210 research outputs found
Translation of Henrich Klebahn's 'Damaging agents of the klippfish - a contribution to the knowledge of the salt-loving organisms'
Pest categorisation of Cronartium spp. (non-EU)
Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest
categorisation of Cronartium spp. (non-EU), a well-defined and distinguishable group of fungal
pathogens of the family Cronartiaceae. There are at least 40 species described within the Cronartium
genus, of which two are considered native to the EU (C. gentianeum and C. pini) and one has been
introduced in the 19th century (C. ribicola) and is now widespread in the EU â these three species are
thus not part of this pest categorisation. In addition, the non-EU C. harknessii, C. kurilense and C.
sahoanum were already dealt with in a previous pest categorisation. All the non-EU Cronartium species
are not known to be present in the EU and are regulated in Council Directive 2000/29/EC (Annex IAI) as
harmful organisms whose introduction into the EU is banned. Cronartium spp. are biotrophic obligate
plant pathogens. Many of the North American Cronartium species alternate between the aecial host
Pinus spp. and telial hosts of various dicotyledonous plants. C. conigenum, C. orientale, C. quercuum
and C. strobilinum have different Quercus spp. as their telial hosts. C. orientale and C. quercuum also
infect Castanea spp. and Castanopsis spp. The pathogens could enter the EU via host plants for
planting and cut flowers and branches. Non-EU Cronartium spp. could establish in the EU, as climatic
conditions are favourable to many of them and Pinus and Quercus spp. are common. The pathogens
would be able to spread following establishment by movement of host plants, as well as natural spread.
Should non-EU Cronartium spp. be introduced in the EU, impacts can be expected on pine, oak and
chestnut woodlands, plantations, ornamental trees and nurseries. The Cronartium species present in
North America cause important tree diseases. Symptoms on Pinus spp. differ between Cronartium spp.,
but include galls, cankers, dieback of branches and stems, deformity, tree and cone death. The main
knowledge gap concerns the limited available information on (sub)tropical Cronartium spp. The criteria
assessed by the Panel for consideration of Cronartium spp. (non-EU) as potential quarantine pests are
met, while, for regulated non-quarantine pests, the criterion on the pest presence in the EU is not met
Leaf-inhabiting genera of the Gnomoniaceae, Diaporthales
The Gnomoniaceae are characterised by ascomata that are generally
immersed, solitary, without a stroma, or aggregated with a rudimentary stroma,
in herbaceous plant material especially in leaves, twigs or stems, but also in
bark or wood. The ascomata are black, soft-textured, thin-walled, and
pseudoparenchymatous with one or more central or eccentric necks. The asci
usually have a distinct apical ring. The Gnomoniaceae includes
species having ascospores that are small, mostly less than 25 ÎŒm long,
although some are longer, and range in septation from non-septate to
one-septate, rarely multi-septate. Molecular studies of the
Gnomoniaceae suggest that the traditional classification of genera
based on characteristics of the ascomata such as position of the neck and
ascospores such as septation have resulted in genera that are not
monophyletic. In this paper the concepts of the leaf-inhabiting genera in the
Gnomoniaceae are reevaluated using multiple genes, specifically
nrLSU, translation elongation factor 1-alpha (tef1-α), and RNA
polymerase II second largest subunit (rpb2) for 64 isolates. ITS sequences
were generated for 322 isolates. Six genera of leaf-inhabiting
Gnomoniaceae are defined based on placement of their type species
within the multigene phylogeny. The new monotypic genus
Ambarignomonia is established for an unusual species, A.
petiolorum. A key to 59 species of leaf-inhabiting Gnomoniaceae is
presented and 22 species of Gnomoniaceae are described and
illustrated
Laying the foundation for a taxonomic review of Puccinia coronata s.l. in a phylogenetic context
Biogenic gas nanostructures as ultrasonic molecular reporters
Ultrasound is among the most widely used non-invasive imaging modalities in biomedicine, but plays a surprisingly small role in molecular imaging due to a lack of suitable molecular reporters on the nanoscale. Here, we introduce a new class of reporters for ultrasound based on genetically encoded gas nanostructures from microorganisms, including bacteria and archaea. Gas vesicles are gas-filled protein-shelled compartments with typical widths of 45â250 nm and lengths of 100â600 nm that exclude water and are permeable to gas. We show that gas vesicles produce stable ultrasound contrast that is readily detected in vitro and in vivo, that their genetically encoded physical properties enable multiple modes of imaging, and that contrast enhancement through aggregation permits their use as molecular biosensors
Verticillium wilt of olive: a case study to implement an integrated strategy to control a soil-borne pathogen
Caractérisation morphologique et biologique des Melampsora spp. pathogÚnes des pins en Europe
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