Biological control is the control of disease by the application of biological agents to a host animal or plant that prevents the development of disease by a pathogen. With regard to plant diseases the biocontrol agents are usually bacterial or fungal strains isolated from the endosphere or rhizosphere. Viruses can also be used as biocontrol agents and there is a resurgent interest in the use of bacterial viruses for control of plant diseases. The degree of disease suppression achieved with biological agents can be comparable to that achieved with chemicals. Our understanding of the ways in which biocontrol agents protect plants from disease has developed considerably in recent years with the application of genomics and genetic modification techniques. We have uncovered mechanisms by which biocontrol agents interact with the host plant and other members of the microbial community associated with the plant. Understanding these mechanisms is crucial to the isolation of effective biocontrol agents and the development of biocontrol strategies for plant diseases. This review looks at recent developments in our understanding of biocontrol agents for plant diseases and how they work.

Myostatin, or growth and differentiation factor 8 (GDF8), has been identified as the factor causing a phenotype known as double muscling, in which a series of mutations render the gene inactive, and therefore, unable to regulate muscle fibre deposition. This phenotype occurs at a high frequency in some breeds of cattle such as Belgian Blue and Peidmontese. Phylogenetic analysis has shown that there has been positive selection pressure for non-synonymous mutations within the myostatin gene family, around the time of the divergence of cattle, sheep and goats, and these positive selective pressures on non-ancestral myostatin are relatively recent. To date, there have been reports of nine mutations in coding regions of myostatin that cause non-synonymous changes, of which three cause missense mutations, including two in exon 1 and one in exon 2. The remaining six mutations, located in exons 2 and 3, result in premature stop codons, which are the mutations responsible for the double-muscling phenotype. Unfortunately, breed management problems exist for double-muscled cattle, such as birthing difficulties, which can be overcome through genetically controlled breeding programmes, as shown in this review.

The genetic structure of populations of Phytophthora cinnamomi, a pathogen of an enormous variety of woody plants, was investigated using microsatellites. Three intensively sampled disease sites in southwest Australia were analyzed along with a large culture collection of Austra-lian isolates and some isolates from elsewhere in the world. The mutation in the four microsatellite loci analyzed revealed spatial patterns at the disease sites that correlated with the age of the infestation. Only three clonal lineages were identified in Australian populations and these same clonal lineages were present in worldwide populations, where it is suggested that a limited number of clonal lineages have spread in most regions. No evidence for sexual reproduction between these clonal lineages in Australia has been found even though the pathogen has the opportunity. Instead, mitotic recombination is frequent within the clonal lineages. The implications of this are discussed.

This paper describes the effect of phosphite (Phi), a systemic chemical, on the induction of defence responses in Phytophthora cinnamomi-infected Arabidopsis thaliana accessions Ler and Col-0. Application of Phi to non-inoculated A. thaliana seedlings of accession Ler elevated transcription of defence genes in the salicylic acid (PR1 and PR5) and jasmonic acid ⁄ ethylene (THI2.1 and PDF1.2) pathways. Furthermore, a systemic increase in the expression of the PR1 gene was demonstrated in Phi-treated seedlings using the transgenic line PR1::GUS in the presence ⁄ absence of the pathogen by 72 h after inoculation. The cells of Phi-treated A. thaliana Ler leaves responded to P. cinnamomi zoospore inoculation with a rapid increase in callose deposition and hydrogen peroxide (H 2 O 2 ) production. Phi treatment resulted in the production of callose papillae 6 h earlier than in non-Phi-treated inoculated seedlings and enhanced the production of H 2 O 2 in the leaves of A. thaliana at the site of hyphal penetration and in cells away from the inoculation point. By 24 h after infection, clear differences in the amount of H 2 O 2 production were observed between the Phi-treated and non-Phi-treated plants. These rapid host responses did not occur in non-Phi-treated inoculated seedlings. There was also a significant (P < 0AE001) decrease in lesion size in Phi-treated plants. These results indicate that Phi primes the plant for a rapid and intense response to infection involving heightened activation of a range of defence responses.

Abstract. Diurnal air sampling campaigns at the Royal Holloway site on the western fringe of London, United Kingdom, have been used to: (1) test the validity of using carbon isotopes to identify local methane sources, (2) determine the isotopic signature of overnight build-up profiles, in order to estimate regional emissions, and (3) possible to use atmospheric concentration, isotopic, and meteorological data together to verify statistical estimates testing them for internal consistency and using better constrained data to calibrate more poorly known source fluxes. Importantly, atmospheric data can place constraints on poorly constrained landfill emission estimates for the region. These quasi-independent methods for verification of greenhouse gas emissions will contribute in assessing compliance with the Kyoto agreement.

Phosphite, an analog of phosphate is used to control oomycete diseases on a wide range of horticultural crops and in native ecosystems. In this study, we investigated morphological and transcriptional changes induced in Phytophthora cinnamomi by phosphite. Cytological observations revealed that phosphite caused hyphal distortions and lysis of cell walls and had an adverse effect on hyphal growth. At the molecular level, the expression levels of 43 transcripts were changed. Many of these encoded proteins involved in cell wall synthesis, or cytoskeleton functioning. The results of both the microscopic and molecular investigations are consistent with phosphite inhibiting the function of the cytoskeleton and cell wall synthesis.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT RESEARCH HIGHLIGHTS• P. cinnamomi survival propagules in annuals/herbaceous perennials in nature • Formation of stromata by Phytophthora cinnamomi, novel for the species • Dense oospore clusters of P. cinnamomi, forming viable colonies in new hosts • Thick walled chlamydospores inside naturally infected roots • Presence of haustoria suggest a biotrophic mode in asymptomatic host species M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT ABSTRACTStudies were conducted to determine how Phytophthora cinnamomi survives during hot and dry Mediterranean summers in areas with limited surviving susceptible hosts.Two Western Australian herbaceous perennials Chamaescilla corymbosa and Stylidium diuroides and one Western Australian annual Trachymene pilosa were collected weekly from a naturally infested site from the Eucalyptus marginata (jarrah) forest from winter to spring and less frequently during summer 2011/12. Selfed oospores, thick walled chlamydospores and stromata of P. cinnamomi were observed in each species. Oospores and thick-walled chlamydospores germinated in planta confirming their viability. This is the first report of autogamy by P. cinnamomi in naturally infected plants. Stromata, reported for the first time for P. cinnamomi, were densely aggregated inside host cells, and germinated in planta with multiple germ tubes with hyphae capable of producing oospores and chlamydospores.Trachymene pilosa was completely asymptomatic, S. diuroides did not develop root lesions but some plants wilted, whilst C. corymbosa remained asymptomatic above ground but lesions developed on some tubers. The presence of haustoria suggests that P. cinnamomi grows biotrophically in some hosts. Asymptomatic, biotrophic growth of P. cinnamomi in some annual and herbaceous perennials and the production of a range of survival structures have implications for pathogen persistence over summer and its management. KEYWORDSPhytophthora cinnamomi, survival structures, life cycle, facultative homothallic, biotrophic growth, endophyte, haustoria M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 2 INTRODUCTIONPhytophthora cinnamomi is a soil-borne root pathogen with a broad host range and necrotrophic mode of infection (Cahill et al. 2008; Zentmyer 1980) and results in the death of many susceptible plant species and the degradation of ecosystems worldwide including 15 global biodiversity hotspots (Dunstan et al. 2010). Phylogenetically and taxonomically, this pathogen belongs to the class Oomycetes in which swimming zoos...

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