Der Einfluß des Lichtes auf die Konidienbildung von Peronospora tabacina Adam an Tabakblättern

Uozumi, T.; Kröber, H.

doi:10.1111/j.1439-0434.1967.tb04731.x

Cited by 6 publications

(6 citation statements)

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“…Cruickshank (1963) reported that sporulation of P. tabacina is a 'dark-induction phenomenon' as it could occur under otherwise continuous light conditions (540 lux) if leaf discs were given a preceding dark treatment (PDT) of > 3 h. He also observed a slight suppressive effect on sporulation at high light intensity (8640 lux). Uozumi and Krober (1967) reported similar results, and Raffray and Sequeira (1970) agreed that sporulation of Bremia lactucae on lettuce is also a dark-induction phenomenon.…”

Section: Effect Of Preceding Dark Treatments Sucrose Supply and Demusupporting

confidence: 59%

“…Maximal spore yield of P. tabacina per unit area is obtained at 20°C in the dark. Consequently, most if not all studies related to light effects upon sporulation were conducted at this temperature (Cruickshank 1963;Shepherd and Mandryk 1964;Uozumi and Krober 1967). The following results indicate that light can strongly suppress spore formation at 20°C or above but not below this temperature.…”

Section: In~eraction Between Temperature and Level Of Direct Irradiationmentioning

confidence: 83%

“…Sporulation of Peronospora tabacina Adam on tobacco leaves has been investigated in detail by various workers (e.g. Cruickshank 1963;Shepherd and Mandryk 1964;Uozumi and Krober 1967;Rotem and Cohen 1970). Sporulation of this pathogen, as of some other fungal plant pathogens of the Peronosporales, is controlled by light in a dual way: light is an ultimate prerequisite (for host photosynthesis) before sporophore emergence (Cohen and Rotem 1970), and it is a strong inhibitor if applied during the wet sporulation period (Cruickshank 1963;Jadot 1966;Uozumi and Krober 1967).…”

Section: Introductionmentioning

confidence: 99%

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Interacting Effects of Light and Temperature on Sporulation of Peronospora tabacina on Tobacco Leaves

Cohen¹

1976

Aust. Jnl. Of Bio. Sci.

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The interacting effects of light and temperature on spore formation of P. tabacina on tobacco leaves were investigated. The following points indicated that an enzymic build-up of an antisporulant during a wet light period and its enzymic decay over a dry dark period may explain the inhibitory effect of light upon sporulation, and its reversal by darkness. (1) Fluorescent blue light of relatively low photon flux density (3 �7 /lE m - 2 S -1) inhibited sporulation by 99 % at 20oe. (2) Light level and temperature during the sporulation period determined spore yield of the pathogen: at high temperatures (in the range 8-24�C) sporulation was inhibited at low light level, whilst no inhibition occurred at much higher light levels at low temperatures. (3) Preceding dry dark treatments given at 200e considerably diminished the inhibitory effect of light, but not if given at 100e. (4) The diffusion of an inhibitory compound from irradiated to unirradiated areas of detached leaves was demonstrated. (5) The continuing photosynthetic activity of the host in the light at 20oe, and the lack of sucrose following dark periods at lOoe, were not associated with the inhibitory effect of light. The similarity between the role of light in the present system and the role of light in activation and decay of phenylalanine ammonia-lyase is discussed.

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Section: Effect Of Preceding Dark Treatments Sucrose Supply and Demusupporting

confidence: 59%

Section: In~eraction Between Temperature and Level Of Direct Irradiationmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Interacting Effects of Light and Temperature on Sporulation of Peronospora tabacina on Tobacco Leaves

Cohen¹

1976

Aust. Jnl. Of Bio. Sci.

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“…In the cucumber downy mildew system, conversion of poly to oligosaccharides proceeds in darkness, and, preferably in dryness (dry darkness). Apparently, for the role of dry-darkness in the conversion pro cess, the highest amount of sporangia produced in several downy mildew-host systems appears on plants first exposed to dry and dark condi tions and only then wetted (15, 24,53,77). The effect of dry-darkness in the sporulation of these pathogens is demonstrated by the case of P. cubensis on cucumber, where similar amounts of sporangia were formed after 6 hr of dry-darkness followed by only 6 hr of wet-darkness, as after 12 hr of wet-darkness (15, 53).…”

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confidence: 99%

Host and Environmental Influences on Sporulation In Vivo

Rotem¹,

Cohen²,

Bashi³

1978

Annu. Rev. Phytopathol.

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INTRODUCTION +3678Theoretical and practical studies of sporulation in vivo have been neglected for years. Consequently, although factors influencing sporulation are as important in disease development as those influencing infection or dispersal, they have seldom been accounted for quantitatively in the theory of epidem ics. This situation evolved probably from (a) the tedious experiments re quired, with endless counting of spores, and frustrations due to variations between replicates of similar treatments, (b) an incorrect view that the number of spores trapped over an infected fi eld is simply related to the number of spores produced during the previous night, and (c) a misconcep tion that sporulation in petri dishes refl ects the situation in nature. Conse quently, the literature contains thousands of publications on processes like infection, dispersal, and sporulation in cultures, but fewer than one hundred studies in which sporulation in vivo has been evaluated quantitatively. 83 0066-4286/78/090 1-0083$0 1.00 Annu. Rev. Phytopathol. 1978.16:83-101. Downloaded from www.annualreviews.org Access provided by McGill University on 02/04/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS 84 ROTEM, COHEN & BASHISporulation in vitro is apparently a fascinating subject. The relatively simple system of a fungus reproducing on a defi ned medium has provided an insight into physiological, biochemical, and genetic phenomena which are difficult to study in the complicated host-parasite system. However, the studies in vitro are often irrelevant to the sporulation patterns of the same fungus in vivo. First, they do not account for the infl uence of the host on reproduction. Second, they deal only with facultative parasites. Third, they fail to evaluate some environmental factors, such as humidity, which is constantly high in petri dishes, or temperature, which may affect differently sporulation of the same fungus in vivo (81). Space limitation prevents us from citing studies of sporulation in vitro; the reader is referred to reviews by Cochrane (11), Hawker (29), Smith & Galbraith (70), and Turian (76), and to the literature cited in these reviews. We deal only with sporulation on the host plant and are fully aware of the danger in discussing phenomena supported by a limited number of published studies and some unpublished data of our own and of our co-workers. We hope to induce future research and are encouraged by the changing approach to our subject. We follow Johnson & Taylor, who concluded that the number of spores produced by a pathogen on its host refl ects the pathogenicity of the pathogen and is the sum of the effects of all components of resistance mechanisms in the host (38). We are inspired by Waggoner & Horsfall (80), Waggoner et al (81), and Kranz et al (43), who consider numerical values of sporulation a basic ingredient of simulation programs of epidemics. We believe that epidemi ology, control, breeding, and other research programs could be assisted by improved knowledge on sporu...

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“…For sporangiospores to appear in the early morning hours, the relatively humidity must have exceeded 95% for at least 3 hr and darkness must have lasted for a minimum of 1.5 hr (Cruickshank, 1963). Uozumi and Krober (1967) found that at 20 'C, after a 13 hr dry photoperiod, a minimum of a 2 hr moist dark period was required to induce sporulation, and maximum sporulation was induced after 5 hr of darkness. P. tabacina is capable of sporulating repeatedly for several successive nights on the same lesion.…”

Section: Introductionmentioning

confidence: 99%

A regional analysis of the meteorological aspects of the spread and development of blue mold on tobacco

Davis

Main

1984

Boundary-Layer Meteorol

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Der Einfluß des Lichtes auf die Konidienbildung von Peronospora tabacina Adam an Tabakblättern

Cited by 6 publications

References 4 publications

Interacting Effects of Light and Temperature on Sporulation of Peronospora tabacina on Tobacco Leaves

Interacting Effects of Light and Temperature on Sporulation of Peronospora tabacina on Tobacco Leaves

Host and Environmental Influences on Sporulation In Vivo

A regional analysis of the meteorological aspects of the spread and development of blue mold on tobacco

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