Intraspecific Variation in Armillaria Species from Shrubs and Trees in Northwestern Spain

Until recently, the identification of Armillaria species relied upon morphological characteristics and mating tests, but now molecular techniques based on polymorphisms in the IGS region of the fungal rDNA are more commonly used, since these are more rapid and reliable. Differences found in RFLP patterns identifying Armillaria species have suggested the existence of intraspecific variation. In this work, 185 Armillaria isolates from different plant species (including fruit trees, broadleaf and coniferous trees, ornamental shrubs, kiwifruit and grapevine) affected by white root rot were analyzed by RFLP-PCR, in order to study intraspecific variation in Armillaria and the relationship with the plant host. Armillaria mellea was found in the majority of samples (71%), and was the most frequent Armillaria species in symptomatic ornamental shrubs, kiwifruit, grapevine, fruit trees and broadleaf trees. In conifers however white root rot was generally caused by Armillaria ostoyae. Armillaria gallica was identified, although with low incidence, in ornamental, coniferous, broadleaf and fruit hosts. Intraspecies variation was recorded only in A. mellea, for which RFLP patterns mel 1 and mel 2 were found. Most plants infected with A. mellea showed the mel 2 pattern. Further research is needed to study whether Armillaria RFLP patterns are specific to certain plant hosts, and whether intraspecific variation is related to differences in pathogenicity

Método selectivo de PCR para la identificación de Phytophthora hibernalis Carne

Preharvest and postharvest brown rot of citrus fruit is responsible for important economic losses thoroughout the world. The disease is commonly caused by several species of Phytophthora. In Spain, citrus brown rot is mainly caused by P. citrophthora, but in the last years outbreaks of the disease in lemon and sweet orange caused by P. hibernalis Carne have been recorded in northwestern citrus-growing areas. In this work, a PCR method has been developed for the diagnostic of P. hibernalis either from isolated mycelia or directly from fruit lesions. One specific primer pair, PHIB1 and PHIB2, was designed from the nucleotide sequences of ITS1 and ITS2 regions. The two primers amplified a 407-bp fragment from the genomic DNA of P. hibernalis that was sequenced (Acc. No. AY827556). Results demonstrated that PCR amplification of ITS regions by primers PHIB1 and PHIB2 followed by DNA sequencing can provide a rapid, selective and reliable identification of P. hibernalis.La podredumbre marrón del fruto en cítricos ha ocasionado importantes pérdidas económicas en pre y postcosecha en todo el mundo. Por lo general esta enfermedad está provocada por varias especies de Phytophthora. En España, P. citrophthora es el principal agente causante de esta patología, sin embargo, en los últimos años, P. hibernalis Carne ha sido detectado ocasionando daños en limoneros y naranjos localizados en el noroeste del país. En el presente trabajo, se ha desarrollado un método de PCR para el diagnóstico de P. hibernalis tanto a partir de micelio en cultivo como directamente de lesiones del fruto. Se diseñó un par de primers específicos, PHIB1 y PHIB2, a partir de secuencias de las regiones ITS1 e ITS2. Estos dos primers amplificaron un fragmento de 407 pb, que fue secuenciado (Acc. No. AY827556). Los resultados demostraron que la amplificación por PCR de las regiones ITS mediante los primers PHIB1 y PHIB2 seguida por la secuenciación del ADN permiten una identificación rápida, selectiva y fiable de P. hibernalis

Phylogenetic reassessment of Mycosphaerella spp. and their anamorphs occurring on Eucalyptus. II

Species of Eucalyptus are widely planted as exotics in the tropics and Southern Hemisphere and to some extent in southern Europe, for timber and fibre production. Species of Mycosphaerella are commonly associated with leaves and twigs of Eucalyptus and can result in defoliation, dieback, and even tree death. In the present study, numerous isolates of Mycosphaerella species were collected from leaf litter, living leaves exhibiting leaf spot symptoms or severe Mycosphaerella leaf blotch symptoms. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. These data, together with characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species

Phylogenetic reassessment of Mycosphaerella spp. and their anamorphs occurring on Eucalyptus

Species of Eucalyptus, mostly native to Australia, are widely planted as exotics in the tropics and Southern Hemisphere. These plantations represent an important source of fuel-wood, structural timber and pulp. Eucalyptus plantations are, however, vulnerable to infection by pathogens, including Mycosphaerella spp. and their anamorphs, which have caused substantial damage, in many parts of the world. More than 30 species of Mycosphaerella, and close to 30 anamorph species for which the Mycosphaerella state remains unknown, are associated with leaf and shoot disease on Eucalyptus spp., worldwide. Although several studies using DNA sequence data have been applied to resolve the phylogenetic relationships between Mycosphaerella spp. on Eucalyptus, the number of species treated has been incomplete. In the present study, isolates of 44 Mycosphaerella species or their anamorphs associated with lesions on Eucalyptus leaves were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. In addition, DNA sequence data from the elongation factor 1-¿ and the ß-tubulin gene regions were used to resolve species in the M. nubilosa species complex. As a result of these comparisons, 11 new species are described. Mycosphaerella juvenis is reduced to synonymy with M. nubilosa and an epitype specimen and ex-epitype culture are designated for the latter. Mycosphaerella nubilosa is recorded as a serious agent of Mycosphaerella leaf blotch on E. globulus in Spain. This is also the first definitive record of this pathogen occurring on Eucalyptus in Europe

Phylogenetic reassessment of Mycosphaerella spp. and their anamorphs occurring on Eucalyptus. II

Species of Eucalyptus are widely planted as exotics in the tropics and Southern Hemisphere and to some extent in southern Europe, for timber and fibre production. Species of Mycosphaerella are commonly associated with leaves and twigs of Eucalyptus and can result in defoliation, dieback, and even tree death. In the present study, numerous isolates of Mycosphaerella species were collected from leaf litter, living leaves exhibiting leaf spot symptoms or severe Mycosphaerella leaf blotch symptoms. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. These data, together with characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species

XPS analysis of down stream plasma treated wool: Influence of the nature of the gas on the surface modification of wool

13 pages, 12 figures, 4 tables.-- Printed version published Dec 15, 2005.A microwave plasma treatment in a down stream configuration was used to modify the natural hydrophobocity of untreated wool fibers. This property is a consequence of the presence of a Fatty acid monolayer (F-layer) on the outermost part of the fiber surface. The wool fibers treated with plasma were analyzed by means of X-ray photoelectron spectroscopy (XPS) without previous exposure to the air. Experiments have been carried out with air, water vapor, oxygen and nitrogen as plasma gas. The “in situ” analysis of the treated samples has permitted to differentiate between the plasma effects and those other linked to the exposure of the fibers to the air after their treatment. The results have evidenced the effects induced by the different active species generated by plasma from the different components of the air. In general, the intensity of Csingle bondC peaks decreases and that of the Csingle bondO, Cdouble bond; length as m-dashO and Osingle bondCdouble bond; length as m-dashO increases when using a gas containing oxygen species. Simultaneously, the intensity of the Ssingle bondS groups decreases and that of the sulphonate (SO3−) increases. Other changes are also detected in the intensity of the N 1s level. The extent and characteristics of the oxidation and functionalisation of the hydrocarbon chains of the F-layer depend on the nature of gas. Thus, whereas treatments with plasmas of air and water vapor strongly affect the hydrocarbon chains of the F-layer, oxygen is less effective in the oxidation process. It has been also noted that the active species formed in the nitrogen plasma do not induce any significant change in the surface composition of the wool fibers.Financial support by the CICYT (PN MAT 2002-02613 Project) and AGAUR from Catalonia Government (Fellowship for R. Molina).Peer reviewe