Patterns of Genetic Diversification in the Invasive Hybrid Plant Pathogen Phytophthora × alni and Its Parental Species P. uniformis

Climate change impacts on plant pathogens, food security and paths forward

Plant disease outbreaks pose significant risks to global food security and environmental sustainability worldwide, and result in the loss of primary productivity and biodiversity that negatively impact the environmental and socio-economic conditions of affected regions. Climate change further increases outbreak risks by altering pathogen evolution and host-pathogen interactions and facilitating the emergence of new pathogenic strains. Pathogen range can shift, increasing the spread of plant diseases in new areas. In this Review, we examine how plant disease pressures are likely to change under future climate scenarios and how these changes will relate to plant productivity in natural and agricultural ecosystems. We explore current and future impacts of climate change on pathogen biogeography, disease incidence and severity, and their effects on natural ecosystems, agriculture and food production. We propose that amendment of the current conceptual framework and incorporation of eco-evolutionary theories into research could improve our mechanistic understanding and prediction of pathogen spread in future climates, to mitigate the future risk of disease outbreaks. We highlight the need for a science-policy interface that works closely with relevant intergovernmental organizations to provide effective monitoring and management of plant disease under future climate scenarios, to ensure long-term food and nutrient security and sustainability of natural ecosystems.

Influence of delta-hexachlorocyclohexane (δ-HCH) to Phytophthora ×alni resistant Alnus glutinosa genotypes - Evaluation of physiological parameters and remediation potential

Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 - 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.

MALDI-TOF MS as a method for rapid identification of Phytophthora de Bary, 1876

The number of described species of the oomycete genus Phytophthora is growing rapidly, highlighting the need for low-cost, rapid tools for species identification. Here, a collection of 24 Phytophthora species (42 samples) from natural as well as anthropogenic habitats were genetically identified using the internal transcribed spacer (ITS) and cytochrome c oxidase subunit I (COI) regions. Because genetic identification is time consuming, we have created a complementary method based on by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Both methods were compared and hypothesis that the MALDI-TOF MS method can be a fast and reliable method for the identification of oomycetes was confirmed. Over 3500 mass spectra were acquired, manually reviewed for quality control, and consolidated into a single reference library using the Bruker MALDI Biotyper platform. Finally, a database containing 144 main spectra (MSPs) was created and published in repository. The method presented in this study will facilitate the use of MALDI-TOF MS as a complement to existing approaches for fast, reliable identification of Phytophthora isolates.

Genome-wide microsatellites and species specific markers in genus Phytophthora revealed through whole genome analysis

Genome wide microsatellite maps shall support Phytophthora systematics through the development of reliable markers, enabling species discrimination and variability analyses. Whole genome sequences of 17 Phytophthora accessions belonging to 14 species were retrieved from GenBank and the genome-wide microsatellites in each species were mined. A total of 51,200 microsatellites, including dinucleotide to decanucleotide motifs, have been identified across all the species and each one was characterized for uniqueness and repeat number. The P. infestans T30-4 genome had the highest (6873) and P. multivora 3378 had the lowest number of microsatellites (1802). Dinucleotide motifs (63.6%) followed by trinucleotide motifs (30.1%) were most abundant in all the genome. From 14 species, 250 microsatellites which are unique for the respective genomes are detailed along with their primer combinations and product sizes. P. sojae had the highest number of unique microsatellite motifs. Genome wide microsatellite maps for all the 14 Phytophthora species including the chromosome, position, motif, repeat number, forward and reverse primer sequences and expected PCR product size, for every microsatellite are presented. Markers based on the unique microsatellites could be used to identify each species, whereas the ones common to all species could be used to identify the genetic variability. Furthermore, to confirm the results, pure cultures of P. capsici, P. nicotianae and P. palmivora were procured from the Phytophthora Repository, DNA was isolated and the unique markers were screened across the species. The characteristic markers developed have confirmed the genome analysis results.