Showing papers on "Sclerotinia sclerotiorum published in 1977"

Importance of Coniothyrium minitans in survival of sclerotia of Sclerotinia sclerotiorum in wilted sunflower

Abstract: The relationship between Sclerotinia sclerotiorum, causal agent of wilt or basal stem rot of sunflower (Helianthus annuus L.), and its hyperparasite Coniothyrium minitans was investigated in a sunf...

Purification of an Endo-β-1,4 Galactanase Produced by Sclerotinia sclerotiorum: Effects on Isolated Plant Cell Walls and Potato Tissue

Abstract: BAUER, W. D., D. F. BATEMAN, and C. H. WHALEN. 1977. Purification of an endo-/3-1,4 galactanase produced by Sclerotinia sclerotiorum: effects on isolated plant cell walls and potato tissue. Phytopathology 67: 862-868. Sclerotinia sclerotiorum produces an endo-f3-1,4 enzyme, free of endopolygalacturonase or pectic lyase galactanase when grown in a liquid mineral salts medium activity, readily solubilized substantial amounts of supplemented with 2.0 g of Difco yeast extract and 2.0 g or carbohydrate including a major portion of the galactan 6.0 g D-galactose per liter. This enzyme was purified by CM component from isolated sycamore and potato cell walls. Sephadex ion exchange chromatography and by Sephadex However, endo-/3-1,4 galactanase, at a concentration of 0.3 G-50 and G-75 gel filtration. The purified enzyme has an units/ ml, did not cause maceration of potato tuber tissue isoelectric point of 8.3, a pH optimum of approximately 4.5, disks during a 20-hr exposure at pH 5.0, even though some and a molecular weight of 22,000 to 24,000 daltons. This galactose was released from the tissue. Many phytopathogenic fungi and bacteria produce pectic enzymes are known to be responsible for tissue enzymes capable of hydrolyzing the polymeric maceration (4). During the process of tissue maceration, carbohydrate constituents of higher plant cell walls, cell walls become unable to support the plant protoplast These polysaccharidases are normally inducible, under osmotic stress (2, 32). This dual effect of pectic extracellular, and often highly stable. A number of enzymes on plant tissues gives these enzymes an different cell-wall-degrading enzymes can be readily important role in many types of tissue decay. The detected in plant tissues infected with facultative depletion or alteration of cell wall polysaccharides pathogens (4). following pathogenic infection has been demonstrated in When grown on plant cell wall material, plant a number of suscept-pathogen systems (3, 16, 25). Aside pathogens commonly produce a variety of from the pectic enzymes and cellulase, the specific polysaccharidases (6, 13, 19, 29). The principal kinds of contributions of individual cell-wall-degrading enzymes enzymes produced are believed to correspond to the to plant cell wall or tissue breakdown are poorly major types of glycosidic linkages present in the understood. The current view of primary cell wall polysaccharides of the plant cell wallrmaterial used as the structure holds that an arabinogalactan containing 03-1,4 carbon source. There is evidence that the monosaccharide linked galactose is a key constitutent linking the or oligosaccharide fragments formed by enzymatic rhamnogalacturonan fraction to the hemicellulosic hydrolysis of a particular polysaccharide can serve as fraction in primary cell walls (21). The availability of a effective inducers of specific hydrolases, or of a set of purified endo-f3-1,4 galactanase could aid structural related enzymes (11). Recent studies in which isolated studies of plant cell walls as well as permit studies on the plant cell walls have been used as carbon sources for plant role of galactanases in cell-wall degradation. pathogens, suggest that the cell-wall-degrading enzymes This is a report of the partial purification and may be produced in a temporal sequence, with properties of an endo-3-1,4 galactanase produced by polygalacturonases being first and cellulases being last in Sclerotinia sclerotiorum, and the effects of this enzyme on the sequence (13, 19, 29). isolated plant cell walls and potato tissue. A preliminary Highly purified preparations of report of this work has been published (7). endopolygalacturonases and endoglucanases (cellulase) have proven to be useful tools in the elucidation of higher MATERIALS AND METHODS plant cell wall structure (8, 21, 33). Purified endo-pectic enzymes readily degrade isolated plant cell walls. The Substrates and chemicals.-Lupine galactan was action of these enzymes on isolated cell walls appears to isolated from the seeds of Lupinus albus by the method of render the nonuronide polymers more accessible or Jones and Tanaka (18). Soy galactan was prepared from susceptible to hydrolysis by other enzymes (20, 33). The soybean flour as described by Morita (26). Pectin and sodium polypectate were obtained from Sunkist Copyright © 1977 The American Phytopathological Society, 3340 Growers, Inc., Sherman Oaks, CA 91403; and Pilot Knob Road, St. Paul, MN 55121. All rights reserved. carboxymethyl cellulose (type 7MP) from Hercules

A preliminary study of the influence of water potential on sclerotium germination in Sclerotinia sclerotiorum

Abstract: Sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary buried in a heavy clay soil at 15 °C germinated over a range of moisture levels from 15% to 50%. A method of germinating sclerotia held at constant matric water potentials was tested. Sclerotia were placed in soil in bags of a semipermeable membrane; the bags were immersed in solutions of polyethylene glycol 20 000.Germination occurred between 0 and −7.5 bars but not at lower potentials.

Morphogenesis in sclerotium-forming fungi

Abstract: SUMMARY Sclerotium production by Sclerotinia sclerotiorum (Lib.) de Bary, Sclerotium rolfsii Sacc. and S. delphinii Welch was enhanced by white light, the most effective wavelengths being in the blue and near-ultraviolet regions of the spectrum. Sensitivity of dark-grown cultures to light decreased with age. The effect of light appeared to be through the direct induction of sclerotium initials on undifferentiated hyphae. The relevance of these observations to the general study of sclerotium morphogenesis is discussed.

Induction of Sclerotium formation by acid staling compounds in Sclerotinia sclerotiorum and Sclerotium rolfsii

Abstract: Sterile medium staled by the growth of Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotium rolfsii Sacc. enhanced sclerotium production when applied to test colonies, the active components being acidic and heat stable. In S. sclerotiorum, sclerotium production appeared to be associated with secretion of organic acids, and two unidentified acids with morphogenetic properties were isolated from staled medium.

Severity of Sclerotinia Blight of Peanuts as Detected By Infrared Aerial Photography

Abstract: The severity of Sclerotinia sclerotiorum as detected on aerial infrared photography was correlated with actual yield losses in the field. Peanut pod losses in the soil increased as disease severity became more pronounced as determined by imagery interpretation. In areas of fields on the imagery interpreted to be slightly, moderately and severely infected with S. sclerotiorum, pod losses due to infection were 2, 5 and 7 times greater, respectively, than normally expected losses in nondiseased areas (ca. 300 kg/ha). Sclerotial populations were 10 times greater in soil from severely infested areas on the field than from slightly and noninfested areas.

Effects of leaf maturation on development of the Sclerotinia/Botrytis complex of tobacco

Abstract: In field experiments natural infection of tobacco leaves by Botrytis cinerea Pers. ex Fr. and Sclerotinia sclerotiorum de Bary did not usually occur until approximately 2 weeks after the leaves had completed their main phase of expansion. Exceptions were infections originating from senescing corollas that had lodged on the leaves, but these early infections represented only a small proportion of the total infections that originated from fallen corollas. The age of a leaf at the time of infection was related to its position on the plant, a relationship affected by the “topping” and “suckering” treatment applied. When all the flowers were allowed to develop, the upper leaves became infected when they were slightly younger than the middle leaves, but when all the flower buds were removed at an early stage of development, leaf age at the time of infection increased with ascending leaf position. Infection spread faster in the lamina of old leaves than in that of young leaves. Sclerotinia destroyed lam...

Survey on the fruit rot occurrence and damages of shipping mandarin.

Abstract: Penicillium digitatum SACCARD, P. italicum WEHMER, Botrytis cinerae PERSOON and Sclerotinia sclerotiorum MASSE. were the main storage diseases on the cold injured mandarin at Jeju in 1975. The losses observed through the materials used were which consists of by diseases and by water rot as the result of cold and snow damages at harvest stage in Jeju. The total amount of damages estimated at shipping stage were 915M/T in value of 135 million Won from the rot waste of 675M/T by the end of 1975. Since cold injury is known as the main factor of the fruit rot, shipping and storage process as well as disease control measures are discussed.