Pathotype variation of barley powdery mildew in Western Australia

Barley powdery mildew caused by the fungus Blumeria graminis f. sp. hordei (Bgh) has emerged as the most damaging disease of barley in Western Australia (WA). Many of the available cultivars display high levels of disease in the field when climatic conditions are conducive. As a result, fungicides have become the main method of disease control in the last 10 years. Different types and sources of genetic disease resistance are available but to optimise their deployment it is necessary to evaluate the spectrum of pathotypes present in the pathogen population. Sixty isolates of Bgh were collected in the 2009 season from 9 locations, single spored and characterised by infection on reference barley lines and cultivars. Eighteen unique pathotypes were resolved. Virulence against many of the R-genes in the reference lines was present in at least one pathotype. Isolates were virulent against 16 out of a total of 23 resistance gene combinations. Undefeated resistance genes included the major R-genes Mla-6, Mla-9, Ml-ra and the combinations of Mla-1 plus Mla-A12 and Mla-6 plus Mla-14 and Mla-13 plus Ml-Ru3 together with the recessive resistance gene mlo-5. There was significant pathotype spatial differentiation suggesting limited gene flow between different regions with WA or localised selection pressures and proliferation. On the basis of the results we recommend a number of strategies to manage powdery mildew disease levels within WA

PRGdb: a bioinformatics platform for plant resistance gene analysis

PRGdb is a web accessible open-source (http://www.prgdb.org) database that represents the first bioinformatic resource providing a comprehensive overview of resistance genes (R-genes) in plants. PRGdb holds more than 16 000 known and putative R-genes belonging to 192 plant species challenged by 115 different pathogens and linked with useful biological information. The complete database includes a set of 73 manually curated reference R-genes, 6308 putative R-genes collected from NCBI and 10463 computationally predicted putative R-genes. Thanks to a user-friendly interface, data can be examined using different query tools. A home-made prediction pipeline called Disease Resistance Analysis and Gene Orthology (DRAGO), based on reference R-gene sequence data, was developed to search for plant resistance genes in public datasets such as Unigene and Genbank. New putative R-gene classes containing unknown domain combinations were discovered and characterized. The development of the PRG platform represents an important starting point to conduct various experimental tasks. The inferred cross-link between genomic and phenotypic information allows access to a large body of information to find answers to several biological questions. The database structure also permits easy integration with other data types and opens up prospects for future implementations

iGentifier: indexing and large-scale profiling of unknown transcriptomes

Development and refinement of methods to analyse differential gene expression has been essential in the progress of molecular biology. A novel approach called iGentifier is presented for profiling known and unknown transcriptomes, thus bypassing a major limitation in microarray analysis. The iGentifier technology combines elements of fragment display (e.g. Differential Display or RMDD) and tag sequencing (e.g. SAGE, MPSS) and allows for analysis of samples in high throughput using current capillary electrophoresis equipment. Application to epidermal tissue of wild-type and mlo5 barley (Hordeum vulgare) plants, infected with powdery mildew [Blumeria graminis (DC.) E.O. Speer f.sp.hordei], led to the identification of several 100 genes induced or repressed upon infection with many well known for their response to fungal pathogens or other stressors. Ten of these genes are suggested to be classified as marker genes for durable resistance mediated by the mlo5 resistance gene

Characterization of four rice mutants with alterations in the defence response pathway

SUMMARY A fast-neutron mutagenized population of rice seedlings was screened with Magnaporthe grisea, the causal agent of rice blast disease, to identify mutants with alterations in the defence response. Three mutant lines, ebr1, ebr2 and ebr3 (enhanced blast resistance) were identified that display enhanced resistance to M. grisea. ebr1 and ebr3 also confer enhanced resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). ebr3 develops a lesion mimic (LM) phenotype upon inoculation with M. grisea, and the phenotype is also induced by a shift in environmental conditions. The fourth mutant line, ncr1 (necrosis in rice), has an LM phenotype under all conditions tested and lacks enhanced resistance to either M. grisea or Xoo. Complementation testing using the mutant lines ebr3 and ncr1 indicates that the ebr3 and ncr1 loci are nonallelic and recessive. ebr1 and ebr2 display no alterations in expression of the rice pathogenesis-related (PR) genes PBZ1 and PR1, compared to wild-type CO39. ebr3 has an elevated expression of PBZ1 and PR1 only in tissue displaying the LM phenotype. ncr1 strongly expresses PBZ1 in tissue displaying the LM phenotype, whereas PR1 expression in this tissue is similar to wild-type CO39

Neural circuits controlling behavior and autonomic functions in medicinal leeches

In the study of the neural circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system of medicinal leeches, Hirudo sp., has been particularly informative. These leeches express well-defined behaviors and autonomic movements which are amenable to investigation at the circuit and neuronal levels. In this review, we discuss some of the best understood of these movements and the circuits which underlie them, focusing on swimming, crawling and heartbeat. We also discuss the rudiments of decision-making: the selection between generally mutually exclusive behaviors at the neuronal level

Neural mechanisms for prediction:do insects have forward models?

forward models