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Phytophthora cactorum is an oomycete species that causes enormous losses on horticultural crops, including strawberries. The purpose of this work was to investigate the alterations caused by P. cactorum inoculation in hydroponically grown strawberry plantlets ( Fragaria  ×  ananassa Duch.) using quantitative magnetic resonance imaging (qMRI). It was observed that with MRI, spatial and temporal progression of the infection could be observed in the crown using quantitative MR parameters, namely relaxation time maps. Relaxation times are numeric subject-specific properties that describe the MR signal behavior in an examined anatomical region. Elevated T 2 relaxation time values were observed inside the infected plant crowns with respect to the healthy references. The T 2 and T 2 ∗ values of healthy plants were small in the crown region and further diminished during the development of the plant. Furthermore, elevated T 1 relaxation time values were seen in regions where P. cactorum progression was observed in corresponding plant dissection photographs. Quantitative susceptibility maps (QSM) were calculated to estimate the local magnetic field inhomogeneities. The QSM suggests magnetic susceptibility differences near the center of the pith. This study provides novel non-invasive information on the structure and development of strawberry plants and the effects caused by the P. cactorum infection.

Crown rot (Phytophthora cactorum) causes significant economic losses in strawberry production. The best control strategy would be to use resistant cultivars, but polygenically inherited resistance makes the breeding of the garden strawberry (Fragaria × ananassa) challenging. The diploid wild strawberry Fragaria vesca Hawaii 4 genotype was shown previously to have resistance against crown rot. To explore the resistance mechanisms, we inoculated the roots of Hawaii 4 with P. cactorum in a novel in vitro hydroponic system to minimize interference caused by other microbes. Major reprogramming of the root transcriptome occurred, involving 30% of the genes. The surveillance system of the plant shifted from the development mode to the defense mode. Furthermore, the immune responses as well as many genes involved in the biosynthesis of the defense hormones jasmonic acid, ethylene and salicylic acid were up-regulated. Several major allergen-like genes encoding PR-10 proteins were highly expressed in the inoculated plants, suggesting that they also have a crucial role in the defense responses against P. cactorum. Additionally, flavonoids and terpenoids may be of vital importance, as several genes involved in their biosynthesis were up-regulated. The cell wall biosynthesis and developmental processes were down-regulated, possibly as a result of the down-regulation of the key genes involved in the biosynthesis of growth-promoting hormones brassinosteroids and auxin. Of particular interest was the expression of potential resistance genes in the recently identified P. cactorum resistance locus RPc-1. These new findings help to target the breeding efforts aiming at more resistant strawberry cultivars.

Crayfish plague, caused by the pathogen Aphanomyces astaci, is one of the main factors responsible for the decimation of the native European crayfish species Austropotamobius pallipes. In Spain, two North American freshwater crayfish species, Procambarus clarkii and Pacifastacus leniusculus, were intentionally introduced during the 1970s for aquaculture and fishery purposes. Since then, incidences of crayfish plague have been continually reported. In this work, we evaluated more than 50 diagnosed cases of crayfish plague that have occurred in the Iberian Peninsula since 2004 by performing a microscopic examination of infected specimens and by molecularly identifying and haplotyping the pathogen. Our results showed that (i) the pathogen A. astaci has been active 45 years since the first introductions of the invasive North American crayfish species in the Iberian Peninsula, and (ii) P. clarkii and P. leniusculus are chronic reservoirs of the crayfish plague pathogen. Moreover, our data confirmed a correspondence between pathogen origin and spread and the specific haplotypes carried by the North American invasive crayfish located in the vicinity of each outbreak. We generated a crayfish plague incidence map of the Iberian Peninsula that shows (i) a northern area, mainly inhabited by alien P. leniusculus, where crayfish plague cases are associated with the b-haplotype specific to P. leniusculus, and (ii) southern, central and eastern areas that are basically inhabited by alien P. clarkii, where crayfish plague cases are associated with the d1- and d2-haplotypes specific to P. clarkii. The results presented here are evidence of the long standing and negative impact of the two invasive crayfish species on the native species, indicating the need for more extensive control measures.

Global introductions of aquatic species and their associated pathogens are threatening worldwide biodiversity. The introduction of two North American crayfish species, Procambarus clarkii and Pacifastacus leniusculus, into Japan in 1927 seems to have negatively affected native Japanese crayfish populations of Cambaroides japonicus. Several studies have shown the decline of these native populations due to competition, predation and habitat colonization by the two invasive North American crayfish species. Here, we identify an additional factor contributing to this decline. We report the first crayfish plague outbreaks in C. japonicus populations in Japan, which were diagnosed using both histological and molecular approaches (analyses of the internal transcribed spacer region). Subsequent analyses of the mitochondrial ribosomal rnnS and rnnL regions of diseased specimens indicate that these outbreaks originated from a P. clarkii population and identify a novel haplotype of Aphanomyces astaci, d3-haplotype, hosted by P. clarkii. Overall, our findings demonstrate the first two cases of crayfish plague in Japan, and the first case in a non-European native crayfish species, which originated from the red swamp crayfish P. clarkii. This finding is a matter of concern for the conservation of the native freshwater species of Japan and also highlights the risk of introducing crayfish carrier species into biogeographic regions harboring species susceptible to the crayfish plague.

The narrow-clawed crayfish ( Pontastacus leptodactylus ) is an alien species in Finland with only a few populations reported from the southeastern region during the last century. We discovered a productive population in the lake Jängynjärvi, which is upstream from the previously reported wild narrow-clawed crayfish population in that region. Preliminary studies indicated that this population is not infected with Aphanomyces astaci . We collected narrow-clawed crayfish samples from the lake Jängynjärvi population for both infection challenge and genetic studies, in order to investigate possible A. astaci resistance among this Finnish population and to evaluate their phylogenetic position that would enable us to speculate different scenarios of distribution pathways or origin of the population. The infection studies indicated that the narrow-clawed crayfish in this population were more resistant against A. astaci infection (B haplogroup A. astaci ) compared to the noble crayfish ( Astacus astacus ) from the lake Rytky in North Savo, while all crayfish of both species in the B haplogroup A. astaci challenged groups died within 58 days post-infection. Results of the phylogenetic reconstruction indicate that the lake Jängynjärvi narrow-clawed crayfish are closely related to narrow-clawed crayfish from the lake Bolshoye near Krasnoye, located on the White Sea island of Solovestky and also populations from Tyumen region, both in Russia. This could confirm previous speculations about introduction of the narrow-clawed crayfish from Russia into Finland or could indicate previous hydrological connection. L'écrevisse à pattes grêles ( Pontastacus leptodactylus ) est une espèce exotique en Finlande, avec seulement quelques populations signalées dans la région sud-est au cours du siècle dernier. Nous avons découvert une population productive dans le lac Jängynjärvi, qui se trouve en amont de la population sauvage d'écrevisses à pinces étroites signalée précédemment dans cette région. Des études préliminaires ont indiqué que cette population n'est pas infectée par Aphanomyces astaci . Nous avons prélevé des échantillons d'écrevisses à pinces étroites dans la population du lac Jängynjärvi, à la fois pour des études sur le test de l'infection et des études génétiques, afin d'étudier la résistance possible à A. astaci dans cette population finlandaise et d'évaluer leur position phylogénétique, ce qui nous permettrait de spéculer sur différents scénarios de voies de diffusion ou d'origine de la population. Les études d'infection ont montré que les écrevisses à pinces étroites de cette population étaient plus résistantes à l'infection par A. astaci (haplogroupe B A. astaci ) que les écrevisses nobles ( Astacus astacus ) du lac Rytky dans le nord du Savo, tandis que toutes les écrevisses des deux espèces de l'haplogroupe B A. astaci ayant été infectées sont mortes dans les 58 jours suivant l'infection. Les résultats de la reconstitution phylogénétique indiquent que les écrevisses à pinces étroites du lac Jängynjärvi sont étroitement apparentées aux écrevisses à pinces étroites du lac Bolshoye près de Krasnoïe, situé sur l'île de Solovestky dans la mer Blanche, ainsi qu'aux populations de la région de Tioumen, toutes deux en Russie. Cela pourrait confirmer les hypothèses antérieures sur l'introduction en Finlande d'écrevisses à pinces étroites en provenance de Russie ou pourrait indiquer un lien hydrologique antérieur.

Crop improvement by genetic modification remains controversial, one of the major issues being the potential for unintended effects. Comparative safety assessment includes targeted analysis of key nutrients and antinutritional factors, but broader scale-profiling or \"omics\" methods could increase the chances of detecting unintended effects. Comparative assessment should consider the extent of natural variation and not simply compare genetically modified (GM) lines and parental controls. In this study, potato (Solanum tuberosum) proteome diversity has been assessed using a range of diverse non-GM germplasm. In addition, a selection of GM potato lines was compared to assess the potential for unintended differences in protein profiles. Clear qualitative and quantitative differences were found in the protein patterns of the varieties and landraces examined, with 1,077 of 1,111 protein spots analyzed showing statistically significant differences. The diploid species Solanum phureja could be clearly differentiated from tetraploid (Solanum tuberosum) genotypes. Many of the proteins apparently contributing to genotype differentiation are involved in disease and defense responses, the glycolytic pathway, and sugar metabolism or protein targeting/storage. Only nine proteins out of 730 showed significant differences between GM lines and their controls. There was much less variation between GM lines and their non-GM controls compared with that found between different varieties and landraces. A number of proteins were identified by mass spectrometry and added to a potato tuber two-dimensional protein map.

We studied the presence of possible Aphanomyces astaci infections in eight Turkish narrow-clawed crayfish ( Astacus leptodactylus ) populations by analyzing the prevalence and genotypes of the disease agent A. astaci . The qPCR analyses revealed A. astaci infection in seven of the studied eight populations, with the agent level A2 or higher. The agent levels among the infected populations varied from A0 to A5, i.e., from negative to high level of infection, based on qPCR ranking. Based on the sequencing of the chitinase gene and the mitochondrial ribosomal rnnS and rnnL subunits, we detected both A (As) and B (PsI) haplogroups of A. astaci in our samples, with each of the studied populations being carriers of only one haplotype. The results confirm previous detections of A. astaci in Turkish narrow-clawed crayfish populations and reveal, that both A and B haplogroup A. astaci carriers exist widely in A. leptodactylus populations of Turkey. Nous avons étudié la présence possible d' Aphanomyces astaci dans huit populations turques d'écrevisses à pattes grêles ( Astacus leptodactylus ) en analysant la prévalence et les génotypes de l'agent pathogène A. astaci . Les analyses qPCR ont révélé une infection à A. astaci dans sept des huit populations étudiées, avec le niveau d'agent A2 ou plus. Les taux d'agents chez les populations infectées variaient de A0 à A5, c'est-à-dire du niveau négatif au niveau élevé d'infection, selon le classement qPCR. En se basant sur le séquençage du gène de la chitinase et des sous-unités rnnS et rnnL du ribosome mitochondrial, nous avons détecté les haplogroupes A (As) et B (PsI) d' A. astaci dans nos échantillons, chacune des populations étudiées n'étant porteuse que d'un seul haplotype. Les résultats confirment les détections précédentes d' A. astaci dans les populations d'écrevisses à pattes grêles et révèlent que les porteurs des deux haplogroupes d' A. astaci existent largement dans les populations d' A. leptodactylus de Turquie.

Phytophthora fragariae causes drastic damage in strawberry crops. P. fragariae infects strawberry roots and causes red stele root rot. Although P. fragariae is a quarantine organism, its spread in Finland continues as more and more fields contract the disease. The spread can be halted through developing rapid and reliable detection assays. We have developed a rapid recombinase polymerase amplification (RPA) assay for P. fragariae targeting the Phytophthora mitochondrial DNA intergenic atp9 - nad9 marker. The assay is DNA-extraction free and capable of detecting as low as 10 fg of P. fragariae genomic DNA. We found the assay reliable for diagnosing field plants when samples are adequately collected. We also applied the RPA assay to the detection of the pathogen in the soil through coupling the assay with baiting with the host plant. The results suggest that if only a small number of samples are analysed, the baiting results will not be reliable.

In Finland, massive signal crayfish introductions started towards the end of 1980s, with an estimated total of 2.2 million signal crayfish been stocked before year 2016. During that period, Finnish fisheries authorities have implemented three national management strategies setting guidelines for the crayfish introductions. The main aims of the strategies have been conservation of native noble crayfish stocks and a controlled spreading of the alien signal crayfish within a designated region. In this study, we report the current distribution of signal crayfish in Finland in comparison to the guidelines set in these three national strategies. The present distribution area of the signal crayfish covers most of the Southern Finland. The signal crayfish has been introduced with a stocking permits to over 480 water bodies. In addition, there have been numerous stockings without permits, which are often next to the region designated for the signal crayfish. Based on the results, we conclude that crayfish management strategies adopted in Finland have only had limited effect on the spread of signal crayfish. We presume that main causes for the uncontrolled spreading of the signal crayfish in Finland have been lack of strict official supervision and general lack of awareness about the risks associated with the alien species spreading. En Finlande, l'introduction massive d'écrevisses a commencé vers la fin des années 1980, avec un total estimé à 2,2 millions d'écrevisses signal stockées avant 2016. Au cours de cette période, les autorités finlandaises de la pêche ont mis en œuvre trois stratégies nationales de gestion fixant des lignes directrices pour l'introduction des écrevisses. Les principaux objectifs de ces stratégies ont été la conservation des stocks indigènes d'écrevisses nobles et la diffusion contrôlée des écrevisses exotiques dans une région désignée. Dans cette étude, nous présentons la répartition actuelle des écrevisses en Finlande par rapport aux lignes directrices établies dans ces trois stratégies nationales. L'aire de distribution actuelle de l'écrevisse signal couvre la majeure partie du sud de la Finlande. L'écrevisse signal a été introduite avec autorisation dans plus de 480 plans d'eau. De plus, il y a eu de nombreux cas sans permis, souvent à proximité de la région désignée pour les écrevisses signal. Sur la base des résultats, nous concluons que les stratégies de gestion des écrevisses adoptées en Finlande n'ont eu qu'un effet limité sur la propagation des écrevisses signal. Nous présumons que les principales causes de la propagation incontrôlée de l'écrevisse signal en Finlande sont le manque de surveillance officielle stricte et le manque général de sensibilisation aux risques associés à la propagation des espèces exotiques.

The oomycete-specific ITS primers published by Riit et al. (2016) have been put to use in the scientific community working with oomycetes. Recently, however, it has been brought to our attention that the sequences of the primers ITS1oo and ITS3oo shown in the first Figure of the published manuscript are incomplete, when compared to the sequences of the same primers as listed on the UNITE website. This discrepancy is derived from re-checking primer sequences from tube labels that are restricted to the first 18 bases.Closer examination revealed that the sequence of primer ITS1oo in Figure 1 is missing one nucleotide from the 3’ end and the primer ITS3oo is missing two nucleotides from the 3’ end. These errors are expected to reduce relative primer specificity to Oomycetes, which probably results in lower proportion of this group in metabarcoding studies. We hereby provide the updated figure (Figure 1) with correct information. We apologize to all users of these erroneous primers for their suboptimal performance. We are grateful to Dr. Diana Marčiulynienė and Dr. Sannakajsa Velmala for pointing out these problems.