Beitrag zur Protomitose bei Polymyxa betae Keskin

Zusammenfassung Es werden elektronenoptische Bilder der Protomitose erstmalig am Beispiel von Polymyxa betae dargestellt und erläutert

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Contribution to protomitosis in Polymyxa betae Keskin

Summary Electronoptic pictures of the metaphase during protomitosis in the fungus Polymyxa betae are demonstrated.

     

Evaluation of Polymyxa betae Keskin Contaminated by Beet Necrotic Yellow Vein Virus in Soil

The fungus Polymyxa betae Keskin belongs to the family Plasmodiophoraceae and lives in the soil as an obligatory parasite of the roots of the Chenopodiaceae. When contaminated by beet necrotic yellow vein virus, this viruliferous fungus causes a serious disease of sugar beet known as rhizomania, whereas the infection by the fungus alone (aviruliferous fungus) causes only slight damage to the plant with little economic consequence. The manifestation of rhizomania in sugar beet is directly related to the concentration of infecting units of viruliferous P. betae present in the soil. (One infecting unit is a group of one or more sporosori that liberate zoospores capable of visibly infecting a plant.) By using current methods of analysis, it is possible to estimate the total quantity of P. betae present in the soil, but one cannot distinguish quantitatively the infecting units of aviruliferous from viruliferous P. betae. A new method has been developed based on the technique of the most probable number and enzyme-linked immunosorbent assay to estimate the concentration of infecting units of viruliferous P. betae in soil. The method is suitable for the routine analysis of numerous soil samples and allows one to estimate the concentration of viable forms of the fungus P. betae, whether or not contaminated by beet necrotic yellow vein virus, present in a soil affected by rhizomania or presumed healthy. The analyses performed with this method are economical and use a reagent kit and equipment in wide use.     

Virus Content and Virulence of Polymyxa betae Keskin Isolates Obtained from Different Regions in Europe

Polymyxa betae isolates were obtained by means of bait plants from a large number of soil samples collected in eastern Germany. Additional P. betae isolates were received from several institutions in western Germany and abroad. Isolates were grown on sugarbeet seedlings and tested for the presence of beet necrotic yellow vein virus (BNYVV) and beet soilborne virus (BSBV). BNYVV was only present in isolates from western Germany and abroad but absent in all isolates from eastern Germany., In contrast, BSBV was detected in more uniform geographic distribution in 14 out of 33 P. betae isolates tested. The virulence of P. betae isolates was estimated on the basis of the extent of resting spore formation in the root system of sugarbeet seedlings. Differences in virulence were found among virus-free as well as virus-carrying P. betae isolates. The mean value of virulence ratings was distinctly lower with BNYVV-carrying isolates and slightly lower with BSBV-carrying isolates as compared to virus-free isolates.     

Der Infektionsvorgang bei Polymyxa betae

Zusammenfassung Die früher beschriebene Stilettbildung bei der Infektion von Polymyxa betae wird auf Grund elektronenoptischer Aufnahmen näher untersucht. Es zeigt sich, daß bei dieser Art ein besonders ausgebildetes Infektionsorgan vorliegt, aus dem ein als Stachel bezeichneter Körper in die Wirtszelle eindringt.

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The process of infection by Polymyxa betae

Summary In zoospores of Polymyxa betae, attached to the root surface of the host plant, before infection a tubular structure is formed which points with its open site towards the host and extends into the interior of the spore. Within this tube an osmiophilic missile or bullet-like body is visible which is found after the infection within the host cell.

     

Parassitismo di Trichoderma harzianum su cistosori di Polymyxa betae

Parasitism of Trichoderma harzianum on Cystosori of Polymyxa betae Transmission electron microscope investigations revealed that cystosori of Polymyxa betae Keskin are, in vitro conditions, parasitized and completely degraded by Trichoderma harzianum Rifai. The hyperparasite showed a high ability in colonizing excised, surface-sterilized lateral roots of sugar beet and in invading the cystosori present in them. Both the walls of the root cells and of the cysts are enzymatically perforated. However, in cysts penetration, mechanical forces are also involved. After penetration, cysts undergo a rapid degradation and finally they appear to be completely empty or to contain only small amounts of degradated cytoplasm. Cyst walls are also strongly altered and deformed and only two thin osmiophylic residual layers are detectable.     

Zur Verbreitung von Nachtigall und Sprosser in Mecklenburg 1954

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Use of the Most-Probable-Number Technique To Detect Polymyxa betae (Plasmodiophoromycetes) in Soil

The fungus Polymyxa betae is an obligate parasite of the roots of many plants of the family Chenopodiaceae. In the sugar beet, it acts as a vector of beet necrotic yellow vein virus, the agent of a serious disease known as rhizomania. With indirect methods of analysis, such as bioassay, one can establish only the presence or absence, but not the quantity, of P. betae in soil. A new method based on the technique of the most probable number (MPN) of infective units of P. betae present in the soil was developed on the basis of the biological characteristics of this microorganism. Compared with traditional bioassay methods, the MPN method is suitable for determining the contamination level of P. betae in a soil, and it appears promising for the routine analysis of many soil samples, whether they were affected by rhizomania or presumed noninfested. The instrumentation designed especially for the recovery of viable P. betae from soil with the MPN technique is made from commercially available materials, results in a saving of space during sample incubation, and permits this method to be used for any laboratory analysis.     

Zur Verbreitung derVeronica grandis Fisch

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Zur Verbreitung desSerinus luteolus

Ohne Zusammenfassung     

Zur alpinen Verbreitung derChrysomyxa Abietis Ung

Ohne Zusammenfassung     

Zur Verbreitung und Teratologie vonTypha undSparganium

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Eradication of Polymyxa betae by Thermal and Anaerobic Conditions and in the Presence of Compost Leachate

The abiotic conditions required for eradication of Polymyxa betae, the vector of Beet necrotic yellow vein virus in sugar beet, were investigated. Survival of resting spores of P. betae was determined under aerobic (30 min, 4 days and 21 days) and anaerobic (4 days) conditions under several temperature regimes in a water suspension and in leachate extracted from an aerobic compost heap. In water under aerobic conditions the lethal temperature was 60, 55 and 40°C for exposure times of 30 min, 4 days and 21 days, respectively. The effect of compost leachate and/or anaerobic conditions on survival of P. betae depended on temperature. After incubation for 4 days at 20°C, no significant effects of anaerobic conditions or leachate on the survival of P. betae were found. However, at 40°C for 4 days under anaerobic conditions, survival of P. betae was significantly lower than survival under aerobic conditions in water as well as in leachate. In leachate taken from an aerobic compost heap, aerobically incubated at 40°C for 4 days, survival of P. betae was significantly lower than survival in water at the same temperature. As anaerobic spots are prevalent in aerobic compost heaps, especially during the thermophilic phase, actual inactivation temperatures under composting conditions are likely to be lower than the temperatures we found for eradication in water under aerobic conditions.     

Studies on the Biology of Polymyxa betae, the Vector of Beet Necrotic Yellow Vein Virus

The development of Polymyxa betae within the roots of a sugar beet variety susceptible to Rhizomania was observed in hydroponic culture over a period of 10 days. Light microscope studies showed that at an average temperature of 20 °C the life cycle of the fungus, containing beet necrotic yellow vein virus (BNYW), was completed within 10 days. A change from the multiplication phase to the survival phase of P. betae became evident. At the beginning of the life cycle the fungus produced mainly zoospores whereas at a later stage plasmodia developed into resting spores. Zoospore density in the nutrient solution reached a maximum between the 5th and 7th day after inoculation and then declined to the initial concentration. The number of zoospores attached to the root surface increased progressively at 48 h intervals, correlated with a parallel increase in BNYW-content of the roots. Light- and fluorescence microscopy revealed that zoospores of P. betae often attach near the point of release and do not move very long distances. In addition it became evident that zoospores may attach to the thallus wall inside the zoosporangium that they have developed in.     

Characteristics of Serially Produced Zoospore Suspensions of Polymyxa betae for Transmission of Beet Necrotic Yellow Vein Virus

Zoospore suspensions of Polymyxa betae were analysed for their potential as inocula to infect sugar beet plants with beet necrotic yellow vein furovirus. The infectivity could be maintained when zoospore suspensions were serially transferred. When zoospore-producing seedlings were individually transferred some of these seedlings lost their infectivity after several passages. Infectivity was first detected in suspensions within I day after inoculation of the plant by zoospores. The suspensions remained infectious for at least 10 h after removal of the plants producing viruliferous zoospores. Both the number of test plants infected and the concentration of virus that developed were greater at 25 C than at 20 C.     

Die Verbreitung von Protoporphyrin in Vogeleischalen

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