Ascospore Production, Release, Germination, and Infection of<i>Populus</i>by<i>Mycosphaerella populorum</i>

Luley, Christopher J.; McNabb, Harold S.

doi:10.1094/phyto-79-1013

Cited by 18 publications

(14 citation statements)

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“…However, wetting may not be the only factor involved in initiating dispersal, as ascospores were rarely collected at night even if dew or rain occurred. An almost identical diurnal pattern of ascospore release has been reported for Mycosphaerella populorum (Luley & McNabb, 1989 ascospore state (Figs 7, 8;Inman et al, 1991;Inman, 1993). The sexual cycle appears to be initiated in summer with the production of spermogonia and protoascomata in white leaf spot lesions on pods, racemes or stems in June or July.…”

Section: Ascospores As Primary Inoculum For White Leaf Spot Epidemicssupporting

confidence: 79%

Ascospores as primary inoculum for epidemics of white leaf spot (Mycosphaerella capsellae) in winter oilseed rape in the UK

et al. 1999

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In the UK, conidia of Pseudocercosporella capsellae, the anamorph of Mycosphaerella capsellae, were observed on white leaf spot lesions on leaves throughout the growing season. Ascomata were not observed on lesions on either green or senescent leaves, although stromatic knots and spermogonia were occasionally seen in summer. However, spermogonia and protoascomata were produced in white leaf spot pod and stem lesions in early summer. Protoascomata continued to mature after harvest in these lesions on the debris. Mature ascomata subsequently developed by early autumn, but were exhausted by early January and did not overwinter. A diurnal periodicity in numbers of air-borne M. capsellae ascospores discharged from infected debris was observed with a Burkard spore sampler, with greatest numbers of ascospores collected near the middle of the day; the records also suggested that ascospores were released in response to wetting by dew or rain. Studies of natural white leaf spot epidemics in winter oilseed rape provided evidence that air-borne ascospores are the primary inoculum for initiating epidemics in the autumn in the UK. White leaf spot disease gradients over 100 m across a winter oilseed rape crop at Rothamsted were fitted by both negative exponential and inverse power-law models, with gradient slopes suggesting the deposition of air-borne spores dispersed from a single local source of inoculum. In comparison, no obvious white leaf spot gradients were observed over 250 m in a severely diseased crop near North Petherton, Somerset, suggesting that the air-borne spores were dispersed from a number of more distant sources in the area. Both patterns of disease were unlikely to have been initiated by P. capsellae conidia, which are dispersed only very short distances by rain-splash. However, once epidemics have been initiated by air-borne ascospores in the autumn, subsequent disease spread within an infected crop is dependent only on splash-dispersed conidia. A revised disease cycle of the pathogen is proposed.

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Section: Ascospores As Primary Inoculum For White Leaf Spot Epidemicssupporting

confidence: 79%

Ascospores as primary inoculum for epidemics of white leaf spot (Mycosphaerella capsellae) in winter oilseed rape in the UK

et al. 1999

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“…Two epidemiological studies carried out in hybrid poplar plantations in the northern Midwest of the USA (Iowa, Minnesota and Wisconsin) indicate that ascospores released from the leaf litter may constitute the primary inoculum (Ostry, 1987;Luley & McNabb, 1989). The existence of an additional source of inoculum, such as asexual conidia released from overwintering mycelia in the trees or on fallen leaves, remains hypothetical (Ostry, 1987;Luley & McNabb, 1989;Sinclair & Lyon, 2005).…”

Section: Infectionmentioning

confidence: 99%

“…The existence of an additional source of inoculum, such as asexual conidia released from overwintering mycelia in the trees or on fallen leaves, remains hypothetical (Ostry, 1987;Luley & McNabb, 1989;Sinclair & Lyon, 2005). The ascospores penetrate the leaves through the stomata.…”

Section: Infectionmentioning

confidence: 99%

Recent advances related to poplar leaf spot and canker caused bySeptoria musiva

Feau

Mottet

Périnet

et al. 2010

Canadian Journal of Plant Pathology

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The expansion of poplar culture in the north-central and northeastern regions of North America has been limited because many poplar clones are susceptible to the leaf spot and canker disease caused by the fungus Septoria musiva (teleomorph Mycosphaerella populorum). This review provides a brief historical account and summarizes the current state of knowledge focussing on developments in the areas of taxonomy and systematics, host associations and symptomatology. Since selection and deployment of resistant clones is one of the best disease-control strategies against S. musiva, recent advances in our knowledge of epidemiology, genetics and variability in virulence and aggressiveness of the populations of this fungus are also addressed.Résumé: L'expansion de la culture du peuplier dans les régions du centre-nord et du nord-est de l'Amérique du Nord a été freinée parce que de nombreux clones de ce dernier sont sensibles à la tache foliaire et au chancre causés par Septoria musiva (téléomorphe de Mycosphaerella populorum). Cet examen offre un bref aperçu historique de nos connaissances ainsi qu'un résumé de l'état actuel de ces dernières relativement aux progrès effectués dans les domaines de la taxonomie et de la systématique, des associations d'hôtes ainsi que de la symptomatologie. Étant donné que la sélection et l'utilisation de clones résistants comptent parmi les meilleures stratégies de lutte contre S. musiva, nous abordons également les récentes percées effectuées dans les domaines de l'épidémiologie, de la génétique ainsi que de la variabilité de la virulence et de l'agressivité chez les populations de ce champignon.Mots clés: maladies du peuplier, Mycosphaerella populorum, peuplier hybride, résistance à la maladie, Tache septorienne

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“…Studies have indicated a light requirement for pseudothecial and ascospore formation by Mycosphaerella ligulicola, the ray-blight pathogen of chrysanthemum (McCoy et al, 1972). However, cultures of M. populorum develop pseudothecia and ascospores under continuous darkness (Luley & McNabb, 1989).…”

Section: R Kennedy Et Al 304mentioning

confidence: 99%

Production and immunodetection of ascospores of Mycosphaerella brassicicola: ringspot of vegetable crucifers

Kennedy¹,

Wakeham²,

Cullington³

1999

Plant Pathology

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Pseudothecia containing abundant ascospores of Mycosphaerella brassicicola were produced in vitro on Brussels sprout decoction agar at 15ЊC under a 16-hour photoperiod of different light regimes. Spermogonia containing spermatia were also produced on the decoction agar. Ascospores were released when cultures were misted with SDW and placed under continuous light. Germination of ascospores was highest between 20ЊC and 25ЊC and spores remained viable at relative humidities above 93·5%. Exposure of ascospores to 55% relative humidity for 24 h reduced their germination to 75%. A polyclonal antiserum raised against whole ascospores was used to detect, by immunofluorescence, the ascospore and mycelial wall of M. brassicicola, following reaction with anti-rabbit IgG FITC conjugate. Autofluorescence of spore and mycelial components of other fungal species could be eliminated using the counterstains Evan's blue and eriochrome black at 0·2% and 0·5%, respectively, in phosphate buffered saline (pH 7·2). A procedure was developed to detect, by immunofluorescence, ascospores of M. brassicicola on artificially inoculated Melinex spore tape. Coating of the spore tape with bovine serum albumin provided a suitable support medium and blocking agent for detection of ascospores in the field. The potential use of the system for selective detection of ascospores of M. brassicicola in infected crops of vegetable brassicas in the presence of other ascosporic fungi is discussed.

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Ascospore Production, Release, Germination, and Infection ofPopulusbyMycosphaerella populorum

Cited by 18 publications

References 0 publications

Ascospores as primary inoculum for epidemics of white leaf spot (Mycosphaerella capsellae) in winter oilseed rape in the UK

Ascospores as primary inoculum for epidemics of white leaf spot (Mycosphaerella capsellae) in winter oilseed rape in the UK

Recent advances related to poplar leaf spot and canker caused bySeptoria musiva

Production and immunodetection of ascospores of Mycosphaerella brassicicola: ringspot of vegetable crucifers

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