First Report of Papaya Fruit Anthracnose Caused by Colletotrichum brevisporum in Brazil

Papaya fruits (Carica papaya L.) (cv. Golden) showing post-harvest anthracnose symptoms were observed during surveys of papaya disease in northeastern Brazil from 2008 to 2012. Fruits affected by anthracnose showed sunken, prominent, dark brown to black lesions. Small pieces (4 to 5 mm) of necrotic tissue were surface sterilized for 1 min in 1.5% NaOCl, washed twice with sterile distilled water, and plated onto potato dextrose agar (PDA) amended with 0.5 g liter^-1 streptomycin sulfate. Macroscopic colony characters and microscopic morphology characteristics of four isolates were observed after growth on PDA (2) for 7 days at 25°C under a 12-hr light/dark cycle. Colonies varied between colorless and pale brown in reverse, with orange conidial mass. Conidia were hyaline, aseptate, cylindrical with round ends, slightly flattened, smooth-walled, guttulate, and 13.5 (10.5 to 17.1) μm × 3.8 (2.1 to 4.8) μm (l/w ratio = 3.5, n = 50), typical of Colletotrichum spp. DNA sequencing of partial sequences of actin (ACT) gene and the internal transcribed spacer (ITS1-5.8S-ITS2 rRNA) were conducted to accurately identify the species. Sequences of the papaya isolates were 99% similar to those of Colletotrichum brevisporum (GenBank Accession Nos. JN050216, JN050217, JN050238, and JN050239). A phylogenetic analysis using Bayesian inference and including published ACT and ITS data for C. brevisporum and other Colletotrichum species was carried out (1). Based on morphological and molecular data, the papaya isolates were identified as C. brevisporum. Conidia of the papaya isolates were narrower than those described for C. brevisporum (2.9 to 4.8 μm and 5 to 6 μm, respectively) (1), which may be due to differences in incubation temperature or a typical variation in conidial size in Colletotrichum species (3). Sequences of the isolates obtained in this study are deposited in GenBank (ACT Accession Nos. KC702903, KC702904, KC702905, and KC702906; ITS Accession Nos. HM163181, HM015851, HM015854, and HM015859). Cultures are deposited in the Culture Collection of Phytopathogenic Fungi of the Universidade Federal Rural de Pernambuco, Recife, Brazil (CMM 1672, CMM 1702, CMM 1822, and CMM 2005). Pathogenicity testing was conducted with all four strains of C. brevisporum on papaya fruits (cv. Golden). Fruits were wounded at the medium region by pushing the tip of four sterile pins through the surface of the skin to a depth of 3 mm. Mycelial plugs taken from the margin of actively growing colonies (PDA) of each isolate were placed in shallow wounds. PDA discs without fungal growth were used as control. Inoculated fruits were maintained in a humid chamber for 2 days at 25°C in the dark. After 6 days, anthracnose symptoms developed that were typical of diseased fruit in the field. C. brevisporum was successfully reisolated from symptomatic fruits to fulfill Koch's postulates. C. brevisporum was described from Neoregalia sp. and Pandanus pygmaeus in Thailand (1). To our knowledge, this is the first report of C. brevisporum in Brazil and the first report of this species causing papaya fruit anthracnose. References: (1) P. Noireung et al. Cryptogamie Mycol., 33:347, 2012. (2) B. C. Sutton. The Genus Glomerella and its anamorph Colletotrichum. CAB International, Wallingford, UK, 1992. (3) B. S. Weir et al. Stud. Mycol. 73:115, 2012.

Species-specific real-time PCR detection of Colletotrichum kahawae

AIMS

Colletotrichum kahawae is a strongly aggressive pathogen causing coffee berry disease and is specific to Arabica coffee (Coffea arabica) in Africa. In this article, we developed a real-time PCR assay for the species-specific diagnosis of C. kahawae by designing the primers and a TaqMan probe derived from the single nucleotide polymorphism-rich region of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene.

METHODS AND RESULTS

DNA markers from rDNA internal transcribed spacer, actin, β-tubulin and GAPDH genes of the ex-type culture of C. kahawae and 10 reference strains of Colletotrichum species were analysed for intra- and interspecific variations. The GAPDH gene was selected to develop a species-specific DNA marker. A TaqMan real-time PCR assay for species-specific detection of C. kahawae was developed, and its accuracy was tested against type strains of other phylogenetically closely related species in the C. gloeosporioides species complex, with the detection sensitivity of 80 fg μl(-1) of genomic DNA.

CONCLUSIONS

This real-time PCR assay is highly specific and sensitive for the diagnosis of C. kahawae and can be applied in qualitative and quantitative tests.

SIGNIFICANCE AND IMPACT OF THE STUDY

This protocol allows for a rapid and sensitive detection of C. kahawae and will be useful in disease management and pest detection to prevent further spread of this pathogen.

Phyllosticta ophiopogonis sp. nov. from Ophiopogon japonicus (Liliaceae)

A leaf spotting disease of an ornamental variety of Ophiopogon japonicus was discovered at several locations in northern Thailand. In all cases a species of Phyllosticta was associated with the lesions. Phyllosticta ophiopogonis sp. nov. is distinguished from Phyllosticta species from Liliaceae in conidia size, mucilaginous sheath and appendage thus the species is introduced as new in this paper. The new species which causes unsightly lesions on this ornamental plant is described, illustrated and compared with other similar Phyllosticta species.

A class-wide phylogenetic assessment of Dothideomycetes

We present a comprehensive phylogeny derived from 5 genes, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, for 356 isolates and 41 families (six newly described in this volume) in Dothideomycetes. All currently accepted orders in the class are represented for the first time in addition to numerous previously unplaced lineages. Subclass Pleosporomycetidae is expanded to include the aquatic order Jahnulales. An ancestral reconstruction of basic nutritional modes supports numerous transitions from saprobic life histories to plant associated and lichenised modes and a transition from terrestrial to aquatic habitats are confirmed. Finally, a genomic comparison of 6 dothideomycete genomes with other fungi finds a high level of unique protein associated with the class, supporting its delineation as a separate taxon.

A novel phylogenetic group within Thozetella (Chaetosphaeriaceae): a new taxon based on morphology and DNA sequence analyses

A new species, Thozetella pinicola, was isolated from leaf litter of Pinus elliottii Engelm. in Hong Kong. This taxon is described and compared with existing species in the genus. It occurs on the substrate as creamy white sporodochia and has short black conidiophores. Morphological characters are typical of Thozetella and it most closely resembles Thozetella falcata, Thozetella gigantea and Thozetella nivea, but may be distinguished by its distinct microawns and different conidial size. To gain further taxonomic insight into the phylogenetic relationships of our new taxon and its allies, we sequenced and analysed 6 different regions of 3 genes (ribosomal DNA and protein coding genes: RNA polymerase II largest subunit (RBP2) and b-tubulin). Resulting phylogenies are compared with existing morphological information. Molecular data support the relationship between Thozetella species and the Chaetosphaeriaceae (Chaetosphaeriales, Sordariomycetes). In addition, we recovered a new phylogenetic lineage (or group) within the existing phylogenetic framework of Thozetella as previously proposed. In particular, there is a close association between T. pinicola and T. nivea, which is strongly supported. The affinities of these 2 newly sequenced taxa are discussed in light of morphological and molecular characters.

A novel phylogenetic group withinThozetella(Chaetosphaeriaceae): a new taxon based on morphology and DNA sequence analyses

A new species, Thozetella pinicola , was isolated from leaf litter of Pinus elliottii Engelm. in Hong Kong. This taxon is described and compared with existing species in the genus. It occurs on the substrate as creamy white sporodochia and has short black conidiophores. Morphological characters are typical of Thozetella and it most closely resembles Thozetella falcata , Thozetella gigantea and Thozetella nivea , but may be distinguished by its distinct microawns and different conidial size. To gain further taxonomic insight into the phylogenetic relationships of our new taxon and its allies, we sequenced and analysed 6 different regions of 3 genes (ribosomal DNA and protein coding genes: RNA polymerase II largest subunit (RBP2) and β-tubulin). Resulting phylogenies are compared with existing morphological information. Molecular data support the relationship between Thozetella species and the Chaetosphaeriaceae (Chaetosphaeriales, Sordariomycetes). In addition, we recovered a new phylogenetic lineage (or group) within the existing phylogenetic framework of Thozetella as previously proposed. In particular, there is a close association between T. pinicola and T. nivea, which is strongly supported. The affinities of these 2 newly sequenced taxa are discussed in light of morphological and molecular characters.

Molecular and morphological characterization of Pyricularia and allied genera

The phylogenetic relationships of Pyricularia species and species from related genera were established from sequences of the internal transcribed spacer ribosomal RNA gene. Phylogenetic analysis disclosed a consistent correlation with spore morphology. Most Pyricularia species studied, and two species of Dactylaria that have obpyriform conidia, fell within the Magnaporthaceae cluster with high bootstrap support. Pyricularia variabilis was more related to Dactylaria, Tumularia or Ochroconis species than to the Magnaporthaceae. Dactylaria and species of Nakataea, Ochroconis, Pyriculariopsis and Tumularia were distinct from the Magnaporthaceae, and the genus Dactylaria is polyphyletic. The combination of morphological and molecular characters, such as spore morphology and ITS ribosomal DNA sequences data, suggested that conidial shape could be a primary character to distinguish Pyricularia from related genera.

Phylogeny of Rosellinia capetribulensis sp. nov. and its allies (Xylariaceae)

A new Rosellinia species, R. capetribulensis isolated from Calamus sp. in Australia is described. R. capetribulensis is characterized by perithecia immersed within a carbonaceous stroma surrounded by subiculum-like hyphae, asci with large, barrel-shaped amyloid apical apparatus and large dark brown spores. Morphologically, R. capetribulensis appears to be similar to R. bunodes, R. markhamiae and R. megalospora. To gain further insights into the phylogeny of this new taxon we analyzed the ITS-5.8S rDNA using maximum parsimony and likelihood methods. In addition, a morphological dataset also was analyzed phylogenetically to investigate possible affinities. ITS rDNA based phylogenies reveal that R. capetribulensis is closely related to other Rosellinia species showing closest affinity to R. arcuata, RL necatrix and R. pepo. However, analysis of R. capetribulensis forms an unsupported branch sister to these taxa. Results from the morphological matrix indicate a close morphological affinity to members of Rosellinia subgenus Rosellinia. Despite that ITS rDNA and morphological analyses present difficulties in constructing a proper phylogenetic framework among Rosellinia and allied genera, there is sufficient evidence to support the establishment of the new taxon in the genus Rosellinia. The morphological similarities and differences between R. capetribulensis and allied genera such as Astrocystis and Entoleuca are also briefly discussed.

Production of wood decay enzymes, loss of mass, and lignin solubilization in wood by diverse tropical freshwater fungi

In vitro production of cellulase and xylanase was common among diverse freshwater ascomycetes and their hyphomycetous anamorphs. Production of enzymes involved in lignin degradation was rare. Most isolates were capable of causing mass loss in angiosperm wood, although values were low, at approximately 10% during a 24-week period. A few isolates caused higher mass loss of up to 26.5%, and five of these were shown to solubilize significant amounts of lignin. This is the first report of lignin solubilization by freshwater fungi. Torula herbarum (hyphomycete) and Ophioceras dolichostomum (ascomycete) produced indices of lignin solubilization equivalent to those of terrestrial white-rot basidiomycetes. In all cases wood decay was 2.2- to 3-fold higher in exposed rather than submerged conditions.

Succession of fungi on dead and live wood in brackish water in Brunei

We observed the sequence of fungi appearing on submerged wood of Hibiscus tiliaceus that initially was either dead or alive. Branches that were dead, but still attached to the tree, and live branches were cut from H. tiliaceus in the riparian vegetation in a brackish habitat on the Tutong River, Brunei. Branch segments were connected to the riverbank using monofilament line. Samples were examined for fungi before the branches were placed in the river and after the branches had been submerged 3 or 6 mo. Fifty taxa were found on the samples. Before being placed in the water different fungal assemblages were found on live as compared to deadwood. Branches that were alive when cut supported a distinctly different fungal assemblage after 3 mo in the water. Dead branches after 3 mo and both dead and initially live samples after 6 mo had been colonized by a fungal assemblage that is typical at this site. It is unknown whether the differences in colonization of dead and initially live wood can be attributed to differences in the substratum (i.e., the presence or absence of bark), inhibitory substances in more recently live wood or to assembly rules resulting from the different fungi that already were present in dead and live branches.

Dyrithiopsis lakefuxianensis gen. et sp. nov. from Fuxian Lake, Yunnan, China, and notes on the taxonomic confusion surrounding Dyrithium

A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceae in that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J+ subapical ring, and brown ascospores. It is similar to Dyrithium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J+ subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.

Microfungi on the Pandanaceae: Linocarpon lammiae sp. nov., L. siamensis sp. nov. and L. suthepensis sp. nov. are described with a key to Linocarpon species from the Pandanaceae

Linocarpon species are reported from Pandanaceae in Australia, Brunei, Hong Kong, Nepal, New Zealand, Philippines, Seychelles, Thailand and Vanuatu. Linocarpon lammiae sp. nov. were collected on decaying leaves of Pandanus tectorius in Hong Kong. Linocarpon siamensis sp. nov. and L. suthepensis sp. nov. were collected from decaying leaves of P. penetrans in Thailand. These taxa are described, illustrated and compared with Linocarpon species with similar ascospore morphology and dimensions. Included are a synoptic table, which compares the new species to similar known species, and a dichotomous key to species of Linocarpon known from members of the Pandanaceae.

Variations in the Phytophthora infestans Population in Nepal as Revealed by Nuclear and Mitochondrial DNA Polymorphisms

ABSTRACT Phytophthora infestans isolates collected from potato and tomato crops from various parts of Nepal during the 1999 and 2000 crop seasons were characterized for nuclear and mitochondrial DNA polymorphisms using restriction fragment length polymorphism markers. The nuclear DNA probe RG57 detected 11 multilocus genotypes among 280 isolates. Three genotypes were detected 21 times or more, constituting 94% of the total population, whereas frequencies of other genotypes ranged from 0.004 to 0.014. The overall genotypic diversity as estimated by the Gleason index was 1.78. Most of the overall diversity was present at the highest level (i.e., interregional, 46%), indicating limited gene flow among regions. Cluster analysis of multilocus genotypes derived from RG57 and mating type data for Nepalese isolates and representative isolates worldwide showed Nepalese isolates grouping into four clusters. Characterization of 67 isolates for mitochondrial DNA polymorphisms revealed the presence of two mt-haplotypes, Ia and Ib with the proportions of 0.88 and 0.12, respectively. Polymorphisms in nuclear and mitochondrial DNA revealed a moderate level of diversity in this population. Genotype NP3 had an identical RG57 fingerprint to US1 and had mt-haplotype Ib, confirming the presence of an old population in Nepal. Most of the genotypes had a different RG57 fingerprint than that of US1 and mt-haplotype Ia, the common characteristics of new populations. The presence of a new population at high proportions in Nepal was consistent with the global trend of mt-haplotype distribution, and suggests the displacement of old populations. This study indicates at least three possible introductions of P. infestans to Nepal.

Endophytic fungi from Amomum siamense

Endophytic fungi were isolated from apparently healthy organs of the wild ginger Amomum siamense Criab.. including leaves, pseudostems, and rhizomes, collected from two sites in Doi Suthep-Pui National Park, Thailand. Endophytes were relatively common with an isolate prevalence of 70%-83% at the two sites sampled in the wet and dry seasons. The endophyte assemblages from the two sites were diverse and comprised 7 Ascomycetes and 26 mitosporic fungi. Colletotrichum "gloeosporioides" (Penz.) Penz. & Sacc. in Penz., Glomerella spp., xylariaceous fungi, and Phomopsis spp. were consistently dominant as endophytes on Amomum siamense, but many rare species and mycelia sterilia were also recorded. There was no significant difference between the number of isolates recovered from leaves containing vein tissues and those containing intervein tissues, independent of leaf age. Most taxa showed a preference for either leaf tissue or pseudostems. Two new Ascomycetes species. Gaeumannomyces amomi and Leiosphaerella amomi, were discovered from leaves and rhizomes, respectively, and four species of Pyricularia, including three new species, were isolated from leaves.