Action of spermidine, N1-acetylspermidine, and N8-acetylspermidine at apurinic sites in DNA

The cleavage efficiency of spermidine and its acetyl derivatives (N1-acetylspermidine and N8-acetylspermidine) at apurinic sites in DNA were examined by PAGE-urea analysis. The three polyamines induced different rates of cleavage when compared at 1 mM concentrations. The order of effectiveness were: spermidine greater than N8-acetylspermidine greater than N1-acetylspermidine. Thus a decrease in efficiency was observed when the first order amino-groups of spermidine were blocked. The N-8amino-group of spermidine was less effective in inducing cleavage at AP-sites than the N1-amino-group. Among several proposed models of polyamine-DNA interactions, our results can best be explained by the model postulated by Liquori et al.     

Ny-1 and Ny-2 genes conferring hypersensitive response to potato virus Y (PVY) in cultivated potatoes: mapping and marker-assisted selection validation for PVY resistance in potato breeding

Potato virus Y (PVY) is one of the most important viruses affecting potato (Solanum tuberosum) production. In this study, a novel hypersensitive response (HR) gene, Ny-2, conferring resistance to PVY was mapped on potato chromosome XI in cultivar Romula. In cultivars Albatros and Sekwana, the Ny-1 gene was mapped on chromosome IX. In cv. Romula, the local lesions appeared in leaves inoculated with the PVY^N-Wi isolate at 20 and 28 °C; PVY systemic infections were only occasionally observed at the higher temperature. In cvs. Albatros and Sekwana, expression of the necrotic reaction to virus infection was temperature-dependent. PVY^N-Wi was localized at 20 °C; at 28 °C, the systemic, symptomless infection was observed. We developed the B11.6₁₆₀₀ marker co-segregating with Ny-2 and the S1d11 marker specific for the Ny-1 gene. Fifty potato cultivars were tested with markers B11.6 and S1d11 and marker SC895 linked to the Ny-1 gene in cv. Rywal. These results indicated the utility of these markers for marker-assisted selection of HR-like PVY resistance in potato breeding programs.     

The novel gene Ny-1 on potato chromosome IX confers hypersensitive resistance to Potato virus Y and is an alternative to Ry genes in potato breeding for PVY resistance

Hypersensitive resistance (HR) is an efficient defense strategy in plants that restricts pathogen growth and can be activated during host as well as non-host interactions. HR involves programmed cell death and manifests itself in tissue collapse at the site of pathogen attack. A novel hypersensitivity gene, Ny-1, for resistance to Potato virus Y (PVY) was revealed in potato cultivar Rywal. This is the first gene that confers HR in potato plants both to common and necrotic strains of PVY. The locus Ny-1 mapped on the short arm of potato chromosome IX, where various resistance genes are clustered in Solanaceous genomes. Expression of HR was temperature-dependent in cv. Rywal. Strains PVY^O and PVY^N, including subgroups PVY^NW and PVY^NTN, were effectively localized when plants were grown at 20°C. At 28°C, plants were systemically infected but no symptoms were observed. In field trials, PVY was restricted to the inoculated leaves and PVY-free tubers were produced. Therefore, the gene Ny-1 can be useful for potato breeding as an alternative donor of PVY resistance, because it is efficacious in practice-like resistance conferred by Ry genes.     

Extreme resistance to Potato virus Y in potato carrying the Rysto gene is mediated by a TIR‐NLR immune receptor

Potato virus Y (PVY) is a major potato (Solanum tuberosum L.) pathogen that causes severe annual crop losses worth billions of dollars worldwide. PVY is transmitted by aphids, and successful control of virus transmission requires the extensive use of environmentally damaging insecticides to reduce vector populations. Ry_sto, from the wild relative S. stoloniferum, confers extreme resistance (ER) to PVY and related viruses and is a valuable trait that is widely employed in potato resistance breeding programmes. Ry_sto was previously mapped to a region of potato chromosome XII, but the specific gene has not been identified to date. In this study, we isolated Ry_sto using resistance gene enrichment sequencing (RenSeq) and PacBio SMRT (Pacific Biosciences single‐molecule real‐time sequencing). Ry_sto was found to encode a nucleotide‐binding leucine‐rich repeat (NLR) protein with an N‐terminal TIR domain and was sufficient for PVY perception and ER in transgenic potato plants. Ry_sto‐dependent extreme resistance was temperature‐independent and requires EDS1 and NRG1 proteins. Ry_sto may prove valuable for creating PVY‐resistant cultivars of potato and other Solanaceae crops.     

Endonuclease restriction of SCAR amplicons SC811 is required to identifyNs-false-positive markers in PVS-susceptible potato cultivars

The Ns gene confers resistance of potato to Potato virus S (PVS). Sixteen German and Dutch potato cultivars, all registered in Poland, were found to be susceptible to PVS infection. However, scoring of the cultivars for the presence of the Ns-linked SCAR marker SC811(454) revealed additional amplicons with a similar electrophoretic migration rate as that of SC811(454), which resulted in ambiguous determination of the genotype at the Ns locus. MboI or FokI treatment of the PCR products allowed to detect their Ns-unspecificity in PVS-susceptible potato cultivars.     

Nanoparticle analysis of cancer cells by light transmission spectroscopy

We have measured the optical properties of cancer and normal whole cells and lysates using light transmission spectroscopy (LTS). LTS provides both the optical extinction coefficient in the wavelength range from 220 to 1100 nm and (by spectral inversion using a Mie model) the particle distribution density in the size range from 1 to 3000 nm. Our current work involves whole cells and lysates of cultured human oral cells in liquid suspension. We found systematic differences in the optical extinction between cancer and normal whole cells and lysates, which translate to different particle size distributions (PSDs) for these materials. Specifically, we found that cancer cells have distinctly lower concentrations of nanoparticles with diameters less than 100 nm and have higher concentrations of particles with diameters from 100 to 1000 nm—results that hold for both whole cells and lysates. We also found a power-law dependence of particle density with diameter over several orders of magnitude.     

Quantitative proteomic analysis of differentially expressed proteins in tubers of potato plants differing in resistance to Dickeya solani

Plant and Soil - This study aims the detection of proteins associated with increased resistance of tubers to necrotrophic bacteria Dickeya solani in tetraploid and diploid potato plants....