A new species of the lenticel fungal genus Claviradulomyces (Ostropales) from the Brazilian Atlantic forest tree Xylopia sericea (Annonaceae)

Claviradulomyces xylopiae sp. nov. is introduced for a fungus occurring in association with abnormal (enlarged, spongy) lenticels of Xylopia sericea (Annonaceae), a common tree of the Atlantic forest and Cerrado ecosystems in Brazil. This is the second species described in the genus and, although it is morphologically distinct from the type species, C. dabeicola from West Africa, it possesses the same characteristics. Apothecial ascomata have periphysoids and paraphyses that are inflated apically (clavate), and ornamented with denticles (raduliform). Furthermore, similar to the type species, it also has long-cylindric or acerose, aseptate ascospores and conidia. An additional asexual morph was produced in culture and is described. Molecular studies of C. dabeicola and the new species confirmed a placement in Ostropales, although a relationship to Odontotremataceae was not supported. Both species were consistently in association with abnormal lenticular development on their woody hosts. It remains to be ascertained, however, if these are the causal agents of the bark disorders, or, simply, opportunistic colonisers. The finding of the second species in the genus Claviradulomyces on a plant from a distantly related family to that of the host of C. dabeicola (Erythroxylaceae) for the genus on a different continent suggests that fungi in this genus may be common on lenticels of other woody plants, and could even have a pantropical distribution. It is possible that fungi in the genus have remained unreported until now because lenticels have remained neglected as a habitat surveyed by mycologists

Pilidiella tibouchinae sp. nov. associated with foliage blight of Tibouchina granulosa (quaresmeira) in Brazil

Tibouchina granulosa (Melastomataceae), Brazilian glorytree (Brazilian common name - quaresmeira), a common tree of the Atlantic Forest of Brazil, is widely used as an ornamental for its violet or pink blossoms. Little is known about fungal diseases affecting this species, although these represent a known limitation for its cultivation in nurseries. Among these there is a foliage blight that occurs in combination with distortion of branch apices and die-back. A consistent association of a species of Pilidiella with the diseased tissues was observed. The fungus was isolated in pure culture and based on its morphology and DNA phylogeny, we conclude that it represents a new species, for which the name Pilidiella tibouchinae is introduced

Toxicidade de filtrados de cultura de Alternaria euphorbiicola em folhas de Euphorbia heterophylla

A espécie fúngica Alternaria euphorbiicola é agente causal de severas necroses de inflorescência, queimas de folhas e cancros da haste em Euphorbia heterophylla (leiteiro ou amendoim-bravo), importante planta daninha responsável por grandes prejuízos à agricultura brasileira. A aplicação de suspensões de esporos do fungo sobre populações da planta hospedeira resulta em rápida produção de necrose dos tecidos das plantas (24 a 48 horas após aplicação). Essas observações levaram à conjectura de que o fungo possa produzir fitotoxinas in vitro capazes de causar lesão às plantas. O objetivo deste trabalho foi investigar preliminarmente a produção in vitro de fitotoxinas por A. euphorbiicola sob diferentes condições de cultivo. Os resultados mostraram que a composição do meio de cultura e as condições de cultivo influenciaram a fitotoxicidade de filtrados de cultura, tendo o cultivo sob agitação e na ausência de luz favorecido a produção de metabólitos fitotóxicos pelo fungo. O filtrado da cultura em meio de Jenkins-Prior modificado, crescida sob agitação, no escuro e a 28 oC, apresentou a maior atividade fitotóxica, tendo produzido extensas necroses foliares e desfolha em plantas de E. heterophylla. Esse filtrado de cultura foi submetido a extração seguida por fracionamento guiado por bioensaios. Uma fração cromatográfica constituída majoritariamente por ácidos graxos de cadeia longa produziu halos cloróticos e necrose de folhas, assim como observado após a inoculação de E. heterophylla com o fungo. Esses resultados sugerem a participação de ácidos graxos no processo infeccioso na associação A. euphorbiicola x E. heterophylla.The fungal species Alternaria euphorbiicola was identified as causal agent of inflorescence necrosis, leaf blight, and stem cancer in Euphorbia heterophylla (wild poinsettia), a major weed responsible for great agricultural losses in Brazil. The application of spore suspensions of the fungus on specimens of the host plant resulted in production of disseminated necrosis at short time intervals (24 to 48 hours) after application. These observations led to the hypothesis that the fungus could produce phytotoxins capable of causing damage to the plant. The objective of this study was to investigate the in vitro production of phytotoxins by A. euphorbiicola under different growth conditions. The results showed that the culture medium and growth conditions influenced the phytotoxicity of the culture filtrates. Growing the fungus under agitation in the dark resulted in higher production of phytotoxic metabolites. The filtrate from the culture formed in modified Jenkins-Prior medium, under agitation, at 28 oC in the dark showed the highest phytotoxic activity. This filtrate produced foliar necrosis and defoliation in E. heterophylla and was subjected to extraction followed by bioassay-guided fractionation. A chromatographic fraction consisting mainly of long-chain fatty acids produced bleached lesions and necrosis of the leaves, the same symptoms observed after inoculation of the fungus in the host plant. These results suggest the involvement of these phytotoxic fatty acids in the process of tissue invasion of E. heterophylla by A. euphorbiicola

New and Interesting Fungi. 1

This study introduces two new families, one new genus, 22 new species, 10 new combinations, four epitypes, and 16 interesting new host and / or geographical records. Cylindriaceae (based on Cylindrium elongatum) is introduced as new family, with three new combinations.Xyladictyochaetaceae (based on Xyladictyochaetalusitanica) is introduced to accommodate Xyladictyochaeta. Pseudoanungitea gen. nov. (based on P.syzygii)is described on stems of Vaccinium myrtillus(Germany). New species include: Exophiala eucalypticola on Eucalyptus obliqua leaf litter, Phyllosticta hakeicola on leaves of Hakea sp.,Setophaeosphaeriacitricola on leaves of Citrus australasica, and Sirastachyscyperacearum on leaves of Cyperaceae(Australia); Polyscytalum chilense on leaves of Eucalyptus urophylla (Chile); Pseudoanungitea vaccinii on Vaccinium myrtillus (Germany); Teichospora quercus on branch tissue of Quercus sp. (France); Fusiconidiumlycopodiellae on stems of Lycopodiella inundata,Monochaetiajunipericola on twig of Juniperus communis,Myrmecridiumsorbicola on branch tissues of Sorbus aucuparia, Parathyridariaphiladelphi on twigs of Philadelphus coronarius, and Wettsteininaphiladelphi on twigs of Philadelphus coronarius (Germany); Zygosporium pseudogibbum on leaves of Eucalyptus pellita (Malaysia); Pseudoanungiteavariabilis on dead wood (Spain); Alfaria acaciae on leaves of Acacia propinqua, Dictyochaeta mimusopis on leaves of Mimusops caffra,and Pseudocercosporabreonadiae on leaves of Breonadia microcephala (South Africa); Colletotrichumkniphofiae on leaves of Kniphofia uvaria,Subplenodomusiridicola on Iris sp., and Trochila viburnicola on twig cankers on Viburnum sp. (UK); Polyscytalum neofecundissimum on Quercus robur leaf litter, and Roussoellaeuonymi on fallen branches of Euonymus europaeus (Ukraine). New combinations include: Cylindrium algarvense on leaves of Eucalyptus sp. (Portugal), Cylindrium purgamentum on leaf litter (USA), Cylindrium syzygii on leaves of Syzygium sp. (Australia), Microdochium musae on leaves of Musa sp. (Malaysia), Polyscytalum eucalyptigenum on Eucalyptus grandis × pellita (Malaysia), P. eucalyptorum on leaves of Eucalyptus (Australia), P. grevilleae on leaves of Grevillea (Australia), P. nullicananum on leaves of Eucalyptus (Australia), Pseudoanungiteasyzygii on Syzygium cordatum leaf litter (South Africa), and Setophaeosphaeriasidae on leaves of Sida sp. (Brazil). New records include: Sphaerellopsis paraphysata on leaves of Phragmites sp., Vermiculariopsiella dichapetali on leaves of Melaleuca sp. and Eucalyptus regnans, and Xyladictyochaetalusitanica on leaf litter of Eucalyptus sp. (Australia); Camarosporidiella mackenziei on twigs of Caragana sp. (Finland); Cyclothyriella rubronotata on twigs of Ailanthus altissima, Rhinocladiella quercus on Sorbus aucuparia branches (Germany); Cytospora viticola on stems of Vitis vinifera (Hungary); Echinocatena arthrinioides on leaves of Acacia crassicarpa (Malaysia); Varicosporellopsis aquatilis from garden soil (Netherlands); Pestalotiopsis hollandica on needles of Cupressus sempervirens (Spain), Pseudocamarosporiumafricanum on twigs of Erica sp. (South Africa), Pseudocamarosporium brabeji on branch of Platanus sp. (Switzerland); Neocucurbitaria cava on leaves of Quercus ilex (UK); Chaetosphaeriamyriocarpaon decaying wood of Carpinus betulus,Haplograhium delicatum on decaying Carpinus betulus wood (Ukraine). Epitypes are designated for: Elsinoë mimosae on leaves of Mimosa diplotricha (Brazil), Neohendersonia kickxii on Fagus sylvatica twig bark (Italy), Caliciopsis maxima on fronds of Niphidium crassifolium (Brazil), Dictyochaeta septata on leaves of Eucalyptus grandis ×urophylla (Chile), and Microdochium musae on leaves of Musa sp. (Malaysia)

Search for single top quarks in the tau+jets channel using 4.8 fb−1^{-1} of ppˉp\bar{p} collision data

We present the first direct search for single top quark production using tau leptons. The search is based on 4.8 fb$^{-1}$ of integrated luminosity collected in $p\bar{p}$ collisions at $\sqrt{s}$=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We select events with a final state including an isolated tau lepton, missing transverse energy, two or three jets, one or two of them $b$ tagged. We use a multivariate technique to discriminate signal from background. The number of events observed in data in this final state is consistent with the signal plus background expectation. We set in the tau+jets channel an upper limit on the single top quark cross section of \TauLimObs pb at the 95% C.L. This measurement allows a gain of 4% in expected sensitivity for the observation of single top production when combining it with electron+jets and muon+jets channels already published by the D0 collaboration with 2.3 fb$^{-1}$ of data. We measure a combined cross section of \SuperCombineXSall pb, which is the most precise measurement to date.Comment: 12 pages, 5 figure

Measurement of Z/gamma*+jet+X angular distributions in ppbar collisions at sqrt{s}=1.96 TeV

We present the first measurements at a hadron collider of differential cross sections for Z+jet+X production in delta phi(Z, jet), |delta y(Z, jet)| and |y_boost(Z, jet)|. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.Comment: Published in Physics Letters B 682 (2010), pp. 370-380. 15 pages, 6 figure

Search for the standard model Higgs boson in tau final states

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 inverse femtobarn of data collected with the D0 detector at the Fermilab Tevatron ppbar collider. We select two final states: tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.Comment: publication versio

Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits

The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication