Genomic architecture of potato resistance to Synchytrium endobioticum disentangled using SSR markers and the 8.3k SolCAP SNP genotyping array

BACKGROUND: The soil borne, obligate biotrophic fungus Synchytrium endobioticum causes tumor-like tissue proliferation (wart) in potato tubers and thereby considerable crop damage. Chemical control is not effective and unfriendly to the environment. S. endobioticum is therefore a quarantined pathogen. The emergence of new pathotypes of the fungus aggravate this agricultural problem. The best control of wart disease is the cultivation of resistant varieties. Phenotypic screening for resistant cultivars is however time, labor and material intensive. Breeding for resistance would therefore greatly benefit from diagnostic DNA markers that can be applied early in the breeding cycle. The prerequisite for the development of diagnostic DNA markers is the genetic dissection of the factors that control resistance to S. endobioticum in various genetic backgrounds of potato. RESULTS: Progeny of a cross between a wart resistant and a susceptible tetraploid breeding clone was evaluated for resistance to S. endobioticum pathotypes 1, 2, 6 and 18 most relevant in Europe. The same progeny was genotyped with 195 microsatellite and 8303 single nucleotide polymorphism (SNP) markers. Linkage analysis identified the multi-allelic locus Sen1/RSe-XIa on potato chromosome XI as major factor for resistance to all four S. endobioticum pathotypes. Six additional, independent modifier loci had smaller effects on wart resistance. Combinations of markers linked to Sen1/RSe-XIa resistance alleles with one to two additional markers were sufficient for obtaining high levels of resistance to S. endobioticum pathotypes 1, 2, 6 and 18 in the analyzed genetic background. CONCLUSIONS: Potato resistance to S. endobioticum is oligogenic with one major and several minor resistance loci. It is composed of multiple alleles for resistance and susceptibility that originate from multiple sources. The genetics of resistance to S. endobioticum varies therefore between different genetic backgrounds. The DNA markers described in this paper are the starting point for pedigree based selection of cultivars with high levels of resistance to S. endobioticum pathotypes 1, 2, 6 and 18. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12863-015-0195-y) contains supplementary material, which is available to authorized users

DEVELOPMENT OF ADAPTIVE RESONATOR TECHNIQUES FOR HIGH-POWER LASERS

The design of an adaptive wavefront control system for a high-power Nd:Glass laser will be presented. Features of this system include: an unstable resonator in confocal configuration, a multi-module slab amplifier, and real-time intracavity adaptive phase control using deformable mirrors and high-speed wavefront sensors. Experimental results demonstrate the adaptive correction of an aberrated passive resonator (no gain)

The dynamics of entry, exit and profitability: an error correction approach for the retail industry

We develop a two equation error correction model to investigate determinants of and dynamic interaction between changes in profits and number of firms in retailing. An explicit distinction is made between the effects of actual competition among incumbants, new firms competition and potential competition from firms outside the market. Effects of cost, demand and general income changes on profitability are investigated to gain insight in the role of retailing in the cost, demand and wage inflationary processes. The relative importance of profitability, growth and unemployment as determinants of net entry are studied. The model is tested using a panel data set of 36 Dutch shoptypes covering the 1977–1988 period

Multiple alleles for resistance and susceptibility modulate the defense response in the interaction of tetraploid potato (Solanum tuberosum) with Synchytrium endobioticum pathotypes 1, 2, 6 and 18

The obligate biotrophic, soil-borne fungus Synchytrium endobioticum causes wart disease of potato (Solanum tuberosum), which is a serious problem for crop production in countries with moderate climates. S. endobioticum induces hypertrophic cell divisions in plant host tissues leading to the formation of tumor-like structures. Potato wart is a quarantine disease and chemical control is not possible. From 38 S. endobioticum pathotypes occurring in Europe, pathotypes 1, 2, 6 and 18 are the most relevant. Genetic resistance to wart is available but only few current potato varieties are resistant to all four pathotypes. The phenotypic evaluation of wart resistance is laborious, time-consuming and sometimes ambiguous, which makes breeding for resistance difficult. Molecular markers diagnostic for genes for resistance to S. endobioticum pathotypes 1, 2, 6 and 18 would greatly facilitate the selection of new, resistant cultivars. Two tetraploid half-sib families (266 individuals) segregating for resistance to S. endobioticum pathotypes 1, 2, 6 and 18 were produced by crossing a resistant genotype with two different susceptible ones. The families were scored for five different wart resistance phenotypes. The distribution of mean resistance scores was quantitative in both families. Resistance to pathotypes 2, 6 and 18 was correlated and independent from resistance to pathotype 1. DNA pools were constructed from the most resistant and most susceptible individuals and screened with genome wide simple sequence repeat (SSR), inverted simple sequence region (ISSR) and randomly amplified polymorphic DNA (RAPD) markers. Bulked segregant analysis identified three SSR markers that were linked to wart resistance loci (Sen). Sen1-XI on chromosome XI conferred partial resistance to pathotype 1, Sen18-IX on chromosome IX to pathotype 18 and Sen2/6/18-I on chromosome I to pathotypes 2,6 and 18. Additional genotyping with 191 single nucleotide polymorphism (SNP) markers confirmed the localization of the Sen loci. Thirty-three SNP markers linked to the Sen loci permitted the dissection of Sen alleles that increased or decreased resistance to wart. The alleles were inherited from both the resistant and susceptible parents

The On-orbit Calibrations for the Fermi Large Area Telescope

The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope began its on--orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic