Highly Diverse Phytophthora infestans Populations Infecting Potato Crops in Pskov Region, North-West Russia

There is limited understanding of the genetic variability in Phytophthora infestans in the major potato cultivation region of north-western Russia, where potato is grown primarily by small households with limited chemical treatment of late blight. In this study, the mating type, sensitivity to metalaxyl, and genotype and population genetic diversity (based on 12 simple sequence repeat (SSR) markers) of 238 isolates of P. infestans from the Pskov region during the years 2010–2013 were characterized. The aim was to examine the population structure, phenotypic and genotypic diversity, and the prevalent reproductive mode of P. infestans, as well as the influence of the location, time, and agricultural management practices on the pathogen population. The frequency of the A2 mating was stable over the four seasons and ranged from 33 to 48% of the sampled population. Both mating types occurred simultaneously in 90% of studied fields, suggesting the presence of sexual reproduction and oospore production in P. infestans in the Pskov region. Metalaxyl-sensitive isolates prevailed in all four years (72%), however, significantly fewer sensitive isolates were found in samples from large-scale conventional fields. A total of 50 alleles were detected in the 141 P. infestans isolates analyzed for genetic diversity. Amongst the 83 SSR multilocus genotypes (MLGs) detected, 65% were unique and the number of MLGs varied between locations from 3 to 20. These results, together with the high genotypic diversity observed in all the locations and the lack of significance of linkage disequilibrium, suggest that sexual recombination is likely responsible for the unique MLGs and the high genetic diversity found in the Pskov region population, resembling those of north-eastern European populations

Modelling the response of urban lichens to broad-scale changes in air pollution and climate

To create more resilient cities, it is important that we understand the effects of the global change drivers in cities. Biodiversity-based ecological indicators (EIs) can be used for this, as biodiversity is the basis of ecosystem structure, composition, and function. In previous studies, lichens have been used as EIs to monitor the effects of global change drivers in an urban context, but only in single-city studies. Thus, we currently do not understand how lichens are affected by drivers that work on a broader scale. Therefore, our aim was to quantify the variance in lichen biodiversity-based metrics (taxonomic and trait-based) that can be explained by environmental drivers working on a broad spatial scale, in an urban context where local drivers are superimposed. To this end, we performed an unprecedented effort to sample epiphytic lichens in 219 green spaces across a continental gradient from Portugal to Estonia. Twenty-six broad-scale drivers were retrieved, including air pollution and bio-climatic variables, and their dimensionality reduced by means of a principal component analysis (PCA). Thirty-eight lichen metrics were then modelled against the scores of the first two axes of each PCA, and their variance partitioned into pollution and climate components. For the first time, we determined that 15% of the metric variance was explained by broad-scale drivers, with broad-scale air pollution showing more importance than climate across the majority of metrics. Taxonomic metrics were better explained by air pollution, as expected, while climate did not surpass air pollution in any of the trait-based metric groups. Consequently, 85% of the metric variance was shown to occur at the local scale. This suggests that further work is necessary to decipher the effects of climate change. Furthermore, although drivers working within cities are prevailing, both spatial scales must be considered simultaneously if we are to use lichens as EIs in cities at continental to global scales.info:eu-repo/semantics/publishedVersio

Patterns of intraspecfic variability in Phacelia secunda

Liikide võime varieeruda on väga oluline faktor nende püsimajäämisel erinevates keskkonnatingimustes. Tänu asetleidvatele kliimamuutustele on oluline teada, millisel määral suudavad liigid varieeruda, ehk kui plastilised nad on kiiresti muutuvate elutingimuste juures, ja kas ning kui suurel määral mõjutab see liikide levikut tulevikus. Magistritöö eesmärgiks oli Lauri Laanisto poolt läbi viidud välitööde andmete ja WorldClimi kliimamudeli põhjal panna kokku süstematiseeritud ja ühtlustatud andmebaas, mis hõlmaks tšiili keerispea (Phacelia secunda) funktsionaalsete tunnuste väärtusi ja nende väärtuste liigisisest varieeruvust. Samuti oli eesmärgiks uurida populatsioonipõhiste biootiliste ja abiootiliste kliimaparameetrite põhjal liigisisest varieeruvust ja selle mustreid (määra, struktuuri ja ulatust) tšiili keerispea leviala ulatuses ning vaadelda liigisisese varieeruvuse üldiseid tendentse. Tšiili keerispea on laia ökoloogilise amplituudiga endeemne Tšiili taim, mis kasvab paljudes erinevates bioomides ja on võimeline taluma ekstreemseid kliimaolusid, mistõttu on teda hea kasutada liigisisese varieeruvuse uurimise mudelobjektina. Koostatud andmebaasi põhjal uuriti tunnuste absoluutväärtuste ning nende varieeruvuse seoseid erinevatel gradientidel. Tulemused näitasid, et biootilised gradiendid mõjutasid eelkõige tšiili keerispea generatiivseid tunnuseid (õisikud ja neid kandvad varred) ja abiootilised gradiendid vegetatiivseid tunnuseid (rosetina kasvavaid lehti). Enim mõjutas tunnuseid ja nende varieeruvust aastane sademetehulga varieerumine ja ka keskmise õhutemperatuuri aastaringne kõikumine. Sealjuures mõjutas õhutemperatuuri varieerumine pigem tunnuseid negatiivselt (taimed olid väiksemad ja liigisisene varieeruvus samuti väiksem) ja sademete varieerumine pigem positiivselt (taimed olid suuremad ja liigisisese varieeruvuse määr ka suurem). Tunnusete absoluutväärtused ning nende varieeruvused näitasid muutlikust eelkõige indiviidi tasandil ning vähem populatsiooni tasandil. Antud töö on heaks aluseks tulevastele, liigisisest varieeruvust detailsemalt uurivatele teadustöödele.Intraspecific variation is essential for species to survive in different environmental conditions. Due to changing climate it´s important to know how will species adapt in rapidly changing conditions and how will it affect their distribution patterns. The first aim of this master thesis was to put together database which would include all data from the field work done by Lauri Laanisto, plus pertinent climate data from WorldClim. This data allowed to investigate – which was the second aim of this master thesis – intraspecific variability and its patterns across the whole distribution range of Phacelia secunda. It´s an endemic species to Chile, which grows in very different biomes and is able to cope with extreme environmental conditions (high altitude, long periods of drought and cold etc.), being therefore suitable object for intraspecific variability study. The relationships and trends of trait values and their variability against abiotic and biotic gradients were studied. Results indicate that biotic factors predominately affected the generative parts and abiotic factors the vegetative parts of Phacelia secunda. Precipitation seasonality and temperature seasonality showed similarly strong effects on traits and their variability, but while precipitation seasonality had mainly positive effects (plants were bigger and trait variability higher), temperature seasonality had predominately negative effects (plants were smaller and variability trait lower). Both biotic and abiotic factors affected traits and their variability mainly on individual plant level and less on population level. Present work is good fundamental base for future, more comprehensive work investigating intraspecific variability

Contrasting latitudinal patterns in phylogenetic diversity between woody and herbaceous communities

AbstractAlthough many studies have shown that species richness decreases from low to high latitudes (the Latitudinal Diversity Gradient), little is known about the relationship between latitude and phylogenetic diversity. Here we examine global latitudinal patterns of phylogenetic diversity using a dataset of 459 woody and 589 herbaceous plant communities. We analysed the relationships between community phylogenetic diversity, latitude, biogeographic realm and vegetation type. Using the most recent global megaphylogeny for seed plants and the standardised effect sizes of the phylogenetic diversity metrics ‘mean pairwise distance’ (SESmpd) and ‘mean nearest taxon distance’ (SESmntd), we found that species were more closely-related at low latitudes in woody communities. In herbaceous communities, species were more closely-related at high latitudes than at intermediate latitudes, and the strength of this effect depended on biogeographic realm and vegetation type. Possible causes of this difference are contrasting patterns of speciation and dispersal. Most woody lineages evolved in the tropics, with many gymnosperms but few angiosperms adapting to high latitudes. In contrast, the recent evolution of herbaceous lineages such as grasses in young habitat types may drive coexistence of closely-related species at high latitudes. Our results show that high species richness commonly observed at low latitudes is not associated with high phylogenetic diversity.</jats:p

Publisher Correction: Contrasting latitudinal patterns in phylogenetic diversity between woody and herbaceous communities

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.</jats:p

The variability of Phytophthora infestans isolates collected from Estonian islands in the Baltic Sea

Knowledge of a pathogen's genetic variability and population structure is of benefit to effective disease management. In this study, 193 isolates of Phytophthora infestans collected from three Estonian islands, were characterized over three years using SSRs marker data complemented by information on their mating type and resistance to metalaxyl. In combination with SSR marker data from samples in the neighbouring Pskov region of north west Russia, the impact of regional and landscape structure on the level of genetic exchange was also examined. Among the Estonian islands 111 P. infestans isolates, forty-nine alleles were detected among twelve SSR loci, and 59 SSR multilocus genotypes (MLGs) were found, of which 64% were unique. The genetic variation was higher among years than that among islands, as revealed by AMOVA. The frequency of metalaxyl-resistant isolates increased from 9% in 2012 to 30% in 2014, and metalaxyl resistant was most frequent among A1 isolates. The test for isolation by distance among the studied regions was not significant, and coupled with the absence of genetic differentiation revealed gene flow, and the absence of local adaptation. The data are consistent with a sexual population in which diversity is driven by an annual germination of soil-borne oospores. The absence of shared genotypes over the years has important implications when it comes to the management of disease. Such population diversity can make it difficult to predict the nature of the outbreak in the coming year as the genetic makeup are different for each year.</p