Competition between Phytophthora infestans Effectors Leads to Increased Aggressiveness on Plants Containing Broad-Spectrum Late Blight Resistance

BACKGROUND: The destructive plant disease potato late blight is caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary. This disease has remained particularly problematic despite intensive breeding efforts to integrate resistance into cultivated potato, largely because of the pathogen's ability to quickly evolve to overcome major resistance genes. The RB gene, identified in the wild potato species S. bulbocastanum, encodes a protein that confers broad-spectrum resistance to most P. infestans isolates through its recognition of highly conserved members of the corresponding pathogen effector family IPI-O. IpiO is a multigene family of effectors and while the majority of IPI-O proteins are recognized by RB to elicit host resistance, some variants exist that are able to elude detection (e.g. IPI-O4). METHODS AND FINDINGS: In the present study, analysis of ipiO variants among 40 different P. infestans isolates collected from Guatemala, Thailand, and the United States revealed a high degree of complexity within this gene family. Isolate aggressiveness was correlated with increased ipiO diversity and especially the presence of the ipiO4 variant. Furthermore, isolates expressing IPI-O4 overcame RB-mediated resistance in transgenic potato plants even when the resistance-eliciting IPI-O1 variant was present. In support of this finding, we observed that expression of IPI-O4 via Agrobacterium blocked recognition of IPI-O1, leading to inactivation of RB-mediated programmed cell death in Nicotiana benthamiana. CONCLUSIONS: In this study we definitively demonstrate and provide the first evidence that P. infestans can defeat an R protein through inhibition of recognition of the corresponding effector protein

Genetic signatures of variation in population size in a native fungal pathogen after the recent intensive plantation of its host tree

Historical fluctuations in forests’ distribution driven by past climate changes and anthropogenic activities can have large impacts on the demographic history of pathogens that have a long co-evolution history with these host trees. Using a population genetic approach, we investigated that hypothesis by reconstructing the demographic history of Armillaria ostoyae, one of the major pathogens of the maritime pine (Pinus pinaster), in the largest monospecific pine planted forest in Europe (south-western France). Genetic structure analyses and approximate Bayesian computation approaches revealed that a single pathogen population underwent a severe reduction in effective size (12 times lower) 1080–2080 generations ago, followed by an expansion (4 times higher) during the last 4 generations. These results are consistent with the history of the maritime pine forest in the region characterized by a strong recession during the last glaciation (~19 000 years ago) and massive plantations during the second half of the nineteenth century. Results suggest that recent and intensive plantations of a host tree population have offered the opportunity for a rapid spread and adaptation of their pathogens

Results of the contingent valuation to estimate the environmental impacts caused by rock-ash discharge in the Dominican Republic

This paper shows the results of a contingent valuation exercise carried out to assess the environmental impacts caused by the disposal of 56,000 tons of rock ash in the Dominican Republic in 2003 and 2004. In March 2007, the Dominican government and AES Corporation reached a legal settlement for US$6 million in penalties to avoid a lengthy legal process. The willingness to pay for a watching and monitoring program to prevent and mitigate environmental impacts caused by rock ash was estimated at US$194 million in 2007, reflecting the welfare losses experienced by the Dominican society at that moment

Health Care–Associated Infection in Solid Organ Transplant Recipients

11th Congress of the Andalusian Society of Organ and Tissue Transplantation. General transplantation topics.[Background] Health care–associated infection (HAI) represent a global health problem with an increase in hospital stays, deaths, and monetary costs. Recipients of solid organ transplants are a population at risk. The objectives of the study were to characterize the incidence of HAI in renal and hepatic transplant recipients as well as to compare them with the population without transplants in intensive care units (ICU).[Methods] The data on the incidence of HAI, localization, microorganisms, and demographics were taken from the patients admitted between the years 2013 to 2018 (n = 4307) from the registration of the Project for the Reduction of Nosocomial Infection in Intensive Care Units. The variables were compared with those of renal transplant (n = 96) and liver transplants (n = 68) recipients.[Results] Renal transplant recipients showed 26% incidence of HAI. The most frequent were surgical site infection (SSI), urinary tract infection, and primary bacteremia; the most frequent microorganism was Staphylococcus spp, mortality 3.8%. Liver transplant recipients showed 41% incidence of HAI. The most frequent were tracheobronchitis associated with mechanical ventilation, SSI, and primary bacteremia; the most frequent microorganism was Staphylococcus spp, mortality 37%. The population without transplants in the ICU showed 17% incidence of HAI. The most frequent were respiratory infections associated with mechanical ventilation, primary bacteremia, and SSI; the most frequent microorganism was Acinetobacter spp, mortality 21%.[Conclusions] HAI in recipients of solid organ transplants (renal and hepatic) have a higher incidence than in a population without transplants. The location and causal microorganisms have particularities that must be taken into account for the development of prevention protocols