Itersonilia Perplexans Research Articles

Identification of Some Fungi Causing Okra Root Rot Disease from Different Regions of Anbar and Waist and Testing Pathogenicity

The study was conducted in the Department of Plant Protection - College of Agriculture - University of Anbar for the year 2022, as the results of collecting samples from the regions of Anbar and Waist governorates showed the spread of okra root rot disease in most of the study areas, and the results of phenotypic and molecular diagnosis showed the presence of the fungal species Pythium Aphanidermatum, Fusarium proliferatum, Epicoccum nigrum, Itersonilia perplexans, Fusarium chlamydosporum, Rhizoctonia solani, which were deposited in the International Genbank OQ572440, OQ540926, OQ566939, OQ540927, OQ540928, OQ540929 (NCBI) seeds, respectively. Okra, as the tested isolates achieved a significant decrease in the germination of okra seeds on the culture medium (W.A. Water agar) compared with the control treatment that was not contaminated with any of the tested isolates, in which the infection rate was 0.0%.

Confirmation of Itersonilia perplexans infecting pyrethrum (Tanacetum cinerariifolium) in Australia.

Pyrethrum (Tanacetum cinerariifolium (Trevir.) Sch. Bip.) is grown to extract pyrethrins which are active ingredients for insecticides (Greenhill 2007). The Australian pyrethrum industry supplies over 50% of the world market. Surveys of Tasmanian crops in spring 2013, detected the presence of a fungus putatively identified as Itersonilia perplexans Derx. on foliage in 54 of 86 surveyed fields (Hay et al. 2015). This fungus was associated with necrotic leaf tips often spreading to encompass whole leaves. However, pathogenicity to pyrethrum was not confirmed. To isolate, tissue was excised from foliar lesions, surface sterilised using 0.4% NaClO, placed onto 2% water agar and incubated at 20°C for 5 days. Colonies were pure-cultured by hyphal-tip transfer onto potato-dextrose agar. Eleven isolates were cultured onto yeast mold agar (YMA) for 14 days at 15°C in the dark (Horita and Yasuoka 2002). Colonies were slow growing (1.9 to 2.3 mm/day) white to buff on both surfaces, with a darker center visible on lower surfaces. Mycelia were straight and hyaline with clamp connections at the septa. Squares transferred from the edge of YMA colonies onto microscope slides produced ballistoconidia that were aseptate, granular and lunate, kidney or lemon-shaped after 24 h. Ballistoconidia lengths and widths (n = 50/isolate) ranged from 14.6 to 20.4 µm and 10.0 to 13.6 µm. Chlamydospores were not observed. These observations were consistent with descriptions of I. perplexans (Koike and Tjosvold 2001; Liu et al. 2015). All 11 isolates were sequenced across the internal transcribed spacer (ITS) region of rDNA (ITS; primers V9G/ITS4; de Hoog and van den Ende 1998; White et al. 1990), and large (LSU; primers LROR/LR7; Rehner and Samuels 1995), and small (SSU; NS1/NS4; White et al. 1990) subunits of rDNA (Genbank accession nos. KU563626 to KU563658). The ITS (673 bp), SSU (1,047 bp) and LSU (1,318 bp) differed by 3, 1 and 0 bp, respectively, across isolates. Maximum parsimony and maximum likelihood analyses of a concatenated 3 loci alignment with Cystofilobasidiales representatives (Liu et al. 2015) placed all isolates and the I. perplexans ex-neotype strain CBS 363.85 within a single monophyletic clade with 100% bootstrap support. Two representative isolates are stored at the Plant Pathology Herbarium (accession nos. BRIP 57986 and 57987). Leaves of 46-day-old pyrethrum plants (n = 45), generated from surface sterilised seed, were inoculated with a 1.5 × 105 ballistoconidia/ml suspension (equal mix of eight isolates) and maintained between 10 and 22°C under a 12-h photoperiod for 14 days. Brown necrotic leaf tips, consistent with reported field symptoms were observed on 71% of plants and I. perplexans was recovered from 69% of symptomatic plants. For flower inoculations, pyrethrum plants were removed from fields as vegetative plants in spring and maintained in a greenhouse set at 20:14°C and 14:10 h day:night. Open flowers (10 per plant) were dipped into a 1.2 × 104 ballistoconidia/ml suspension mix of three isolates. Brown withered ray florets were observed on 10/12 plants 18 days post-inoculation, matching those described in petal blight of chrysanthemum (McRitchie et al. 1973). I. perplexans was re-isolated from 11/12 inoculated plants and 1 control plant (of 12) which exhibited the same symptoms. In both experiments, I. perplexans was identified based on its distinctive morphology. This confirms the pathogenicity of I. perplexans to both pyrethrum leaves and flowers.

First report of dill blight caused by Itersonilia perplexans in Turkey

First report of dill blight caused by Itersonilia perplexans in Turkey

In vitro effectiveness of difenoconazole against Itersonilia perplexans Derx

Leaf blight caused by Itersonilia perplexans Derx is commonly observed on dill (Anethum graveolens L.) at the crop maturity stage. In the fields of southern Italy, I. perplexans attacks begin in late autumn, when the weather is cool and humid. In laboratory, the fungal growth rate was maximum at 20 °C, the ballistoconidia production was null at temperatures of 25 °C or higher, and growth was interrupted at 30 °C or above. It is difficult to manage the disease because very few fungicides are admitted for use on dill. Therefore, we screened in vitro several fungicides for their toxicity against I. perplexans, and discovered the high effectiveness of difenoconazole, with EC50 and EC95 of 0.5 and 0.95 μg mL−1, respectively, both for mycelium growth and ballistoconidia production. Ciprodinil+fludioxonil, azoxystrobin (both with EC50 = 0.69 μg mL−1) and boscalid (EC50 = 7.32 μg mL−1) were toxic to I. perplexans, but did not suppress completely the pathogen even at doses of 10,000 μg mL−1. Mancozeb+metalaxil showed EC50 of 15.5 μg mL−1 and completely suppressed the fungus at 100 μg mL−1. Copper oxychloride was toxic only at doses higher than 100 μg mL−1, and sulphur did not affect the pathogen growth. Therefore, difenoconazole is worthy of further evaluations in the field for the control of leaf blight of dill caused by I. perplexans.

First Report of Dill Blight in Cyprus Caused by Itersonilia perplexans

First Report of Dill Blight in Cyprus Caused by <i>Itersonilia perplexans</i>

Changes in Distribution and Frequency of Fungi Associated With a Foliar Disease Complex of Pyrethrum in Australia

In Australia, pyrethrum (Tanacetum cinerariifolium) is affected by a foliar disease complex that can substantially reduce green leaf area and yield. Historically, the most important foliar disease of pyrethrum in Australia has been ray blight, caused by Stagonosporopsis tanaceti, and other fungi generally of minor importance. Temporal fluctuations in the frequency of fungi associated with foliar disease were quantified in each of 83 fields in northern Tasmania, Australia, during 2012 and 2013. Sampling was conducted throughout winter (April to July), spring (August to September), and summer (November) representing different phenological stages. Microsphaeropsis tanaceti, the cause of tan spot, was the pathogen most prevalent and isolated at the highest frequency, irrespective of sampling period. The next most common species was S. tanaceti, whose isolation frequency was low in winter and increased in spring and summer. Known pathogens of pyrethrum, Alternaria tenuissima, Colletotrichum tanaceti, and Stemphylium botryosum were recovered sporadically and at low frequency. Two species of potential importance, Paraphoma chrysanthemicola and Itersonilia perplexans, were also found at low frequency. This finding suggests a substantial shift in the dominant pathogen associated with foliar disease, from S. tanaceti to M. tanaceti, and coincides with an increase in defoliation severity in winter, and control failures of the spring fungicide program. Factors associated with this finding were also investigated. Sensitivity of M. tanaceti and S. tanaceti populations to the fungicides boscalid and cyprodinil collected prior to and following disease control failures in the field were tested under in vitro conditions. A high proportion (60%) of the M. tanaceti isolates obtained from fields in which no response to the spring fungicide program was found were insensitive to 50 µg a.i./ml boscalid. This represented a 4.2-fold increase in the frequency of this phenotype within the M. tanaceti population over 2 years. No shifts in sensitivities to cyprodinil of M. tanaceti and S. tanaceti, or S. tanaceti to boscalid, were observed. Considering the increase in defoliation severity over winter, the benefits of applying fungicides in autumn, in addition to the commercial standard (spring only), were quantified in 14 individual field trials conducted in 2011 and 2012. Mixed-model analysis suggested fungicide application in autumn may improve pyrethrum growth during late winter and early spring, although effects on defoliation and yield were minimal. The increasing prevalence and isolation frequency of M. tanaceti and boscalid resistance within the population is of concern and highlights the urgent need for adoption of nonchemical methods for disease management in Australian pyrethrum fields.

FIRST REPORT OF ITERSONILIA PERPLEXANS ON ANETHUM GRAVEOLENS IN ITALY

In Apulia (southern Italy), dill (Anethum graveolens) is cultivated in a few greenhouses and fields, mainly located between Bari and Brindisi. In December-January of 2010 to 2014, leaf blight was observed in greenhouse-grown dill crops, when they were near the harvest stage. Symptoms differed from those induced by some known foliar pathogens of dill, i.e. Sclerotinia sclerotiorum and Erysiphe heraclei, but recalled those caused by Botrytis cinerea. In fact, leaves that were first discolored, turned light to dark brown, and finally wilted, rendering the affected plants unsuitable for harvest. In the presence of high relative humidity, a whitish-cream mycelium developed on symptomatic leaves. Light microscope observations revealed the presence of hyaline hyphae with clamp connections and lunate ballistospores [16.4 ± 1.7 (standard deviation) × 11.0 ± 1.3 μm]. A 609 bp product amplified by PCR from fungal DNA using the ITS1/ITS4 primer pair was sequenced (BMR Genomics, Italy) and the sequence of an isolate designated IPSP-GB520 was deposited in GenBank under the accession No. KP890654. BLAST alignment revealed a 99% homology at the nucleotide level with several accessions of Itersonilia perplexans Derx (Basidiomycota, Cystofilobasidiaceae), including two isolates (DQ667163 and NR_077117) conserved at the CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands. Koch’s postulates were fulfilled with a successful detachedleaf assay. Based on morphological characteristics and nucleotide sequence homology, the fungus was identified as I. perplexans. In Italy, an early report ascribed leaf blight of dill to I. pastinacae, based on morphometric observations and pathogenicity tests (Matta and Garibaldi, 1968). To the best of my knowledge, this is the first report of I. perplexans on dill in Italy.

English

A study to determine the fungal profile in leaves of both highland and lowland tea in Nigeria was performed. Healthy leaves were harvested from nineteen tea clones: T-14, T-19, T-33, T-35, T-61, T-68, T-74, T-108, T-143, T-228, T-229, T-236, T-238, T-318, T-354, T-355, T-367, T-368 and T-369 on the highland and lowland areas. Potato dextrose agar (PDA) was used as the growth medium to culture associated mycoflora from the tea leaves in five replications. The healthy tea leaves of the clones from the highland and the lowland areas show the presence of ten and six fungi respectively which include Pleurothecium recurvatum, Candida albicans, Aspergillus niger, Aspergillus fumigatus, Itersonilia perplexans, Penicillium italicum, Lasiodiplodia theobromae, Trichordema viride, Rhizopus stolonifer and Botrytis cinerea. Clones T-369, T-14, T-108 and T-368 have the highest (4) mycoflora load found on the tea leaves but three were found associated with each of clones T-228, T-68 and T-236 on the highland. Only one fungus was isolated from each of the clones T-108, T-61, T-229 and T-318, two fungi from each of T-355, T-19 and T-236 while the highest mycoflora load on the lowland tea were found in clones T-368 and T-228. Key words: Tea, two and a bud, clones, highland, lowland, mycoflora.

First report of Itersonilia perplexans on Heracleum sosnowskyi in Russia

Sosnowsky's hogweed ( Heracleum sosnowskyi ; Apiaceae) is cultivated as a forage plant. However, in some regions it appears as a weed dangerous for human health. Over the period July-August 2008, individual H . sosnowskyi plants with vigorous …

PCR-SSCP-based reconstruction of the original fungal flora of heat-processed meat products

Food processing of spoiled meat is prohibited by law, since it is a deception and does not comply with food safety aspects. In general, spoilage of meat is mostly caused by bacteria. However, a high contamination level of fungi could be also found in some meat or meat products with certain preserving conditions. In case that unhygienic meat is used to produce heat processed products, the microorganisms will be deactivated by heat, so that they cannot be detected by a standard cultivation method. Therefore, this study aimed to develop and apply a molecular biological method—polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP)—to reconstruct the original fungal flora of heat processed meat. Twenty primer pairs were tested for their specificity for fungal DNA. Since none of them fully complied with all study criteria (such as high specificity and sensitivity for fungal DNA; suitability of the products for PCR-SSCP) in the matrix “meat”, we designed a new reverse primer, ITS5.8R. The primer pair ITS1/ITS5.8R amplified DNA from all tested fungal species, but not DNA from meat-producing animals or from ingredients of plant origin (spices). For the final test, 32 DNA bands in acrylamide gel from 15 meat products and 1 soy sauce were sequenced—all originating from fungal species, which were, in other studies, reported to contaminate meat e.g. Alternaria alternata, Aureobasidium pullulans, Candida rugosa, C. tropicalis, C. zeylanoides, Eurotium amstelodami and Pichia membranifaciens, and/or spices such as Botrytis aclada, Guignardia mangiferae, Itersonilia perplexans, Lasiodiplodia theobromae, Lewia infectoria, Neofusicoccum parvum and Pleospora herbarum. This confirms the suitability of PCR-SSCP to specifically detect fungal DNA in heat processed meat products, and thus provides an overview of fungal species contaminating raw material such as meat and spices.

First record of Itersonilia perplexans on Anethum graveolens (dill) in Australia

Itersonilia perplexans was found for the first time on hydroponically grown potted plants of dill (Anethum graveolens) in Victoria. All affected plants were destroyed.

The captured launch of a ballistospore

Ballistospore discharge is a feature of 30 000 species of mushrooms, basidiomycete yeasts and pathogenic rusts and smuts. The biomechanics of discharge may involve an abrupt change in the center of mass associated with the coalescence of Buller’s drop and the spore. However this process occurs so rapidly that the launch of the ballistospore has never been visualized. Here we report ultra high-speed video recordings of the earliest events of spore dispersal using the yeast Itersonilia perplexans and the distantly related jelly fungus Auricularia auricula. Images taken at camera speeds of up to 100 000 frames/s demonstrate that ballistospore discharge does involve the coalescence of Buller’s drop and the spore. Recordings of I. perplexans demonstrate that although coalescence may result from the directed collapse of Buller’s drop onto the spore, it also may involve the movement of the spore toward the drop. The release of surface tension at coalescence provides the energy and directional momentum to propel the drop and spore away from the fungus. Analyses show that ballistospores launch into the air at initial accelerations in excess of 10 000 g. There is no known analog of this micromechanical process in animals, plants or bacteria, but the recent development of a surface tension motor may mimic the fungal biology described here.

Effects of inoculum density, leaf age, moisture, temperature, and wetness duration on black streak of edible burdock

Inoculum density, temperature, leaf age, and wetness duration were evaluated for their effects on the development of black streak (Itersonilia perplexans) on edible burdock (Arctium lappa L.) in a controlled environment. The effect of relative humidity (RH) on ballistospores production by I. perplexans was also evaluated. Symptoms of black streak on leaves increased in a linear fashion as the inoculum density of I. perplexans increased from 102 to 106 ballistospores/ml. Rugose symptoms on young leaves were observed at densities of ≥104 ballistospores/ml. Disease severity of I. perplexans in relation to leaf age followed a degradation curve when the leaves were inoculated with ballistospores. Disease severity was high in newly emerged leaves up to 5 days old, declined as leaf age increased to 29 days, and was zero when leaf age increased from 30 to 33 days. Disease development of edible burdock plants exposed to ballistospores of I. perplexans was evaluated at various combinations of temperature (10°, 15°, 20°, 25°C) and duration of leaf wetness (12, 24, 36, 48, and 72 h). Disease was most severe when plants were in contact with the ballistospore sources at 15° or 20°C. The least amount of disease occurred at 25°C regardless of wetness duration. Ballistospores required 24–36 h of continuous leaf wetness to cause visible symptoms by infection on edible burdock. Ballistospores production in infected lesions required at least 95.5% RH.

The captured launch of a ballistospore

Ballistospore discharge is a feature of 30000 species of mushrooms, basidiomycete yeasts and pathogenic rusts and smuts. The biomechanics of discharge may involve an abrupt change in the center of mass associated with the coalescence of Buller's drop and the spore. However this process occurs so rapidly that the launch of the ballistospore has never been visualized. Here we report ultra high-speed video recordings of the earliest events of spore dispersal using the yeast Itersonilia perplexans and the distantly related jelly fungus Auricularia auricula. Images taken at camera speeds of up to 100,000 frames/ s demonstrate that ballistospore discharge does involve the coalescence of Buller's drop and the spore. Recordings of I. perplexans demonstrate that although coalescence may result from the directed collapse of Buller's drop onto the spore, it also may involve the movement of the spore toward the drop. The release of surface tension at coalescence provides the energy and directional momentum to propel the drop and spore away from the fungus. Analyses show that ballistospores launch into the air at initial accelerations in excess of 10,000 g. There is no known analog of this micromechanical process in animals, plants or bacteria, but the recent development of a surface tension motor may mimic the fungal biology described here.

Black Streak of Edible Burdock Caused by Itersonilia perplexans in Japan

Black streak disease of edible burdock (Arctium lappa L.) has been observed periodically in Hokkaido Prefecture, Japan since 1988. Symptoms appeared initially as small, dark brown to black spots on the leaf veins and petioles. The necrotic spots developed longitudinally along the leaf veins or petioles. Diseased leaf veins or petioles occasionally snapped off at the necrotic lesions. An Itersonilia sp. was isolated from rotting leaf veins and petioles. Laboratory inoculations of edible burdock seedlings using ballistospore suspensions produced typical symptoms observed in nature. The fungus had a feathery mycelium and developed a white to pale cream colony color. The mycelium was composed primarily of branched hyphae with clamp connections at the septa. Ballistospores, formed at the apex of inflated cells, were lunate, ovoid to pyriform. The fungus occasionally produced appressoria, chlamydospores and yeast cells. Based on the morphological characteristics, the causal agent was identified as Itersonilia perplexans Derx. Edible burdock strains were also pathogenic to chrysanthemum and caused petal blight. This report is the first of a foliar disease of edible burdock caused by I. perplexans in Japan.

A Blight Disease of Dill in California Caused by Itersonilia perplexans.

In 2000, a foliar disease was observed in commercial field plantings of dill (Anethum graveolens) in coastal California. Initial symptoms consisted of a gray-green discoloration and wilting of the tips of dill leaves. As disease developed, many of the leaves discolored and collapsed, which gave the foliage a blighted appearance and made the leaves unsuitable for harvest. A fungus was consistently isolated from symptomatic leaves. Slow growing colonies were cream-colored, velutinous, and flat with minimal aerial mycelium. Mycelium was hyaline and had clamp connections. Ovoid to subglobose sporogenous cells were abundant and measured 11 to 14 × 12 to 16 μm. Spores were ballistospores that were bilaterally symmetrical, lunate, 16 to 18 × 12 to 13 μm, and germinated with hyphae or secondary ballistospores. The fungus was identified as Itersonilia perplexans Derx (1,2). Pathogenicity was tested by preparing spore suspensions (1 × 104) and spray-inoculating potted dill plants. Plants were placed in a dew chamber for 24 h and then maintained in a greenhouse (23 to 25°C). After 10 days, leaves showed symptoms similar to those observed in the field and the same fungus was reisolated. Control plants sprayed with water did not develop symptoms. Inoculations were repeated and the results were the same. In another experiment, sets of dill plants and flowers of five cultivars of potted florist's chrysanthemum (Dendranthema × grandiflorum [= Chrysanthemum × morifolium]) and one cultivar of Leucanthemum paludosum (= C. paludosum) were spray-inoculated with several dill isolates and incubated as described previously. Dill plants developed symptoms and the fungus was reisolated. However, flowers of the six chrysanthemum cultivars did not develop any petal blight symptoms. Inoculations were repeated and the results were the same. These findings are consistent with previous studies that indicate I. perplexans consists of pathogenic forms that are host-specific to either chrysanthemum and closely related Compositae or to Apiaceae plants such as dill, carrot (Daucus carota subsp. sativus), parsley (Petroselinum crispum), and parsnip (Pastinaca sativa) (1,2,3). To our knowledge, this is the first report of I. perplexans on dill in California, and also appears to be the first record of this disease in North America.

Petal Blight of Sunflower Caused by Itersonilia perplexans.

In February 1999, a cut-flower grower from Florida reported post-harvest losses of approximately 25% in Helianthus annuus (sunflower) cvs. Sunrich Orange and Sunbright. Symptoms began as small, pinpoint brown lesions on the petals, which enlarged and coalesced, leading to necrosis of the entire blossom. Symptomatic petals were surface disinfested for 30 sec with 0.5% NaOCl and suspended over plates containing acidified 25% potato-dextrose agar. Petals adhered to lids of the petri dishes by the surface tension of the water on the petals. Itersonilia perplexans Derx was consistently isolated. Inoculation of sunflower with I. perplexans was achieved using three detached, mature blossoms of the cv. Sundance Kid with their pedicels placed in sterile water. Each blossom was inoculated with 3.5 ml of a spore suspension (1 × 105 spores/ml) applied as a spray. Three noninoculated control blossoms were sprayed with sterile, distilled water. Blossoms were incubated in a controlled environment chamber at near 100% RH, a constant temperature of 18°C, and a 12-h photoperiod. Three days following inoculation all of the inoculated blossoms were symptomatic, with necrosis ranging from 50 to 100% on individual petals. I. perplexans was recovered from all of the inoculated blossoms. Noninoculated controls remained symptomless, and I. perplexans was not recovered. I. perplexans has been reported to cause lesions on the cotyledons, first true leaves, and the hypocotyl region of sunflower seedlings in Canada and Uruguay (1,2). However, this is the first report of post-harvest petal blight in sunflower caused by I. perplexans and the first report in the United States of infection of sunflower by I. perplexans.

Petal Blight of Callistephus chinensis Caused by Itersonilia perplexans

From November 1997 to March 1998, a cut-flower grower in southwest Florida reported post-harvest losses due to a petal blight of 10 and 50%, respectively, in China aster (Callistephus chinensis (L.) Nees) cultivars Rainbow Mix and Matsumoto Lavender. Initial symptoms observed included pinpoint, bleached lesions on petals. Enlargement of lesions resulted in bleached streaks on ray flowers and eventually necrosis of entire blossoms. Symptomatic petals were surface disinfested in 0.5% NaOCl and suspended on the lids of plastic culture plates over acidified potato dextrose agar (APDA). Itersonilia perplexans Derx was isolated consistently from diseased petals but not from symptomless controls. Confirmation of the pathogenicity of I. perplexans used three detached, mature flowers of China aster cv. Matsumoto Rose and seven mature flowers of Bidens bipinnata L., a common composite found near the production site. The pedicels of flowers were placed in sterile, deionized water, and 1 ml of a spore suspension (1.2 × 104 spores per ml) of I. per-plexans was sprayed on aster flowers, and 0.5 ml was applied to flowers of B. bipinnata. An equal number of noninoculated control flowers were sprayed with sterile, deionized water only. The flowers were incubated in a controlled environment chamber at near 100% relative humidity, a constant temperature of 18°C, and a 12-h photoperiod. Bleached spots were detected on the petals of Matsumoto Rose flowers 10 days after inoculation, and the fungus was reisolated on APDA. Control asters remained symptomless, and were negative for I. perplexans. Brown blotches appeared on the petals of B. bipinnata flowers 12 days after inoculation, and infection by I. perplexans was confirmed by reisolation. The fungus was not detected in noninoculated B. bipinnata flowers, including some that exhibited brown discoloration. A survey was conducted in early March 1998 to examine the incidence of Itersonilia petal blight in China aster and the occurrence of the fungus in B. bipinnata. Fifty flowers of each of four China aster cultivars were collected at random without regard to symptoms. Approximately 20 flowers of B. bipinnata exhibiting brown spots were also collected near this site. The fungus was isolated at incidences of 18, 6, 8, and 6% in flowers from aster cultivars Rainbow Mix, Matsumoto Blue, Matsumoto Pink, and Matsumoto Scarlet, respectively. I. perplexans was not detected in B. bipinnata flowers collected from the field during this period. I. perplexans previously was detected in florists' chrysanthemum (Chrysanthemum × morifolium Ramat.) at the same cut-flower production site in January 1973 during a period of uncharacteristically cool weather (2). The weather during the recent outbreak of Itersonilia petal blight in aster was also unusually cool and rainy and resulted from the “El Niño” weather pattern prevalent during the period. I. perplexans has been found to over-season on many weeds in Great Britain, particularly on those in the Compositae (1). Experimental transmission of I. perplexans to B. bipinnata suggests that it and other wild composites may serve as reservoirs of the fungus in Florida.

Mannitol and hexoses are components of Buller's drop

The mechanism of ballistospore self-propulsion by basidiomycetes involves the hygroscopic adsorption of water vapour by a drop of liquid (Buller's drop) on the hilar appendix of the spore until it makes contact with another expanding drop, the adaxial drop on the face of the spore above it. Aliquots of liquid from Buller's drop have been collected from Itersonilia perplexans using micropipettes. Analysis of the droplets by microfluorescence assays indicated the presence of mannitol and hexoses. Using the same technique, washings from basidiospore deposits of I. perplexans, containing the evaporated remnants of Buller's drops and the adaxial drops carried away by the spores on discharge, were further shown to contain mannitol and hexoses. Glc analyses of washings from spore deposits of a range of basidiomycetes also indicated the presence of mannitol and hexoses. Calculations based on the estimated concentrations of mannitol and hexoses in Buller's drop from Itersonilia show that the concentration of solutes is sufficient to bring about the condensation of water vapour from a saturated atmosphere and thus to cause the growth of Buller's drop at rates previously measured. When brought close to, but not in contact with, the surface of an agar plate, crystals of pure mannitol rapidly deliquesced. Mannitol and hexoses contribute significantly to the hygroscopic nature of Buller's drop in basidiomycetes.

Analysis of cell wall carbohydrates (neutral sugars) from ascomycetous and basidiomycetous yeasts with and without derivatization.

The presence or absence of fucose, galactose, rhamnose, and xylose as well as the ratio of glucose to mannose after hydrolysis of purified yeast cell walls are valuable characters to assign yeasts or yeast states of Ascomycetes and Basidiomycetes phylogenetically. The coupling of pellicular anion-exchange resins (Dionex CarboPac PA-1) with pulsed amperometric detection provides a simple, quick, selective, and sensitive method for the analysis of yeast cell wall carbohydrates. Phragmobasidial smut fungi of monocotyledonous (Ustilago s. str., Sporisorium) and dicotyledonous (Microbotryum, Sphacelotheca) host plants cluster in two different, phylogenetically distinct yeast types, the Microbotryum type and the Ustilago type. In contrast, all smut fungi with simple holobasidia (Entyloma, Melanotaenium) from monocots and dicots investigated so far, exhibit a cell wall carbohydrate spectrum characteristic for the Ustilago type. Ustilentyloma fluitans, although a phragmobasidial smut fungus on grasses, whose smut spores and parasitic symptoms resemble Entyloma species, display the neutral sugar pattern of the Microbotryum type. The close phylogenetic relationship between the Graphiolales, Ustilaginales s. str. (phragmobasidial smuts of monocots), and Exobasidiales was substantiated further by additional strains. The presence of xylose and balanced amounts of glucose and mannose is characteristic for yeast states of the Dacrymycetaceae. The production of extracellular amyloid compounds (EAC) as well as the cell wall carbohydrate pattern point to a Tremella type affinity of Atractogloea stillata, Itersonilia perplexans, and Sterigmatosporidium polvmorphum. A meiosporangial evolution starting from coccal yeast basidia (Sterigmatosporidium) via transversely (auricularioid) septate (Atractogloea) to longitudinally divided phragmobasidia (Tremella) and simple holobasidia (Cystofilobasidium) was substantiated further within the Tremella type. The complex holobasidia (Collybia) of the Homobasidiomycetes evolved polyphyletically from longitudinally septate phragmobasidia via partially divided holobasidia (Carcinoryces). On the basis of the cell wall carbohydrate composition of approximately 250 yeasts and yeast stages of Ascomycetes and Basidiomycetes, seven distinct yeast types are described and interpreted phylogenetically.