Formation Of Apothecia Research Articles

Identification of stem rot of stock (Matthiola incana) caused by Sclerotinia sclerotiorum in China

The ornamental plant stock flower (Matthiola incana (L.) R. Br.) has been widely cultivated in China. In 2021, stem rot on M. incana, which caused plant death, was first observed in Shanghai, China. Field surveys indicated a disease incidence of 15%–20%. Following pathogen isolation, identification was performed by combining morphological observation of colonies, sclerotia and apothecia, with molecular methods, including DNA sequencing and phylogenetic analysis. Morphological characteristics of the isolates, including white cottony mycelium, blackish globular to irregularly shaped sclerotia and apothecia formation, were consistent with Sclerotinia sclerotiorum. Results of sequence comparison and phylogenetic analysis based on the internal transcribed spacer (ITS) sequences supported morphological data. Pathogenicity assays were conducted successfully according to Koch's postulates. Considering the results of the morphological and molecular identification, along with the pathogenicity assessment, S. sclerotiorum was confirmed as the causal agent of stem rot of stock flower in Shanghai, China. A combination of cultural practices, rotation of resistant ornamentals, and biological and chemical treatments is recommended to control stem rot of stock.

Molecular characterization, mycelial compatibility grouping, and aggressiveness of a newly emerging phytopathogen, Sclerotinia sclerotiorum, causing white mold disease in new host crops in Bangladesh

Sclerotinia sclerotiorum is a newly emerging phytopathogen in Bangladesh causing white mold disease in many plants, including important horticultural and field crops. In this study, we isolated S. sclerotiorum strains from infected parts of various host crops and characterized them using morphophysiological and genetic approaches. White mold of mustard; pod rot or fruit rot of bush bean and garden pea; head rot of cauliflower; flower rot or blossom rot of rose and Salvia; fruit rot of squash; inflorescence rot and pod rot of country bean; and leaf drop or rot of coriander and lettuce were observed in several regions of Bangladesh. From the infected crops, a total of 36 fungal strains were isolated and identified as S. sclerotiorum using internal transcribed spacer (ITS) sequencing. The S. sclerotiorum isolates showed white to off-white mycelial growth with loose to dense velvety aerial mycelia. Round to irregular shaped sclerotia formation was observed, with 4-38 sclerotia present per Petri plate. Apothecia formation from sclerotia was also noted under both natural and artificial conditions. In the present study, as many as 13 crops: Cosmos bipinnatus, Amaranthus cruentus, Leucas aspera, Glycine max, Dahlia hortensis, Hibiscus rosa-sinensis, Rosa chinensis, Salvia officinalis, Cucurbita pepo, Lagenaria siceraria, Brassica oleracea var. italica, Coriandrum sativum, and Lactuca sativa were identified as new host crops of S. sclerotiorum in Bangladesh based on morphological characteristics and ITS sequences.

Survey, morphology and white mold disease of country bean (Lablab purpureus L.) caused by Sclerotinia sclerotiorum (Lib.) de Bary in-relation to soil physico-chemical properties and weather conditions in Bangladesh

A survey was conducted to document the incidence of white mold disease in country bean production areas at Bogra, Pabna, Jessore, Sylhet, Hobigonj and Gazipur districts in Bangladesh during 2016–17. A total of 115 farmers’ fields was surveyed from early vegetative to end of harvesting stages. Pathogens were collected from diseased stems, racemes and pods. Soil samples were collected from the same fields. White mold disease was identified based on symptoms in the field. White mold disease infection was recorded in 100% of the surveyed fields in Shahjahanpur upazila of Bogra district, while approx. 90, 80, 60 and 20% of the fields were infected in Bahubal of Hobigonj; Golapganj of Sylhet; Ishordi of Pabna and Monirampur of Jessore, respectively. White mold was not found in any of the fields surveyed in Joydebpur, Gazipur. Disease incidence and severity were higher in Shahjahanpur of Bogra and Bahubal of Hobigonj district. Moderate disease incidence and severity were observed in Golapganj of Sylhet. Pathogen infection was higher in the fields with loamy fine sandy soil with pH of 5.11–6.22. Globose to irregular black sclerotia developed in infected plant parts and the sclerotia germinated and produced apothecia in the fields after rain. Hyaline, branched, well developed and septate mycelia developed on potato dextrose agar medium. The hyphae were 2.0–7.2 μm in width. After five days of incubation, the subsurface mycelial cells swelled and formed dark black sclerotia. The sclerotia were 1.5–6 mm in width and 2–17 mm in length. Sclerotia germinated, and brown colored round to globose shaped apothecia developed at the end of a long stipe. The length and diameter of apothecia were approximately 4–21 mm and 2–8 mm, respectively. Asci were hyaline and cylindrical in shape, while the ascospores were elliptical. The size of ascus and ascospore was 68–155 × 4.5–6.01 μm and 4.7–6.94 x 4–6.2 μm, respectively. Calcium oxalate was formed on the wall surface of the asci. Disease incidence was negatively correlated with pH and calcium content in the soil while apothecia formation was positively correlated with rainfall and humidity.

Produção de soja e germinação carpogênica de Sclerotinia sclerotiorum sob diferentes coberturas de solo

The aim of this work was to evaluate the influence of different soil cover crops on the carpogenic germination of Sclerotinia sclerotiorum and the development and yield of soybean. The treatments consisted of mulches of brachiaria, canola, safflower, crambe, sunflower and forage radish mulch, and a control with no cover mulch. The crops were sown in pots containing 4.4 dm³ of soil type Rhodic Acrustox. After 45 days the plant material was cut into pieces in order to standardize the amount of straw to 2800 kg ha-1. Soybean seeds were sown and seven days after seedling emergence two sclerotia were allocated in each pot. With regard to carpogenic germination, we analyzed the time to germination of sclerotia and formation of apothecia, number of stipes and apothecia per sclerotia and the percentage apothecia formed. In the soybean crop was determined plant height at flowering and harvest, relative chlorophyll index, dry matter mass and root, number of pods per plant, number of seeds per pod, grain yield, number of nodules per plant and dry mass of nodules. With the exception of safflower mulch, the use of cover crops reduced the formation of stipes and apothecia of S. sclerotiorum. The covers with brachiaria, sunflower and forage radish mulch increased by 16, 10 and 6 days respectively the overall period of apothecium formation, but only brachiaria reduced the percentage of apothecia formed. The sunflower mulch hindered soybean development and yield.

Reproductive mode and life cycle of the ash dieback pathogen Hymenoscyphus pseudoalbidus

Ash dieback caused by the fungal pathogen Hymenoscyphus pseudoalbidus is currently ravaging in Europe, killing Fraxinus excelsior and Fraxinus angustifolia trees of all age classes. The aim of this work was to elucidate aspects of the reproduction biology of this fungal pathogen and its cryptic, non-pathogenic sister species Hymenoscyphus albidus. The mating type (MAT) locus of both species was identified, partly sequenced and characterized. Whereas a heterothallic MAT organization was detected in H. pseudoalbidus, H. albidus was shown to be structurally homothallic. The molecular MAT determination of H. pseudoalbidus was confirmed by crossing experiments on sterile ash petioles. Crossings of strains exhibiting alternate MAT idiomorphs produced fertile apothecia whereas crosses of strains with identical MAT idiomorphs were never successful. Offspring genotyping with microsatellites (MSs) and the MAT marker confirmed that both parental strains were involved in apothecia formation. In addition, polymorphic MS were shown to follow Mendelian inheritance. However, for yet unknown reasons the MAT ratio of progenies of one successful cross revealed a significant segregation distortion. Based on the MAT sequences of H. pseudoalbidus a multiplex PCR was developed, allowing for a quick and reliable MAT determination. The PCR was applied to screen the MAT ratio of two H. pseudoalbidus populations derived from the country of the disease outbreak in Poland and two populations from the disease periphery in Switzerland. None of the screened populations showed a significant deviation from the 1:1 ratio, expected under random mating. Therefore, an initial clonal distribution through asexually produced conidiospores as observed for other fungal pathogens holds not true for H. pseudoalbidus. Instead, our data is highly supportive for a distribution through ascospores. Leaf petioles collected in the field were thoroughly analyzed for the number of different colonizing strains and their mating behavior. Up to eight different H. pseudoalbidus genotypes were found on a single petiole. Cross-fertilizations of strains on the same petiole and fertilizations of unknown strains from outside were found, indicating that fertilization is mediated by spermatia. The presented study complements our understanding of the life cycle of this highly destructive pathogen. The possibility to perform sexual crosses in the lab provides ample opportunities for further genetic studies of H. pseudoalbidus and related species in the future.

Effects of carbon and nitrogen sources on sexual reproduction of five strains from the ascomyceteOrbilia

This study examined the effects of carbon and nitrogen sources as well as the ratio of carbon to nitrogen on apothecia formation of five anamorphic strains from the genusOrbilia. The ability of apothecia formation in chemically-defined media varies depending on the species and strains and is distinctly affected by carbon and nitrogen sources. Among the 11 nitrogen sources examined, two (L-proline and L-tyrosine) showed superior stimulating effects for sexual reproduction. Similarly, of the 10 carbon sources examined, and two (D-mannose and D-cellobiose) were highly effective. In contrast, we found little effect of variable carbon-nitrogen ratio on apothecia formation.

The effect of the substrate on the growth and reproduction of the lichens Cladonia rangiferina and C. mitis

The growth rate and percentage of fertile individuals were studied in the lichens Cladonia rangiferina and C. mitis growing on various substrates in a heath-lichen pine forest and a bilberry-cowberry pine forest with Pleurozium and other mosses, both on the White Sea coast. The substrates were soil, rocks, and pine wood. The proportion of different forms of C. rangiferina growing on the same substrate was compared between the two forest types. C. rangiferina f. rangiferina was more abundant on soil, while C. rangiferina f. crispata dominated on wood. The effect of the substrate on the development of different lichen forms is discussed. The maximum growth rate and the maximum percentage of fertile individuals were recorded in the lichens growing on soil; these parameters were minimal in the lichens growing on wood. These differences were more pronounced in C. rangiferina than in C. mitis. The effects of the nutritive quality and the humidity of the substrate on the growth rate and apothecia formation in lichens are discussed.

Studies on the germination of sclerotia of Sclerotinia sclerotiorum

Sclerotial germination of 33 isolates of Sclerotinia sclerotio-rum, which were collected from different regions and crops, was compared at 10†C in a climate chamber. Germination of S. sclerotiorum, measured as the number of sclerotia producing stipes and apothecia, was the predominant mode that was affected significantly by isolate. Isolates which originated from a warmer area generally germinated more quickly. The culture media affected the viability of sclerotia of isolates M01 and MZ. Sclerotia germinated on different substrates such as standard gardener`s soil, sand and vermiculite, but did not germinate well when the sclerotia had developed on nutrient-rich or nutrient-poor medium. The optimum medium for sclerotial development was wheat grain. Sclerotia produced on wheat grain were well-suited for studies on germination of sclerotia and formation of apothecia. The production of apothecia was optimal at a temperature of 10†C and an illumination of 500 lux, and after an incubation period of 2 to 3 months. One apothecium produced over 1 million ascospores and survived over 15 days in the climate chamber.

Pezicula cinnamomea from cherry tree: pathogenicity tests and photomorphogenesis in culture

Pezicula cinnamomea (DC.: Fr.) Sacc. was frequently isolated from dead twigs of flowering cherry (Prunus × yedoensis Matsum.) in Aomori Prefecture, Japan. Inoculations of flowering cherry tree twigs with the fungus resulted in longitudinal browning of heartwood tissues 3–4cm long after 7 months, showing no apparent symptoms on the bark. The fungus were reisolated at high rates from the affected tissues. Apothecia were formed on cut affected twigs when they were placed in a moist Petri dish and kept under near-UV (Black Light Blue; BL-B) light irradiation. On potato sucrose agar (PSA) plates, the fungus failed to form apothecia in the dark, while many apothecia were formed under BL-B and, to a lesser extent, under white light. In nature, the light, especially near-UV, might be an important factor in apothecium formation. Under near-UV from BL-B conidiomata with conidia formed after 5–6 days and mature apothecia after about 14 days. The developmental processes of the apothecium were histologically studied under light and electron microscopes. Pezicula cinnamomea, which is homothallic and fruits easily in culture, may be very useful for life cycle studies and the elucidation of ecological role of this group of fungi.

Risk Analysis of Sclerotinia sclerotiorum for Biological Control of Cirsium arvense in Pasture: Ascospore Dispersal

Natural levels of Sclerotinia sclerotiorum ascsospores in the Canterbury region were determined over 3 years by trapping depositing ascospores in dishes containing a selective agar. Mean levels in 'horticulture', 'biocontrol-pasture', 'mixed cropping' and 'pasture' strata were 115, 56, 10 and 3 ascospores m -2 day -1 , respectively. Ascospore deposition downwind of small experimental biocontrol sites was measured on 2 days in 1994 and 9 days in 1997 in late spring. Exponential depletion models scaled up to represent a 1 ha biocontrol site, revealed that dispersing ascospores declined to natural levels at downwind distances of 2.5-7.9 m. These results imply that biological weed control in pasture using S. sclerotiorum creates no greater risk of crop disease than does horticulture, and that under the conditions of our experiments, an isolation distance of 8 m would have sufficed. However, such a safety zone may be inadequate under certain meteorological conditions not encountered in the experiments when ascospores may disperse in larger numbers over longer distances. To complete the information required to build a mechanistic model of spore dispersal (beyond the scope of this paper) which would cope with a variety of meteorological conditions, two studies were conducted on the dynamics of apothecium formation and ascospore release. In a two-year study, apothecium formation was confined to the spring (September-November), and population size peaked in mid October. In a 5-day study, ascospore release occurred during the daytime, reaching a maximum late morning on frost-free days and a lower maximum mid afternoon on days with morning frost.

Variation and Heritability of Phenology in the FungusMonilinia vaccinii-corymbosion Blueberry

ABSTRACT The germination of field-collected pseudosclerotia and the development of apothecia from eight New Jersey populations of the mummy berry fungus Monilinia vaccinii-corymbosi were evaluated under controlled conditions in the greenhouse. Development data for apothecia were used to describe the timing of apothecium formation and to estimate broad- and narrow-sense heritabilities of fungal phenology. Mean development times for the formation of apothecia ranged from 35.4 to 54.7 days. The mean development times for populations collected from early-season cv. Weymouth ranged from 35.4 to 39.6 days and were significantly shorter than the development times for three of the four populations collected from late-season cv. Jersey (46.9 to 54.7 days) or for the population collected from mixed stands of cultivated blueberries (42.7 days). The development of populations from late cultivars planted in very close proximity to early cv. Weymouth was early (36.5 to 39.0 days) and not significantly different from the development of populations collected from cv. Weymouth. Phenotypic and genetic variances of apothecium development for individual populations ranged from 18.9 to 44.8 and 7.2 to 30.9, respectively. Broad-sense heritabilities of apothecia development for each fungal population, calculated by partitioning phenotypic variation into genetic and environmental components, ranged from 0.31 to 0.78. Narrow-sense heritabilities of apothecia development, based on parent-offspring regression, ranged from 0.58 to 0.78. These results indicate that populations of M. vaccinii-corymbosi differ in phenology and that a significant portion of the phenological variation within populations is genetic. Thus, it is plausible to propose that the phenology of apothecium development is a component of fungal fitness and that host phenology can influence the timing of pathogen development.

A methodology for risk analysis of plurivorous fungi in biological weed control: Sclerotinia sclerotiorum as a model

In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete Sclerotinia sclerotiorum, as a biocontrol agent for Cirsium arvense in pasture. As a consequence of the wide host range of this fungus, the proposed biocontrol may pose a risk to non-target arable plants. Crop disease risk is primarily due to the formation of sclerotia. These perennating bodies may directly infect susceptible crops sown at the biocontrol site in years after the biocontrol event. Additionally they may cause infection in neighbouring crops through the formation of apothecia from which airborne ascospores are dispersed. A methodology for a risk analysis is proposed, embodying both temporal and spatial processes, where the relative disease risk from biocontrol is defined as the ratio of added to naturally occurring inoculum.

Der Einfluß verschiedener Pilzarten und -isolate auf die Apothezienbildung von Sclerotinia sclerotiorum unter simulierten Frühjahrsbedingungen

Summary A method is presented which can be used for testing the effect of microbial antagonists on the apothecia formation of Sclerotinia sclerotiorum in a climate chamber. Especially three of nine fungus isolates investigated by this method showed good or very good antagonistic effects. These isolates belong to the fungus species Trichoderma hamatum, Coniothyrium minitans and Fusarium aquaeductuum . The antagonistic effect of the investigated fungus species depended strongly on the inoculum concentration. On average the lower concentration showed a better effect than the higher. The isolate of T. hamatum Ma I (4) inhibited the apothecia formation at low inoculum concentration (1.75 × 10 4 conidia per cubic centimeter soil) entirely.

Occurrence of Tapesia yallundae apothecia on field and laboratory‐inoculated material and evidence for recombination between isolates

Tapesia yallundae was observed in early July on wheat straws, which had been inoculated with isolates of Pseudocercosporella herpotrichoides (W‐type) 9 months previously and placed in plots of winter wheat, to act as inoculum in a resistance screen. A perfect state was not observed on straws inoculated with R‐type isolates in the same experiment. One hundred and thirty‐four single‐ascospore isolates were obtained and observations on morphology in culture, pathogenicity to wheat and rye seedlings, resistance to benomyl and the pattern of restriction fragment length polymorphisms demonstrated that all isolates were W‐type, although some grew at half the expected rate on agar, and at least two isolates were involved in the production of apothecia. Apothecia were produced in vitro on straws inoculated with single isolates of P. herpotrichoides only when they were incubated in contact with other straws similarly inoculated with certain other isolates. No apothecia were produced on straws with only isolate present, suggesting the need for at least two strains, possibly representing different mating types, for apothecium formation. Apothecia of T. yallundae were produced in vitro on straw pieces which had been inoculated individually with W‐type isolates, 14‐16 weeks after straws of different isolates were mixed. Evidence for genetic recombination between isolates was obtained when single‐ascopore colonies were analysed for resistance to benomyl in culture and for restriction‐length polymorphisms (RFLPs).

Effects of medium composition and light on formation of apothecia and sclerotia by Pyronema domesticum

Pyronema domesticum (Sow.) Sacc. was cultured in a 12 h light: 12 h dark cycle and in the dark on water agar; an inorganic salts medium (Claussen's agar); Claussen's agar supplemented with casein hydrolysate, biotin, thiamine, asparagine, glycine, or urea; and media containing a variety of natural materials, either supplemented or not with dextrose or another carbohydrate. Apothecial formation was favored by illumination, while sclerotial formation was favored by darkness. Maximum production of apothecia and sclerotia occurred on low-carbohydrate media supporting scant to moderate mycelial growth but was prevented on medium with a high carbohydrate concentration (20 g/L). Large numbers of well-developed apothecia formed on dilute media containing only inorganic nutrients (Claussen's agar), a small amount (3.0 g/L) of casein hydrolysate, or the extract from 20 g potatoes/L. Fewer incompletely developed apothecia formed on 2% water agar. Apothetical production was depressed or prevented by the addition of asparagine, glycine, urea, biotin, or thiamine to Claussen's agar. Sclerotia formed in maximum numbers on rabbit food agar, vegetable juice agar, and on dilute potato extract agar. Fewer sclerotia were produced on Claussen's agar.

Effects of Ultraviolet a Radiation and Inhibitory Volatile Substances on the Discomycete, Pyronema Domesticum

Pyronema domesticum forms apothecia in white light but not in darkness in a closed Petri dish and in the absence of circulating air in the incubator. Ultraviolet A radiation (320400 nm) at an intensity of 104 microwatts cm-2 induces large numbers of apothecia in sealed flask cultures. These apothecia have impaired development of the ascogenous system but development is normal in a closed Petri dish in which some diffusion of air can occur between the interior and exterior environments. The numbers of apothecia decrease sharply at either higher or lower irradiances of ultraviolet A. Exposure to an irradiance greater than 3.8 microwatts cm-2 inhibits mycelial growth which is prevented at 4030 microwatts cm2. At the intensity inducing large numbers of apothecia, mycelial growth is less than that of the dark control. Exposure to intense ultraviolet A radiation is damaging and results in the death of some of the cultures. Apothecia can be induced to form in darkness in stagnant air in the presence of activated charcoal because unknown volatile substances released by the fungus and inhibitory to apothecia formation are adsorbed. The discomycete Pyronema domesticum (Sow. ex Gray) Saccardo normally requires light to form apothecia (Moore-Landecker, 1979a, b). Apothecia will form in white, blue, or far-red light but not in red light or darkness in well-aerated growth chambers. Far-red light and the relatively strong air currents near the forced air outlet of the ventilating system in a growth chamber can interact to influence development but far-red light alone is ineffective in inducing apothecial formation on a medium containing amino acids (Moore-Landecker and Shrop? shire, 1982). Apothecia can be induced to form in the dark by air currents in a well-aerated growth chamber (Moore-Landecker and Shropshire, 1982) or by chemieal treatment (Moore-Landecker, 1983). Sclerotial formation is inhibited by blue light (Moore-Landecker and Shropshire, 1982). One purpose of the present study was to clarify further the response of P. domesticum to light quality and to determine which wavelengths present in white light could induce apothecial formation in the absence of air exchange between the culture vessel and the environment. Another purpose was to clarify further the exact properties of the air that were modified by diffusion of air into or out ofthe culture vessel that could promote apothecial production in the dark. Critical factors that could be affected by air exchange occurring normally in an unsealed Petri dish are the concentrations of volatile materials present, oxygen, or carbon dioxide (Moore-Landecker and Shropshire, 1982). Apothecia of P. domesticum formed within a sealed culture flask when the mycelium was exposed to ultraviolet A radiation (320-400 nm). Several other Ascomycetes are known to respond to ultraviolet A radiation. Perithecium for? mation in Pleospora herbarum (Pers.) Rabenh. (Leach and Trione, 1966) and ascostromal formation in Leptosphaerulina trifolii (Rost.) Petr. (Leach, 1972) have

Formation of Apothecia by Sclerotia ofSclerotinia trifoliorumand Infection of Crimson Clover in the Field

Formation of Apothecia by Sclerotia of<i>Sclerotinia trifoliorum</i>and Infection of Crimson Clover in the Field

Forecast of Sclerotinia rot of cabbage with apothecium formation

Forecast of Sclerotinia rot of cabbage with apothecium formation

Apothecial ontogeny in Saccobolus versicolor (Pezizales: Ascomycetes)

Apothecial ontogeny in Saccobolus versicolor was followed by scanning electron and light microscopy from ascogonial coil initiation through spore discharge. Several slender, recurved branches functioned as ascogonia and initiated apothecium formation. Since antheridia were never observed, development was assumed to be parthenogenetic. Soon after ascogonia appeared, slender investing hyphae grew up from nearby vegetative hyphae and from the ascogonium. Subsequently, the basal cells in the ascogonia greatly increased in diameter and their septa broke down. Apothecium ontogeny was either eugymnohymenial with a poorly developed ectal excipulum or paragymnohymenial opening in the prehymenial phase. As a result of the presence of several functional ascogonia, asci developed by typical crozier formation and exhibited a strong positive phototrophic response as they protruded before spore discharge.

Anthracobia, Ascodesmis, Pyronema, and Trichophaea in Culture

SUMMARYBrief descriptions of apothecia, asexual states present, and cultural characteristics of operculate Discomycetes, Anthracobia muelleri, Ascodesmis sphaerospora, Pyronema domesticum, and Trichophaea abundans, on various agar media are provided. Rabbit food agar is an excellent medium for obtaining apothecia of these species. Formation of apothecia and the Rhizoclonia-like asexual cells of Anthracobia muelleri in culture is reported for the first time. Lasiobolus equinus, Trichophaea hemisphaeroides, and Trichophaea sp. ATCC 14016 did not form apothecia or any asexual state.