An internet-based bioinformatics toolkit for plant biosecurity diagnosis and surveillance of viruses and viroids.

Background: Detection and preventing entry of exotic viruses and viroids at the border is critical for protecting plant industries trade worldwide. Existing post entry quarantine screening protocols rely on time-consuming biological indicators and/or molecular assays that require knowledge of infecting viral pathogens. Plants have developed the ability to recognise and respond to viral infections through Dicer-like enzymes that cleave viral sequences into specific small RNA products.

Phytophthora niederhauserii sp. nov., a polyphagous species associated with ornamentals, fruit trees and native plants in 13 countries.

A non-papillate, heterothallic Phytophthora species first isolated in 2001 and subsequently from symptomatic roots, crowns and stems of 33 plant species in 25 unrelated botanical families from 13 countries is formally described here as a new species. Symptoms on various hosts included crown and stem rot, chlorosis, wilting, leaf blight, cankers and gumming. This species was isolated from Australia, Hungary, Israel, Italy, Japan, the Netherlands, Norway, South Africa, Spain, Taiwan, Turkey, the United Kingdom and United States in association with shrubs and herbaceous ornamentals grown mainly in greenhouses.

The molecular phylogeny of the white blister rust genus Pustula reveals a case of underestimated biodiversity with several undescribed species on ornamentals and crop plants.

Despite their economic importance, the knowledge of the biodiversity of many plant pathogens is still fragmentary. In this study we show that this is true also for the white blister rust genus Pustula that is parasitic on several genera in the asterids, including sunflower and the gentian, Eustoma. It is revealed that several distinct species exist in Pustula, suggesting that species are mostly host genus specific.

Neoerysiphe kerribeeensis sp. nov. (Ascomycota: Erysiphales), a new species of Neoerysiphe on native and introduced species of Senecio (Asteraceae) in Australia.

Anamorphic powdery mildew fungi on introduced taxa of Senecio and Pericallis × hybrida in Australia have previously been identified as Neoerysiphe cumminsiana on the basis of a combination of Euoidium-type conidiophores and lobed mycelial and germ tube appressoria. But, two specimens with chasmothecia on the indigenous Senecio glossanthus did not agree with published descriptions of N. cumminsiana.

Phytophthora bisheria sp. nov., a new species identified in isolates from the Rosaceous raspberry, rose and strawberry in three continents.

A homothallic semipapillate slow growing Phytophthora species associated with root rot of strawberries from greenhouse-grown plants in North Carolina, USA, root rot of roses in the Netherlands, and root rot of raspberry in Knoxfield, Australia, was identified. The main character of this organism is the production of paragynous antheridia with broad attachment to the oogonial wall. The morphology of the pathogen does not match that of any of the more than 85 described Phytophthora species.

Phylogeny and taxonomy of the oak powdery mildew Erysiphe alphitoides sensu lato.

Phylogenetic analyses of Erysiphe alphitoides s. lat. using sequences of the rDNA ITS region and the D1/D2 domains of the 28S rDNA revealed a complex consisting of several genetically and morphologically distinguished taxa, including the already described Erysiphe alphitoides s.

Genetic variation within Podosphaera tridactyla reveals a paraphyletic species complex with biological specialization towards specific Prunus subgenera.

Podosphaera tridactyla (Ascomycota: Erysiphales) is a morphologically variable species occurring on Prunus s. lat. In order to assess the genetic variation within this species, the rDNA ITS region was amplified from 29 specimens from a range of Prunus species collected in Australia, Switzerland, and Korea.

Molecular Identification of Oidium neolycopersici as the Causal Agent of the Recent Tomato Powdery Mildew Epidemics in North America.

A previous morphological study of Oidium anamorphs responsible for the recent tomato (Lycopersicon esculentum) powdery mildew outbreaks worldwide suggested that, despite controversial data in the literature, the North American epidemics were caused solely by a newly erected species, O. neolycopersici. We report here the first molecular evidence that the North American anamorphs do belong to O.

Two new closely related species of Pseudocercospora on unrelated host families from south-eastern Australia.

A species of Pseudocercospora causing foliar lesions on Hibbertia aspera (Dilleniaceae) is morphologically indistingushable from a species of Pseudocercospora causing foliar lesions on Platylobium formosum (Fabaceae) from the same locality. In order to assess the degree to which these fungi were related, we sequenced the ribosomal DNA ITS region of cultures derived from single conidial isolates. Cultures were obtained from four specimens of each respective host.