Size Of Conidia Research Articles

Pathogenesis and Pathology of Invasive Aspergillosis

Invasive aspergillosis occurs in immunosuppressed individuals and is associated with high morbidity and mortality. Understanding the host defenses and pathogen characters is important in the causation of disease. Neutropenia and/or corticosteroid administration increase the risk of invasive infections and majority are due to Aspergillus fumigatus. The size of the conidia, thermotolerance, hydrophobins and melanin on conidial surface, adaptability to host environment, and angioinvasive nature contribute to pathogenecity. The large conidial size, hot and humid environment, and constant exposure to high spore content are implicated in the pathogenesis of chronic invasive infections in a normal host due to Aspergillus flavus. Pathology depends on the immune status and varies from granuloma with fibrosis or suppuration to abscess or infarction. The risk factors and the interplay of host pathogen in the pathogenesis of invasive aspergillosis are reviewed. Genetic predisposition and identification of such genetic factors are necessary for prevention and treatment.

Spissiomyces endophytica (Dothideomycetes, Ascomycota), a new endophytic fungus from Thailand

A new species of endophytic fungi, described herein as Spissiomyces endophytica, was isolated from tubers of Balanophora fungosa in Lampang Province, Thailand. A morphological investigation revealed that this species was distinguished from the previously described Spissiomyces species by its lager conidial size. Phylogenetic analysis was performed using combined sequence datasets of the small subunit (SSU), large subunit (LSU) and internal transcribed spacers (ITS) of the nuclear ribosomal DNA (rDNA), a part of the RNA polymerase (RPB2) and β-tubulin (TUB) genes, in order to support the morphological results. A full description, illustrations, phylogenetic tree and key to the species are provided.

First Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in Korea

HomePlant DiseaseVol. 101, No. 12First Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in Korea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Colletotrichum aenigma Causing Anthracnose on Sedum kamtschaticum in KoreaH.-W. Choi, Y. K. Lee, and S. K. HongH.-W. ChoiSearch for more papers by this author, Y. K. LeeSearch for more papers by this author, and S. K. Hong†Corresponding author: S. K. Hong; E-mail: E-mail Address: [email protected]Search for more papers by this authorAffiliationsAuthors and Affiliations H.-W. Choi Y. K. Lee S. K. Hong † , National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea. Published Online:10 Oct 2017https://doi.org/10.1094/PDIS-07-17-0938-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Orange stonecrop (Sedum kamtschaticum Fisch. and C.A. Mey.) is a perennial herbaceous plant belonging to the family Crassulaceae. It has been used as an ornamental vegetable and for folk medicine for treating inflammatory disorders in Korea. In October 2010, anthracnose occurred on leaves of orange stonecrop grown in a field in Bonghwa, Korea (36.92°N, 128.77°E). Diseased plants were about 5 to 10% of 1,000 total orange stonecrops in the field. Symptoms appeared as circular to irregular lesions with blackish brown discoloration on margins of leaves. Fragments of diseased leaves were surface sterilized with 1% NaOCl for 30 s, then rinsed in sterile water. Tissue pieces were placed on water agar (WA) and incubated at 25°C for 5 days. Three isolates were cultured on potato dextrose agar (PDA) at 25°C in darkness for 7 days. Colonies were at first cottony, floccose, grayish white, becoming gray with age, dark brown at the center in reverse, with mycelial growth of 58.3 mm after 7 days at 25°C. Conidiomata on PDA were slimy, dark brown, forming setae in abundance. Setae were brown, 1 to 3 septate, with tapering acute apices, and 41.5 to 103.2 × 4.6 to 5.9 μm (mean 78.1 × 5.2). There were some differences between shape and size of conidia from natural lesions and those from cultures. The former was cylindrical, tapering toward one or both ends, rarely fusiform, sometimes slightly curved, and 14.1 to 19.1 × 6.7 to 8.8 μm (mean 16.6 × 7.5, l/b 2.2) in size, while the latter was usually cylindrical, straight, with both ends rounded, rarely tapering toward one end, and 16.5 to 22.7 × 6.0 to 7.0 μm (mean 18.7 × 6.4, l/b 2.9) in size. Appressoria were brown to dark brown, usually clavate to ovate, crenate or irregular, and 8.7 to 15.2 × 6.1 to 10.2 μm (mean 11.1 × 8.6) in size. Based on morphological and cultural characteristics, the three isolates were identified as Colletotrichum gloeosporioides species complex (Phoulivong et al. 2010; Weir et al. 2012). To clarify taxonomic placement of the present isolate (IY1059) within the C. gloeosporioides complex, chitin synthase 1 (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), β-tubulin (TUB2), actin (ACT), rDNA internal transcribed spacers regions (ITS), and glutamine synthetase (GS) from IY1059 were amplified by PCR as previously described (Prihastuti et al. 2009). The PCR products were sequenced and deposited in GenBank with accession numbers KY820888–93, and MF401417, respectively. Six sequences of IY1059, except the GS gene, were 99 or 100% identical with the reference strains, C. aenigma C1253.4 or ICMP 18608. The GS sequence of IY1059 showed 98% identity with the reference strain. Based on morphological and molecular characteristics, the isolate was identified as C. aenigma. A pathogenicity test of the three isolates was made on wounded and unwounded leaves of orange stonecrop by dropping 30 µl of conidial suspensions (5 × 105 conidia ml−1). The same quantity of sterile distilled water placed on unwounded or wounded leaves was used as control. Both inoculated and control leaves were placed in plastic boxes with 100% relative humidity at 25°C. After 3 days, symptoms started to develop only on inoculated and wounded leaves. No symptoms developed on the unwounded and control leaves for 7 days after inoculation. The fungus was consistently reisolated from the only inoculated leaves, thus fulfilling Koch’s postulates. To our knowledge, this is the first report that C. aenigma causes anthracnose on leaves of orange stonecrop. Further studies are required to better define the host range of C. aenigma in Korea.

Walnut anthracnose caused by Colletotrichum siamense in China

The genus Colletotrichum includes a number of important plant pathogens, which cause anthracnose diseases on a broad range of hosts in the world. In recent years, walnut has been severely damaged by anthracnose disease in China with significant yield losses. Thus, it is necessary to verify the etiology of anthracnose on walnut using both morphological and molecular approaches. In 2014, walnut fruits with anthracnose symptoms were collected from five walnut orchards in Shandong Province, China, and 24 isolates were isolated. Among them, six similar single-spore isolates obtained were used for pathogenicity testing of walnut anthracnose. Acervuli were brown, circular and the average size was 50.4–101.8 μm. Conidiophores were hyaline, septate, not branched or branching at the base, conidiogenous cells were enteroblastic, phialidic, hyaline, cylindrical, ampulliform. Conidia were single celled, smooth-walled with a large guttule, colorless, fusiform to cylindrical, and had obtuse to slightly rounded ends. The size of conidia was (11.6-)13–15(−16.2) × (4.1-)4.6–5.6(−6) μm. Appressoria were brown, ovoid to ellipsoid or slightly irregularly to irregularly shaped, and the average size was 6.8–9 × 5.1–6.5 μm. Pathogenicity of the isolates to fruits and leaves were compared, and genes from all six isolates were sequenced. The isolates were identified as C. siamense based on four-gene phylogenetic analyses (ribosomal DNA-ITS, GAPDH, ACT and CHS-1) and morphological as well as cultural characters. This is the first report of C. siamense as a causal agent of anthracnose of walnut in China.

First Report of Seiridium cardinale Causing Bark Cankers on MacNab Cypress (Cupressus macnabiana) in California

HomePlant DiseaseVol. 101, No. 10First Report of Seiridium cardinale Causing Bark Cankers on MacNab Cypress (Cupressus macnabiana) in California PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Seiridium cardinale Causing Bark Cankers on MacNab Cypress (Cupressus macnabiana) in CaliforniaG. Della Rocca, R. Danti, and M. GarbelottoG. Della RoccaSearch for more papers by this author, R. DantiSearch for more papers by this author, and M. Garbelotto†Corresponding author. E-mail: E-mail Address: [email protected]Search for more papers by this authorAffiliationsAuthors and Affiliations G. Della Rocca R. Danti , Institute for Sustainable Plant Protection IPSP-CNR, 50019 Sesto Fiorentino, Italy; and M. Garbelotto † , Department of ESPM, University of California, Berkeley 94720. Published Online:15 Aug 2017https://doi.org/10.1094/PDIS-05-17-0746-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Cypress canker is a pandemic disease of cupressaceous plants caused by Seiridium cardinale (Wagener) Sutton & Gibson, a fungus recently shown to be native to California (Della Rocca et al. 2011). Disease outbreaks in California can be severe, especially in areas where cypresses are not indigenous (Danti and Della Rocca 2017). This paper describes a case of cypress canker on MacNab cypress (Cupressus macnabiana A. Murray), a species native to a few inland counties of northern California (Farjon 2005). In July 2009, dieback of several branches was shown to be associated with bark necrosis on a young C. macnabiana in the botanical garden of the University of California at Berkeley (37°52′28.00″ N, 122°14′18.54″ W; 223 m a.s.l.), Alameda County, California. Although an isolate from this diseased tree was used in a study published by Della Rocca et al. (2011), symptoms were not described in that study, and Koch’s postulates were not performed. Four dying shoots were collected and fragments of necrotic tissue 0.5 cm2 in size were placed on potato dextrose agar (PDA) in standard 9-cm diameter Petri dishes at the U.C. Berkeley Forest Pathology Laboratory. The fungus S. cardinale was cultured out of all four shoots. Its identity was determined based on cultural, microscopic, and molecular traits. After a 10-day-long incubation at 25°C, the developing colonies had a soft and floccose surface, becoming deep green or grayish-olive in the middle with time. Conidia (mitospores) were obtained from acervuli (asexual fruiting bodies) produced on water agar amended with autoclaved cypress seeds and kept for 2 to 3 weeks at 18°C under a fluorescent and near UV light. They were oblong-fusoid in shape, 6-celled (penta-euseptate), with four dark brown median cells and two hyaline small end cells. Conidial size was 26.4 × 10.0 µm on average (± 0.8234 × 0.2604 SD). The β-tubulin locus sequence (GenBank accession no. HQ678150) showed a 100% match with S. cardinale sequences of β-tubulin A-type genotypes (Della Rocca et al. 2013). Inoculations on stems were carried out in the greenhouse on six 3-year-old MacNab cypress plants growing in 5-liter pots. A mycelial plug 3 mm in diameter was taken from the margin of a 1-week-old colony of the S. cardinale isolate grown on PDA. A bark plug of the same size as the inoculum plug was excised with a sterile cork borer and a colonized plug was inserted directly on the exposed phloem. After 4 months, necrotic lesions 20.7 × 9 mm in size (± 11.0 × 4.7 SD) were observed on the bark around the inoculation site. S. cardinale was successfully reisolated from all necrotic lesions. Lesions were identical to those observed in the naturally infected tree. This report demonstrates the ability of S. cardinale to infect a native California cypress species regarded as moderately susceptible to the disease (Wolf and Wagener 1948). The natural range of the pathogen (Danti and Della Rocca 2017) currently matches that of the host only marginally (Farjon 2005), but predicted climatic changes could cause a shift northward in the distribution of the disease, increasing the overlap between the geographic range of the pathogen and that of the host, and possibly causing significant damage to this endemic cypress species.

Mating-type genes of the anamorphic fungus Ulocladium botrytis affect both asexual sporulation and sexual reproduction

Ulocladium was thought to be a strictly asexual genus of filamentous fungi. However, Ulocladium strains were shown to possess both MAT1-1-1 and MAT1-2-1 genes as observed in homothallic filamentous Ascomycetes. Here, we demonstrate that the U. botrytis MAT genes play essential roles for controlling asexual traits (conidial size and number). Using reciprocal genetic transformation, we demonstrate that MAT genes from the related heterothallic species Cochliobolus heterostrophus can also influence U. botrytis colony growth, conidial number and size, and have a strong effect on the range of the number of septa/conidium. Moreover, U. botrytis MAT genes can also affect similar aspects of asexual reproduction when expressed in C. heterostrophus. Heterologous complementation using C. heterostrophus MAT genes shows that they have lost the ability to regulate sexual reproduction in U. botrytis, under the conditions we employed, while the reciprocal heterologous complementation demonstrates that U. botrytis MAT genes have the ability to partially induce sexual reproduction in C. heterostrophus. Thus, the genetic backgrounds of C. heterostrophus and U. botrytis play significant roles in determining the function of MAT genes on sexual reproduction in these two fungi species. These data further support the role of MAT genes in controlling asexual growth in filamentous Ascomycetes but also confirm that heterothallic and homothallic Dothideomycete fungi can be interconverted by the exchange of MAT genes.

First Report of a Leaf Spot Caused by Bipolaris oryzae on Peanut (Arachis hypogaea) in China

Peanut is an economical crop of global importance and grown widely in both tropics and subtropics. Currently, China is the largest peanut production, consumption and trade countries around the world. In August 2014, light-brown foliar spots with dark brown, irregular borders were found on peanut (Yuhua 22) at Xinyang in Henan province, China. Symptomatic leaf samples were collected, and surface-sterilized (75% ethanol, 30 s; 3% NaClO, 2 min), rinsed in sterile water for three times, air-dried, plated on potato dextrose agar (PDA) medium, and incubated at 25°C under a 12-h dark/light cycle. Colonies on PDA were initially gray, fluffy mycelium with unevenly distributed mycelial pellets, then becoming dark gray with age. Conidia were oblong, slightly curved, and light-brown with 6 to 10 septa. Conidial sizes (length × width) were 57.5 to 144.7×8.4 to 21.4 (average 102.0×13.8) μm. Pathogenicity tests were conducted with 6-week-old peanut plants. Ten 16×12-cm pots with six plants per pot were inoculated onto t...

New finding of the Phoma leaf spot of the varnish tree (Koelreuteria paniculata) in Himachal Pradesh

A new foliar disease of Koelreuteria paniculata tree is reported during continuous surveys conducted at Solan district of Himachal Pradesh during August, 2015 to December, 2015. On the basis of morphological characteristics the fungus, the fungus was identified as Phoma eupyrena which produces symptoms on the leaves as numerous small, pale, irregular spots which are light brown with dark black margins and blightening appearance at the apex region initially. Phoma eupyrena form pycnidia, whose range varied between 240-250 μm in diameter and conidia are hyaline, short, cylindrical, mostly straight and unicellular. Conidial size ranged between 3-6 × 1.5-3 μm.

RNAi-mediated silencing of MAP kinase signalling genes (Fmk1, Hog1, and Pbs2) in Fusarium oxysporum reduces pathogenesis on tomato plants

Fusarium oxysporum is a soil-borne plant fungal pathogen, and causes colossal losses in several crop plants including tomato. Effective control measures include the use of harmful fungicides and resistant cultivars, but these methods have shown limited success. Conventional methods to validate fungal pathogenic genes are labour intensive. Therefore, an alternative strategy is required to efficiently characterize unknown pathogenic genes. RNA interference (RNAi) has emerged as a potential tool to functionally characterize novel fungal pathogenic genes and also to control fungal diseases. Here, we report an efficient method to produce stable RNAi transformants of F. oxysporum using Agrobacterium-mediated transformation (AMT). We have transformed F. oxysporum spores using RNAi constructs of Fmk1, Hog1, and Pbs2 MAP kinase signalling genes. Fmk1 RNAi fungal transformants showed loss of surface hydrophobicity, reduced invasive growth on tomato fruits and hypo-virulence on tomato seedlings. Hog1 and Pbs2 RNAi transformants showed altered conidial size, and reduced invasive growth and pathogenesis. These results showed that AMT using RNAi constructs is an effective approach for dissecting the role of genes involved in pathogenesis in F. oxysporum and this could be extended for other fungal systems. The obtained knowledge can be easily translated for developing fungal resistant crops by RNAi.

In Vitro Morphological Characteristics of Pyrenophora tritici-repentis Isolates from Several Algerian Agro-Ecological Zones.

Tan spot caused by the fungus Pyrenophora triticirepentis is a serious disease of wheat, which is on increase in recent years in Mediterranean region. In the field this fungus produces a diamond-shaped necrotic lesions with a yellow halo on wheat foliage. The objective of this study was to characterize and compare several monospore isolates of P. tritici-repentis collected from different infected wheat fields in various locations of Algeria, and find the morphological differences between them, if any. The results revealed wide morphologically variation among the isolates based on colony colors and texture, mycelial radial growth and conidial size.

Keragaman Morfologi, Genetika, dan Patogenisitas Colletotrichum acutatum PenyebabAntraknosa Cabai di Jawa dan Sumatera

Colletotrichum acutatum is known as the major causal agents of anthracnose disease of chilli pepper in Indonesia. This research was aimed to study genetic variability of C. acutatum in Java and Sumatera based on morphological and molecular characteristics and to evaluate pathogenicity of several isolates . Observation on morphological characteristics involved colour and growth of each colony as well as shape and size of conidia. Molecular identification was performed by DNA amplification using specific primer for C. acutatum , i.e. CaInt2/ITS4 followed by sequencing and nucleotide sequence analysis. Pathogenicity test for each isolate on Capsicum annuum and C. frutescens was conducted in the laboratory using detached chilli. Morphology variability was observed from 40 isolates of C. acutatum. Most of the isolates have white/beige colonies with fusiform conidia of 6.11–9.73 µm in length and 2.24­–2.73 µm in width. Pathogenicity of 3 C. acutatum isolates varies from moderate to high based on lesions size on infected chilli. Sequence analysis of 8 C. acutatum isolates indicated high homology among isolates from Java and Sumatera

Efficacy of garlic extract and yeast for the control of post harvest diseases of grape

The present investigations were carried out with collection of diseased samples, isolation of the organisms responsible for post harvest spoilage, their pathogenicity, symptomatology, morphological characters and effect of temperature on growth and sporulation in order to suggest suitable control measures in respect of yeast as a bioagent and garlic extract as a botanical in controlling post harvest fungal diseases of grape. The causal organisms were isolated from infected grape berries and recorded association of three fungal pathogens viz., Aspergillus niger, Alternaria alternata and Penicillium digitatum. The conidial size of A. niger, A. alternata and P. digitatum are measured as 4.4 μm, 42.47 x 16.37 μm and 4.33 – 4.5 μm in size (average), respectively. Use of 5 per cent yeast, (Eremothecium cymbalariae) was found effective against Aspregillus niger (both in vitro and in vivo) and 1 per cent garlic extract was found effective against Alternaria alternata (both in vitro and in vivo).Both yeast and garlic extract increases shelf-life and market quality of fruits, with increase in glossiness of fruits. Temperature 27 ±10C was found optimum for both growth and sporulation of all isolated fungal pathogens. How to view point the article : Shinde, R.P., Barhate, B.G. and Bandgar, M.S. (2016). Efficacy of garlic extract and yeast for the control of post harvest diseases of grape. Internat. J. Plant Protec., 9(2) : 434-438, DOI : 10.15740/HAS/IJPP/9.2/434-438.

New and interesting chaetothyrialean fungi from Spain

In the course of taxonomic studies on saprobic microfungi from Spain, several slow-growing, dematiaceous hyphomycetes were isolated from soil, submerged plant material and river sediments. Sixteen of these strains were identified as members of the ascomycete order Chaetothyriales on the basis of morphology and DNA sequence analyses of the internal transcribed spacer region and partial large subunit ribosomal RNA gene. These included three novel species (Cladophialophora pseudocarrionii, Cyphellophora chlamydospora, and Rhinocladiella amoena) and five interesting, little-known or clinically-relevant species (Cyphellophora suttonii, Exophiala aquamarina, E. lacus, E. radicis, and Rhinocladiella similis). In addition, Exophiala oligosperma, an emerging opportunistic fungus, was found for the first time in an aquatic freshwater environment (river sediments). Cladophialophora pseudocarrionii resembles C. carrionii in the branching pattern of its conidial chains, but differs from the latter species in its inability to grow at 30 °C. Cyphellophora chlamydospora differs from other species of the genus in the absence of conidiation, producing only chlamydospores in vitro. Rhinocladiella amoena shows branched conidiophores similar to those of R. anceps, R. atrovirens, R. basitona and R. similis, but differs from them in conidial shape and size. The ex-type strain of Phialophora livistonae, included in the phylogenetic study, clustered with high statistical support with members of the genus Cyphellophora and is transferred to this genus.

A new endophytic species ofNeostagonospora(Pleosporales) from the coastal grassSpinifex littoreusin Taiwan

A new species of Neostagonospora associated with Spinifex littoreus was found. Endophytic isolates remained sterile, but a specimen collected on living leaves could be used for morphological characterization and cultivation. The ITS sequences from the cultures as well as from direct total DNA extraction from the plant indicated conspecificity and a broader geographic distribution than the single field collection, but yielded low support on the genus level in phylogenetic analyses. Analysis of the RPB2 sequences, however, sufficiently supported a placement of the species in Neostagonospora. The shape of conidiogenous cells as well as numbers of septa and sizes of conidia are useful characters for distinguishing Neostagonospora species.

RAPD-PCR technique for molecular detection and diversity of Fusarium oxysporum f.sp. dianthi causing vascular wilt of carnation

Fusarium wilt disease is one of the major economic constraint which hampers carnation cut flower production. Thirteen isolates of Fusarium oxysporum f.sp. dianthi inciting vascular wilt of carnation were evaluated for their molecular characterization using random amplified polymorphic DNA (RAPDPCR). The isolates were categorized based on the morphological characteristics, produced colonies with circular pattern growth. However, differences were obtained in colony colour, shape and size of conidia. The 5.8S-rDNA of ITS region was amplified the specific amplicon size of 398 bp which confirmed the pathogen as Fusarium oxysporum. The molecular polymorphism among isolates were analysed by means of RAPD-PCR and the genetic coefficient matrix derived from the scores of RAPD profile showed that minimum and maximum per cent similarities and diversity among isolates were in the range of 70 to 96 per cent, respectively. The cluster analysis by un-weighted pair-group method with arithmetic average (UPGMA), separated the isolates into four clusters which confirming the genetic diversity among isolates.

Aspergillus section Nidulantes (formerly Emericella): Polyphasic taxonomy, chemistry and biology.

Aspergillus section Nidulantes includes species with striking morphological characters, such as biseriate conidiophores with brown-pigmented stipes, and if present, the production of ascomata embedded in masses of Hülle cells with often reddish brown ascospores. The majority of species in this section have a sexual state, which were named Emericella in the dual name nomenclature system. In the present study, strains belonging to subgenus Nidulantes were subjected to multilocus molecular phylogenetic analyses using internal transcribed spacer region (ITS), partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) sequences. Nine sections are accepted in subgenus Nidulantes including the new section Cavernicolus. A polyphasic approach using morphological characters, extrolites, physiological characters and phylogeny was applied to investigate the taxonomy of section Nidulantes. Based on this approach, section Nidulantes is subdivided in seven clades and 65 species, and 10 species are described here as new. Morphological characters including colour, shape, size, and ornamentation of ascospores, shape and size of conidia and vesicles, growth temperatures are important for identifying species. Many species of section Nidulantes produce the carcinogenic mycotoxin sterigmatocystin. The most important mycotoxins in Aspergillus section Nidulantes are aflatoxins, sterigmatocystin, emestrin, fumitremorgins, asteltoxins, and paxillin while other extrolites are useful drugs or drug lead candidates such as echinocandins, mulundocandins, calbistrins, varitriols, variecolins and terrain. Aflatoxin B1 is produced by four species: A. astellatus, A. miraensis, A. olivicola, and A. venezuelensis.

Cultural and morphological studies on Ponnampet leaf and neck blast isolates of Magnaporthe grisea (Herbert) barr on rice (Oryza sativa L.)

The study was carried out to standardize the optimal growth, sporulation and production of perfect stage of pathogen on different media. Among different media used such as Potato dextrose Agar (PDA), Oat meal Agar, Ragi flour agar, yeast extract + 2% soluble starch, Host extract + 2% soluble sucrose agar, Potato dextrose agar + Biotin + Thiamine and Rice flour agar, Oat meal agar and potato dextrose agar was found to be best media for radial growth and sporulation of M. grisea. Maximum conidia length (9.46?m) and breadth (7.36?m) was recorded in Oat meal agar followed by Potato dextrose agar and least conidia length (6.15 ?m) and breadth (5.11 ?m) was recorded in ragi flour media after 20 days of inoculation. Conidial size varied in leaf and neck blast isolates, the maximum mean colony diameter of 88.00mm and 89.16mm in neck and leaf blast was recorded in Oat meal agar respectively. The maximum sporulation mean index was observed in Oat Meal agar of 3.15 ?m in leaf and 3.20 ?m in neck blast was recorded. The best growth of the pathogen was recorded at optimum pH range from 6.0 - 7.0 and temperature of 27oC. Therefore oat meal agar media was found to be best among all the media used for growth, sporulation, conidial size and colony characters of M. grisea.

Taxonomy and phylogeny of Cryptocoryneum (Pleosporales, Dothideomycetes)

Species of Cryptocoryneum were taxonomically reassessed on the basis of morphological observations and the results of molecular phylogenetic analysis. Eighteen isolates of Cryptocoryneum species, namely two strains from Africa, three from Europe, and 13 from Japan, were phylogenetically analysed using sequences of nuclear rDNA internal transcribed spacers (ITS) and the partial sequence of the translation elongation factor 1α gene (TEF1). The phylogenetic analysis indicated that Cryptocoryneum species formed a monophyletic clade and were closely related to Lophiotrema (Lophiotremataceae) and Aquasubmersa (incertae sedis) in the Pleosporales (Dothideomycetes). We examined holotype specimens of C. fasciculatum, C. hysterioides, and Torula uniformis and concluded that these species are conspecific, with C. hysterioides having priority. Although C. hysterioides has long been regarded as a synonym of C. condensatum, we consider C. hysterioides to be a distinct species within the genus. We found several cryptic species that were morphologically similar to C. condensatum sensu lato, but that could be separated on the basis of conidial size and the number of conidial arms and conidial septa, characters that seem to be informative for species delimitation within Cryptocoryneum. A total of seven new species, namely C. akitaense, C. brevicondensatum, C. congregatum, C. japonicum, C. longicondensatum, C. paracondensatum, and C. pseudorilstonei, are described and illustrated. A key to species accepted in Cryptocoryneum is provided.

The cacao pathogen Moniliophthora roreri (Marasmiaceae) produces rhexolytic thallic conidia and their size is influenced by nuclear condition

Moniliophthora roreri, the causal agent of frosty pod rot of cacao, is a member of the mushroom-forming family Marasmiaceae (Marasmiineae, Agaricales, Basidiomycota). Yet, M. roreri has never been observed to produce a mushroom fruiting body, but rather produces billions of spores on the surface of infected pods. The question of whether these spores are produced via meiosis or mitosis has been the subject of some speculation. However, numerous molecular-based studies have been unable to support a hypothesis of sexual recombination for this fungus. We re-examined sporogenesis and the nuclear condition of hyphae and spores in M. roreri via nuclear staining and spore germination studies. Conidia are produced asexually in a thallic and rhexolytic manner as is true for other Marasmiineae species such as M. perniciosa, Flammulina velutipes and Marasmius puerariae. We also found that hyphal cells as well as spores harbor one or two nuclei, rarely three, that conidium size is influenced by number of nuclei within, and that individual isolates produced consistently and significantly different proportions of binucleate and mononucleate spores regardless of varietal group.

Morphology, Molecular Identity, and Pathogenicity of Verticillium dahliae and V. longisporum Associated with Internally Discolored Horseradish Roots.

During 2008 to 2009, 255 isolates of Verticillium were obtained from internally discolored horseradish roots collected from California, Illinois, and Ontario. Twenty representative isolates were selected according to morphological features and geographic origin for further characterization. Based on the conidial size, the isolates were divided into two groups: Verticillium dahliae (4.4 ± 1.23 μm) and V. longisporum (7.8 ± 1.76 μm). Genetic diversity of the isolates was determined by sequence analysis of the internal transcribed spacer (ITS) and two mitochondrial genes (cytochrome oxidase subunit III [cox3] and NADH dehydrogenase subunit I [nad1]). Based on ITS analysis, Verticillium isolates were divided into two clades: V. dahliae and V. longisporum. However five isolates of V. longisporum (identified based on conidial size) were clustered with a V. dahliae clade, whereas the other five isolates formed a distinct V. longisporum clade. Combined analysis of the mitochondrial genes cox3 and nad1 showed that the two genetic clades of V. longisporum in ITS region analysis corresponded to the previously reported V. longisporum lineage A1/D3 and A1/D2. Pathogenicity tests revealed that all tested Verticillium isolates caused internal discoloration of horseradish roots, and there were no significant differences in either incidence or severity of root discoloration among the genetic groups.