keyword(s):  
Koch’S Postulates ◽  
Koch's Postulates

A Microbiology Teaching Lab: Using Koch's Postulates to Determine the Cause of “Peep Pox” in Marshmallow Peeps

2018 ◽  
Vol 80 (9) ◽  
pp. 676-679
Author(s):  
John L. Dahl ◽  
Wayne Gatlin
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Cost Effective ◽  
Time Constraints ◽  
Limited Time ◽  
Koch’S Postulates ◽  
Ethical Concerns ◽  
Effective Time ◽  
Microbial Isolation ◽  
Koch's Postulates

Koch's postulates are regularly included in the lecture portion of microbiology courses, but rarely are they demonstrated in a microbiology teaching lab. This is understandable given the logistical challenges of undergraduates working with pathogenic bacteria, ethical concerns using animals, and limited time constraints of a weekly lab period. Here we present a cost-effective, time-friendly lab activity that demonstrates the principles of microbial isolation and infection assays that are part of fulfilling Koch's postulates. The disease is “peep pox” caused by a gelatinase-positive bacterial species hydrolyzing marshmallow peeps that proxy as infected animals.

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