Cob rot epidemics occurred in NSW in sweet corn in 2002 and maize in 2003. Investigations were undertaken to establish the species of Fusarium associated with both instances. Dependent on region, F. ...verticillioides, F. proliferatum, and F. subglutinans were isolated more frequently. The epidemics were unique in their occurrence being in two corn types, in consecutive years, and in two regions.
Fusarium
species associated with plants as pathogens, saprobes and endophytes in Australia are listed with notes on their pathogenicity and toxicity provided. A list of
Fusarium
species not known to ...occur in Australia also is provided and their quarantine significance evaluated.
Crown rot, caused by the fungus Fusarium pseudograminearum (teleomorph Gibberella coronicola) is a major disease of wheat in the Australian grain belt. However, there is little information available ...on the population structure of this pathogen. We measured genetic diversity as assessed with amplified fragment length polymorphism (AFLP) analysis within and between populations of F. pseudograminearum from northeastern, south central, and southwestern regions of the Australian grain belt. Amongst the 217 isolates, 176 haplotypes were identified and grouped into two main clusters. One cluster contained isolates from populations in northeastern Australia, and the other cluster contained isolates from populations in south central and southwestern Australia. The southern populations were distinguished from the northeastern populations by higher levels of population differentiation (Gst) between them and genetic identity amongst the regional populations. We hypothesize that the F. pseudograminearum populations from northeastern and southern Australia are independent, which could result from different founding events or from geographic isolation and the accumulation of genetic differences due to genetic drift and/or selection.
Cultures morphologically similar to
F. brevicatenulatum
and
F. pseudoanthophilum
were recovered from millet collected in Kenya. Morphological characterisation showed that the production of pyriform ...microconidia and chlamydospores, key characters separating these species from each other and from other
Fusarium
species, was variable in these cultures. Sexual compatibility studies of these isolates and holotype cultures of
F. brevicatenulatum
and
F. pseudoanthophilum
revealed that they belonged to the same biological species. No fertile crosses were observed between putative isolates of
F
.
brevicatenulatum
from millet and tester strains of
F. verticillioides
,
F. sacchari
,
F. proliferatum
,
F. subglutinans
,
F. thapsinum
, and
F. konzum.
Neither were fertile crosses obtained from any self-cross tests, indicating that the cultures were heterothallic. Further studies using AFLP, and sequencing of the β-tubulin, calmodulin, and translation elongation factor 1-α genes revealed that the isolates from the millets and those of the ex-holotype cultures of
F. brevicatenulatum
and
F. pseudoanthophilum
belonged to the same species. The species epithet
F. brevicatenulatum
is preferred on the basis of priority.
The genus Eucalyptus is host to numerous species of Mycosphaerella, several of which are only known as anamorphs, and for which no Mycosphaerella state is known. In this study new Mycosphaerella ...teleomorph states are described for Nothostrasseria dendritica and Trimmatostroma excentrica. Two new hyphomycete genera are introduced. Of these, Cibiessia gen. nov., with three new species accommodates an arthoconidial synanamorph of Readeriella. Phaeothecoidea gen. nov. is described for species with brown, thick-walled endoconidia. Four additional new species of Mycosphaerella are introduced with several new anamorph species described in Dissoconium, Phaeophleospora, Pseudocercospora, Ramularia and Stenella, Furthermore, an epitype is designated for Mycosphaerella molleriana. This study also presents new Eucalyptus host and distribution records including M. mexicana from Hawaii, M. ohnowa from Australia, M. acaciigena from Australia and Venezuela, M. heimii from Venezuela and Thailand, M. konae from Venezuela, and M. thailandica from Thailand.
To assess the variability among histopathologists in diagnosing and grading cervical intraepithelial neoplasia eight experienced histopathologists based at different hospitals examined the same set ...of 100 consecutive colposcopic cervical biopsy specimens and assigned them into one of six diagnostic categories. These were normal squamous epithelium, non-neoplastic squamous proliferations, cervical intraepithelial neoplasia grades I, II, and III, and other. The histopathologists were given currently accepted criteria for diagnosing and grading cervical intraepithelial neoplasia and asked to mark their degree of confidence about their decision on a visual linear analogue scale provided. The degree of agreement between the histopathologists was characterised by kappa statistics, which showed an overall poor agreement (unweighted kappa 0.358). Agreement between observers was excellent for invasive lesions, moderately good for cervical intraepithelial neoplasia grade III, and poor for cervical intraepithelial neoplasia grades I and II (unweighted kappa 0.832, 0.496, 0.172, and 0.175, respectively); the kappa value for all grades of cervical intraepithelial neoplasia taken together was 0.660. The most important source of disagreement lay in the distinction of reactive squamous proliferations from cervical intraepithelial neoplasia grade I. The histopathologists were confident in diagnosing cervical intraepithelial neoplasia grade III and invasive carcinoma (other) but not as confident in diagnosing cervical intraepithelial neoplasia grades I and II and glandular atypia (other). Experienced histopathologists show considerable interobserver variability in grading cervical intraepithelial neoplasia and more importantly in distinguishing between reactive squamous proliferations and cervical intraepithelial neoplasia grade I. It is suggested that the three grade division of cervical intraepithelial neoplasia should be abandoned and a borderline category introduced that entails follow up without treatment.
Two new species of
Fusarium
associated with Australian indigenous grasses in natural ecosystems are described as
F. lyarnte
and
F. werrikimbe
on the basis of morphology, DNA fingerprinting and ...phylogenetic analysis of EF-1α and β-tubulin sequence data. Isolates of these species were initially recovered from soil in the McGraths Creek area of central Australia and subsequently recovered from soil and stems of the indigenous grass
Sorghum interjectum
from Litchfield National Park in the Northern Territory, and from
Sorghum leiocladum
from Werrikimbe National Park in New South Wales. The common feature of both of these species is the production of large globose microconidia in false heads on polyphialides. Attempts to apply the biological species concept were unsuccessful.
Fusarium solani is responsible for leaf yellowing and root and collar rot across a broad range of orchid species. The forma specialis, ‘phalaenopsis’, of Fusarium solani has recently been described ...using molecular methods as being the causal organism of disease in Phalaenopsis and Cymbidium orchids, and is the predominant pathogen of Taiwanese glasshouse-grown Phalaenopsis orchids. A study in 1996 reported F. solani as the causal agent of root necrosis of Cymbidium in NSW, Australia, but the study did not use molecular methods and predated the forma specialis ‘phalaenopsis’ designation. By comparing the phylogeny of the Australian isolates of F. solani from glasshouse-grown orchids with isolates of F. solani f.sp. phalaenopsis from Taiwan, the current study showed that the Australian and Taiwanese isolates were identical on the basis of the internal transcribed spacer (ITS) and β-tubulin (benA) regions and resulted in the first identification of F. solani f.sp. phalaenopsis in Australia.
Little information is available on Fusarium associations with non-crop hosts in grasslands despite extensive studies on Fusarium species in agricultural systems. The Fusarium species associated with ...the Australian indigenous grass, Austrostipa aristiglumis , including the key pathogenic species Fusarium pseudograminearum , F. thapsinum and Gibberella zeae , in addition to several saprobic Fusarium species, are reported.
The fungus, Alternaria alternata (Fr.) Keissler Strain 501, has been evaluated as a bioherbicide for control of Eupatorium adenophorum Spreng., but the biology of the pathogen-host interaction and ...the optimal environmental conditions for disease development and effective weed control are unknown. Disease development of A. alternata Strain 501 mycelia on E. adenophorum was assessed under several factors including pathogen inoculum concentration, plant age, dew period duration, post-dew temperature, storage temperature and duration. The minimum inoculum concentration required to kill E. adenophorum seedlings was 3.2x10(6) mycelial fragment mL-1. E. adenophorum seedlings at the four-leaf-pair stage were more susceptible than the older plants, especially those at the older than seven-leaf-pair stage. With a dew period of at least 14 h, 100% mortality occurred. The optimal post-dew temperature for disease development was 18-25°C. Storage at <4°C maintained the infectivity of A. alternata strain 501 mycelia on E. adenophorum longer. Using light and scanning electron microscopy to examine the infection process of A. alternata Strain 501 mycelia, it was shown that the time from initiation to completion of infection with mycelia was much shorter (14 h) than with conidia (72 h). It was further shown that mycelial infection occurred predominately through direct penetration at intercellular junctions, while conidial infection occurred predominately through stomatal penetration. This suggests that mycelia are more suitable as infection propagules for A. alternata strain 501 in a bioherbicide for the control of E. adenophorum.
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