Sgt1, but not Rar1, is essential for the RB-mediated broad-spectrum resistance to potato late blight

<p>Abstract</p> <p>Background</p> <p>Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes.</p> <p>Results</p> <p>We previously cloned a late blight resistance gene, <it>RB</it>, from a diploid wild potato species <it>Solanum bulbocastanum</it>. Transgenic potato lines containing a single <it>RB </it>gene showed a rate-limiting resistance against all known races of <it>Phytophthora infestans</it>, the late blight pathogen. To better understand the <it>RB</it>-mediated resistance we silenced the potato <it>Rar1 </it>and <it>Sgt1 </it>genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The <it>Rar1 </it>and <it>Sgt1 </it>genes of a <it>RB</it>-containing potato clone were silenced using a RNA interference (RNAi)-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the <it>Rar1 </it>and <it>Sgt1 </it>silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged <it>P. infestans </it>strain. The resistance of the <it>Rar1</it>-silenced plants was not affected. However, silencing of the <it>Sgt1 </it>gene abolished the <it>RB</it>-mediated resistance.</p> <p>Conclusion</p> <p>Our study shows that silencing of the <it>Sgt1 </it>gene in potato does not result in lethality. However, the <it>Sgt1 </it>gene is essential for the <it>RB</it>-mediated late blight resistance. In contrast, the <it>Rar1 </it>gene is not required for <it>RB</it>-mediated resistance. These results provide additional evidence for the universal role of the <it>Sgt1 </it>gene in various <it>R </it>gene-mediated plant defense responses.</p

Higher copy numbers of the potato RB transgene correspond to enhanced transcript and late blight resistance levels.

Late blight of potato ranks among the costliest of crop diseases worldwide. Host resistance offers the best means for controlling late blight, but previously deployed single resistance genes have been short-lived in their effectiveness. The foliar blight resistance gene RB, previously cloned from the wild potato Solanum bulbocastanum, has proven effective in greenhouse tests of transgenic cultivated potato. In this study, we examined the effects of the RB transgene on foliar late blight resistance in transgenic cultivated potato under field production conditions. In a two-year replicated trial, the RB transgene, under the control of its endogenous promoter, provided effective disease resistance in various genetic backgrounds, including commercially prominent potato cultivars, without fungicides. RB copy numbers and transcript levels were estimated with transgene-specific assays. Disease resistance was enhanced as copy numbers and transcript levels increased. The RB gene, like many other disease resistance genes, is constitutively transcribed at low levels. Transgenic potato lines with an estimated 15 copies of the RB transgene maintain high RB transcript levels and were ranked among the most resistant of 57 lines tested. We conclude that even in these ultra–high copy number lines, innate RNA silencing mechanisms have not been fully activated. Our findings suggest resistance-gene transcript levels may have to surpass a threshold before triggering RNA silencing. Strategies for the deployment of RB are discussed in light of the current research

Feasibility of the Radner reading chards in low vision patients

Background: Being unable to read is a major problem for visually impaired patients. Since distance visual acuity (VA) does not adequately reflect reading ability, it is important to also evaluate near VA. The Radner Reading Charts (RRCs) are available to measure patients' reading performance. The present study tested the inter-chart and test-retest reliability of the RRCs in Dutch low-vision patients (i.e., visual acuity ≥0.3 logMAR) with various eye disorders. Methods: Thirty-eight patients read the three RRCs in random order. Then, about 1 month after the initial measurements, a test-retest procedure was performed in 15 of the 38 patients. Tested variables were reading acuity (logRAD), logRAD score, logRAD/logMAR ratio, maximum reading speed (MRS), and critical print size (CPS). Both MRS and CPS were calculated in two different ways. To determine the variability, a mixed-model analysis was used. Results: For all variables, the largest part of the variance was explained by the individual subject (86-89%) whereas the chart accounted for only 0-0.78% of the variability. Therefore, the inter-chart and test-retest reliability was high, except for the CPS which had a poor to moderate reliability (31-62%) when calculated in the two different ways. Conclusions: The inter-chart and test-retest results showed high reliability in patients with low vision due to various diseases; therefore, the charts are feasible to determine effects in large groups. © 2010 Springer-Verlag

Design for Mobile Mental Health:An Exploratory Review

A large number of mobile mental health apps are available to the public but current knowledge about requirements of designing such solutions is scarce, especially from sociotechnical and user centred points of view. Due to the significant role of mobile apps in the mental health service models, identifying the design requirements of mobile mental health solutions is crucial. Some of those requirements have been addressed individually in the literature, but there are few research studies that show a comprehensive picture of this domain. This exploratory review aims to facilitate such holistic understanding. The main search keywords of the review were identified in a cross-disciplinary requirements workshop. The search was started by finding some core references in the healthcare databases. A wider range of references then has been explored using a snowball method. Findings showed that there is a good understanding of individual design requirements in current literature but there are few examples of implementing a combination of different design requirements in real world products. The design processes specifically developed for mobile mental health apps are also rare. Most studies on operational mobile mental health apps address major mental health issues while prevention and wellbeing areas are underdeveloped. In conclusion, the main recommendations for designing future mobile mental health solutions include: moving towards sociotechnical and open design strategies, understanding and creating shared value, recognizing all dimensions of efficacy, bridging design and medical research and development, and considering an ecosystem perspective

, but not , is essential for the -mediated broad-spectrum resistance to potato late blight-3

Control (+); Katahdin: susceptible control (-); PT29: a clone as the resistant control (+); Non-silenced line (+): a transgenic, but non-silenced -RNAi line (clone 3007); RNAi line #1 (silenced, +, clone 3128); RNAi line #2 (silenced, +, clone 2998); RNAi line (silenced, +, clone 3095); Non-silenced line (+): a non-silenced -RNAi line (clone 3061). Error bars represent the standard deviation from the means.<p><b>Copyright information:</b></p><p>Taken from ", but not , is essential for the -mediated broad-spectrum resistance to potato late blight"</p><p>http://www.biomedcentral.com/1471-2229/8/8</p><p>BMC Plant Biology 2008;8():8-8.</p><p>Published online 23 Jan 2008</p><p>PMCID:PMC2267190.</p><p></p

, but not , is essential for the -mediated broad-spectrum resistance to potato late blight-5

L (+); Non-silenced line (+): a transgenic, but non-silenced -RNAi line (clone 3007); A -RNAi line (clone 3128); Non-silenced line (+): a non-silenced -RNAi line (clone 3061); A -RNAi line (clone 3095). Using a one-way ANOVA, with unequal variance, and Fisher's LSD at an alpha of 0.01, the only group that has significantly higher sporangial growth is the -silenced line.<p><b>Copyright information:</b></p><p>Taken from ", but not , is essential for the -mediated broad-spectrum resistance to potato late blight"</p><p>http://www.biomedcentral.com/1471-2229/8/8</p><p>BMC Plant Biology 2008;8():8-8.</p><p>Published online 23 Jan 2008</p><p>PMCID:PMC2267190.</p><p></p

, but not , is essential for the -mediated broad-spectrum resistance to potato late blight-4

inoculation and photographed on a dissecting microscope under a narrow-band GFP filter. Untransformed K41 control. Katahdin. A silenced -RNAi line (clone 3128). A -silenced line (clone 3095). The red circles outline the original location of the 10 μl inoculation drops. Green fluorescence is only observed within the circles in A and C but spreads out of the original inoculation sites in B and D. Bars = 2.5 mm.<p><b>Copyright information:</b></p><p>Taken from ", but not , is essential for the -mediated broad-spectrum resistance to potato late blight"</p><p>http://www.biomedcentral.com/1471-2229/8/8</p><p>BMC Plant Biology 2008;8():8-8.</p><p>Published online 23 Jan 2008</p><p>PMCID:PMC2267190.</p><p></p