Myrtaceae, a cache of fungal biodiversity

Twenty-six species of microfungi are treated, the majority of which are associated with leaf spots of Corymbia, Eucalyptus and Syzygium spp. (Myrtaceae). The treated species include three new genera, Bagadiella, Foliocryphia and Pseudoramichloridium, 20 new species and one new combination. Novelties on Eucalyptus include: Antennariella placitae, Bagadiella lunata, Cladoriella rubrigena, C. paleospora, Cyphellophora eucalypti, Elsinoë eucalypticola, Foliocryphia eucalypti, Leptoxyphium madagascariense, Neofabraea eucalypti, Polyscytalum algarvense, Quambalaria simpsonii, Selenophoma australiensis, Sphaceloma tectificae, Strelitziana australiensis and Zeloasperisporium eucalyptorum. Stylaspergillus synanamorphs are reported for two species of Parasympodiella, P. eucalypti sp. nov. and P. elongata, while Blastacervulus eucalypti, Minimedusa obcoronata and Sydowia eucalypti are described from culture. Furthermore, Penidiella corymbia and Pseudoramichloridium henryi are newly described on Corymbia, Pseudocercospora palleobrunnea on Syzygium and Rachicladosporium americanum on leaf litter. To facilitate species identification, as well as determine phylogenetic relationships, DNA sequence data were generated from the internal transcribed spacers (ITS1, 5.8S nrDNA, ITS2) and the 28S nrDNA (LSU) regions of all taxa studie

Molecular and morphological characterization of Phyllactinia cassiae-fistulae (Erysiphaceae; Ascomycota) from Thailand

Phyllactinia cassiae-fistulae and its Ovulariopsis anamorph, a causal agent of powdery mildew on Cassia fistula, have been found in Thailand for the first time. Phylogenetic analysis using the 28S ribosomal DNA sequences clearly demonstrated that P. cassiae-fistulae distinctly formed a unique clade at the basal part of Phyllactinia with 100% bootstrap support. This phylogenetic analysis supports the unique morphology of P. cassiae-fistulae anamorph having cylindrical-ellipsoil conidia and short conidiophores similar to Oidium species.Keywords: Morphology, phylogeny, powdery mildew, Cassia fistula, Senna siameaAfrican Journal of Biotechnology Vol. 12(2), pp. 109-11

Phyllosticta citriasiana sp. nov., the cause of Citrus tan spot of Citrus maxima in Asia

Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range of other hosts. Recently, necrotic spots similar to those caused by G. citricarpa were observed on fruit of Citrus maxima intercepted in consignments exported from Asia. In these spots, pycnidia and conidia of a Guignardia species closely resembling G. citricarpa were observed, and therefore measures were taken for the consignments in line with the European Union legislation for G. citricarpa. To determine the identity of the causal organism on this new host, fungal isolates were subjected to DNA sequence analysis of the internal transcribed spacer region (ITS1, 5.8S, ITS2), translation elongation factor 1-alpha (TEF1) and actin genes. A combined phylogenetic tree resolved three species correlating to G. citricarpa, G. mangiferae and a previously undescribed species, Phyllosticta citriasiana sp. nov., closely related to G. citricarpa. Morphologically P. citriasiana can be distinguished from G. citricarpa by having larger conidia, longer conidial appendages, and in not producing any diffuse yellow pigment when cultivated on oatmeal agar (OA). Furthermore, it is distinguishable from G. mangiferae by having smaller conidia, with a narrower mucoid sheath. In culture, colonies of P. citriasiana can also be distinguished from G. citricarpa and G. mangiferae by being darker shades of grey and black on OA, malt extract agar (MEA), potato-dextrose agar, and cornmeal agar. Furthermore, cultures of P. citriasiana achieved optimal growth after 2 weeks at 21-27°C, and ceased to grow at 30-33°C. In contrast, colonies of G. citricarpa and G. mangiferae achieved optimal growth at 27-30°C, and ceased to grow at 30-36°C Colonies of P. citriasiana also grew faster than those of G. citricarpa and G. mangiferae on OA and MEA. Phyllosticta citriasiana appears to be a harmful pathogen of Citrus maxima, causing a tan spot on fruit, underlining the need for further surveys and research to determine its distribution and host range

Application of biological fungicides to control citrus root rot under field condition in Cambodia

Pythium ultimum was recorded to be the first time to cause citrus root rot in Cambodia. The pathogen causes a serious damage almost everywhere planted to citrus in Battambang province. The pathogen infects the plants starting from seedlings which show yellow leaves, die back, stem rot, root rot and die. Mainly, the citrus trees express slowly decline from the second year and slowly die which starting from six to seven years old, even using the chemical fungicides. In laboratory test, the detached leave method has shown that only three days after inoculation of pathogen, the citrus leaves turning completely dark brown showing aggressive pathogen and proved for pathogenicity. In field trials, the chemical and biological fungicides namely Chaetomium and Trichoderma biological products were peroidically applied to four year old citrus trees in one year. All products were spayed above plants and to rhizosphere soil every month (metalaxyl-10g/20L of water in combination with chemical fertilizers, Chaetomium20g/20 L of water and Trichoderma-20g/20L of water in combination with biocompost). Result showed that all treated citrus trees recovered significantly within 3-4 months of applications. The new flashes of leaves and root were emerged and citrus tress recovered. It is proved that the biological products of Chaetomium and Trichoderma gave significantly disease control as equal as the chemical fungicide (metalyxyl) when compared to the non-treated control

Phylogeny and taxonomy of the genus Cylindrocladiella

The genus Cylindrocladiella was established to accommodate Cylindrocladium-like fungi that have small, cylindrical conidia and aseptate stipe extensions. Contemporary taxonomic studies of these fungi have relied on morphology and to a lesser extent on DNA sequence comparisons of the internal transcribed spacer regions (ITS 1, 2 and 5.8S gene) of the ribosomal RNA and the ß-tubulin gene regions. In the present study, the identity of several Cylindrocladiella isolates collected over two decades was determined using morphology and phylogenetic inference. A phylogeny constructed for these isolates employing the ß-tubulin, histone H3, ITS, 28S large subunit and translation elongation factor 1-alpha gene regions resulted in the identification of several cryptic species in the genus. In spite of the 18 new Cylindrocladiella species described in this study based on morphological and sequence data, several species complexes remain unresolved

Taxonomy and phylogeny of Cercospora spp. from Northern Thailand

The genus Cercospora represents a group of important plant pathogenic fungi with a wide geographic distribution, being commonly associated with leaf spots on a broad range of plant hosts. The goal of the present study was to conduct a morphological and molecular phylogenetic analysis of the Cercospora spp. occurring on various plants growing in Northern Thailand, an area with a tropical savannah climate, and a rich diversity of vascular plants. Sixty Cercospora isolates were collected from 29 host species (representing 16 plant families). Partial nucleotide sequence data for two gene loci (ITS and cmdA), were generated for all isolates. Results from this study indicate that members of the genus Cercospora vary regarding host specificity, with some taxa having wide host ranges, and others being host-specific. Based on cultural, morphological and phylogenetic data, four new species of Cercospora could be identified: C. glycinicola (from Glycine max), C. cyperacearum and C. cyperina (from Cyperus alternifolius), and C. musigena (from Musa sp.). The most common Cercospora sp. found in Northern Thailand was C. cf. malloti, which occurred on a wide host range. Several collections could not be resolved to species level due to the lack of reference cultures and DNA data for morphologically similar species. Further collections from other countries are needed to help resolve the taxonomy of some species complexes occurring on various plant hosts in Thailand.The Royal Golden Jubilee Ph.D. Program (PHD/0061/2551) and the Thailand Research Fund (DBG5380011 and MRG5580163).http://www.mapress.com/phytotaxahb2017Microbiology and Plant Patholog

Species concepts in Cercospora: spotting the weeds among the roses

The genus Cercospora contains numerous important plant pathogenic fungi from a diverse range of hosts. Most species of Cercospora are known only from their morphological characters in vivo. Although the genus contains more than 5 000 names, very few cultures and associated DNA sequence data are available. In this study, 360 Cercospora isolates, obtained from 161 host species, 49 host families and 39 countries, were used to compile a molecular phylogeny. Partial sequences were derived from the internal transcribed spacer regions and intervening 5.8S nrRNA, actin, calmodulin, histone H3 and translation elongation factor 1-alpha genes. The resulting phylogenetic clades were evaluated for application of existing species names and five novel species are introduced. Eleven species are epi-, lecto- or neotypified in this study. Although existing species names were available for several clades, it was not always possible to apply North American or European names to African or Asian strains and vice versa. Some species were found to be limited to a specific host genus, whereas others were isolated from a wide host range. No single locus was found to be the ideal DNA barcode gene for the genus, and species identification needs to be based on a combination of gene loci and morphological characters. Additional primers were developed to supplement those previously published for amplification of the loci used in this study. TAXONOMIC NOVELTIES: New species - Cercospora coniogrammes Crous & R.G. Shivas, Cercospora delaireae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora euphorbiae-sieboldianae C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora pileicola C. Nakash., Crous, U. Braun & H.D. Shin, Cercospora vignigena C. Nakash., Crous, U. Braun & H.D. Shin. Typifications: epitypifications - Cercospora alchemillicola U. Braun & C.F. Hill, Cercospora althaeina Sacc., Cercospora armoraciae Sacc., Cercospora corchori Sawada, Cercospora mercurialis Pass., Cercospora olivascens Sacc., Cercospora violae Sacc.; neotypifications - Cercospora fagopyri N. Nakata & S. Takim., Cercospora sojina Hara

Decomposition of wood, petiole and leaf litter by Xylaria species from northern Thailand

Ten Xylaria isolates (five obtained from wood and five from leaf litter) collected in northern Thailand were tested for their ability to decompose 13 types of wood, petiole, and lamina from seven tropical tree species under pure culture conditions. The mass loss of the 13 substratum types caused by the 10 Xylaria isolates ranged from 1.2 % to 37.4 % of the original mass. The substratum, the origin of isolates, and the contents of lignin, total carbohydrates, and nitrogen in substrata affected the mass loss. Mass loss was generally in the order: petiole > lamina > wood. Overall, the strains isolated from wood caused greater mass loss than the strains isolated from litter. The mass loss caused by the 10 Xylaria isolates was negatively affected by lignin and total carbohydrate contents, and positively correlated with nitrogen content of the substrata. The values of mass loss in wood in the present study were in the same range as those reported for other Xylaria isolates in previous studies, whereas the mass losses in leaf litter were generally higher than those of previous results, which is partly due to the relatively low lignin contents in leaf litter used in the present study