A study of selected factors affecting efficacy of compost tea against several fungal pathogens of potato.

AIM: To investigate selected factors of two nonaerated compost teas (NCT) and mechanisms that influence the restriction of several fungal potato pathogens. METHODS AND RESULTS: Two NCTs, made from either commercial compost, (CCT) or vineyard compost (VCT), were tested for their ability to suppress potato pathogens. The VCT was more suppressive than CCT to mycelial growth of Alternaria solani and Rhizoctonia solani isolate 299, but not for R. solani isolate 422. Metagenomic studies of microbial diversity revealed that the CCT had higher fungal and bacterial diversity and richness than the VCT. Use of CCT significantly reduced lesion area of Alternaria alternata on detached leaves, however, a gum adjuvant did not lead to significantly greater control. Scanning microscopy showed that the spatial distribution of microbes from the CCT was altered with gum addition, to resemble what may have been a microbial biofilm. CONCLUSION: We confirmed that each NCT could suppress the mycelial growth of selected potato pathogens in culture, and CCT reduced A. alternata lesions on detached leaves. Factors including concentration, microbial communities and physio-chemical properties could not be consistently linked to NCT efficacy. SIGNIFICANCE AND IMPACT OF THE STUDY: This study particularly highlights the application of scanning microscopy to study the interaction between pathogens and putative NCT microbes on foliar surfaces. This adds insight to mechanisms of NCT efficacy, along with physico-chemical and microbial characterization of the teas. This study shows the potential for the use of NCTs as a crop protection tool of low-cost which could be of particular benefit in smallholder agriculture.

Diverse microbial communities in non-aerated compost teas suppress bacterial wilt.

Non-aerated compost teas (NCTs) are water extracts of composted organic materials and are used to suppress soil borne and foliar disease in many pathosystems. Greenhouse trials were used to test the effectiveness of NCTs to suppress potato bacterial wilt caused by Ralstonia solanacearum on plants grown in soils inoculated with a virulent isolate of the pathogen (biovar II). NCTs prepared from matured compost sources: agricultural waste (AWCT), vermicompost (VCT) and solid municipal waste (SMWCT) were evaluated at three initial application times (7 days before inoculation, at time of inoculation and 7 days after inoculation) prior to weekly applications, in a randomized complete-block design. AWCT applied initially at the time of inoculation resulted in the greatest disease suppression, with the disease severity index 2.5-fold less than the non-treated plants and the "area under the disease progress curve" (AUDPC) 3.2-fold less. VCT and SMWCT were less suppressive than AWCT regardless of initial application time. Next generation sequencing of the v4 region of 16S rRNA gene and the internal transcribed spacer region (ITS1) revealed that diversity and composition of the bacterial and fungal communities across the NCTs varied significantly. Dominant bacterial phyla such as Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, Verrucomicrobia, Chloroflexi, Planctomycetes, Acidobacteria, and a fungal phylum Ascomycota were detected in all NCTs. AWCT had optimum physico-chemical measurements with higher bacterial Shannon diversity indices (H) and fungal richness (S) than the other treatments. We conclude that bacterial wilt of potatoes grown in controlled conditions can be suppressed by a non-aerated compost tea with a high microbial diversity when applied at planting and weekly thereafter.

Characters of aerated compost tea from immature compost that limit colonization of bean leaflets by Botrytis cinerea.

AIMS: The aim was to produce and characterize an aerated compost tea (ACT) that suppressed growth of the plant pathogen Botrytis cinerea. METHODS AND RESULTS: Three different open-windrow composts were sampled weekly from the early secondary mesophilic stage until maturity. Each 10kg of compost sample was extracted in 30 l of aerated water for 24, 48 or 72h. Relative to water, all batches of ACT applied to detached bean leaflets reduced lesion development following single-point inoculations of B. cinerea. There was a significant linear, inverse relationship between the internal windrow temperature of compost (≤51°C) used to prepare ACT and the extent of lesion development. Bacterial diversity in ACTs from one windrow was highest using compost sampled at 48°C. The compost weight-to-water volume ratios of 1:3, 1:10 or 1:30, using compost sampled from a fourth windrow at 50°C, also produced ACTs that reduced the growth of B. cinerea on bean leaflets. The '1 : 3' ACT, and to a lesser degree the same ACT filtered to remove micro-organisms, inhibited the germination of B. cinerea conidia. CONCLUSIONS: ACT produced using the methods reported here suppressed the growth of B. cinerea on bean leaflets, with an abundant and diverse microbial community likely to contribute to pathogen suppression. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of the use of immature compost to produce a pathogen-suppressive ACT, suggesting that compost stage is an important production variable.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 December 2009-31 January 2010.

This article documents the addition of 220 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Allanblackia floribunda, Amblyraja radiata, Bactrocera cucurbitae, Brachycaudus helichrysi, Calopogonium mucunoides, Dissodactylus primitivus, Elodea canadensis, Ephydatia fluviatilis, Galapaganus howdenae howdenae, Hoplostethus atlanticus, Ischnura elegans, Larimichthys polyactis, Opheodrys vernalis, Pelteobagrus fulvidraco, Phragmidium violaceum, Pistacia vera, and Thunnus thynnus. These loci were cross-tested on the following species: Allanblackia gabonensis, Allanblackia stanerana, Neoceratitis cyanescens, Dacus ciliatus, Dacus demmerezi, Bactrocera zonata, Ceratitis capitata, Ceratitis rosa, Ceratits catoirii, Dacus punctatifrons, Ephydatia mülleri, Spongilla lacustris, Geodia cydonium, Axinella sp., Ischnura graellsii, Ischnura ramburii, Ischnura pumilio, Pistacia integerrima and Pistacia terebinthus.

Dynamics of introduced populations of Phragmidium violaceum and implications for biological control of European blackberry in Australia.

Phragmidium violaceum causes leaf rust on the European blackberry (Rubus fruticosus L. aggregate). Multiple strains of this pathogen have been introduced into southern Australia for the biological control of at least 15 taxa of European blackberry, a nonindigenous, invasive plant. In climates conducive to leaf rust, the intensity of disease varies within and among infestations of the genetically variable host. Genetic markers developed from the selective amplification of microsatellite polymorphic loci were used to assess the population genetic structure and reproductive biology of P. violaceum within and among four geographically isolated and diseased infestations of the European blackberry in Victoria, Australia. Despite the potential for long-distance aerial dispersal of urediniospores, there was significant genetic differentiation among all populations, which was not associated with geographic separation. An assessment of multilocus linkage disequilibrium revealed temporal and geographic variation in the occurrence of random mating among the four populations. The presence of sexual spore states and the results of genetic analyses indicated that recombination, and potentially random migration and genetic drift, played an important role in maintaining genotypic variation within populations. Recombination and genetic differentiation in P. violaceum, as well as the potential for metapopulation structure, suggest the need to release additional, genetically diverse strains of the biocontrol agent at numerous sites across the distribution of the Australian blackberry infestation for maximum establishment and persistence.

Transgenic Leishmania and the immune response to infection.

Genetic manipulation of single-celled organisms such as the Leishmania parasite enables in depth analysis of the consequences of genotypic change on biological function. In probing the immune responses to infection, use of transgenic Leishmania has the potential to unravel both the contribution of the parasite to the infection process and the cellular interactions and mechanisms that characterize the innate and adaptive immune responses of the host. Here, we briefly review recent technical advances in parasite genetics and explore how these methods are being used to investigate parasite virulence factors, elucidate immune regulatory mechanisms and contribute to the development of novel therapeutics for the leishmaniases. Recent developments in imaging technology, such as bioluminescence and intravital imaging, combined with parasite transfection with fluorescent or enzyme-encoding marker genes, provides a rich opportunity for novel assessment of intimate, real-time host-parasite interactions at a previously unexplored level. Further advances in transgenic technology, such as the introduction of robust inducible gene cassettes for expression in intracellular parasite stages or the development of RNA interference methods for down-regulation of parasite gene expression in the host, will further advance our ability to probe host-parasite interactions and unravel disease-promoting mechanisms in the leishmaniases.

Spontaneous intratesticular hemorrhage masquerading as a testis tumor.

Spontaneous, intratesticular hemorrhage is a rare occurrence. We report on a patient who presented with painless testis enlargement, and was believed to have a testis tumor based on physical examination and ultrasonography. Diagnosis was made only after orchiectomy and histopathological examination.

Cystitis follicularis in children with primary vesicoureteral reflux.

In an attempt to determine whether cystitis follicularis affects the spontaneous resolution of primary vesicoureteral reflux we reviewed the records of 65 children with reflux and cystitis follicularis. A group of children with primary vesicoureteral reflux but without cystitis follicularis was included as controls. The data did not reveal a statistically significant difference in either the rate of spontaneous resolution of reflux or the need for surgical correction between these 2 groups of children.