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1.
Forecasting sclerotinia disease on lettuce: toward developing a prediction model for carpogenic germination of sclerotia 总被引：1，自引：0，他引：1
ABSTRACT The feasibility of developing a forecasting system for carpogenic germination of Sclerotinia sclerotiorum sclerotia was investigated in the laboratory by determining key relationships among temperature, soil water potential, and carpogenic germination for sclerotia of two S. sclerotiorum isolates. Germination of multiple burials of sclerotia to produce apothecia also was assessed in the field with concurrent recording of environmental data to examine patterns of germination under different fluctuating conditions. Carpogenic germination of sclerotia occurred between 5 and 25 degrees C but only for soil water potentials of >/=-100 kPa for both S. sclerotiorum isolates. Little or no germination occurred at 26 or 29 degrees C. At optimum temperatures of 15 to 20 degrees C, sclerotia buried in soil and placed in illuminated growth cabinets produced stipes after 20 to 27 days and apothecia after 27 to 34 days. Temperature, therefore, had a significant effect on both the rate of germination of sclerotia and the final number germinated. Rate of germination was correlated positively with temperature and final number of sclerotia germinated was related to temperature according to a probit model. Thermal time analysis of field data with constraints for temperature and water potential showed that the mean degree days to 10% germination of sclerotia in 2000 and 2001 was 285 and 279, respecttively, and generally was a good predictor of the observed appearance of apothecia. Neither thermal time nor relationships established in the laboratory could account for a decline in final percentage of germination for sclerotia buried from mid-May compared with earlier burials. Exposure to high temperatures may explain this effect. This, and other factors, require investigation before relationships derived in the laboratory or thermal time can be incorporated into a forecasting system for carpogenic germination. 相似文献
2.
Extensive studies have been conducted on the carpogenic germination of Sclerotinia sclerotiorum, but carpogenic germination in S. minor has not been studied adequately. It remains unclear why apothecia of this pathogen have seldom been observed in nature. In this study, a new method was developed to produce apothecia in the absence of soil or sand, and carpogenic germination without preconditioning was recorded for 95 of the 96 S. sclerotiorum isolates tested. Carpogenic germination of the two species was compared under a variety of temperature, soil moisture, burial depths, and short periods of high temperature and low soil moisture. The optimal temperatures for rapid germination and for maximum germination rates were both lower for S. minor than for S. sclerotiorum. The temperature range for carpogenic germination was also narrower for S. minor than for S. sclerotiorum. A 5-day period at 30 degrees C, either starting on the 10th or 20th day of incubation, did not significantly affect carpogenic germination of S. sclerotiorum. For both S. minor and S. sclerotiorum, the percentage of carpogenically germinated sclerotia increased as soil water potential increased from -0.3 to -0.01 MPa. In the greenhouse, a 10- or 20-day dry period completely arrested carpogenic germination of S. sclerotiorum, and new apothecia appeared after an interval of 35 days following rewetting, similar to the initial carpogenic germination regardless of when the dry period was imposed. In naturally infested fields, the number of sclerotia in 100 cc of soil decreased as depth increased from 0 to 10 cm before tillage, but became uniform between 0 and 10 cm after conventional tillage for both species. Most apothecia of S. minor were, however, produced from sclerotia located at a depth shallower than 0.5 cm while some apothecia of S. sclerotiorum were produced from sclerotia located as deep as 4 to 5 cm. These results provide the much needed information to assess the epidemiological roles of inoculum from sexual reproduction in diseases caused by the two Sclerotinia species in different geographical regions. However, more studies on effects of shorter and incompletely dry periods are still needed to predict production of apothecia of S. sclerotiorum in commercial fields under fluctuating soil temperature and moisture. 相似文献
3.
The effects of different inocula of the mycoparasite Coniothyrium minitans on carpogenic germination of sclerotia of Sclerotinia sclerotiorum at different times of year were assessed. A series of three glasshouse box bioassays was used to compare the effect of five spore-suspension inocula of C. minitans , including three different isolates (Conio, IVT1 and Contans), with a standard maizemeal–perlite inoculum. Apothecial production, as well as viability and C. minitans infection of S. sclerotiorum sclerotia buried in treated soil, were assessed. Maizemeal–perlite inoculum at 107 CFU per cm3 soil reduced sclerotial germination and apothecial production in all three box bioassays, decreasing sclerotial recovery and viability in the second bioassay and increasing C. minitans infection of sclerotia in the first bioassay. Spore-suspension inocula applied at a lower concentration (104 CFU per cm3 soil) were inconsistent in their effects on sclerotial germination in the three box bioassays. Temperature was an important factor influencing apothecial production. Sclerotial germination was delayed or inhibited when bioassays were made in the summer. High temperatures also inhibited infection of sclerotia by C. minitans . Coniothyrium minitans survived these high temperatures, however, and infected the sclerotia once the temperature decreased to a lower level. Inoculum level of C. minitans was an important factor in reducing apothecial production by sclerotia. The effects of temperature on both carpogenic germination of sclerotia and parasitism of sclerotia by C. minitans are discussed. 相似文献
4.
ABSTRACT A predictive model for production of apothecia by carpogenic germination of sclerotia is presented for Sclerotinia sclerotiorum. The model is based on the assumption that a conditioning phase must be completed before a subsequent germination phase can occur. Experiments involving transfer of sclerotia from one temperature regime to another allowed temperature-dependent rates to be derived for conditioning and germination for two S. sclerotiorum isolates. Although the response of each isolate to temperature was slightly different, sclerotia were fully conditioned after 2 to 6 days at 5 degrees C in soil but took up to 80 days at 15 degrees C. Subsequent germination took more than 200 days at 5 degrees C and 33 to 52 days at 20 degrees C. Upper temperature thresholds for conditioning and germination were 20 and 25 degrees C, respectively. A predictive model for production of apothecia derived from these data was successful in simulating the germination of multiple burials of sclerotia in the field when a soil water potential threshold of between -4.0 and -12.25 kilopascals (kPa) was imposed. The use of a germination model as part of a disease forecasting system for Sclerotinia disease in lettuce is discussed. 相似文献
5.
ABSTRACT Sclerotial germination of three isolates each of Sclerotinia minor and S. sclerotiorum was compared under various soil moisture and temperature combinations in soils from Huron and Salinas, CA. Sclerotia from each isolate in soil disks equilibrated at 0, -0.03, -0.07, -0.1, -0.15, and -0.3 MPa were transferred into petri plates and incubated at 5, 10, 15, 20, 25, and 30 degrees C. Types and levels of germination in the two species were recorded. Petri plates in which apothecia were observed were transferred into a growth chamber at 15 degrees C with a 12-h light-dark regime. All retrievable sclerotia were recovered 3 months later and tested for viability. Soil type did not affect either the type or level of germination of sclerotia. Mycelial germination was the predominant mode in sclerotia of S. minor, and it occurred between -0.03 and -0.3 MPa and 5 and 25 degrees C, with an optimum at -0.1 MPa and 15 degrees C. No germination occurred at 30 degrees C or 0 MPa. Soil temperature, moisture, or soil type did not affect the viability of sclerotia of either species. Carpogenic germination of S. sclerotiorum sclerotia, measured as the number of sclerotia producing stipes and apothecia, was the predominant mode that was affected significantly by soil moisture and temperature. Myceliogenic germination in this species under the experimental conditions was infrequent. The optimum conditions for carpogenic germination were 15 degrees C and -0.03 or -0.07 MPa. To study the effect of sclerotial size on carpogenic germination in both S. minor and S. sclerotiorum, sclerotia of three distinct size classes for each species were placed in soil disks equilibrated at -0.03 MPa and incubated at 15 degrees C. After 6 weeks, number of stipes and apothecia produced by sclerotia were counted. Solitary S. minor sclerotia did not form apothecia, but aggregates of attached sclerotia readily formed apothecia. The number of stipes produced by both S. minor and S. sclerotiorum was highly correlated with sclerotial size. These results suggest there is a threshold of sclerotial size below which apothecia are not produced, and explains, in part, why production of apothecia in S. minor seldom occurs in nature. 相似文献
6.
The rate of conidiogenic germination of Botrytis squamosa was highest at 16°C and the greatest numbers of conidia per sclerotium (up to 5 × 104 ) were produced at temperatures of 5–10°C. At temperatures above 20°C, the percentage of sclerotia producing conidia declined rapidly. Decreasing water potential reduced the rate at which conidia were produced and also resulted in fewer conidia produced per sclerotium. However, conidia were produced at water potentials as low as −2 MPa, at which sclerotial germination was at least 60%. A simulation model that included effects of both temperature and water potential was developed from laboratory and field data obtained for conidial production in sclerotia exposed for periods of 1, 2, 3 or 4 weeks during an entire year. There was good agreement between conidiogenic germination predicted by the model and conidial production observed in onion plots artificially inoculated with sclerotia. Temperature and water potential were therefore considered to be the principal microclimatic factors affecting conidial production by B. squamosa. The role of sclerotia in the context of UK onion production is discussed. 相似文献
7.
The effects ofSclerotinia sclerotiorum live and autoclaved sclerotia, and sclerotial exudates, and commercial oxalic acid were testedin vitro on sevenConiothyrium minitans strains differing in aggressiveness towardsS. sclerotiorum. Only sclerotial exudates and autoclaved sclerotia affected the mycelial growth rate of almost all the strains tested, whereas
a change in theC. minitans mycelial growth pattern was observed in the presence of autoclaved sclerotia and live sclerotia germinating by the myceliogenic
eruptive germination. In addition, sclerotial exudates had a stimulatory effect on spore germination. These findings indicate
that the various treatments could influence theC. minitans strains regardless of their aggressiveness. 相似文献
8.
Sj. J. Gerbrandy 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(6):319-326
The effects of various storage temperatures on germination of sclerotia ofSclerotium cepivorum Berk. were investigated. Sclerotia buried in soil for 10 weeks at temperatures of 5 and 10 °C were conditioned to a fast germination. When germination was performed at 15 °C and induced byAllium extracts, 50% of these sclerotia germinated within 10 days and the total of germination was over 90%. Sclerotia buried at temperatures of 15, 20 and 25 °C were conditioned to a slow germination. About 50% of these sclerotia could be induced to germinate at 15 °C byAllium extracts. The conditioning by high or low temperatures proved to be reversible.The optimum temperature for germination of the cold (5°C) conditioned sclerotia was 10–20 °C. The optimum temperature for germination of sclerotia conditioned at 20 °C was about 10 °C. WithoutAllium extracts 90%, 80%, 50% and 40% of the sclerotia stored at 5 °C, germinated at temperatures of 10, 5, 15 and 20 °C respectively. Sclerotia stored at 20 °C did not germinate withoutAllium extracts at any temperature.Samenvatting Sclerotiën vanSclerotium cepivorum Berk. werden onder niet steriele omstandigheden bewaard bij verschillende temperaturen. Het effect van de bewaring bij verschillende temperaturen op de kieming werd onderzocht. Het bleek dat sclerotiën, die 70 dagen bewaard werden in zakjes met zand in niet steriele grond bij een temperatuur van 5 °C of 10 °C, geconditioneerd werden tot een snelle, vrijwel volledige kieming. Onder invloed van vluchtige stoffen uit gesnipperde ui en knoflook kiemden meer dan 90% van deze sclerotiën bij een temperatuur van 15 °C. Sclerotiën die bij een hogete temperatuur bewaard werden, namelijk bij 15, 20 of 25 °C, kiemden na de bewaarperiode langzaam bij 15 °C. Ongeveer 50% van deze sclerotiën konden tot kieming gebracht worden onder invloed van ui- en knoflookextract. Sclerotiën die door een koude bewaarperiode geconditioneerd waren, namelijk bij 5 of bij 10 °C, kiemden ook zonder ui-en knoflookextract; 78% en 90% van deze sclerotiën kiemden bij temperaturen van respectievelijk 5 en 10 °C. De sclerotiën die een warme bewaarperiode ondergaan hadden, namelijk bij 15, 20 of 25 °C, kiemden niet zonder ui en knoflook. De optimum temperatuur voor de kieming was 15–20 °C voor sclerotiën die bij 5 °C bewaard waren. De optimum temperatuur voor de kieming van sclerotiën die bij 20 °C bewaard waren was lager, en wel ca. 10 °C.De conditionering door een hoge of door een lage bewaartemperatuur bleek reversibel te zijn. Sclerotiën die eerst bij 5 °C bewaard werden en daarna bij 20 °C onderscheidden zich niet van sclerotiën die continu bij 20 °C bewaard werden. Sclerotiën die eerst bij 20 °C bewaard werden en vervolgens bij 5 °C, kiemden als sclerotiën die continu bij 5 °C bewaard waren. 相似文献
9.
ABSTRACT The relationship of cumulative chill-hours (hours with a mean temperature <7.2 degrees C) and heating degree-days (base 7.2 degrees C) to carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi, which causes mummy berry disease of blueberry, was investigated. In two laboratory experiments, pseudosclerotia collected from rabbiteye blueberry in Georgia were conditioned at 5 to 6 degrees C for 26 to 1,378 h prior to placement in conditions favorable for germination and apothecium development. The number of chill-hours accumulated during the conditioning period affected the subsequent proportion of pseudosclerotia that germinated and produced apothecia, with the greatest incidence of carpogenic germination occurring after intermediate levels of chilling ( approximately 700 chill-hours). The minimum chilling requirement for germination and apothecium production was considerably lower than that reported previously for pseudo-sclerotia from highbush blueberry in northern production regions. The rate of carpogenic germination was strongly affected by interactions between the accumulation of chill-hours and degree-days during the conditioning and germination periods; pseudosclerotia exposed to prolonged chilling periods, once transferred to suitable conditions, germinated and produced apothecia more rapidly (after fewer degree-days had accumulated) than those exposed to shorter chilling periods. Thus, pseudosclerotia of M. vaccinii-corymbosi are adapted to germinate carpogenically following cold winters (high chill-hours, low degree-days) as well as warm winters (low chill-hours, high degree-days). Results were validated in a combined field-laboratory experiment in which pseudosclerotia that had received various levels of natural chilling were allowed to germinate in controlled conditions in the laboratory, and in two field experiments in which pseudosclerotia were exposed to natural chilling and germination conditions. A simple model describing the timing of apothecium emergence in relation to cumulative chill-hours and degree-days was developed based on the experiments. The model should be useful for better timing of field scouting programs for apothecia to aid in management of primary infection by M. vaccinii-corymbosi. 相似文献
10.
Effect of Coniothyrium minitans on sclerotial survival and apothecial production of Sclerotinia sclerotiorum in field-grown oilseed rape 总被引：6，自引：0，他引：6
M. P. McQUILKEN S. J. MITCHELL S. P BUDGE J. M. WHIPPS J. S. FENLON S. A. ARCHER 《Plant pathology》1995,44(5):883-896
In two field trials with oilseed rape, Coniothyrium minitans was applied to soil as a maizemeal-perlite preparation in order to determine its effect on sclerotial survival and apothecial production of Sclerotinia selerotiorum. The mycoparasite infected sclerotia and decreased sclerotial survival, carpogenic germination and production of apothecia. Effects were greatest when inoculum of C. minitans was applied in autumn, at the time of sowing, rather than when it was applied in spring. C. minitans survived in soil for 2 years and spread to adjacent control plots and infected sclerotia within those plots. However, despite the fact that the inoculum potential of S. selerotiorum was reduced by C. minitans treatment, no disease control was obtained either in trial 1, where disease levels were low (0-20% of plant stems affected), or in trial 2, where disease levels were high (up to 70% of plant stems affected). Possible reasons for this failure of C minitans to control sclerotinia disease in oilseed rape, and strategies to improve its efficacy in the field, are discussed. 相似文献
11.
Sj J. Gerbrandy 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(5):269-276
The variability of dormancy of sclerotia of ten isolates ofSclerotium cepivorum was investigated. Of all isolates tested, the freshly harvested sclerotia were dormant. After drying for 48 hours the sclerotia of six isolates were able to germinate, two isolates stayed dormant and two isolates were infested by hyperparasitic fungi. After storage in soil at 5°C or 20°C, the sclerotia of the different isolates exhibited considerable differences in respect to germination capability, but all isolates showed highest germination after a treatment of 8 weeks at 20°C followed by 8 weeks at 5°C. The sclerotia of all isolates showed an increased capacity to germinate withoutAllium extracts at 10°C after pretreatment at 30°C for 28 days. 相似文献
12.
M. P. McQuilken J. M. Whipps 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(1):101-110
Coniothyrium minitans grew on all ten solid-substrates (barley, barley-rye-sunflower, bran-vermiculite, bran-sand, maizemed-perlite, millet, oats, peat-bran, rice and wheat) tested, producing high numbers of germinable pycnidiospores (1.9–9.3×108 g–1 air dry inocula). All solid substrate inocula survived better in the laboratory at 5 and 15 °C than at 30 °C for at least 64 weeks.In pot bioassays carried out in the glasshouse and field, soil incorporations of each inoculum almost completely inhibited carpogenic germination ofS. sclerotiorum. In the field bioassay, no sclerotia were recovered after 38 weeks fromC. minitans-treated pots compared to 56% from control pots. In the glasshouse bioassay, 9–30% of sclerotia were recovered after 20 weeks fromC. minitans-treated pots, but 88–100% of these were infected by the antagonist. The antagonist also spread to infect sclerotia in control pots.In larger scale glasshouse trials, single preplanting soil-incorporations of five inocula (barley-ryesunflower, maizemeal-perlite, peat-bran, rice and wheat) controlled Sclerotinia disease in a sequence of lettuce crops, with only small differences between the types of inocula tested. At harvest,C. minitans reduced sclerotial populations on the soil surface and over 74% of sclerotia recovered fromC. minitans-treated plots were infected by the antagonist.C. minitans survived in soil in all solid-substrate inocula-treated plots for at least 39 weeks at levels of 104–105 colony forming units cm–3 soil and spread to infect over 36% of sclerotia recovered from control plots. 相似文献
13.
采用菌丝生长速率法测定了四霉素对采自山东省不同地区不同蔬菜作物的151株菌核病菌的毒力作用,同时比较了其对蔬菜菌核病菌不同生育阶段的抑制活性,并通过离体叶片法评价了四霉素对蔬菜菌核病的防治效果。结果表明:菌核病菌对四霉素比较敏感,敏感性频率呈单峰正态分布,151株病菌菌丝生长的平均EC50值为 (0.29 ± 0.01) μg/mL,该值可作为蔬菜菌核病菌对四霉素的敏感基线。此外,经四霉素处理后,该病菌的菌核数量以及干重明显降低,菌核明显变小;2 μg/mL的处理对菌核萌发的抑制率达到100.00%。 离体黄瓜叶片接种试验表明,四霉素对菌核病具有较好的保护和治疗效果,且保护作用较为显著。在质量浓度为20 μg/mL时,四霉素对该病的防效显著高于对照药剂多菌灵和异菌脲。因此,四霉素具有防治蔬菜菌核病的潜在价值,可进一步通过田间试验验证其应用效果。 相似文献
14.
15.
Effect of Inoculum Rates and Sources of Coniothyrium minitans on Control of Sclerotinia sclerotiorum Disease in Glasshouse Lettuce 总被引：1，自引：0，他引：1
E.E. Jones J.M. Whipps 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(6):527-538
Coniothyrium minitans isolate Conio grew on both maizemeal-perlite and ground maizemeal-perlite, producing high numbers (1.6×107 conidiag–1 inoculum) of germinable conidia. Coniothyrium minitans isolate Conio applied as a preplanting soil incorporation of maizemeal-perlite inoculum at full application rate (0.6lm–2; 1011 colony forming units (cfu)m–2) significantly reduced Sclerotinia disease in a sequence of three lettuce crops grown in a glasshouse. No reduction in disease was achieved with any of the reduced rate treatments (108cfum–2) of a range of C. minitans isolates (Conio ground maizemeal-perlite at reduced rate, Conio and IVT1 spore suspensions derived from maizemeal-perlite, IVT1 spore suspension derived from oats and Contans® WG spore suspension). After harvest of the second and third crops, C. minitans maizemeal-perlite at full rate reduced the number and viability of sclerotia recovered on the soil surface and increased infection by C. minitans compared with spore suspension and reduced rate maizemeal-perlite inocula. Coniothyrium minitans was recovered from the soil throughout the trial, between 105 and 107cfucm–3 in maizemeal-perlite inoculum full rate treated plots and 101–104cfu cm–3 in all other inoculum treated plots.Pot bioassays were set up corresponding to the inoculum used in the glasshouse, with the addition of Conio ground maizemeal-perlite at a rate corresponding to the full rate maizemeal-perlite. Coniothyrium minitans maizemeal-perlite and ground maizemeal-perlite at full rate significantly decreased carpogenic germination, recovery and viability of sclerotia and increased infection of sclerotia by C. minitans in comparison with spore suspension treatments, reflecting results of the glasshouse trials. Additionally, reduced maizemeal-perlite treatment also decreased apothecial production, recovery and viability of sclerotia compared with the spore suspension treatment, despite being applied at similar rates. Simultaneous infection of sclerotia by several isolates of C. minitans was demonstrated. Inoculum level in terms of colony forming unitscm–3 of soil appears to be a key factor in both control of Sclerotinia disease and in reducing apothecial production by sclerotia. 相似文献
16.
番茄茎基腐病病原菌的生物学特性 总被引：1，自引：0，他引：1
对番茄茎基腐病病原菌生物学特性研究结果表明:病菌菌丝在供试PDA、PSA、2%水琼脂、Richard、番茄煎汁、燕麦片和番茄燕麦等7种培养基中均能良好生长,而在2%水琼脂培养基上生长较为缓慢;菌丝在2～32℃范围内均能生长,最适20℃,致死温度为50℃,10min;菌丝生长的pH范围为3～10,最适为5～7;光照对菌丝生长影响较小。病菌在7种供试培养基上均能产生菌核;菌核在10种供试营养物质中均能萌发,萌发温度范围为5～30℃,最适20℃,致死温度为59℃,10min;菌核萌发pH范围为3～10,最适为7。 相似文献
17.
Dirk Jan van der Gaag Herman D. Frinking 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(6):573-580
The effects of host plant exudates, light and temperature on germination of oospores of Peronospora viciae f.sp. pisi in vitro were investigated. Seed and root exudates did not increase percentage germination, whereas light inhibited germination. The first germ tubes appeared after 4, 7, and 14 days of incubation at 15, 10 and 5 °C, respectively. The eventual level of germination was highest and had similar values at 5 and 10 °C. At 20 °C germination was poor and at 25 °C no germination was observed. Oospores placed on membrane filters were incubated on soil. When oospores were retrieved from the membrane filters after six days and placed in water at 10 °C, they germinated within 2 days. On soil significantly less oospores germinated than in water. Germinability of oospores stored in the dark at 5 or 20 °C at 30 or 76% RH was studied over a two-year period. Germinability generally increased over time, but fluctuations were observed indicating the occurrence of secondary dormancy. Time courses of germinability were generally similar for oospores stored at several temperatures and humidities. No effect of light on time course of germinability was found when oospores were exposed to alternating light-dark periods or stored in continuous dark for 140 days. Percentage germination observed in a germination assay was correlated with percentage infection determined in a bioassay. 相似文献
18.
Role of temperature in regulating timing of germination in soil seed reserves of Lamium purpureum L.
Fresh seeds of Lamium purpureum L. were dormant at maturity, and when buried and exposed to natural seasonal temperature changes they exhibited an annual dormancy/non-dormancy cycle. During burial in summer, fresh seeds and those that had been buried for 1 year afterripened and thus were non-dormant by September and October; light was required for germination. During autumn and winter seeds re-entered dormancy, and during the following summer they became non-dormant again. Dormant seeds afterripened when buried and stored over a range of temperatures, becoming conditionally dormant at low (5, 15/6°C) and non-dormant at high (20/10, 25/15, 30/15 and 35/20°C) temperatures. Conditionally dormant seeds germinated to high percentages at 5, 15/6 and 20/10°C, while non-dormant seeds germinated to high percentages additionally at 25/15, 30/15 and 35/20°C. Low temperatures caused non-dormant seeds to re-enter dormancy, while high temperatures caused a sharp decline in germination only at 30/15 and 5°C. The temperature responses of L. purpureum seeds are compared to those of L. amplexicaule L. 相似文献
19.
Microsphaeropsis sp. strain P130A was evaluated for the control of tuber-borne inoculum of Rhizoctonia solani based on the viability of sclerotia produced in vitro and on both the viability and production of tuber-borne sclerotia. The interactions between the antagonist and the pathogen, as well as the effect of the toxins produced by the antagonist on mycelial growth of R. solani were studied using transmission electron microscopy. On sclerotia produced in vitro, for all incubation periods (1 to 42 days), Microsphaeropsis sp. significantly reduced germination. Percent germination of sclerotia treated with Microsphaeropsis sp. decreased with increasing incubation period from an average of 82.0% after 1 day to stabilize at an average of 5.8% after 35 days. Similarly, percent germination of tuber-borne sclerotia was significantly lower when tubers were treated with Microsphaeropsis sp. Both 2% formaldehyde and Microsphaeropsis sp. treatments significantly reduced sclerotia germination to approximately 10% after 42 days of incubation at 4 degrees C. Furthermore, on tubers treated with the antagonist, the number of sclerotia per square centimeter decreased from 1.6 to 0.5 during the 8 months of storage at 4 degrees C, whereas an increase from 1.2 to 7.8 sclerotia per square centimeter was observed on untreated tubers. Microsphaeropsis sp. (strain P130A) colonized hyphae of R. solani within 4 days after contact on culture media. Transmission electron microscopic observations showed that the antagonist induced a rupture of the pathogen plasma membrane and that a chitin-enriched matrix was deposited at sites of potential antagonist penetration. Host penetration was not associated with pathogen cell wall alterations, which occurred at the time of progress of the antagonist in the pathogen cytoplasm. In the presence of a crude extract of Microsphaeropsis sp., cells of R. solani showed cytoplasm disorganization and breakdown of plasma membranes. Antibiosis and mycoparasitism were involved in the antagonism of R. solani by Microsphaeropsis sp., but the sequence by which these events occur, as well as the significance of wall appositions produced by R. solani, is yet to be established. 相似文献
20.
来源于佳木斯茄子上的核盘菌菌株多样性的研究 总被引：12，自引：2，他引：12
从我国黑龙江省佳木斯市同一茄子田采集的菌核样品中分离得到21个核盘菌(Sclerotinia sclerotiorum)单菌核分离物。通过比较其菌丝生长速度、菌落形态、菌核产量及菌核在PDA平板上的萌发特性等将其分成3种类型,记为A、B、C,各包含5、7、9个菌株。A型和B型菌株为正常菌株,而C型菌株为异常菌株,生长慢且呈扇形扩展。对代表性菌株转代培养物及菌核后代的培养特性比较结果说明它们的分化特性是稳定的。致病性的测定结果表明参比菌株Cor-6的致病性最强,A型菌株Ep-1PB和B型菌株Ep-1次之,C型菌株Ep-1PD最弱。3类菌株菌核的可溶性蛋白和酯酶同工酶电泳谱带没有明显的差异。 相似文献