Impact of Erysiphe alphitoides on transpiration and photosynthesis in Quercus robur leaves

International audienceOak powdery mildew, (Erysiphe alphitoides) causes one of the most common diseases of oaks. We assessed the impact of this pathogen on photosynthesis and water relations of infected leaves using greenhouse grown oak seedlings. Transpiration of seedling infected by oak powdery mildew was also investigated. Altogether, E. alphitoides had a low impact on host gas exchange whether at leaf or whole plant scale. Maximal stomatal conductance of infected leaves was reduced by 20-30% as compared to healthy controls. Severely infected seedlings did not experience any detectable change of whole plant transpiration. The reduction in net CO 2 assimilation, A n , was less than proportional to the fraction infected leaf area. Powdery mildew reduced both the maximal light driven electron flux (J max) and the apparent maximal carboxylation velocity (Vc max) although Vc max was slightly more impacted than J max. No compensation of the infection occurred in healthy leaves of partly infected seedlings as the reduced photosynthesis in the infected leaves was not paralleled by increased A n levels in the healthy leaves of the seedlings. However, E. alphitoides had a strong impact on leaf lifespan of infected leaves. It is concluded that the moderate effect of E. alphitoides on oak might be related to the small impact on net CO 2 assimilation rates and on tree transpiration; nevertheless, the severe reduction in leaf lifespan of heavily infected leaves may lead to decreased carbon uptake over the growth season

Parkinson's disease polygenic risk score is not associated with impulse control disorders: A longitudinal study

International audienceObjective: To examine the relationship between a Parkinson's disease (PD) polygenic risk score (PRS) and impulse control disorders (ICDs) in PD. Background: Genome wide association studies (GWAS) have brought forth a PRS associated with increased risk of PD and younger disease onset. ICDs are frequent adverse effects of dopaminergic drugs and are also more frequent in patients with younger disease onset. It is unknown whether ICDs and PD share genetic susceptibility. Methods: We used data from a multicenter longitudinal cohort of PD patients with annual visits up to 6 years (DIG-PD). At each visit ICDs, defined as compulsive gambling, buying, eating, or sexual behavior were evaluated by movement disorders specialists. We genotyped DNAs using the Megachip assay (Illumina) and calculated a weighted PRS based on 90 SNPs associated with PD. We estimated the association between PRS and prevalence of ICDs at each visit using Poisson generalized estimating equations, adjusted for dopaminergic treatment and other known risk factors for ICDs. Results: Of 403 patients, 185 developed ICDs. Patients with younger age at onset had a higher prevalence of ICDs (p < 0.001) as well as higher PRS values (p = 0.06). At baseline, there was no association between the PRS and ICDs (overall, p = 0.84). The prevalence of ICDs increased over time similarly across the quartiles of the PRS (overall, p = 0.88; DA users, p = 0.99). Conclusion: Despite younger disease onset being associated with both higher PRS and ICD prevalence, our findings are not in favor of common susceptibility genes for PD and ICDs