The life history of Plasmodiophora brassicae Woron

1972 ◽  
Vol 180 (1058) ◽  
pp. 103-112 ◽  
Keyword(s):  
Life History ◽  
Root Hair ◽  
Plasmodiophora Brassicae ◽  
Root Hairs ◽  
Secondary Phase ◽  
Tissue Cultures ◽  
Resting Spore ◽  
Resting Spores ◽  
Seedling Roots ◽  
History Of

Resting spore germination and the root hair stages of the life history of Plasmodiophora brassicae were studied in stained preparations of infected Brassica rapa seedling roots. Naked protoplasts, usually possessing two unequal flagella, were released from resting spores through a small circular pore. They penetrated the root hairs of B. rapa and there developed into plasmodia which, after becoming multinucleate, cleaved to form zoosporangia con­taining incipient zoospores. Biflagellate zoospores were released from root hair zoosporangia and fused in pairs, although karyogamy did not occur. The resulting binucleate zoospores infected the cortical dells of B. rapa to form binucleate plasmodia, the earliest stages of the secondary phase of the life history. These findings are discussed in relation to previous studies on the life history of P. brassicae in Brassica plants and in Brassica tissue cultures, and a new complete life history, including nuclear fusion in the secondary plasmodium, is suggested for the organism.

scholarly journals The Role of Primary and Secondary Infection in Host Response to Plasmodiophora brassicae

2014 ◽  
Vol 104 (10) ◽  
pp. 1078-1087 ◽  
Author(s):  
Mary Ruth McDonald ◽  
Kalpana Sharma ◽  
Bruce D. Gossen ◽  
Abhinandan Deora ◽  
Jie Feng ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Secondary Infection ◽  
Root Hairs ◽  
Secondary Phase ◽  
Primary Phase ◽  
Root Cortex ◽  
Resting Spores ◽  
Cortical Infection ◽  
Root Hair Infection

The disease cycle of Plasmodiophora brassicae consists of a primary phase in root hairs followed by a secondary phase in the root cortex and adjacent tissues. However, the role of root hair infection in subsequent cortical infection and development of P. brassicae is not well understood. To examine the role of the primary and secondary stages separately, inoculation studies with resting spores (source of primary zoospores) and secondary zoospores of a virulent and avirulent pathotype were conducted on canola (Brassica napus). The size of secondary zoospores and number of nuclei were also examined. The zoospores were larger (≈9.6 to 14.4 μm) than in previous reports and all were uninucleate. Inoculation with secondary zoospores alone produced both primary and secondary infection, even with the avirulent pathotype. No symptoms developed from inoculation with avirulent primary zoospores but tiny, bead-shaped clubs developed from inoculation with avirulent secondary zoospores. Inoculation with virulent secondary zoospores alone resulted in lower disease severity than inoculation with virulent resting spores alone. The results indicate that recognition of infection by the host and initiation of a response (induction or suppression of resistance) occurs during primary infection, although recognition can also occur during cortical infection and development.

STUDIES ON THE LIFE HISTORY OF THE CLUB ROOT ORGANISM, PLASMODIOPHORA BRASSICAE

1944 ◽  
Vol 22c (4) ◽  
pp. 143-149 ◽  
Author(s):  
G. W. Ayers
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Plasmodiophora Brassicae ◽  
Tap Water ◽  
Root Hairs ◽  
Average Diameter ◽  
Root Cells ◽  
Free Moisture ◽  
History Of ◽  
Bacteria And Fungi

In the present studies on Plasmodiophora Brassicae Wor., attention was focussed principally on the development of the zoosporangium and the formation and discharge of the zoospores.Resting spores, released from thoroughly clubbed tissue by the action of bacteria and fungi, germinated well in tap water at room temperature in 1 to 10 days. Germination was hastened by exposure to frost.The zoospores from the resting spores are biflagellate and heterokont, and vary in size. When such a zoospore comes in contact with root hairs or epidermal root cells of cruciferous seedlings, it settles down as an amoeba and penetrates the cell wall to form a young thallus within the host cell. The thallus may or may not become considerably enlarged before the protoplasm undergoes cleavage and an irregular cluster of zoosporangia is formed. Each zoosporangium contains four to eight zoospores, which, at maturity, are discharged from the root hair if free moisture is present; otherwise the fungal protoplasm disintegrates. At ordinary field temperatures, from four to six days are required from infection of the host to the discharge of zoospores from the zoosporangium. Discharge takes place through small openings at the point of contact of the zoosporangia with the cell wall of the root hair. These zoospores when discharged are not more than one-half the average diameter of the zoospores from germinating resting spores.Controlled temperature, studies have shown that temperatures most favourable for the growth of the host are also most favourable for infection. The optimum temperature for infection was about 70° F., the minimum between 54° and 57° F., and the maximum above 92° F. Only two to two and one-half days were needed for the process.

Sequence of events in the germination of the resting spore of Synchytrium endobioticum, European pathotype 2, the causal agent of potato wart disease

1986 ◽  
Vol 64 (9) ◽  
pp. 2144-2150 ◽  
Author(s):  
Michael C. Hampson
Keyword(s):  
Life History ◽  
Causal Agent ◽  
Wart Disease ◽  
Potato Wart ◽  
Synchytrium Endobioticum ◽  
Potato Wart Disease ◽  
Resting Spore ◽  
Sequence Of Events ◽  
Resting Spores ◽  
History Of

Populations of freshly harvested to 4-year-old resting spores of Synchytrium endobioticum (Schilb.) Perc. from sand compost and aqueous immersion cultures were observed, using normal and television microscopy. Germination vesicles were found in aging cultures: at 49 days in sand compost or peaking at the 11th day in aqueous immersion. Freshly harvested spores gave rise to the largest quantity of vesicles in aqueous immersion. The ability to produce vesicles fell off in rapid exponential fashion with time after spore harvest. Release of the sporangia from the enveloping vesicles and discharge of zoospores from sporangia were studied in detail through the use of videotape recordings. This is the first reported description of these phenomena in the life history of S. endobioticum.

scholarly journals II. On the structure and life-history of Entyloma Ranunculi (bonorden)

1887 ◽  
Vol 41 (246-250) ◽  
pp. 318-318
Keyword(s):  
Life History ◽  
Middle Lamella ◽  
White Powder ◽  
Resting Spores ◽  
History Of ◽  
Open Country

The author found plants of Ranunculus Ficaria , the leaves of which were all spotted with white patches; the white patches spread from leaf to leaf, and the disease assumed the nature of an epidemic The rise, progress, and climax .of the disease were observed both on isolated plants and m the open country, and the nature of the lesions in the leaves was made out. Evidence was found to support the view that some plants succumb more rapidly; this evidence was tested, and the circumstances to which the differences are due explained. The white disease-spots contain the extremely delicate mycelium of Entyloma Ranunculi , and the. resting-spores of this fungus (one of the Ustilagineæ) were observed on it. The mycelium is intercellular, and makes its way in the middle lamella between contiguous cells. The white powder on the outside of the disease-spot consisted of conidia, very like those of some Ascomycetes. The author examined the anatomical connexion between the conidia and the resting-spores, and showed that the conidia really belong to the same mycelium —in other words, the conidia are a second kind of spore of the Entyloma .

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil

2019 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Qixing Zhou ◽  
David Feindel ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

AbstractClubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot has been challenging, due largely to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores g-1 soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C and being buried in the soil were better conditions for spore survival than were −20°C, 30°C and at the soil surface. Most of the spores kept on the soil surface were killed, suggesting the negative effect of light on spore viability. Additional experiments confirmed that ultraviolet (UV) light contributed a large negative effect on spore viability as lower pathogenicity and less DNA content were observed from the 2-and 3-hour UV light treated spores compared to the untreated control. Finally, this work demonstrated that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil.

2021 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Hafiz Ahmed ◽  
Qixing Zhou ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

Clubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot is challenging, largely due to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores/g soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C, and being buried in the soil were more conductive conditions for spore survival compared to -20°C, 30°C, and at the soil surface. 99.99% of the spores kept on the soil surface were non-viable, suggesting a negative effect of light on spore viability. Additional experiments confirmed the negative effect of UV light on spore viability as spores receiving 2- and 3-hour UV light exhibited lower disease potential and contained less DNA content compared to the untreated control. Finally, this work confirmed that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

scholarly journals STUDIES IN THE ENTOMOPHTHORACEAE. I. Observations on the genus Conidiobolus

1969 ◽  
Vol 21 (2) ◽  
pp. 191-200
Author(s):  
Arthur G. Kevorkian
Keyword(s):  
Plant Pathology ◽  
Puerto Rico ◽  
Life History ◽  
New Combination ◽  
College Of Agriculture ◽  
Resting Spores ◽  
History Of ◽  
Biometrical Study ◽  
Infection Experiments

A comparative morphological and biometrical study on artificial media, has been made of strains of Conidiobolus villosus obtained from the Farlow Herbarium, the Centraalbureau door Schimmel-cultures, and isolated directly from termites in Cuba. Furthermore, infection experiments have shown that the fungus which has hitherto been considered a saprophyte may adapt itself to a parasitic habit, especially on termites. The Derx strain from Holland, in contrast to the others, appears to be strictly sapro phytic. Moreover, in the life-history of the species in question an additional stage has been observed which consists of the production of minute conidia borne at the tips of the spiny appendages of the villose conidia or "resting spores". For these reasons a new combination, Entomophthora coronata (Cost.) bas been made and Delacroixia coronata and Conidiobolus villosus have been reduced to synonomy. Department of Botany and Plant Pathology, College of Agriculture, Mayagüez, Puerto Rico.

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