X-ray structure of a vanadium-containing enzyme: chloroperoxidase from the fungus Curvularia inaequalis.

The chloroperoxidase (EC 1.11.1.-) from the fungus Curvularia inaequalis belongs to a class of vanadium enzymes that oxidize halides in the presence of hydrogen peroxide to the corresponding hypohalous acids. The 2.1 A crystal structure (R = 20%) of an azide chloroperoxidase complex reveals the geometry of the catalytic vanadium center. Azide coordinates directly to the metal center, resulting in a structure with azide, three nonprotein oxygens, and a histidine as ligands. In the native state vanadium will be bound as hydrogen vanadate(V) in a trigonal bipyramidal coordination with the metal coordinated to three oxygens in the equatorial plane, to the OH group at one apical position, and to the epsilon 2 nitrogen of a histidine at the other apical position. The protein fold is mainly alpha-helical with two four-helix bundles as main structural motifs and an overall structure different from other structures. The helices pack together to a compact molecule, which explains the high stability of the protein. An amino acid sequence comparison with vanadium-containing bromoperoxidase from the seaweed Ascophyllum nodosum shows high similarities in the regions of the metal binding site, with all hydrogen vanadate(V) interacting residues conserved except for lysine-353, which is an asparagine.

Mg-SINE: a short interspersed nuclear element from the rice blast fungus, Magnaporthe grisea.

A short interspersed nuclear element, Mg-SINE, was isolated and characterized from the genome of the rice blast fungus, Magnaporthe grisea. Mg-SINE was isolated as an insertion element within Pot2, an inverted-repeat transposon from M. grisea and shows typical features of a mammalian SINE. Mg-SINE is present as a 0.47-kb interspersed sequence at approximately 100 copies per haploid genome in both rice and non-rice isolates of M. grisea, indicating a common evolutionary origin. Secondary structure analysis of Mg-SINE revealed a tRNA-related region at the 5' end which folds into a cloverleaf structure. Genomic fusions resulting in chimeric Mg-SINEs (Ch-SINEs) composed of a sequence homologous to Mg-SINE at the 3' end and an unrelated sequence at its 5' end were also isolated, indicating that this and other DNA rearrangements mediated by these elements may have a major effect on the genomic architecture of this fungus.

A cytoplasmically transmissible hypovirulence phenotype associated with mitochondrial DNA mutations in the chestnut blight fungus Cryphonectria parasitica.

Mutations causing mitochondrial defects were induced in a virulent strain of the chestnut blight fungus Cryphonectria parasitica (Murr.) Barr. Virulence on apples and chestnut trees was reduced in four of six extensively characterized mutants. Relative to the virulent progenitor, the attenuated mutants had reduced growth rates, abnormal colony morphologies, and few asexual spores, and they resembled virus-infected strains. The respiratory defects and attenuated virulence phenotypes (hypovirulence) were transmitted from two mutants to a virulent strain by hyphal contact. The infectious transmission of hypovirulence occurred independently of the transfer of nuclei, did not involve a virus, and dynamically reflects fungal diseases caused by mitochondrial mutations. In these mutants, mitochondrial mutations are further implicated in generation of the attenuated state by (i) uniparental (maternal) inheritance of the trait, (ii) presence of high levels of cyanide-insensitive mitochondrial alternative oxidase activity, (iii) cytochrome deficiencies, and (iv) structural abnormalities in the mtDNA. Hence, cytoplasmically transmissible hypovirulence phenotypes found in virus-free strains of C. parasitica from recovering trees may be caused by mutant forms of mtDNA.

A cyclophilin from the polycentric anaerobic rumen fungus Orpinomyces sp. strain PC-2 is highly homologous to vertebrate cyclophilin B.

A cyclophilin (CyP) purified to homogeneity from the polycentric anaerobic rumen fungus Orpinomyces sp. strain PC-2 had a molecular mass of 20.5 kDa and a pI of 8.1. The protein catalyzed the isomerization of the prolyl peptide bond of N-succinyl-Ala-Ala-(cis,trans)-Pro-Phe p-nitroanilide with a kcat/Km value of 9.3 x 10(6) M-1.s-1 at 10 degrees C and pH 7.8. Cyclosporin A strongly inhibited this peptidylprolyl cis-trans isomerase activity with an IC50 of 19.6 nM. The sequence of the first 30 N-terminal amino acids of this CyP had high homology with the N-terminal sequences of other eukaryotic CyPs. By use of a DNA hybridization probe amplified by PCR with degenerate oligonucleotide primers designed based on the amino acid sequences of the N terminus of this CyP and highly conserved internal regions of other CyPs, a full-length cDNA clone was isolated. It possessed an open reading frame encoding a polypeptide of 203 amino acids with a calculated molecular weight of 21,969, containing a putative hydrophobic signal peptide sequence of 22 amino acids preceding the N terminus of the mature enzyme and a C-terminal sequence, Lys-Ala-Glu-Leu, characteristic of an endoplasmic reticulum retention signal. The Orpinomyces PC-2 CyP is a typical type B CyP. The amino acid sequence of the Orpinomyces CyP exhibits striking degrees of identity with the corresponding human (70%), bovine (69%), mouse (68%), chicken (66%), maize (61%), and yeast (54%) proteins. Phylogenetic analysis based on the CyP sequences indicated that the evolutionary origin of the Orpinomyces CyP was closely related with CyPs of animals.

Uso de Metarhizium spp. na produção de mudas pré-brotadas de cana-de-açúcar e seus efeitos na planta, em pragas e doenças

Os fungos do gênero Metarhizium são entomopatogênicos e ainda apresentam relações endofíticas e podem viver saprofiticamente no solo. A associação desses microrganismos com insetos é bem conhecida, mas as interações diretas com as plantas ainda são incipientes. Objetivou-se com este estudo, determinar a capacidade de colonização endofítica em raízes de cana-de-açúcar (Saccharum spp.) de M. robertsii, M. anisopliae e três linhagens brasileiras recém-descobertas, bem como revelar o potencial destes fungos como antagonistas a dois fungos fitopatogênicos responsáveis pela podridão-vermelha (Fusarium moniliforme e Colletotrichum falcatum) e no controle de duas importantes pragas, a broca da cana-de-açúcar, Diatraea saccharalis e o nematóide-das-galhas, Meloidogyne javanica. Foram utilizados 24 isolados de Metarhizium spp. nos experimentos de promoção de crescimento de plantas após a inoculação em gemas de cana-de-açúcar em condições de casa-de-vegetação e campo. O efeito da inoculação do fungo em mudas de cana-de-açúcar foi investigado quanto a mortalidade e redução no desenvolvimento de D. saccharalis e redução nas populações de M. javanica. Experimentos de inibição in vitro em cultivo pareado foram conduzidos com os fungos F. moniliforme e C. falcatum e Trichoderma harzianum. Além disto, foram realizados testes qualitativos \"in vitro\" para avaliar a capacidade desses fungos em produzir β-1,3-Glucanase e Sideróforos. A inoculação de Metarhizium de todas as espécies testadas promoveu o crescimento de parte aérea, peso úmido e seco de raízes em relação ao controle (água). Enquanto o tratamento de gemas rotineiramente usado na usina onde se realizou a produção de mudas pré-brotadas com aplicação do fungicida Comet® + o fertilizante Biozyme TF resultou em pegamento de 32% e 59,6%, apenas com o uso de isolados de Metarhizium spp. estes valores foram de até 50% e 86,4%, nos dois experimentos em campo, respectivamente. As mortalidades observadas em lagartas de D. saccharalis que se alimentaram das plantas inoculadas com isolados de Metarhizium spp. atingiram valores de até 80%, sendo a mortalidade confirmada pela esporulação do fungo de até 55%. As lagartas sobreviventes apresentaram menor peso do que aquelas do controle não tratado. A inoculação de Metarhizium spp. em mudas de cana-de-açúcar conferiu proteção a M. javanica, resultando em uma densidade de massa de ovos por grama de raiz nas mudas inoculadas com o fungo até 59,8% menor no primeiro experimento e 64,1% menor no segundo em relação as mudas sem inoculação. Os ensaios de antagonismo mostraram que, todos os isolados de Metarhizium spp. apresentaram alguma forma de inibição tanto para F. moniliforme como para C. falcatum. Dos 24 isolados testados, 20,8% produziram a enzima hidrolítica, β-1,3-glucanase, o que pode estar associado a capacidade de inibição dos fungos fitopatogênicos. Constatou-se que 8 (33,3%) dos isolados produziram sideróforos e sugere que esses fungos apresentam mecanismos de disponibilização do ferro. O conhecimento gerado com este estudo poderá subsidiar novas estratégias de utilização de Metarhizium spp. em campo na produção de MPB de cana-de-açúcar.

Gene cloning, molecular modeling, and phylogenetics of serine protease P32 and serine carboxypeptidase SCP1 from nematophagous fungi Pochonia rubescens and Pochonia chlamydosporia

The fungi Pochonia chlamydosporia and Pochonia rubescens are parasites of nematode eggs and thus are biocontrol agents of nematodes. Proteolytic enzymes such as the S8 proteases VCP1 and P32, secreted during the pathogenesis of nematode eggs, are major virulence factors in these fungi. Recently, expression of these enzymes and of SCP1, a new putative S10 carboxypeptidase, was detected during endophytic colonization of barley roots by these fungi. In our study, we cloned the genomic and mRNA sequences encoding P32 from P. rubescens and SCP1 from P. chlamydosporia. P32 showed a high homology with the serine proteases Pr1A from the entomopathogenic fungus Metarhizium anisopliae and VCP1 from P. chlamydosporia (86% and 76% identity, respectively). However, the catalytic pocket of P32 showed differences in the amino acids of the substrate-recognition sites compared with the catalytic pockets of Pr1A and VCP1 proteases. Phylogenetic analysis of P32 suggests a common ancestor with protease Pr1A. SCP1 displays the characteristic features of a member of the S10 family of serine proteases. Phylogenetic comparisons show that SCP1 and other carboxypeptidases from filamentous fungi have an origin different from that of yeast vacuolar serine carboxypeptidases. Understanding protease genes from nematophagous fungi is crucial for enhancing the biocontrol potential of these organisms.

Some isolates of the nematophagous fungus Pochonia chlamydosporia promote root growth and reduce flowering time of tomato

The fungal parasite of nematode eggs Pochonia chlamydosporia is also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nine P. chlamydosporia isolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). Seven P. chlamydosporia isolates significantly (P < 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. Six P. chlamydosporia isolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. Again P. chlamydosporia significantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants. P. chlamydosporia increased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found that P. chlamydosporia can produce Indole-3-acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance of P. chlamydosporia as biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.

Chitosan enhances parasitism of Meloidogyne javanica eggs by the nematophagous fungus Pochonia chlamydosporia

Pochonia chlamydosporia (Pc), a nematophagous fungus and root endophyte, uses appressoria and extracellular enzymes, principally proteases, to infect the eggs of plant parasitic nematodes (PPN). Unlike other fungi, Pc is resistant to chitosan, a deacetylated form of chitin, used in agriculture as a biopesticide to control plant pathogens. In the present work, we show that chitosan increases Meloidogyne javanica egg parasitism by P. chlamydosporia. Using antibodies specific to the Pc enzymes VCP1 (a subtilisin), and SCP1 (a serine carboxypeptidase), we demonstrate chitosan elicitation of the fungal proteases during the parasitic process. Chitosan increases VCP1 immuno-labelling in the cell wall of Pc conidia, hyphal tips of germinating spores, and in appressoria on infected M. javanica eggs. These results support the role of proteases in egg parasitism by the fungus and their activation by chitosan. Phylogenetic analysis of the Pc genome reveals a large diversity of subtilisins (S8) and serine carboxypeptidases (S10). The VCP1 group in the S8 tree shows evidence of gene duplication indicating recent adaptations to nutrient sources. Our results demonstrate that chitosan enhances Pc infectivity of nematode eggs through increased proteolytic activities and appressoria formation and might be used to improve the efficacy of M. javanica biocontrol.

Indian paint fungus : a method for recognizing and reducing hazard in advanced grand and white fir regeneration in eastern Oregon and Washington /

Bibliography: p. 9.

Researches on the life-history of Hemileia vastatrix, the fungus of the "coffee-leaf disease".

Linn.soc. Jour.(Bot.) v.19, p.299-335, 1882.

Report on insect and fungus pests no. 1,

Mode of access: Internet.

Immortal holding a numinous fungus

H: 1 ft. 7 1/64 in.; gilt bronze

Dissertatio botanico-medica in qua Fungus melitensis ... /

Also published in Linne's Amoenitates academicae, v. 4, ed. 1, 1759 (and 1760); ed. 2, 1788, p. 351-367; Sel. ex. Amoenitat. v. 2, 1766, p. 153-171. cf. Hulth, Bibl. Linn. (1907) p. 101.

Endemic infection of the amphibian chytrid fungus in a frog community post-decline

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

Reciprocal N ((NH4+)-N-15 or (NO3-)-N-15) transfer between nonN(2)-fixing Eucalyptus maculata and N-2-fixing Casuarina cunninghamiana linked by the ectomycorrhizal fungus Pisolithus sp.

Two-way N transfers mediated by Pisolithus sp. were examined by excluding root contact and supplying (NH4+)-N-15 or (NO3-)-N-15 to 6-month-old Eucalyptus maculata or Casuarina cunninghamiana grown in two-chambered-pots separated by 37 m screens. Mycorrhizal colonization was 35% in Eucalyptus and 66% in Casuarina (c. 29% N-2-fixation). Using an environmental scanning electron microscope, living hyphae were observed to interconnect Eucalyptus and Casuarina. Biomass and N accumulation was greatest in nodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, less in nonnodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, and least in nonnodulated nonmycorrhizal Casuarina/nonmycorrhizal Eucalyptus pairs. In nonnodulated mycorrhizal pairs, N transfers to Eucalyptus or to Casuarina were similar (2.4-4.1 mg per plant in either direction) and were 2.6-4.0 times greater than in nonnodulated nonmycorrhizal pairs. In nodulated mycorrhizal pairs, N transfers were greater to Eucalyptus (5-7 times) and to Casuarina (12-18 times) than in nonnodulated mycorrhizal pairs. Net transfer to Eucalyptus or to Casuarina was low in both nonnodulated nonmycorrhizal (< 0.7 mg per plant) and nonnodulated mycorrhizal pairs (< 1.1 mg per plant). In nodulated mycorrhizal pairs, net transfer to Casuarina was 26.0 mg per plant. The amount and direction of two-way mycorrhiza-mediated N transfer was increased by the presence of Pisolithus sp. and Frankia, resulting in a net N transfer from low-N-demanding Eucalyptus to high-N-demanding Casuarina.