Spillover of a Tobamovirus from the Australian Indigenous Flora to Invasive Weeds.

The tobamovirus yellow tailflower mild mottle virus (YTMMV) was previously reported in wild plants of species (family Solanaceae) and other solanaceous indigenous species growing in natural habitats in Western Australia. Here, we undertook a survey of two introduced solanaceous weeds, namely (black nightshade) and (cape gooseberry) in the Perth metropolitan area and surrounds to determine if YTMMV has spread naturally to these species. At a remnant natural bushland site where both solanaceous weeds and indigenous hosts grew adjacent to one another, a proportion of and plants were asymptomatically-infected with YTMMV, confirming spillover had occurred.

Differential Symptom Development and Viral RNA Loads in 10 Accessions Infected with the Tobamovirus Yellow Tailflower Mild Mottle Virus.

Yellow tailflower mild mottle virus (YTMMV, genus ) was identified from wild plants of solanaceous species in Australia. is a species indigenous to the arid north of Australia. accession RA-4 (the lab type), which has a mutant, functionally defective, RNA-dependent RNA polymerase 1 () gene (), has played a significant role in plant virology, but little study has been done regarding responses to virus infection by other accessions of .

Beneficial effects of Trichoderma secondary metabolites on crops.

Selected microbial strains used as active ingredients of biopesticides for agricultural management practices (e.g., IPM, Integrated Pest Management) are known for their ability to control phytopathogens, promote plant growth, and/or induce disease resistance.

Metabolites of a sp. endophyte with potential as biocontrol and bioremediation agent.

Endophytic fungi have several well-established beneficial effects on plant health and growth, and are a huge source of bioactive compounds. The endophyte sp. strain 678, isolated from the roots of an Australian native grass , demonstrated efficacy against four plant pathogens (, , , ).

Novel and divergent viruses associated with Australian orchid-fungus symbioses.

Terrestrial orchids represent a symbiotic union between plants and mycorrhizal fungi. This study describes the occurrence and nature of viruses associated with one population of wild Pterostylis sanguinea orchids, including their fungal symbionts, over two consecutive years. A generic sequencing approach, which combined dsRNA-enrichment from plant and mycelial tissues, random amplification and high throughput shotgun sequencing was used to identify novel viruses.

The challenges of using high-throughput sequencing to track multiple bipartite mycoviruses of wild orchid-fungus partnerships over consecutive years.

The bipartite alpha- and betapartitiviruses are recorded from a wide range of fungi and plants. Using a combination of dsRNA-enrichment, high-throughput shotgun sequencing and informatics, we report the occurrence of multiple new partitiviruses associated with mycorrhizal Ceratobasidium fungi, themselves symbiotically associated with a small wild population of Pterostylis sanguinea orchids in Australia, over two consecutive years. Twenty-one partial or near-complete sequences representing 16 definitive alpha- and betapartitivirus species, and further possible species, were detected from two fungal isolates.

A simple and rapid in vitro test for large-scale screening of fungal endophytes from drought-adapted Australian wild plants for conferring water deprivation tolerance and growth promotion in Nicotiana benthamiana seedlings.

Some fungal endophytes confer novel phenotypes and enhance existing ones in plants, including tolerance to water deprivation stress. A range of fungal endophytes was isolated from wild Nicotiana plants growing in arid parts of northern Australia. These were screened for ability to enhance water deprivation stress tolerance by inoculating seedlings of the model plant N.

Host Specificity of Endophytic Mycobiota of Wild Nicotiana Plants from Arid Regions of Northern Australia.

In arid regions of northern Australia, plants survive under water deficit, high temperatures, intense solar radiation and nutrient-impoverished soils. They employ various morpho-physiological and biochemical adaptations including interaction with microbial symbionts. We evaluated identity, host and tissue association with geographical distribution of fungal endophytes isolated from above- and below-ground tissues of plants of three indigenous Australian Nicotiana species.

Evolution of a wild-plant tobamovirus passaged through an exotic host: Fixation of mutations and increased replication.

is a group of viruses that have become serious pathogens of crop plants. As part of a study informing risk of wild plant virus spill over to crops, we investigated the capacity of a solanaceous-infecting tobamovirus from an isolated indigenous flora to adapt to new exotic hosts. Yellow tailflower mild mottle virus (YTMMV) (genus , family ) was isolated from a wild plant of yellow tailflower (, family Solanaceae) and initially passaged through a plant of , then one of where a single local lesion was used to inoculate a plant.

Novel Endorna-like viruses, including three with two open reading frames, challenge the membership criteria and taxonomy of the Endornaviridae.

Viruses associated with wild orchids and their mycorrhizal fungi are poorly studied. Using a shotgun sequencing approach, we identified eight novel endornavirus-like genome sequences from isolates of Ceratobasidium fungi isolated from pelotons within root cortical cells of wild indigenous orchid species Microtis media, Pterostylis sanguinea and an undetermined species of Pterostylis in Western Australia. They represent the first endornaviruses to be described from orchid mycorrhizal fungi and from the Australian continent.

A novel member of the Tombusviridae from a wild legume, Gompholobium preissii.

As part of an investigation into viruses of wild plants in Australia, a contiguous sequence of 3935 nucleotides was obtained after shotgun sequencing of RNA isolated from an asymptomatic wild legume, Gompholobium preissii. Phylogenetic analysis of the sequence revealed that it most closely resembled that of Trailing lespedeza virus 1 (TLV1), a virus isolated from a wild legume in America. The proposed virus, named Gompholobium virus A, and TLV1 are genetically closest to viruses in the genera Alphacarmovirus and Pelarspovirus, family Tombusviridae, but they share features distinguishing them from both groups.

Complete genome analysis of three isolates of narcissus late season yellows virus and two of narcissus yellow stripe virus: three species or one?

Complete genome sequences of two new isolates of narcissus late season yellows virus (NLSYV) from Australia were compared with the other NLSYV genome from China and with two complete genomes of isolates designated narcissus yellow stripe virus (NYSV), one from Australia and the other from China. On the basis of symptoms on natural and experimental host species, and genome sequence identity, the isolates could either be classified as closely related members of three different species or placed together in one taxon. Options for classification of these potyvirus isolates are discussed.

Harzianic acid: a novel siderophore from Trichoderma harzianum.

Agriculture-relevant microorganisms are considered to produce secondary metabolites during processes of competition with other micro- and macro-organisms, symbiosis, parasitism or pathogenesis. Many different strains of the genus Trichoderma, in addition to a direct activity against phytopathogens, are well-known producers of secondary metabolites and compounds that substantially affect the metabolism of the host plant. Harzianic acid is a Trichoderma secondary metabolite, showing antifungal and plant growth promotion activities.

Differentially expressed proteins and associated histological and disease progression changes in cotyledon tissue of a resistant and susceptible genotype of brassica napus infected with Sclerotinia sclerotiorum.

Sclerotinia rot caused by Sclerotinia sclerotiorum is one of the most serious diseases of oilseed rape. To understand the resistance mechanisms in the Brassica napus to S. sclerotiorum, comparative disease progression, histological and proteomic studies were conducted of two B.

Mycotoxins produced by Fusarium spp. associated with Fusarium head blight of wheat in Western Australia.

An isolated occurrence of Fusarium head blight (FHB) of wheat was detected in the south-west region of Western Australia during the 2003 harvest season. The molecular identity of 23 isolates of Fusarium spp. collected from this region during the FHB outbreak confirmed the associated pathogens to be F.

Trichoderma secondary metabolites that affect plant metabolism.

Recently, there have been many exciting new developments relating to the use of Trichoderma spp. as agents for biocontrol of pathogens and as plant growth promoters. Several mechanisms have been proposed to explain the positive effects of these microorganisms on the plant host.

Host Range and Phylogenetic Relationships of Albugo candida from Cruciferous Hosts in Western Australia, with Special Reference to Brassica juncea.

White rust, caused by Albugo candida, is a serious pathogen of Brassica juncea (Indian mustard) worldwide and poses a potential hazard to the presently developing canola-quality B. juncea industry in Australia. Nine isolates of A.

Mycotoxins produced by Fusarium species associated with annual legume pastures and 'sheep feed refusal disorders' in Western Australia.

Sheep grazing in Western Australia can partially or completely refuse to consume annual Medicago pods contaminated with a number of different Fusarium species. Many Fusarium species are known to produce trichothecenes as part of their array of toxigenic secondary metabolites, which are known to cause feed refusal in animals. This study reports the identity of Fusarium species using species-specific PCR primers and a characterization of the toxigenic secondary metabolites produced by 24 Fusarium isolates associated with annual legume-based pastures and particularly those associated with sheep feed refusal disorders in Western Australia.

Toxigenicity of enniatins from Western Australian Fusarium species to brine shrimp (Artemia franciscana).

The high prevalence (14 of 24 isolates) of enniatin-producing isolates from Western Australian Fusarium species isolated from pasture legumes associated with sheep feed refusal and rat deaths, and the high toxicity of their crude extracts to brine shrimp (Artemia franciscana) from a previous study warranted further investigation of this class of mycotoxin. Crude extracts from Fusarium acuminatum, Fusarium avenaceum, Fusarium tricinctum and Fusarium sambucinum, along with enniatins A, A1, B and B1 purified from a Western Australian strain of F. acuminatum using semi-preparative HPLC, were bioassayed using brine shrimp.

Proteome analysis of the Albugo candida-Brassica juncea pathosystem reveals that the timing of the expression of defence-related genes is a crucial determinant of pathogenesis.

White rust, caused by Albugo candida, is a serious pathogen of Brassica juncea (Indian mustard) and poses a potential hazard to the presently developing canola-quality B. juncea industry worldwide. A comparative proteomic study was undertaken to explore the molecular mechanisms that underlie the defence responses of Brassica juncea to white rust disease caused by the biotrophic oomycete Albugo candida.

The infection processes of Sclerotinia sclerotiorum in cotyledon tissue of a resistant and a susceptible genotype of Brassica napus.

Background And Aims: Sclerotinia sclerotiorum can attack >400 plant species worldwide. Very few studies have investigated host-pathogen interactions at the plant surface and cellular level in resistant genotypes of oilseed rape/canola (Brassica napus).

Methods: Infection processes of S.

Scarification and Environmental Factors that Enhance Carpogenic Germination of Sclerotia of Sclerotinia sclerotiorum.

Ascospores of Sclerotinia sclerotiorum are the primary source of inoculum for disease epidemics in many economically important crops. Mass production of ascospores under laboratory conditions is required to prepare inoculum for use in selection of genotypes with resistance against Sclerotinia diseases. A study was undertaken, first, to investigate the effect on carpogenic germination of scarifying sclerotia from two S.

Comparison of the coat protein genes of Mirafiori lettuce big-vein virus isolates from Australia with those of isolates from other continents.

The complete coat protein nucleotide encoding sequences of 13 Mirafiori lettuce big-vein virus isolates from Australia were compared to those of 23 other isolates, including one from Australia. On phylogenetic analysis, sub-clade A1 contained isolates from Australia (13), Europe and Japan, A2 contained isolates from Australia (1), Europe and South America, and B1 and B2 contained only European isolates. In the amino acid sequences deduced, the N-terminus and central regions varied considerably between clades A and B.

Comparison of the coat protein genes of Lettuce big-vein associated virus isolates from Australia with those of isolates from other continents.

The complete coat protein (CP) nucleotide sequences of seven Lettuce big-vein associated virus (LBVaV) isolates from Australia were compared to those of 22 other LBVaV and five tobacco stunt virus (TStV) isolates. On phylogenetic analysis, clade I contained only LBVaV isolates from Europe, sub-clade IIa only Australian LBVaV isolates, IIb only Japanese LBVaV isolates, and IIc only TStV isolates from Japan. In the amino acid sequences deduced, the central region of the gene was most divergent.