Several pseudomonads, associated with the cultivated mushrooms Agaricus bisporus or Pleurotus sp., are hemolytic

Pseudomonas tolaasii, causing brown blotch disease on cultivated mushrooms, and yielding a white line precipitate towards P. “reactans”, has been shown to induce lysis of erythrocytes. Some Finnish strains isolated from diseased mushroom fruit bodies, although harboring the typical features of P. tolaasii, proved to be distinct, and have been allocated to a nov. sp. P. costantinii. We examined in these study whether all brown blotch causing agents were hemolytic. The induction of erythrocytes lysis seemed to be a rather common feature of mushroom associated-pseudomonads, especially for strains involved in the production of a white-line-in agar.     

Quantitative trait loci analysis of brown blotch resistance in cowpea variety KN1

Cowpea is one of the most important crops in West Africa and is essential for the region’s food and nutrition security and economic development. Consequently, improving its agronomic performance and yield is a desirable goal. Brown blotch disease, caused by the fungal pathogen Colletotrichum capsici, is an important constraint of cowpea productivity, and at present, only limited genetic resources are available for breeding improved brown blotch-resistant varieties. The current study has characterized the genetic basis for brown blotch resistance conferred by the cowpea cultivar KN1 and identified a major dominant quantitative trait locus (QTL) for resistance on chromosome Vu02. A segregating F₂ population (n?=?200), derived from a cross between KN1 and brown blotch-susceptible Tiligre (KVx775-33-2G), was developed and scored for disease severity following controlled inoculation. A subset of the population (n?=?94) was genotyped with 99 newly developed allele-specific polymerase chain reaction (AS-PCR) markers, and multiple interval mapping was performed. One major and three minor QTL were identified. This is the first reported mapping of QTL conferring resistance to C. capsici in cowpea, and it is expected that the markers identified here will be a valuable resource for developing elite cowpea cultivars with resistance to brown blotch.     

Pseudomonas tolaasii: extra-genomic factor mediates toxin production and efficiency

Pseudomonas tolaasii is responsible for brown blotch symptoms on Agaricus bisporus. Investigations among 15 P. tolaasii wild-type strains revealed the existence of an extra-genomic factor. Pseudomonas tolaasii CNBP2152D, a spontaneous derivative of the wild-type strain CNBP2152 which has lost the factor, exhibited a significant decline in pathogenicity. Comparison of blotch symptoms induced by toxins extracted from CNBP2152 and CNBP2152D showed that the extra-genomic factor mediates toxin production and efficiency.     

Genetic characterization of Pseudomonas 'NZI7'--a novel pathogen that results in a brown blotch disease of Agaricus bisporus

AIMS: To characterize a novel pseudomonad isolate capable of causing brown blotch disease of Agaricus bisporus. METHODS AND RESULTS: Using the white-line-in-agar (WLA) assay, fluorescent pseudomonads isolated from a New Zealand mushroom farm were screened for the lipodepsipeptide tolaasin, a characteristic marker of Pseudomonas tolaasii. One isolate, NZI7, produced a positive WLA assay and caused brown lesions of A. bisporus comparable with those produced by Ps. tolaasii. However, genetic analysis suggested that Ps. tolaasii and NZI7 were genetically dissimilar, and that NZI7 is closely related to Pseudomonas syringae. Nucleotide sequence analyses of a gene involved in tolaasin production indicated that similar genes are present in both NZI7 and Ps. tolaasii. CONCLUSION: NZI7 represents a novel Pseudomonas species capable of causing brown blotch disease of A. bisporus. SIGNIFICANCE AND IMPACT OF THE STUDY: Phenotypic identification of Ps. tolaasii based on A. bisporus browning and positive WLA may have limited specificity.     

Characterization by 16S rRNA sequence analysis of pseudomonads causing blotch disease of cultivated Agaricus bisporus

Bacterial blotch of Agaricus bisporus has typically been identified as being caused by either Pseudomonas tolaasii (brown blotch) or Pseudomonas gingeri (ginger blotch). To address the relatedness of pseudomonads able to induce blotch, a pilot study was initiated in which pseudomonads were selectively isolated from mushroom farms throughout New Zealand. Thirty-three pseudomonad isolates were identified as being capable of causing different degrees of discoloration (separable into nine categories) of A. bisporus tissue in a bioassay. These isolates were also identified as unique using repetitive extragenic palindromic PCR and biochemical analysis. Relationships between these 33 blotch-causing organisms (BCO) and a further 22 selected pseudomonad species were inferred by phylogenetic analyses of near-full-length 16S rRNA gene nucleotide sequences. The 33 BCO isolates were observed to be distributed throughout the Pseudomonas fluorescens intrageneric cluster. These results show that in addition to known BCO (P. tolaasii, P. gingeri, and Pseudomonas reactans), a number of diverse pseudomonad species also have the ability to cause blotch diseases with various discolorations. Furthermore, observation of ginger blotch discoloration of A. bisporus being independently caused by many different pseudomonad species impacts on the homogeneity and classification of the previously described P. gingeri.     

Several pseudomonads,associated with the cultivated mushrooms Agaricus bisporus or Pleurotus sp., are hemolytic

Pseudomonas tolaasii, causing brown blotch disease on cultivated mushrooms, and yielding a white line precipitate towards P. “reactans”, has been shown to induce lysis of erythrocytes. Some Finnish strains isolated from diseased mushroom fruit bodies, although harboring the typical features of P. tolaasii, proved to be distinct, and have been allocated to a nov. sp. P. costantinii. We examined in these study whether all brown blotch causing agents were hemolytic. The induction of erythrocytes lysis seemed to be a rather common feature of mushroom associated-pseudomonads, especially for strains involved in the production of a white-line-in agar.     

Three New Species of Cyphellophora (Chaetothyriales) Associated with Sooty Blotch and Flyspeck

The genus Cyphellophora includes human- and plant-related species from mammal skin and nails, plant materials, and food. On the basis of analysis of ITS, LSU, TUB2 and RPB1 data and morphological characters, three new species, Cyphellophora phyllostachysdis, C. artocarpi and C. musae, associated with sooty blotch and flyspeck disease, were added to this genus. The 2D structure of ITS1 and ITS2 confirmed this taxonomic status. Pathogenicity tests on apple fruit indicated that C. artocarpi could be a sooty blotch and flyspeck pathogen of apple.     

Genome Sequence of the Plant Pathogen Pseudomonas syringae pv. panici LMG 2367

Pseudomonas syringae pv. panici is a phytopathogenic bacterium causing brown stripe disease in economically important crops worldwide. Here, we announce the draft genome sequence of Pseudomonas syringae pv. panici LMG2367 to provide further valuable insights for comparison of the pathovars among species Pseudomonas syringae.     

Molecular phylogeny,morphology and pathogenicity of <Emphasis Type="Italic">Pseudopestalotiopsis</Emphasis> species on <Emphasis Type="Italic">Ixora</Emphasis> in Taiwan

Pestalotiopsis-like species are phytopathogenic, causing numerous diseases on different hosts, and are widely distributed in tropical and temperate ecosystems. These taxa were recently segregated into several genera and species having brown to dark brown or olivaceous median cells, with or without knobbed apical appendages, were classified under the new genus Pseudopestalotiopsis. Pseudopestalotiopsis species are well known for their capability to produce novel medicinal compounds that may have medicinal, agricultural and industrial applications. Ixora is among the largest genera in the family Rubiaceae and is cultivated throughout Taiwan, as a garden plant. During a survey of fungal diseases associated with Ixora species in Taiwan, several Pestalotiopsis-like species causing leaf spot were isolated. Based on morphology coupled with single- and multi-gene (ITS, TUB, TEF) phylogenies, these taxa belong to two novel species of Pseudopestalotiopsis and are introduced herein as Ps. ixorae and Ps. taiwanensis. These two new taxa fit well with Pseudopestalotiopsis in having dark concolourous median cells with knobbed apical appendages, but differ from the known species in the size of conidiomata, size of the conidia, the number of apical appendages, the length of basal appendages plus ecology and distribution. Pathogenicity testing showed that Ps. ixorae and Ps. taiwanensis are capable of causing leaf disease on Ixora and to the best of our knowledge, this is the first record of Pseudopestalotiopsis species associated with leaf spots of Ixora in Taiwan.     

A new marine goby of genus Callogobius (Teleostei: Gobiidae) from Taiwan

A new marine goby Callogobius sheni collected from coral reefs off southern Taiwan is described. The new species can be distinguished from congeneric species by the following combination of features: dorsal fin rays VI-I, 9; anal fin rays I, 7; pectoral fin rays 18; longitudinal scale rows 27–28; predorsal scale rows 9–10; no posterior oculoscapular and preopercular canals; body pale white with five blackish brown cross bands; caudal and pectoral fins each with a large blackish brown blotch.     

The complete life cycle of Petrakia echinata

The teleomorph of Petrakia echinata (Peglion) Syd. & P. Syd. on leaves of Acer pseudoplatanus is described based on field collections, culture studies and ITS sequencing and was assigned to the genus Mycodidymella C.Z. Wei, Y. Harada & K. Katumoto. In addition, a Mycopappus anamorph and a presumed spermatial Phoma stage were observed and conspecificity with P. echinata was confirmed by culture morphology and ITS sequencing. The phylogenetic relationships between the Mycodidymella teleomorph of P. echinata and related taxa were studied using LSU nDNA sequences. The fungus causes brown spots on the leaves of the host plant, known as “Petrakia leaf blotch of sycamore maple”.     

Incidence of Alternaria Species Associated with Watermelon Leaf Blight in Korea

Alternaria leaf blight is one of the most common diseases in watermelon worldwide. In Korea, however, the Alternaria species causing the watermelon leaf blight have not been investigated thoroughly. A total of 16 Alternaria isolates was recovered from diseased watermelon leaves with leaf blight symptoms, which were collected from 14 fields in Korea. Analysis of internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and RNA polymerase II second largest subunit (RPB2) were not competent to differentiate the Alternaria isolates. On the contrary, analysis of amplicon size of the histone H3 (HIS3) gene successfully differentiated the isolates into three Alternaria subgroups, and further sequence analysis of them identified three Alternaria spp. Alternaria tenuissima, A. gaisen, and A. alternata. Representative Alternaria isolates from three species induced dark brown leaf spot lesions on detached watermelon leaves, indicating that A. tenuissima, A. gaisen, and A. alternata are all causal agents of Alternaria leaf blight. Our results indicate that the Alternaria species associated watermelon leaf blight in Korea is more complex than reported previously. This is the first report regarding the population structure of Alternaria species causing watermelon leaf blight in Korea.     

Pathogenicity and taxonomy of Tenuignomonia styracis gen. et sp. nov., a new monotypic genus of Gnomoniaceae on Styrax obassia in Japan

Since 2010, an unknown fungus in the Gnomoniaceae has been found on overwintered leaves and petioles of Styrax obassia (Styracaceae) in Japan. This fungus is characterized by dark brown immersed or partially erumpent ascomata with long necks and fusiform to obovoid asci each with an acute or long tapering stipe. Each ascus bears eight fusiform to filiform ascospores. Our morphological observation and phylogenetic analyses based on the markers LSU, rpb2, and tef-1α indicated that this is a new monotypic genus in the Gnomoniaceae (Diaporthales), and Tenuignomonia styracis gen. et sp. nov. was descried herein. Members of the Gnomoniaceae are commonly isolated as endophytes, saprobes, and plant pathogens from a broad diversity of herbaceous, shade tree, and agriculturally significant plants. We thus carried out a pathogenicity test to determine if T. styracis is the causative agent of leaf blotch on S. obassia. One week after inoculation, this fungus produced small necrotic spots on the leaves and petioles, and all leaves having necrotic spots were abscised in a short time. We thus confirmed that this fungus has weak pathogenicity on S. obassia. This new species may promote early defoliation of S. obassia during the fall.     

Notes on some plant-inhabiting fungi collected from the Nansei Islands (1)

In the course of a survey on plant diseases and their pathogenic fungi in the Nansei Islands, some noteworthy fungi were collected. Among them, four fungi newly found in Japan were described with some mycological and pathological notes. These species are Septoria gardeniae Savelli, causing circular leaf spot of Gardenia; Phyllosticta cordylinophila Young apud Stevens, causing brown leaf spot of Cordyline; Phyllosticta drummondii Vanef et van der Aa, causing brown needle blight of Araucaria; and Phyllachora minuta Hennings, causing tar spot of Hibiscus.     

Corydoras fulleri (Siluriformes: Callichthyidae), a new catfish species from the rio Madeira basin,Peru

A new long-snouted Corydoras species is described from two tributaries of the río Manuripe and a tributary of the río Madre de Dios, rio Madeira basin, Peru. Corydoras fulleri can be distinguished from its congeners by having the following features: (a) branch of the temporal sensory canal at sphenotic, which gives rise to the supraorbital canal, with two pores; (b) upper tooth plate of branchial arch with three series of teeth; (c) area at the corner of the mouth, ventral to the maxillary barbel, with a small fleshy flap; (d) two moderate-sized dark-brown or black blotches on caudal-fin base, one on its lateral portion and another one on its dorsal portion, blotches variably diffuse and/or fused with each other; (e) absence of a dark-brown or black stripe transversally crossing the orbit; (f) a longitudinal dark-brown or black stripe on the postdorsal region of flank midline, variably fused with the lateral peduncular blotch, some specimens with slender, longitudinally elongated, dark-brown or black blotch on flank midline, forming a dash-like marking, stripe or dash-like blotch diffuse in some specimens; and (g) region around dorsal-fin origin generally lacking dark brown or black blotch, or displaying diffuse blotch.     

QTL for spot blotch resistance in bread wheat line Saar co-locate to the biotrophic disease resistance loci Lr34 and Lr46

Spot blotch caused by Bipolaris sorokiniana is a major disease of wheat in warm and humid wheat growing regions of the world including south Asian countries such as India, Nepal and Bangladesh. The CIMMYT bread wheat line Saar which carries the leaf tip necrosis (LTN)-associated rust resistance genes Lr34 and Lr46 has exhibited a low level of spot blotch disease in field trials conducted in Asia and South America. One hundred and fourteen recombinant inbred lines (RILs) of Avocet (Susceptible) × Saar, were evaluated along with parents in two dates of sowing in India for 3 years (2007–2008 to 2009–2010) to identify quantitative trait loci (QTL) associated with spot blotch resistance, and to determine the potential association of Lr34 and Lr46 with resistance to this disease. Lr34 was found to constitute the main locus for spot blotch resistance, and explained as much as 55 % of the phenotypic variation in the mean disease data across the six environments. Based on the large effect, the spot blotch resistance at this locus has been given the gene designation Sb1. Two further, minor QTL were detected in the sub-population of RILs not containing Lr34. The first of these was located about 40 cM distal to Lr34 on 7DS, and the other corresponded to Lr46 on 1BL. A major implication for wheat breeding is that Lr34 and Lr46, which are widely used in wheat breeding to improve resistance to rust diseases and powdery mildew, also have a beneficial effect on spot blotch.     

A new species of Scolecobasidium associated with the sooty blotch and flyspeck complex on banana from China

Sooty blotch and flyspeck is caused by a complex of epiphytic fungi on diverse hosts. A fungus morphologically similar to Scolecobasidium humicola was isolated from a banana fruit exhibiting SBFS signs in Hainan, China. ITS and LSU sequences of rDNA corroborated that it was a Scolecobasidium species. The results of LSU rDNA analysis support the interpretation that Ochroconis is synonymous with Scolecobasidium. Five new combinations, S. anomalum, S. calidifluminale, S. gallopavum, S. gamsii, and S. lascauxense, were proposed. A new species, S. musae, was described based on morphological characteristics and sequence comparison with previous species.     

A new species of Devriesia causing sooty blotch and flyspeck on Rubber Trees in China

Sooty blotch and flyspeck is a fungal disease complex that colonizes a wide range of plants. In a survey of host plants for sooty blotch and flyspeck fungi, we obtained an isolate associated with discrete flyspeck symptom on stems of the Rubber Trees, Ficus elastica, from Haikou, Hainan, China. A pure culture was obtained, and the nuclear ITS region of rDNA was amplified by PCR. Molecular phylogeny inferred from ITS sequence data suggested that it was close to Devriesia strelitziae, reported from South Africa. Morphologically, it was characterized by longer conidia, more conidial septa, and having chlamydospores. Therefore, we describe our isolate as a novel species of Devriesia.     

Mapping quantitative trait loci associated with spot blotch and net blotch resistance in a doubled-haploid barley population

Spot blotch and net blotch are important foliar barley (Hordeum vulgare L.) diseases in Canada and elsewhere. These diseases result in significant yield reduction and, more importantly, loss of grain quality, downgrading barley from malt to feed. Combining resistance to these diseases is a breeding priority but is a significant challenge using conventional breeding methodology. In the present investigation, an evaluation of the inheritance of resistance to spot and net blotch was conducted in a doubled-haploid barley population from the cross CDC Bold (susceptible)?×?TR251 (resistant). The population was screened at the seedling stage in the Phytotron and at the adult-plant stage in the field for several years. Chi-squared analysis indicated one- to four-gene segregation depending on disease, isolate, plant development stage, location and year. A major seedling and adult-plant resistance quantitative trait locus (QTL), designated QRpt6, was re-confirmed for net-form net blotch resistance, explaining 32?C61% of phenotypic variation in different experiments. Additional QTL for seedling and adult-plant resistance to net blotch were identified. For spot blotch resistance, a major seedling resistance QTL (QRcss1) was detected on chromosome 1H for isolate WRS1909, explaining 79% of the phenotypic variation. A highly significant QTL on 3H (QRcs3) was identified for seedling resistance to isolate WRS1908 and adult-plant resistance at Brandon, MB, Canada in 2008. The identification of QTL at only one location or from 1?year suggests spot blotch resistance is complex and highly influenced by the environment. Efforts are being made to combine spot and net blotch resistance in elite barley lines using molecular marker-assisted selection.