Mapping spot blotch resistance genes in four barley populations

Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) is the fungal pathogen responsible for spot blotch in barley (Hordeum vulgare L.) and occurs worldwide in warmer, humid growing conditions. Current Australian barley varieties are largely susceptible to this disease and attempts are being made to introduce sources of resistance from North America. In this study we have compared chromosomal locations of spot blotch resistance reactions in four North American two-rowed barley lines; the North Dakota lines ND11231-12 and ND11231-11 and the Canadian lines TR251 and WPG8412-9-2-1. Diversity Arrays Technology (DArT)-based PCR, expressed sequence tag (EST) and SSR markers have been mapped across four populations derived from crosses between susceptible parental lines and these four resistant parents to determine the location of resistance loci. Quantitative trait loci (QTL) conferring resistance to spot blotch in adult plants (APR) were detected on chromosomes 3HS and 7HS. In contrast, seedling resistance (SLR) was controlled solely by a locus on chromosome 7HS. The phenotypic variance explained by the APR QTL on 3HS was between 16 and 25% and the phenotypic variance explained by the 7HS APR QTL was between 8 and 42% across the four populations. The SLR QTL on 7HS explained between 52 to 64% of the phenotypic variance. An examination of the pedigrees of these resistance sources supports the common identity of resistance in these lines and indicates that only a limited number of major resistance loci are available in current two-rowed germplasm

Development of a D genome specific marker resource for diploid and hexaploid wheat

Citation: Wang, Y., Drader, T., Tiwari, V. K., Dong, L. L., Kumar, A., Huo, N. X., . . . Gu, Y. Q. (2015). Development of a D genome specific marker resource for diploid and hexaploid wheat. Bmc Genomics, 16, 12. https://doi.org/10.1186/s12864-015-1852-2Background: Mapping and map-based cloning of genes that control agriculturally and economically important traits remain great challenges for plants with complex highly repetitive genomes such as those within the grass tribe, Triticeae. Mapping limitations in the Triticeae are primarily due to low frequencies of polymorphic gene markers and poor genetic recombination in certain genetic regions. Although the abundance of repetitive sequence may pose common problems in genome analysis and sequence assembly of large and complex genomes, they provide repeat junction markers with random and unbiased distribution throughout chromosomes. Hence, development of a high-throughput mapping technology that combine both gene-based and repeat junction-based markers is needed to generate maps that have better coverage of the entire genome. Results: In this study, the available genomics resource of the diploid Aegilop tauschii, the D genome donor of bread wheat, were used to develop genome specific markers that can be applied for mapping in modern hexaploid wheat. A NimbleGen array containing both gene-based and repeat junction probe sequences derived from Ae. tauschii was developed and used to map the Chinese Spring nullisomic-tetrasomic lines and deletion bin lines of the D genome chromosomes. Based on these mapping data, we have now anchored 5,171 repeat junction probes and 10,892 gene probes, corresponding to 5,070 gene markers, to the delineated deletion bins of the D genome. The order of the gene-based markers within the deletion bins of the Chinese Spring can be inferred based on their positions on the Ae. tauschii genetic map. Analysis of the probe sequences against the Chinese Spring chromosome sequence assembly database facilitated mapping of the NimbleGen probes to the sequence contigs and allowed assignment or ordering of these sequence contigs within the deletion bins. The accumulated length of anchored sequence contigs is about 155 Mb, representing similar to 3.2 % of the D genome. A specific database was developed to allow user to search or BLAST against the probe sequence information and to directly download PCR primers for mapping specific genetic loci. Conclusions: In bread wheat, aneuploid stocks have been extensively used to assign markers linked with genes/traits to chromosomes, chromosome arms, and their specific bins. Through this study, we added thousands of markers to the existing wheat chromosome bin map, representing a significant step forward in providing a resource to navigate the wheat genome. The database website (http://probes.pw.usda.gov/ATRJM/) provides easy access and efficient utilization of the data. The resources developed herein can aid map-based cloning of traits of interest and the sequencing of the D genome of hexaploid wheat

Rapid Identification of Emerging Pathogens: Coronavirus

New surveillance approach can analyze >900 polymerase chain reactions per day

Inhibition of calcification of glutaraldehyde pretreated porcine aortic valve cusps with sodium dodecyl sulfate: Preincubation and controlled release studies

Calcification of bioprosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium or porcine aortic valves (PAV) is a frequent cause of the failure of these devices. Of all strategies considered thus far, only detergent preincubations using compounds such as sodium dodecyl sulfate (SDS) ingibited PAV bioprosthetic mineralization in circulatory sheep bioprosthetic valve replacements. The present study sought to characterize the mechanism of action of SDS preincubation. Results of transport and material characterization studies showed that SDS had a relatively high affinity for PAV, with a maximum uptake of 167.1 ± 6.8 Μg SDS/mg tissue over 24 h at 37°C with a partition coefficient of 19.3. The PAV diffusion of SDS was 1.95 ± 0.35 10 −6 cm 2 /sec. The principal effect of SDS on PAV was phospholipid extraction. The residual organic phospholipid extraction. The residual organic phosphate in the SDS pretreated tissue was 2.22 ± 0.72 nmol/mg tissue compared to the control untreated group with 18.52 ± 2.1 nmol/mg tissue. Incubations of PAV specimens in a 1% SDS solution for 24 h significantly inhibited calcification after 21 days in subdermal implants in 3-week-old male rats (PAV Ca 2+ = 18.0 ± 11.8 Μg/mg) compared to control (177.8 ± 6.0 Μg/mg). In contrast, coimplants of 30% SDS silicone rubber polymers, for regional sustained SDS administration, did not impede PAV calcification in 21 day implants Ca 2+ = 166.0 ± 14.0 Μg/mg compared to the nondrug silicone matrix controls, (Ca 2+ = 173.0 ± 6.6 Μg/mg). Thus, we conclude that the mechanisms of SDS inhibition of PAV calcification is due to material effects which occur during preincubation, and is not facilitated by sustained SDS administration. © 1993 John Wiley & Sons, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38001/1/820271203_ftp.pd

Structure and radiolytic stability of monoamide-actinide complexes

International audienc

The stem rust resistance gene Rpg5 encodes a protein with nucleotide-binding-site, leucine-rich, and protein kinase domains

We isolated the barley stem rust resistance genes Rpg5 and rpg4 by map-based cloning. These genes are colocalized on a 70-kb genomic region that was delimited by recombination. The Rpg5 gene consists of an unusual structure encoding three typical plant disease resistance protein domains: nucleotide-binding site, leucine-rich repeat, and serine threonine protein kinase. The predicted RPG5 protein has two putative transmembrane sites possibly involved in membrane binding. The gene is expressed at low but detectable levels. Posttranscriptional gene silencing using VIGS resulted in a compatible reaction with a normally incompatible stem rust pathogen. Allele sequencing also validated the candidate Rpg5 gene. Allele and recombinant sequencing suggested that the probable rpg4 gene encoded an actin depolymerizing factor-like protein. Involvement of actin depolymerizing factor genes in nonhost resistance has been documented, but discovery of their role in gene-for-gene interaction would be novel and needs to be further substantiated