Globisporangium and Pythium Species Associated with Yield Decline of Pyrethrum (Tanacetum cinerariifolium) in Australia.

Pyrethrum (Tanacetum cinerariifolium) cultivation in Australia, which accounts for the majority of global production of natural insecticidal pyrethrins, is affected by a persistent yield decline which in part is caused by a complex of pathogens. Globisporangium and Pythium species were isolated from crown and roots of pyrethrum plants showing stunting and brown discoloration of crown tissue, and from soil adjacent to diseased plants from yield-decline-affected sites in Tasmania and Victoria, Australia. Ten known Globisporangium species (Globisporangium attrantheridium, G. erinaceum, G. intermedium, G. irregulare, G. macrosporum, G. recalcitrans, G. rostratifingens, G. sylvaticum, G. terrestris and G. ultimum var. ultimum), two new Globisporangium species (Globisporangium capense sp. nov. and Globisporangium commune sp. nov.) and three Pythium species (Pythium diclinum/lutarium, P. tracheiphilum and P. vanterpoolii) were identified through morphological studies and multigene phylogenetic analyses using ITS and Cox1 sequences. Globisporangium ultimum var. ultimum, G. sylvaticum, G. commune sp. nov. and G. irregulare were most abundant. Globisporangium attrantheridium, G. macrosporum and G. terrestris were reported for the first time in Australia. Seven Globisporangium species were pathogenic on both pyrethrum seeds (in vitro assays) and seedlings (glasshouse bioassays), while two Globisporangium species and three Pythium species only caused significant symptoms on pyrethrum seeds. Globisporangium irregulare and G. ultimum var. ultimum were the most aggressive species, causing pyrethrum seed rot, seedling damping-off and significant plant biomass reduction. This is the first report of Globisporangium and Pythium species causing disease in pyrethrum globally and suggests that oomycete species in the family Pythiaceae may have an important role in the yield decline of pyrethrum in Australia.

Diversity and Pathogenicity of Pythium Species Associated with Reduced Yields of Processing Tomatoes (Solanum lycopersicum) in Victoria, Australia.

Yield decline associated with poor crop establishment, stunting, wilting, and diminished root systems was reported in processing tomato crops in Victoria, Australia. During surveys between 2016 and 2018 Pythium species were isolated by soil baiting and by culturing from the diseased roots and collars of plants exhibiting these symptoms. Eleven species of Pythium were identified based on cultural characteristics and phylogenetic analysis with ITS, Cox-1, and Cox-2 gene sequences. None of the 11 Pythium species had been reported previously from processing or fresh tomatoes in Australia. Pythium dissotocum was the most abundant and widespread species isolated during surveys in each of two growing seasons. In pathogenicity tests, these Pythium species ranged from nonpathogenic to highly aggressive. P. aphanidermatum, P. ultimum, and P. irregulare were consistently the most aggressive species, causing serious damage or death at the pregermination, postgermination, and later stages of plant growth. Five processing tomato cultivars varied significantly in their susceptibility to Pythium disease. These results suggest that Pythium species could be contributing to yield loss in processing tomatoes in Victoria both in the crop establishment phase and through the season.

Colletotrichum Species Causing Anthracnose of Citrus in Australia.

Colletotrichum spp. are important pathogens of citrus that cause dieback of branches and postharvest disease. Globally, several species of Colletotrichum have been identified as causing anthracnose of citrus. One hundred and sixty-eight Colletotrichum isolates were collected from anthracnose symptoms on citrus stems, leaves, and fruit from Victoria, New South Wales, and Queensland, and from State herbaria in Australia. Colletotrichum australianum sp. nov., C. fructicola, C. gloeosporioides, C. karstii, C. siamense, and C. theobromicola were identified using multi-gene phylogenetic analyses based on seven genomic loci (ITS, gapdh, act, tub2, ApMat, gs, and chs-1) in the gloeosporioides complex and five genomic loci (ITS, tub2, act, chs-1, and his3) in the boninense complex, as well as morphological characters. Several isolates pathogenic to chili (Capsicum annuum), previously identified as C. queenslandicum, formed a clade with the citrus isolates described here as C. australianum sp. nov. The spore shape and culture characteristics of the chili and citrus isolates of C. australianum were similar and differed from those of C. queenslandicum. This is the first report of C. theobromicola isolated from citrus and the first detection of C. karstii and C. siamense associated with citrus anthracnose in Australia.

Inheritance of breeding system in Cakile (Brassicaceae) following hybridization: implications for plant invasions.

BACKGROUND AND AIMS: Hybridization is commonly assumed to aid invasions through adaptive introgression. In contrast, a recent theoretical model predicted that there can be non-adaptive demographic advantages from hybridization and that the population consequences will depend on the breeding systems of the species and the extent to which subsequent generations are able to interbreed and reproduce. We examined cross-fertilization success and inheritance of breeding systems of two species in order to better assess the plausibility of the theoretical predictions. METHODS: Reciprocal artificial crosses were made to produce F1, F2 and backcrosses between Cakile maritima (self-incompatible, SI) and Cakile edentula (self-compatible, SC) (Brassicaceae). Flowers were emasculated prior to anther dehiscence and pollen was introduced from donor plants to the recipient's stigma. Breeding system, pollen viability, pollen germination, pollen tube growth and reproductive output were then determined. The results were used to replace the assumptions made in the original population model and new simulations were made. KEY RESULTS: The success rate with the SI species as the pollen recipient was lower than when it was the pollen donor, in quantitative agreement with the 'SI × SC rule' of unilateral incompatibility. Similar outcomes were found in subsequent generations where fertile hybrids were produced but lower success rates were observed in crosses of SI pollen donors with SC pollen recipients. Much lower proportions of SC hybrids were produced than expected from a single Mendelian allele. When incorporated into a population model, these results predicted an even faster rate of replacement of the SC species by the SI species than previously reported. CONCLUSIONS: Our study of these two species provides even clearer support for the feasibility of the non-adaptive hybridization hypothesis, whereby the colonization of an SI species can be assisted by transient hybridization with a congener. It also provides novel insight into reproductive biology beyond the F1 generation.

Comparative genome analysis indicates high evolutionary potential of pathogenicity genes in Colletotrichum tanaceti.

Colletotrichum tanaceti is an emerging foliar fungal pathogen of commercially grown pyrethrum (Tanacetum cinerariifolium). Despite being reported consistently from field surveys in Australia, the molecular basis of pathogenicity of C. tanaceti on pyrethrum is unknown. Herein, the genome of C. tanaceti (isolate BRIP57314) was assembled de novo and annotated using transcriptomic evidence. The inferred putative pathogenicity gene suite of C. tanaceti comprised a large array of genes encoding secreted effectors, proteases, CAZymes and secondary metabolites. Comparative analysis of its putative pathogenicity gene profiles with those of closely related species suggested that C. tanaceti likely has additional hosts to pyrethrum. The genome of C. tanaceti had a high repeat content and repetitive elements were located significantly closer to genes inferred to influence pathogenicity than other genes. These repeats are likely to have accelerated mutational and transposition rates in the genome, resulting in a rapid evolution of certain CAZyme families in this species. The C. tanaceti genome showed strong signals of Repeat Induced Point (RIP) mutation which likely caused its bipartite nature consisting of distinct gene-sparse, repeat and A-T rich regions. Pathogenicity genes within these RIP affected regions were likely to have a higher evolutionary rate than the rest of the genome. This "two-speed" genome phenomenon in certain Colletotrichum spp. was hypothesized to have caused the clustering of species based on the pathogenicity genes, to deviate from taxonomic relationships. The large repertoire of pathogenicity factors that potentially evolve rapidly due to the plasticity of the genome, indicated that C. tanaceti has a high evolutionary potential. Therefore, C. tanaceti poses a high-risk to the pyrethrum industry. Knowledge of the evolution and diversity of the putative pathogenicity genes will facilitate future research in disease management of C. tanaceti and other Colletotrichum spp.

Population Structure of Colletotrichum tanaceti in Australian Pyrethrum Reveals High Evolutionary Potential.

Colletotrichum tanaceti, the causal agent of anthracnose, is an emerging pathogen of commercially grown pyrethrum (Tanacetum cinerariifolium) in Australia. A microsatellite marker library was developed to understand the spatio-genetic structure over three sampled years and across two regions where pyrethrum is cultivated in Australia. Results indicated that C. tanaceti was highly diverse with a mixed reproductive mode; comprising both sexual and clonal reproduction. Sexual reproduction of C. tanaceti was more prevalent in Tasmania than in Victoria. Little differentiation was observed among field populations likely due to isolation by colonization but most of the genetic variation was occurring within populations. C. tanaceti was likely to have had a long-distance gene and genotype flow among distant populations within a state and between states. Anthropogenic transmission of propagules and wind dispersal of ascospores are the most probable mechanisms of long-distance dispersal of C. tanaceti. Evaluation of putative population histories suggested that C. tanaceti most likely originated in Tasmania and expanded from an unidentified host onto pyrethrum. Victoria was later invaded by the Tasmanian population. With the mixed mode of reproduction and possible long-distance gene flow, C. tanaceti is likely to have a high evolutionary potential and thereby has ability to adapt to management practices in the future.

Identification, prevalence and pathogenicity of Colletotrichum species causing anthracnose of Capsicum annuum in Asia.

Anthracnose of chili (Capsicum spp.) causes major production losses throughout Asia where chili plants are grown. A total of 260 Colletotrichum isolates, associated with necrotic lesions of chili leaves and fruit were collected from chili producing areas of Indonesia, Malaysia, Sri Lanka, Thailand and Taiwan. Colletotrichum truncatum was the most commonly isolated species from infected chili fruit and was readily identified by its falcate spores and abundant setae in the necrotic lesions. The other isolates consisted of straight conidia (cylindrical and fusiform) which were difficult to differentiate to species based on morphological characters. Taxonomic analysis of these straight conidia isolates based on multi-gene phylogenetic analyses (ITS, gapdh, chs-1, act, tub2, his3, ApMat, gs) revealed a further seven known Colletotrichum species, C. endophyticum, C. fructicola, C. karsti, C. plurivorum, C. scovillei, C. siamense and C. tropicale. In addition, three novel species are also described as C. javanense, C. makassarense and C. tainanense, associated with anthracnose of chili fruit in West Java (Indonesia); Makassar, South Sulawesi (Indonesia); and Tainan (Taiwan), respectively. Colletotrichum siamense is reported for the first time causing anthracnose of Capsicum annuum in Indonesia and Sri Lanka. This is also the first report of C. fructicola causing anthracnose of chili in Taiwan and Thailand and C. plurivorum in Malaysia and Thailand. Of the species with straight conidia, C. scovillei (acutatum complex), was the most prevalent throughout the surveyed countries, except for Sri Lanka from where this species was not isolated. Colletotrichum siamense (gloeosporioides complex) was also common in Indonesia, Sri Lanka and Thailand. Pathogenicity tests on chili fruit showed that C. javanense and C. scovillei were highly aggressive, especially when inoculated on non-wounded fruit, compared to all other species. The existence of new, highly aggressive exotic species, such as C. javanense, poses a biosecurity risk to production in countries which do not have adequate quarantine regulations to restrict the entry of exotic pathogens.

Chloroplast variation is incongruent with classification of the Australian bloodwood eucalypts (genus Corymbia, family Myrtaceae).

Previous molecular phylogenetic analyses have resolved the Australian bloodwood eucalypt genus Corymbia (~100 species) as either monophyletic or paraphyletic with respect to Angophora (9-10 species). Here we assess relationships of Corymbia and Angophora using a large dataset of chloroplast DNA sequences (121,016 base pairs; from 90 accessions representing 55 Corymbia and 8 Angophora species, plus 33 accessions of related genera), skimmed from high throughput sequencing of genomic DNA, and compare results with new analyses of nuclear ITS sequences (119 accessions) from previous studies. Maximum likelihood and maximum parsimony analyses of cpDNA resolve well supported trees with most nodes having >95% bootstrap support. These trees strongly reject monophyly of Corymbia, its two subgenera (Corymbia and Blakella), most taxonomic sections (Abbreviatae, Maculatae, Naviculares, Septentrionales), and several species. ITS trees weakly indicate paraphyly of Corymbia (bootstrap support <50% for maximum likelihood, and 71% for parsimony), but are highly incongruent with the cpDNA analyses, in that they support monophyly of both subgenera and some taxonomic sections of Corymbia. The striking incongruence between cpDNA trees and both morphological taxonomy and ITS trees is attributed largely to chloroplast introgression between taxa, because of geographic sharing of chloroplast clades across taxonomic groups. Such introgression has been widely inferred in studies of the related genus Eucalyptus. This is the first report of its likely prevalence in Corymbia and Angophora, but this is consistent with previous morphological inferences of hybridisation between species. Our findings (based on continent-wide sampling) highlight a need for more focussed studies to assess the extent of hybridisation and introgression in the evolutionary history of these genera, and that critical testing of the classification of Corymbia and Angophora requires additional sequence data from nuclear genomes.

Hybridization can facilitate species invasions, even without enhancing local adaptation.

The founding population in most new species introductions, or at the leading edge of an ongoing invasion, is likely to be small. Severe Allee effects-reductions in individual fitness at low population density-may then result in a failure of the species to colonize, even if the habitat could support a much larger population. Using a simulation model for plant populations that incorporates demography, mating systems, quantitative genetics, and pollinators, we show that Allee effects can potentially be overcome by transient hybridization with a resident species or an earlier colonizer. This mechanism does not require the invocation of adaptive changes usually attributed to invasions following hybridization. We verify our result in a case study of sequential invasions by two plant species where the outcrosser Cakile maritima has replaced an earlier, inbreeding, colonizer Cakile edentula (Brassicaceae). Observed historical rates of replacement are consistent with model predictions from hybrid-alleviated Allee effects in outcrossers, although other causes cannot be ruled out.

Paraphoma Crown Rot of Pyrethrum (Tanacetum cinerariifolium).

Pyrethrum (Tanacetum cinerariifolium) is commercially cultivated for the extraction of natural pyrethrin insecticides from the oil glands inside seed. Yield decline has caused significant yield losses in Tasmania during the last decade. A new pathogen of pyrethrum causing crown rot and reduced growth of the plants in yield decline affected fields of northern Tasmania was isolated from necrotic crown tissue and described as Paraphoma vinacea. Multigene phylogenetic identification of the pathogen also revealed that P. vinacea was a new species different from other Paraphoma type strains. Glasshouse pathogenicity experiments showed that P. vinacea significantly reduced belowground and total biomass of pyrethrum plants 2 months after inoculation. Dull-tan to reddish-brown discoloration of the cortical and subcortical crown tissue was observed in 100% of the infected plants. P. vinacea infected 75% of the plants inoculated with root dip and soil drench inoculation techniques in an inoculation optimization experiment. P. vinacea, the causal agent of Paraphoma crown rot disease, represents an important pathogen that will negatively impact the commercial cultivation of pyrethrum in Tasmania.

IMA Genome-F 4: Draft genome sequences of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygamai, Leptographium lundbergii, Limonomyces culmigenus, Stagonosporopsis tanaceti, and Thielaviopsis punctulata.

The genomes of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygami, Leptographium lundbergii, Limonomyces culmigenus, Stagonosporopsis tanaceti, and Thielaviopsis punctulata are presented in this genome announcement. These seven genomes are from endophytes, plant pathogens and economically important fungal species. The genome sizes range from 26.6 Mb in the case of Leptographium lundbergii to 44 Mb for Chrysoporthe austroafricana. The availability of these genome data will provide opportunities to resolve longstanding questions regarding the taxonomy of species in these genera, and may contribute to our understanding of the lifestyles through comparative studies with closely related organisms.

Identification of the MAT1 locus in Stagonosporopsis tanaceti, and exploring its potential for sexual reproduction in Australian pyrethrum fields.

Stagonosporopsis chrysanthemi, S. inoxydabilis, and S. tanaceti are closely related Ascomycetes associated with ray blight of the Asteraceae. To date, only S. tanaceti has been identified in Australia, incurring substantial losses to the pyrethrum industry. In contrast to the homothallic S. chrysanthemi and S. inoxydabilis, a sexual state has not been observed for S. tanaceti. The MAT1 locus in S. tanaceti was identified through de novo assembly of shotgun reads, and was further used to develop primers for amplification of the full-length MAT1/2 locus in S. chrysanthemi and S. inoxydabilis. As expected, S. chrysanthemi and S. inoxydabilis possessed a MAT1/2 locus typical of homothallic Dothideomycetes with two adjacent MAT1-1 and MAT1-2 idiomorphs. However, only MAT1-1 could be detected in the assembled genome of S. tanaceti. Although a sexual mode of reproduction cannot be ruled out for S. tanaceti, evidence so far suggests this is absent or occurring at very low frequency in Australian pyrethrum fields.

Rapid Changes in the Genetic Composition of Stagonosporopsis tanaceti Population in Australian Pyrethrum Fields.

A novel set of microsatellite markers were developed and employed for geographical and temporal population analyses of Stagonosporopsis tanaceti, the cause of ray blight of pyrethrum in Australia. Genotyping of 407 isolates, using 13 markers, suggested an asexual mode of reproduction with significant linkage disequilibrium and high levels of clonality. Low geographical differentiation and widespread distribution of a few multilocus genotypes (MLGs), in the absence of airborne ascospores, suggested the role of human-mediated movement of seed as a major means of long-distance pathogen dispersal. The genetic composition of S. tanaceti was stable for a decade then changed rapidly in only 2 years. Bayesian clustering analyses and minimum spanning networks determined only two major clonal lineages in and prior to 2010. However, in 2012, a previously unobserved cluster of MLGs was detected, which significantly increased in frequency and displaced the historically dominant MLGs by 2013. This rapid change in the genetic composition of S. tanaceti could indicate a second introduction then a selective sweep, or strong selection pressures from recently introduced fungicides or pyrethrum varieties. These results may have serious implications for durability of management strategies for this disease.

Chloroplast genome analysis of Australian eucalypts--Eucalyptus, Corymbia, Angophora, Allosyncarpia and Stockwellia (Myrtaceae).

We present a phylogenetic analysis and comparison of structural features of chloroplast genomes for 39 species of the eucalypt group (genera Eucalyptus, Corymbia, Angophora, and outgroups Allosyncarpia and Stockwellia). We use 41 complete chloroplast genome sequences, adding 39 finished-quality chloroplast genomes to two previously published genomes. Maximum parsimony and Bayesian analyses, based on >7000 variable nucleotide positions, produced one fully resolved phylogenetic tree (35 supported nodes, 27 with 100% bootstrap support). Eucalyptus and its sister lineage Angophora+Corymbia show a deep divergence. Within Eucalyptus, three lineages are resolved: the 'eudesmid', 'symphyomyrt' and 'monocalypt' groups. Corymbia is paraphyletic with respect to Angophora. Gene content and order do not vary among eucalypt chloroplasts; length mutations, especially frame shifts, are uncommon in protein-coding genes. Some non-synonymous mutations are highly incongruent with the overall phylogenetic signal, notably in rbcL, and may be adaptive. Application of custom informatics pipelines (GYDLE Inc.) enabled direct chloroplast genome assembly, resolving each genome to finished-quality with no need for PCR gap-filling or contig order resolution. Analysis of whole chloroplast genomes resolved major eucalypt clades and revealed variable regions of the genome that will be useful in lower-level genetic studies (including phylogeography and geneflow).

Lack of genetic variation in tree ring delta13C suggests a uniform, stomatally-driven response to drought stress across Pinus radiata genotypes.

We assessed the variation in delta(13)C signatures of Pinus radiata D. Don stemwood taken from three genetic trials in southern Australia. We sought to determine the potential of using delta(13)C signatures as selection criteria for drought tolerance. Increment cores were taken from P. radiata and were used to determine the basal area increment and the delta(13)C signature of extracted cellulose. Both growth increment and cellulose delta(13)C were affected by water availability. Growth increment and delta(13)C were negatively correlated suggesting that growth was water-limited. While there was significant genetic variation in growth, there was no significant genetic variation in cellulose delta(13)C of tree rings. This suggests that different genotypes of P. radiata display significant differences in growth and yet respond similarly to drought stress. The delta(13)C response to drought stress was more due to changes in stomatal conductance than to the variation in photosynthetic capacity, and this may explain the lack of genetic variation in delta(13)C. The lack of genetic variation in cellulose delta(13)C of tree rings precludes its use as a selection criterion for drought tolerance among P. radiata genotypes.

Analysis of a diverse global Pisum sp. collection and comparison to a Chinese local P. sativum collection with microsatellite markers.

Twenty-one informative microsatellite loci were used to assess and compare the genetic diversity among Pisum genotypes sourced from within and outside China. The Chinese germplasm comprised 1243 P. sativum genotypes from 28 provinces and this was compared to 774 P. sativum genotypes that represented a globally diverse germplasm collection, as well as 103 genotypes from related Pisum species. The Chinese P. sativum germplasm was found to contain genotypes genetically distinct from the global gene pool sourced outside China. The Chinese spring type genotypes were separate from the global gene pool and from the other main Chinese gene pool of winter types. The distinct Chinese spring gene pool comprised genotypes from Inner Mongolia and Sha'anxi provinces, with those from Sha'anxi showing the greatest diversity. The other main gene pool within China included both spring types from other northern provinces and winter types from central and southern China, plus some accessions from Inner Mongolia and Sha'anxi. A core collection of Chinese landraces chosen to represent molecular diversity was compared both to the wider Chinese collection and to a geographically diverse core collection of Chinese landraces. The average gene diversity and allelic richness per locus of both the micro-satellite based core and the wider collection were similar, and greater than the geographically diverse core. The genetic diversity of P. sativum within China appears to be quite different to that detected in the global gene pool, including the presence of several rare alleles, and may be a useful source of allelic variation for both major gene and quantitative traits.

Polybrominated diphenyl ethers and polybrominated biphenyls in Australian sewage sludge.

This paper presents a brief review of the international scientific literature of polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) in sewage sludge and a survey of these compounds in sewage sludge from 16 Australian wastewater treatment plants (WWTPs). The SigmaPBDE mean concentration in the Australian study was 1137microgkg(-1) dry weight (d.w.) (s.d. 1116) and ranged between 5 and 4 230microgkg(-1)d.w. The urban mean of 1308microgkg(-1) (s.d. 1320) and the rural mean of 911microgkg(-1) (s.d. 831) are not statistically different and are similar to levels in European sludges. Principal components analysis was performed on the data set and revealed that 76% of the data variation could be explained by two components that corresponded to overall concentration of the pentaBDE and the decaBDE commercial formulations. An analysis of variance was performed comparing PBDEs levels at three WWTPs over the years 2005 and 2006, finding differences between treatment plants (BDE-47) but no significant difference in PBDE levels in the years 2005 and 2006. Low levels of BB-153 were detected in all samples of this survey (n=16); mean 0.6microgkg(-1)d.w. (s.d. 0.5). This compound has rarely been reported in any other study of sewage sludges undertaken outside Australia. This work highlights the need for a risk assessment of PBDEs in sewage sludge when used for land application, taking into account typical levels found in Australian sludges and soils.

Leaf osmotic potential of Eucalyptus hybrids responds differently to freezing and drought, with little clonal variation.

Concentrations of solutes, and thus leaf osmotic potential (Psi pi), often increase when plants are subject to drought or sub-zero (frost) temperatures. We measured Psi pi and concentrations of individual solutes in leaves of 3-year-old Eucalyptus camaldulensis Dehn., E. globulus Labill., E. grandis W. Hill ex Maid. and 29 hybrid clones on a site subjected to both summer drought and winter frost. We sought to characterize seasonal and genetic variations in Psi pi and to determine whether Psi pi or leaf turgor is related to bole volume increment. Leaf osmotic potential at full turgor (Psi pi(100)) was 0.7 MPa more negative in winter than in late summer, and this trend was uniform across genotypes. Soluble carbohydrates were confirmed as key contributors to Psi pi, accounting for 40-44% of total osmolality. The seasonal trend in Psi pi(100) was facilitated by changes in leaf morphology, such as reduced turgid mass:dry mass ratio and increased apoplastic water fraction in winter. Cell wall elasticity increased significantly from winter to summer. Our results suggest that elastic adjustment may be more important than osmotic adjustment in leaves exposed to drought. Although Psi pi(100) was a reasonable predictor of in situ osmotic potential and turgor, we found no relationship between any physiological trait and bole volume increment. Clone-within-family variation in Psi pi(100) was small in both summer and winter and was unrelated to bole volume increment. We conclude that, for the study species, tree improvement under water-limited conditions should concentrate on direct selection for growth rather than on indirect selection based on osmotic potential.

Dioxin-like compounds in Australian sewage sludge--review and national survey.

An Australian survey of dioxin-like compounds in sewage sludge was conducted in two parts (a) a national survey, and (b) a time-study. All sewage sludge samples analysed as part of these studies had low overall concentrations of dioxin-like compounds. Out of 37 samples, all except one, were within the reported concentration range of soil within the Australian environment. The mean concentration of dioxin-like compounds in the Australian sewage sludge survey of 2006 was found to be 5.6 (s.d. 4.5) ng WHO(05) TEQkg(-1) (n=14) and were within the range of 1.2-15.3 ng WHO(05) TEQ kg(-1). All the Australian sewage sludge samples cited in these studies were below the Victorian EPA "investigation limit" of 50 ng WHO(98) TEQ kg(-1), and well below the European proposed guidelines of 100 ng I-TEQ kg(-1). The burden of dioxin-like compounds in Australian sewage sludge is low and its land application as biosolids is not likely to pose a problem. A general positive relationship was found between population of the town producing the waste and both dioxin-like PCDD/Fs and dioxin-like PCBs. The one exception to this trend was sludge from a town that had a history of smelting and had a relatively high burden of dioxin-like compounds. Sludge from one rural WWTP also had a higher burden of dioxin-like compounds. The treatment plant services a geographically isolated town with a low population and no known emitters of dioxin-like compounds. However, this sample also had a relatively high burden of dioxin-like PCBs, which could be the source of the dioxin-like PCDD/Fs found in this sludge. The time study analyzing sludges from three WWTP from the same city between the years 2002 and 2006 found no apparent difference between WWTPs, but a statistically significant decline of 1.49 ng WHO(05) TEQ kg(-1) per year. Also, a comprehensive review of the scientific literature, presents typical levels and sources of dioxin-like compounds in international sewage sludges.

Development of microsatellite markers for the grapevine fungal pathogen Phaeomoniella chlamydospora.

Twenty polymorphic microsatellite markers from microsatellite-enriched genomic DNA of the grapevine fungal pathogen, Phaeomoniella chlamydospora, were developed and characterized. The markers were used to genotype isolates from Australia and from Europe/Eurasia. The number of alleles per locus ranged from two to 11. Gene diversity per locus ranged from 0.08 to 0.63 among Australian isolates, and from 0.2 to 0.77 among isolates from Europe/Eurasia, demonstrating the suitability of these markers for population genetic studies of P. chlamydospora. Eighteen of the 20 markers also amplified a product in the closely related Phaeoacremonium aleophilum.