Search

We studied interactions between microfungi and herbivores sharing a host tree. In a series of experiments and field observations over a 3-year period, we compared phenotypic and genetic correlations of fungal frequencies and performance of invertebrate herbivores growing on mature half-sib progenies of mountain birches (Betula pubescens ssp. czerepanovii) in two environments, a forested river valley and an adjacent higher-elevation mountain birch woodland. We found little support for direct relation between fungal frequencies and performance of herbivore species. Instead, genetic correlations, particularly between autumnal moth (Epirrita autumnata) and rust fungus (Melampsoridium betulinum), suggest that herbivore performance may be caused by (1) genetic differences in plant quality for fungi and herbivores, or (2) genetic differences in responses to environmental conditions.

We develop a structured metapopulation model for vertically transmitted symbionts in natural host populations. We focus primarily on two questions: Are mutualism and high transmission probability prerequisites for the survival of symbionts in structured host metapopulations? What are the ecological conditions under which coexistence of infected and uninfected hosts is possible? We start with studying in depth the case of qualitatively identical patches and derive conditions for invasion and coexistence of uninfected and infected hosts. Our model predicts that, in a qualitatively uniform environment, coexistence is possible only if the symbionts increase the fitness of their host, so the mutualism is indeed needed for coexistence. We also prove that evolution selects for 100% infection frequency in the metapopulation. Then we generalize the model for different patch qualities and get conditions for invasion in a virgin environment.

We investigated whether genetic variation of a common foliar endophyte of birch trees, Venturia ditricha, is affected by environmental conditions or host genotype. Fungal samples were collected from 10 half-sibling families of mountain birch (Betula pubescens ssp. czerepanovii) grown in two environmental conditions with different daily average temperatures: a forested river valley and an adjacent open tundra (altitudinal difference 180 m). Genetic analysis of V. ditricha isolates was done using random amplified microsatellite polymerase chain reaction. We found that host genotypes, along with prevailing environmental conditions, influence the probability of infection by particular endophyte genotypes. The most susceptible host genotypes were highly infected with genetically similar endophyte genotypes, whereas the most resistant trees were poorly infected and they were infected by genetically dissimilar endophytes. Our results also showed environment-host genotype interactions, suggesting that the susceptibility of the host to a particular endophyte genotype may change in natural environments when environmental conditions are changed. It appears that a particular endophyte genotype needs to find the right host genotype for a successful infection. There are many host genotypes in natural stands; this means, from the point of view of the fungus, the environment is heterogeneous. Thus, under the influence of birch tree genotypes, genetically differentiated subgroups of the endophytic fungus may be formed in different environments.

Theory predicts that (i) vertical transmission of parasites (i.e. when they are passed directly from a host to its offspring) selects for benign association with the host and that (ii) vertically transmitted parasites that lower their hosts' fitness cannot persist if they are not able to infect horizontally (i.e. contagiously) other host individuals in the population. In this paper, we develop a mathematical model to examine whether mutualism is a prerequisite for persistence of exclusively vertically transmitted (from maternal plant to offspring via seeds) fungal endophytes in structured grass metapopulations. Interestingly, endophyte survival does not require plant mutualism, even in a metapopulation consisting of qualitatively identical patches, if vertical transmission of the fungus is perfect, i.e. if all established seedlings in offspring of the endophyte-infected plant are infected. In more realistic situations, when the metapopulation consists of qualitatively different patches, endophyte-infected plants may persist at the metapopulation level even if the vertical transmission is imperfect (due to hyphae inviability or failure to grow into all seeds) and the endophyte decreases the host grass fitness in certain environments. These results have biological importance because they (i) question the requirement of a mutualistic nature in exclusively vertically transmitted symbionts and (ii) emphasize the importance of habitat diversity in relation to symbiont success in vertical transmission.

• Premise of the study: Microsatellite primers were developed for the endophytic fungus Epichloë festucae, which is symbiotic with Festuca rubra, to study the population genetics of the species and to compare population structures between E. festucae and its host F. rubra. • Methods and Results: We developed 14 polymorphic markers using the unplaced genomic scaffold sequences of E. festucae from GenBank. The number of alleles per locus (A) varied from four to 16, and unbiased haploid diversity (h) was 0.717 in eight populations located in the Faroe Islands, Finland, and Spain. The Spanish populations possessed a higher number of alleles and haploid diversity (on average A = 5.1 and h = 0.591, respectively) compared to northern populations (on average A = 1.5 and h = 0.199, respectively). • Conclusions: These polymorphic markers will be used by grass breeders for uses including the improvement of commercial turfgrass cultivars, and by population geneticists to study different species of the Epichloë genus.

Grasses have been considered to primarily employ tolerance in lieu of defense in mitigating damage caused by herbivory. Yet a number of mechanisms have been identified in grasses, which may deter feeding by grazers. These include enhanced silicon uptake, hosting of toxin-producing endophytic fungi and induction of secondary metabolites. While these mechanisms have been individually studied, their synergistic responses to grazing, as well as their effects on grazers, are poorly known. A field experiment was carried out in 5 × 5 m outdoor enclosures to quantify phytochemical changes of either endophyte-infected (E+) or endophyte-free (E-) meadow fescue (Schedonorus pratensis) in response to medium intensity (corresponding with densities of ca. 1200 voles / ha for 5 weeks during 3 months) or heavy intensity (ca. 1200 voles / ha for 8 weeks during 3 months) grazing by a mammalian herbivore, the field vole (Microtus agrestis). A laboratory experiment was then conducted to evaluate the effects of endophyte infection status and grazing history of the grass diet on vole performance. As predicted, grazing increased foliar silicon content, by up to 13 %. Grazing also increased foliar levels of phosphorous and several phenolic compounds, most notably those of the flavonols isorhamnetin-diglycoside and rhamnetin derivative. Silicon concentrations were consistently circa 16 % higher in E+ grasses than in E-grasses, at all levels of grazing. Similarly, concentrations of chlorogenic acid derivative were found to be consistently higher in E+ than in E- grasses. Female voles maintained on heavily grazed grasses suffered higher mortality rates in the laboratory than female voles fed ungrazed grass, regardless of endophyte infection status. Our results conclusively demonstrate that, in addition to tolerance, grasses employ multi-tiered, effective defenses against mammalian grazers.

Correlative evidence suggests that pathogenic leaf rust fungus, Melampsoridium betulinum, in late summer may negatively affect folivorous insects in the following summer. Correlative association does not necessarily, however, reveal causality. Alternatively, other interconnected plant characters may determine rust densities and herbivore performance. In this study, we used birch clones and rust fungus inoculations to manipulatively test the effects of birch rust and birch genotypes on the growth performance of folivorous moth larvae of Epirrita autumnata (Lep. Geometridae) in the subsequent year. The inoculation treatment increased rust densities (three- to 60-fold) compared with natural infection levels. E. autumnata performance varied among birch clones and showed 4% lower growth performance on rust-inoculated trees. However, the larval performance did not differ between rust-treated shoots and untreated control shoots and the use of tree-specific rust densities as a covariant in statistical analyses failed to reveal any negative association between rust fungus and larval performance. As the slight difference in larval growth performance also levelled until pupation, we propose that rust infection has biologically insignificant importance to the performance of E. autumnata. Etude experimentale de la resistance de Betula pendula a un defoliateur sous dependance de la rouille Des correlations suggerent que l’attaque de rouille aMelampsoridium betulinum qui intervient en fin d’ete peut affecter negativement les insectes foliaires au cours de l’ete suivant. Ceci ne revele cependant pas necessairement un phenomene de causalite, et d’autres caracteres lies chez la plante peuvent determiner la densite de rouille et la performance des phyllophages. Dans cette etude nous avons teste les effets de la rouille (inoculations) et du genotype de l’hote (clones) sur la performance de croissance des larves du lepidoptere phyllophage Epirrita autumnata (geometride) l’annee suivante. L’inoculation a augmente la densite de rouille (3 a 60 fois) par rapport a l’infection naturelle. La performance de croissance de E. autumnata variait selon les clones de bouleau; elle etait 4% plus faible chez les arbres inocules. Cependant, la performance larvaire ne differait pas entre les rameaux inocules et les rameaux temoins; l’utilisation de la densite de rouille specifique des arbres comme covariable n’a pas permis de montrer d’association negative entre la rouille et la performance larvaire. Comme les legeres differences de performance de croissance larvaire s’estompaient avant la pupaison, nous pensons que l’infection de rouille n’a qu’une influence insignifiante sur la performance de E. autumnata. Experimentelle Prufung des Einflusses einer Rostinfektion auf die Entwicklung von Epirrita autumnata an Betula pendula Es gibt Hinweise, dass ein Rostbefall (Melampsoridium betulinum) an Birkenblattern im Spatsommer blattfressende Insekten im folgenden Sommer negativ beeinflussen kann. Diese Korrelation bedeutet jedoch nicht notwendigerweise, dass es einen kausalen Zusammenhang gibt, denn es konnten auch andere Eigenschaften der Pflanze sowohl die Intensitat des Rostbefalls als auch die Herbivorenentwicklung bestimmen. In der vorliegenden Untersuchung wurde an mit M. betulinum inokulierten Birkenklonen (Betula pendula) gepruft, wie sich Rostbefall und Birkengenotypen auf das Wachstum der an den Blattern fressenden Larven von Epirrita autumnata (Lepidoptera, Geometridae) im folgenden Jahr auswirken. Durch die Inokulationen wurde der Rostbefall im Vergleich zur naturlichen Infektion um das drei-bis sechzigfache erhoht. Das Wachstum von E. autumnata variierte in Abhangigkeit von den Birkenklonen und war auf den rostinokulierten Baumen um 4% reduziert. Die Larvenentwicklung auf den behandelten und unbehandelten Trieben zeigte jedoch keinen signifikanten Unterschied. Auch mit der Einfuhrung des baumspezifischen Rostbefalles als zusatzliche Variable in die statistische Analyse konnte kein negativer Zusammenhang zwischen Rostbefall und Larvenentwicklung nachgewiesen werden. Da sich der geringe Unterschied in der Larvenentwicklung zudem bis zur Verpuppung ausglich, wird angenommen, dass die Rostinfektion keine biologisch signifikante Auswirkung auf E. autumnata hat.

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris. Festuca arundinacea. F. ovina. F. Pratensis. F. rubra and Phleum pratense (67%, 98%, 29%., 42%. 32% and 33%, respectively). Mean incidences were < 20% in Dactylis glomerata. Deschampsia flexuosa. D. cespitosa and Elymus repens. and no infections were detected in Calamagrostis lapponica. C. epigejos. Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected eonspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. Pratensis and Lolium perenne. and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free.

Neotyphodium endophytes in introduced agronomic grasses are well known to increase resistance to herbivores, but little is known of interactions between Neotyphodium endophytes and herbivores in native grass populations. We investigated whether endophytes mediate plant-herbivore interactions in a native grass species, Festuca arizonica in the southwestern United States, in two ways. First, to test the prediction that the presence and frequency of endophyte-infected (E+) plants should increase with increasing herbivory, we determined endophyte frequencies over a 4-year period in six natural Arizona fescue populations. We compared Neotyphodium frequency among plants growing inside and outside long-term vertebrate grazing exclosures. Second, we experimentally tested the effects of Neotyphodium infection, plant clone, and soil nutrients on plant resistance to the native grasshopper Xanthippus corallipes. Contrary to predictions based upon the hypothesis that endophytes increase herbivore resistance, levels of infection did not increase in plants subjected to grazing outside of exclosures relative to ungrazed plants within exclosures. Instead, endophyte frequencies tended to be greater inside the exclosures, where long-term vertebrate grazing was reduced. The grasshopper bioassay experiment corroborated these long-term patterns. Survival of grasshoppers did not differ between infected (E+) and uninfected (E-) plants. Instead, mean relative growth rate of grasshoppers was higher on E+ grasses than on E- ones. Growth performance of newly hatched grasshopper nymphs varied among host plant clones, although two of six clones accounted for most of this variation. Our results suggest that Neotyphodium-grass-herbivore interactions may be much more variable in natural communities than predicted by studies of agronomically important Neotyphodium-grass associations, and herbivory is not always the driving selective force in endophyte-grass ecology and evolution. Thus, alternative hypotheses are necessary to explain the wide distribution and variable frequencies of endophytes in natural plant populations.

Herbivory is generally assumed to negatively influence mycorrhizal fungi because of reduced photosynthate to support mycorrhizae following defoliation. We examined effects of 60% and 100% defoliation (excluding current year needles) on tree growth and ectomycorrhizal associations of 10–15 year old Scots pines (Pinus sylvestris). Over 98% of short roots were colonized by mycorrhizal fungi, and contrary to expectation, defoliation did not decrease the proportion of living fungi in fine roots. Furthermore, defoliation did not alter the ratios of produced needle biomass to the biomass of fine roots or living fungi in fine roots. The composition of mycorrhizal morphotypes was changed, however, which suggests competition among different mycorrhizal growth forms owing to their carbon demands. We propose that these outcomes are a consequence of a functional balance between carbon sources in plant foliage and below-ground sinks, i.e. growing roots and mycorrhizal associates.

▪ Abstract Endophytic fungi living asymptomatically within plant tissues have been found in virtually all plant species. Endophytes are considered plant mutualists: They receive nutrition and protection from the host plant while the host plant may benefit from enhanced competitive abilities and increased resistance to herbivores, pathogens, and various abiotic stresses. Limited evidence also indicates that endophytes may influence population dynamics, plant community diversity, and ecosystem function. However, most of the empirical evidence for this mutualism and its ecological consequences has been based on a few agronomic grass endophytes. More recent studies suggest that endophyte-host plant interactions are variable and range from antagonistic to mutualistic. A more comprehensive view of the ecology and evolution of endophytes and host plants is needed. This article discusses how life history traits—such as fungal reproduction and pattern of infections and genotypic variation and ecological factors—influence the direction and strength of the endophyte-host plant interaction.

We studied resource allocation between sexual reproduction and clonal prop- agation in a perennial stoloniferous clonal plant, Potentilla anserina, an obligate outcrosser. We manipulated reproductive effort of Potentilla anserine either by hand-pollinating all flowers or by preventing pollination. To test the effect of resource-limiting conditions on resource allocation and reproductive output, we used a control and two levels of heavy metals (copper and nickel) to limit plant growth. The experiment was conducted as a 2 X 3 factorial design to reveal possible interactions between reproductive manipulation and resource limitation. Heavy metals decreased the total biomass of the plants and number of flowers and ramets produced. Only 50% of the plants grown with the higher level of heavy metals produced flowers. Pollination treatment interacted significantly with the heavy-metal treatment. In the metal control (no metals added) and lower heavy-metal treatment, there were no significant differences in total vegetative biomass between the two pollination treatments. Costs of reproduction in terms of subsequent flowering in the later season appeared to be clear, because the number of flowers per whole plant was lower if the plants were hand-pollinated and because the proportion of flowering ramets decreased due to hand- pollination. However, flowering may also be partly hormonally controlled. In contrast, hand- pollinated plants exposed to high concentrations of heavy metals tended to have greater biomass of vegetative plant structures and higher number of flowers compared to nonpol- linated plants. Together, these results suggest that environmental factors may alter costs of reproduction but do not support the idea that these costs are more acute in resource (pho- tosynthate)-limiting conditions.

We determined the occurrence of birth rust fungus (Melampsoridium betulinum) within mature mountain birch (Betula pubescens var. czerepanovii) trees and compared the airborne urediniospore concentrations with overall rust infection levels over five successive years. Fifteen groups of three trees 3–5 m high were chosen from a homogenous mountain birch stand. Each group contained a tree with ‘low’, ‘moderate’ and ‘high’ infection covering the natural range of infection levels. The difference in rust classes remained constant throughout the study; trees in class ‘high’ consistently had always highest infection levels and trees in class ‘low’ always the lowest infection levels. Infection levels remained constant between years in ‘low’ class, while the infection levels varied significantly between years in ‘moderate’ and ‘high’ classes. The incidence of disease caused by M. betulinum varied from year to year and was correlated with the total airborne urediniospore counts. The data indicate that trees differ in resistance to birch rust and that infection levels of susceptible compared to resistant trees are more dependent on environmental conditions.

Insecticide resistance in Trialeurodes vaporariorum W. is unknown in the species' northern distribution range where it inhabits mainly commercial greenhouses. Resistance development in whiteflies feeding on year-round crops in greenhouses is possible owing to the use of chemical treatments to back up biocontrol. The authors tested the response levels to spiromesifen, pymetrozine and imidacloprid in whiteflies collected from seven greenhouses within a 35 km radius in western Finland.All except one (PR) population had LC50 values below the recommended concentrations for the tested compounds. However, some populations showed reduced susceptibility to pymetrozine in comparison with the reference susceptible population. Resistance ratios to pymetrozine were highly variable (resistance ratio 0.5-39.7), even among closely located greenhouses, and higher than those for imidacloprid (resistance ratio 1.05-10.5) and spiromesifen (resistance ratio 0.8-11.5). LC50 values and application frequencies of pymetrozine correlated positively among the sampled populations.High variation in resistance levels to pymetrozine among populations within natural whitefly dispersal limits reflects variation in the usage of this compound among individual greenhouse crop producers. Thus, resistance management is recommended at the individual greenhouse crop producer level, even in a dense production cluster. © 2014 Society of Chemical Industry.

Defensive mutualism is widely accepted as providing the best framework for understanding how seed-transmitted, alkaloid producing fungal endophytes of grasses are maintained in many host populations. Here, we first briefly review current knowledge of bioactive alkaloids produced by systemic grass-endophytes. New findings suggest that chemotypic diversity of the endophyte-grass symbiotum is far more complex, involving multifaceted signaling and chemical cross-talk between endophyte and host cells (e.g., reactive oxygen species and antioxidants) or between plants, herbivores, and their natural enemies (e.g., volatile organic compounds, and salicylic acid and jasmonic acid pathways). Accumulating evidence also suggests that the tight relationship between the systemic endophyte and the host grass can lead to the loss of grass traits when the lost functions, such as plant defense to herbivores, are compensated for by an interactive endophytic fungal partner. Furthermore, chemotypic diversity of a symbiotum appears to depend on the endophyte and the host plant life histories, as well as on fungal and plant genotypes, abiotic and biotic environmental conditions, and their interactions. Thus, joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed to fully understand the endophyte-grass symbiosis, its coevolutionary history, and ecological importance. We propose that endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology. Fil: Saikkonen, Kari. MTT Agrifood Research Finland. Plant Production Research; Finlandia Fil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. MTT Agrifood Research Finland. Plant Production Research; Finlandia Fil: Helander, Marjo. University of Turku. Department of Biology. Section of Ecology; Finlandia

Studying the controls on biomass allocation trade-offs in plants are important since they affect harvestable product yields and are critical to understanding symbiotic interactions. Epichloae fungal endophytes associate with cool-season grasses, growing systemically within the plant inter-cellular spaces and are transmitted through seeds. We explore the endophytes influence on the relationship between the plant reproductive and vegetative aboveground biomass (reproductive effort: RE) and on the trade-off between two components of the reproductive biomass, number and weight of panicles (RPN), using tall fescue as a model system. Naturally endophyte-colonized, manipulatively endophyte-free, and naturally endophyte-free plants from Northern European wild-populations together with the cultivar Kentucky-31 were grown under different environmental conditions (nutrients x water). The endophyte had an effect on the RPN (E+: 6.19, ME-: 4.68 and E-: 4.40) which indicates how reproductive biomass is partitioned into number and mass of panicles, but not on RE (≈0.06). As expected, wild plants showed higher reproductive effort (≈0.06) compared to the cultivar KY-31 (0.05), irrespective of endophyte presence. Endophyte-colonized plants had lighter panicles than endophyte-free plants, a pattern that was clear among low-yielding plants. Similarly, the trade-off between RPN and RE was higher for endophyte-colonized plants. This was again evident among plants with low RE indicating that colonized plants split the yield into either greater number of panicles and/or lighter panicles. The effect of vertically transmitted endophytes has earlier been studied as ratios (e.g. RE); however, our study shows that this approach may hide size-dependent endophyte effects on these relationships. Our study reveals that Neotyphodium endophyte affects trade-offs in tall fescue plants in a complex manner, and is influenced by a number of biological and abiotic factors. Fil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas A la Agricultura; Argentina. MTT Agrifood Research Finland. Department of Plant Production; Finlandia Fil: Garibaldi, Lucas Alejandro. Universidad Nacional de Rio Negro. Sede Andina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Helander, Marjo. University of Turku. Department of Biology. Section of Ecology; Finlandia Fil: Saikkonen, Kari. MTT Agrifood Research Finland. Department of Plant Production; Finlandia

1. The effect of body size on different components of male fitness was studied for Epirrita autumnata, a geometrid known for its eruptive population dynamics. Body size is the main determinant of female fecundity in this species. 2. Longevity of males was found to have a weak negative correlation with body size at low temperatures. No significant correlation was found at higher temperatures. 3. We found no correlation between male size and female fecundity or egg size which is consistent with the small size of spermatophores in this species. 4. Small and large males were equally successful when allowed to compete for females in laboratory conditions. 5. In one or two field collections, males found mating were larger than males found singly. Large males also had an advantage in finding of virgin females, offered experimentally. No size-assortative mating was recorded. 6. We conclude that size-dependent mate location ability is the factor accounting for most of the variance in male fitness in E.autumnata. The dependence of fitness on body size may well be equally strong in males and females.

Vertically transmitted fungal endophytes can be beneficial for host grasses. While the alkaloid-mediated mechanism for herbivore resistance has been widely studied, underlying physiological mechanisms for increased tolerance to abiotic stress remain scarcely explored. In this study we used three maternal lines of perennial grass Festuca rubra to examine the role of antioxidants in endophyte-mediated effects on seed viability over long-term storage. Uncolonized plants (E-) were generated by removing the endophyte from ramets of naturally endophyte-colonized (E+) plants. The E + and E- ramets were planted in a common garden in Salamanca, Spain. Seeds produced in 2009, 2010 and 2011 were harvested at maturity, dried and stored at 10 C until 2011 when we tested seed and endophyte viability, and measured antioxidants. Seed viability and α-tocopherol antioxidant were negatively affected by the endophyte in two maternal lines. In these same lines, the endophyte viability was lowest at the longest storage time. In the maternal line that showed the highest negative effect of endophyte on seed viability, the pattern of glutathione was opposite to that observed for tocopherols since it was higher for E + than for E- seeds. In all maternal lines, the glutathione half-cell reduction potential (E GSSG/2GSH) and % glutathione disulphide (GSSG) increased with storage time but there was no clear pattern associated with endophyte symbiosis. Whether these parameters are good predictors of seed and endophyte longevity in storage and natural conditions should be further explored. © 2012 Springer Science+Business Media Dordrecht. Fil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Plant Production Research; Finlandia Fil: Hamilton, Cyd E.. Plant Production Research; Finlandia Fil: Seal, Charlotte E.. Royal Botanic Gardens; Reino Unido Fil: Helander, Marjo. University of Turku; Finlandia Fil: Ghersa, Claudio Marco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; Argentina Fil: Ghersa, Claudio Marco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; Argentina Fil: Vázquez De Aldana, Beatriz R.. Consejo Superior de Investigaciones Científicas; España Fil: Zabalgogeazcoa, Iñigo. Consejo Superior de Investigaciones Científicas; España Fil: Saikkonen, Kari. Plant Production Research; Finlandia

We propose that symbiotically modified organisms (SMOs) should be taken into account in sustainable agriculture. In this opinion article, we present the results of a meta-analysis of the literature, with a particular focus on the potential of SMOs in forage and turf grass production, to determine the impact of endophytes in grasses on livestock, the grassland ecosystems, and associated environments. SMOs can be incorporated into breeding programs to improve grass yield, resistance to pests and weeds, and forage quality for livestock by decreasing the level of toxic alkaloids. However, the benefits of these selected grass-endophyte symbiota appear to be highly dependent on grass cultivar, fungal strain, and environmental conditions, requiring a comprehensive understanding of the genetic bases and phenotypic plasticity of the traits of the plant-microbe unit in different environments. Fil: Gundel, Pedro Emilio. MTT Agrifood Research Finland; Finlandia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Perez, Luis Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Helander, Marjo. University of Turku; Finlandia Fil: Saikkonen, Kari. MTT Agrifood Research Finland; Finlandia

Reactive oxygen species are in all types of organisms from microbes to higher plants and animals. They are by-products of normal metabolism, such as photosynthesis and respiration, and are responsive to abiotic and biotic stress. Accumulating evidence suggests reactive oxygen species play a vital role in programmed cell death, stress responses, plant defense against pathogens and systemic stress signaling in conjunction with antioxidant production. Here, we propose that reactive oxygen species and antioxidants, as both universal and evolutionarily conserved, are likely to play important role(s) in symbiotic interactions. To support this hypothesis we review the root and foliar fungal endophyte literature specific to fungal-plant symbiotum production of reactive oxygen species and antioxidants in response to stress. These asymptomatic fungi can produce antioxidants in response to both biotic and abiotic stress when grown in culture as well as in planta. In addition, there is a growing but nascent literature reporting a significant impact of endophyte colonization on the antioxidant activity of colonized (E+) hosts when compared to uncolonized (E-) hosts, especially when exposed to stress. Here we summarize general patterns emerging from the growing literature specific to antioxidant activity of endophytes in colonized hosts and bring up possible future research questions and approaches. The consequences of changes in reactive oxygen species production and increased antioxidant activity in the symbiotum appear to be beneficial in many instances; but costs are also indicated. Unexplored questions are: 1) to what extent do antioxidants originating from the fungal endophyte mediate host metabolism, and thereby control host responses to endophyte colonization; (2) what role do fungal, plant, or symbiotum produced reactive oxygen species and antioxidants have in determining symbiotic outcome between extremes of pathogenicity and mutualism; and (3) what role if any, do the production of reactive oxygen species and their antioxidant counterparts play in the symbiotum’s ability to respond to changing selection pressures? If as the literature suggests, such endophyte imposed mediation can be utilized to foster increases in plant production in resource limited habitats then the utilization of fungal endophytes may prove useful in agronomic and conservation settings. Fil: Hamilton, Cyd E.. MTT Agrifood Research Finland; Finlandia Fil: Gundel, Pedro Emilio. MTT Agrifood Research Finland; Finlandia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Helander, M.. University of Turku; Finlandia Fil: Saikkonen, K.. MTT Agrifood Research Finland; Finlandia

Glyphosate is the main nonselective, systemic herbicide used against a wide range of weeds. Its worldwide use has expanded because of extensive use of certain agricultural practices such as no-till cropping, and widespread application of glyphosate-resistant genetically modified crops. Glyphosate has a reputation of being nontoxic to animals and rapidly inactivated in soils. However, recent evidence has cast doubts on its safety. Glyphosate may be retained and transported in soils, and there may be cascading effects on nontarget organisms. These processes may be especially detrimental in northern ecosystems because they are characterized by long biologically inactive winters and short growing seasons. In this opinion article, we discuss the potential ecological, environmental and agricultural risks of intensive glyphosate use in boreal regions.

In addition to natural environmental variation, plants and their associated microorganisms may encounter a series of anthropogenic environmental changes. Direct effects of pollutants on organisms are feasible to study, but impacts of air pollution on more complicated ecosystem functions are often difficult to interpret. Effects of pollutants on various parts of the ecosystem were intensively studied in 1980s and 1990s, and several studies revealed that plant-associated fungi, especially epiphytic fungi on the phyllosphere, were sensitive to air pollutants. Furthermore, endophytic fungi living asymptomatically in the leaf tissues were observed to respond negatively to sulphuric acid and heavy metal deposition. Some fungal endophyte species and strains in tree foliage have been observed to adapt to the toxic environment during long continuous pollution.

Systemic- and seed-transmitted fungal endophytes are suggested to enhance competitive dominance of agronomic grasses by increasing plant growth and defence against herbivores. We studied whether Neotyphodium uncinatum endophyte infection frequencies of meadow fescue (Schedonorus pratensis) and botanical composition of pastures are affected by 4, 5, 7 and 21 years of grazing by dairy cattle. We then examined with one greenhouse and two field experiments, whether endophyte infection and clipping affect regrowth of young or mature plants relative to nutrient availability in soil. The frequencies of infected plants and the number of plant species were less in grazed parts of the pastures. Endophytes significantly reduced relative regrowth and dry biomass of regrowth of the grass irrespective of nutrient levels in a 1-year-old field (on an average 18% in 2 months) and under high nutrient conditions in the greenhouse experiment (on an average 3% in 3 months) respectively. However, effects of endophytes were not detected in 5-year-old fields and under low nutrient conditions in the greenhouse. In contrast to past studies, our results demonstrate that grazing may negatively affect endophyte–grass symbiosis and number of plant species of successional pastures, and suggest that the effects of endophytes may be linked to the ontogeny of the host.

Plant-associated micro-organisms such as mycotoxin-producing endophytes commonly have direct negative effects on herbivores. These effects may be carried over to natural enemies of the herbivores, but this has been rarely explored. We examined how feeding on Neotyphodium endophyte infected (E+) and endophyte free (E−) meadow ryegrass (Scherodonus pratensis) affects body mass, population size and mobility of sibling voles (Microtus levis), and whether the diet mediates the vulnerability of voles to least weasel (Mustela nivalis nivalis) predation. Because least weasels are known to be olfactory hunters, we also examined whether they are able to distinguish olfactory cues of voles fed on E+ and E− diets. Neither body mass of voles nor population size differed between diets. However, contrary to our prediction, least weasels preyed more often on voles fed with E− grass than on voles fed with E+ grass. The mobility of voles fed on E+ grass was reduced compared to voles fed on E− grass, but this effect was unrelated to risk of predation. Least weasels appeared unable to distinguish between excrement odours of voles between the two treatments. Our results suggest that consumption of endophytic grass is not directly deleterious to sibling voles. What's more, consumption of endophytes appears to be advantageous to voles by reducing risk of mammalian predation. Our study is thus the first to demonstrate an effect of plant-associated microbial symbionts on herbivore-predator interactions in vertebrate communities.

It is assumed that climate change will promote pest invasions and their establishment in new regions. We have updated the list of current alien invertebrate pest species in Finland and produced a list of potential new alien pests using a self-organizing map (SOM) that ranks species in terms of their risk of entry into Finland. The 76 pest species recorded included 66 insects, 5 nematodes, 2 mites and 3 slugs. Nearly half of the alien species appeared to have invaded Finland during the last 48 years. The SOM analysis is considered a viable tool for identification of potentially high-risk invasive pests from among the multitude of potential alien invaders, and represents a useful complement to local expert knowledge-based risk assessment of potentially invasive pests. Along with the comparisons with databases of current and potential pest species, SOM analysis suggests that in the changing climate, the habitats at greatest risk from exotic pests in Finland are horticultural: orchards, ornamental hardy-nursery stocks, landscape and ornamental tree nurseries, and greenhouses., Ilmastonmuutokset arvioidaan edistävät kasvintuhoojien leviämistä ja kotoutumista uusille maantieteellisille alueille. Tässä julkaisussa on päivitetty lista Suomessa vuoteen 2010 mennessä tavatuista vierasperäisistä selkärangattomista kasvintuhoojista sekä tuotettu ennusteet Suomesta vielä puuttuvien vierasperäisten tuhohyönteislajien kotoutumisriskin suuruudelle käyttäen neuroverkkomallinnukseen perustuvaa self-organizing map (SOM) -menetelmää ja materiaalina maailmanlaajuista tuhohyönteistietokantaa. Suomessa jo tavattuja vieras- ja tulokaskasvintuhoojalajeja on 77, joista 67 on hyönteisiä, viisi ankeroisia, kaksi punkkeja ja kolme kotiloita. Lähes puolet listan lajeista on saapunut Suomeen viimeisten 48 vuoden aikana. Ennustetut riski-indeksit vierasta alkuperää oleville kasvintuhoojahyönteisille olivat korkeita Suomeen jo saapuneille lajeille. Tämä viittaa siihen, että SOM-menetelmä on käyttökelpoinen väline rajaamaan sitä lajistoa, jonka Suomeen saapumista ja kotoutumista on syytä erityisesti seurata. Menetelmä soveltuu hyvin täydentämään asiantuntijatietoon pohjautuvia riskinarviointeja vieras- ja tulokaslajien kotoutumismahdollisuuksista Suomeen. SOM-analyysin ennusteet viittaavat siihen, että ilmaston vähitellen muuttuessa uusien kasvintuhoojien kotoutumisriski on suurin puutarhatuotannossa (hedelmätarhat, taimitarhat, puistopuut, kasvihuoneet).

The study dealt with the effect of simulated acid rain (both H(2)SO(4) and HNO(3); acidities of pH 4 and pH 3) on the susceptibility of the larvae of Neodiprion sertifer to its nuclear polyhedrosis virus. Scots pines growing in a subarctic area with low ambient pollution levels were irrigated with simulated acid rain during two summers. Neodiprion larvae fed with foliage from the experimental trees were infected with a dilute virus suspension. The acid treatment of host trees had a significant effect on the proportion of virus-treated larvae alive 16 days after the virus application: there were almost no differences between the controls and the pH 4 irrigation group, but on the needles of pH 3-treated trees larval survival was twice as high as with other treatments. The direct spraying of acid water on the needles before they were fed to the larvae did not significantly affect the survival of virus infected larvae. Our results suggest that acid rain may reduce the susceptibility of Neodiprion larvae to virus disease via changes in the quality of pine foliage.

The effect of simulated acid rain on the performance of Neodiprion sertifer larvae fed on treated Scots pine needles was tested in a subarctic area with low ambient pollution level. Acid rain treatments (pH 4 and pH 3, both with H2SO4 and HNO3) did not significantly affect the relative growth rates or cocoon weights of N. sertifer 2 or 3 years after the start of the treatments. The relative growth rate of N. sertifer larvae was slightly (nonsignifi‐cantly) higher on plots receiving only ambient rain than on irrigated control plots. The quality of foliage before the start of the treatments explained a significant proportion of the variation in the performance of N. sertifer larvae in the bioassay conducted 3 years later.

Summary • The effect of environmental fragmentation on the species distribution and frequency of horizontally transmitted endophytic fungi in Betula pubescens and Betula pendula leaves was studied in an archipelago in southwestern Finland. • The study system consisted of 14 islands, ranging in size and distance to the mainland, and five mainland sites. Endophytic fungi were grown out from surface-sterilized leaves. • The frequency of endophytic fungi mainly depended on the size of the island, explaining 32–35% of the variation, and the distance to the mainland explaining 29–35% of the variation. The birch trees on the largest islands near the mainland had the highest endophyte frequencies. Fusicladium betulae, Gnomonia setacea and Melanconium betulinum were the most commonly isolated fungi. • Foliar endophytes of birch trees are able to disperse to fairly fragmented areas, but their frequencies seem to depend on environmental isolation and size of the island.

Model systems can facilitate and focus research efforts but ill-chosen or inapt ones can distract or impede scientific progress. In this Opinion article, we pose the question: how can the literature provide appropriate general conclusions if the model systems upon which the literature is based are unrepresentative of the relevant biological diversity? A good example of this problem is the endophyte–grass symbiosis, which is considered to be a classic example of mutualistic interactions. Meta-analysis of the primary literature demonstrates that the conceptual framework for endophyte–grass interactions has largely been based on endophyte–plant–herbivore studies of two agricultural grass species, tall fescue and perennial ryegrass. Consistent with conventional wisdom, the meta-analysis indicates that endophytes slightly increase grass resistance to herbivores. By contrast, endophytes appear not to affect plant performance or competitive ability. The positive effects of endophytes appear to be dependent on genetic variation in the host and endophyte, and on nutrient availability in soils. Thus, the agronomic grass model systems fail to capture the breadth of variability inherent in wild grass–endophyte populations and communities.

Premise of the study: Chloroplast microsatellite markers were developed for Festuca rubra to examine its population genetic characteristics, taxonomy, and coevolution with its endophyte Epichloe festucae. Methods and Results: Thirteen polymorphic markers were identified from the chloroplast genome of a F. ovina accession and intergenic chloroplast sequences of F. rubra accessions. They amplified a total of 65 alleles in a sample of 93 individuals of F. rubra originating from six different populations located in the Faroe Islands, Finland, Greenland, Norway, and Spain. Conclusions: The developed microsatellite primer pairs can be used by researchers in population genetic and taxonomic studies, and by plant breeders in breeding programs on grasses.

Endophytic fungi are generally viewed as plant mutualists which potentially play important roles in plant-plant, plant-pathogen and plant-herbivore interactions (Carroll, 1986; 1988; Clay, 1987, 1988a, b, 1991, 1992; Miller, 1986; Strong, 1988). Endophytes have been shown to increase plant resistance to both vertebrate and invertebrate herbivores, perhaps through induced resistance, nutrient depletion or toxin production (Carroll, 1986; Clay, 1987, 1990, 1991; Clay et al., 1993; Miller, 1986; Powell & Petroski, 1992; White & Cole, 1985). Besides directly enhancing resistance to herbivores, plant associated endophytes can affect plant fitness under herbivory pressure in many other ways. For instance, intra-and interspecific competitive abilities of plants, and thus, plant abundance and community structure in the presence of herbivores may depend on endophyte infection (Clay et al., 1993).

All fungi invading plant foliage have an asymptomatic period in their life cycle that varies from an imperceptibly short period (e.g. pathogens) to a lifetime (e.g. Neotyphodium endophytes in grasses). Endophytic fungus–grass associations are generally treated separately from parasitic, pathogenic and saprophytic interactions and are viewed as mutualistic associations. However, endophyte–host interactions are based on mutual exploitation. Benefits to the partners are rarely symmetric and conflicting selection forces are likely to destabilize them. Unanswered questions are how (i) genetic diversity of the fungus and phenotypic plasticity in fungal life history traits, (ii) genetic combinations between the fungus and the host, and (iii) the fungus and host individually or in concert as a phenotypic unit, respond to changing selection pressures.

Clay and Holah ([1][1]) used a cultivar of tall fescue, Kentucky 31 (KY-31), to demonstrate that fungal endophyte symbiosis, by enhancing the competitive dominance of tall fescue, reduced species diversity in successional fields. They then extended these results to conservation biology, predicting

The discovery of the anti-herbivore properties of Neotyphodium endophytes, most of the available literature suggests that these endophytic fungi are plant defensive mutualists, and ecologists have readily extrapolated it to all endophyte-plant interactions (Breen 1994, Clay 1990). The current understanding of the mutualistic nature of endophytes is, however, dominated by studies of a few cultivars of two introduced and selectively bred agricultural grass species, tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne) using non-native vertebrate grazers or herbivorous insects. Many other grass species harboring the Neotyphodium endophytes are shown either not to produce mycotoxins or composition of produced mycotoxins varies (Siegel et al., 1990). Thus we propose that plant-endophyte interactions might be much more complex in native grasses under natural conditions than in the agricultural arena of selectively-bred, non-native pasture grasses described in past studies.

We studied the effect of simulated acid rain treatment of host trees on the susceptibility of the European pine sawfly larvae to virus, and possible differences when larvae of two different ages were infected. Older larvae were less susceptible to virus. Most larvae treated with virus 2 days after they started feeding on experimental foliage (group A) died rapidly within 10 days after the virus treatment, and survival to the end of the larval period was only 8–25%. Larvae treated with virus 1 week later (group B) were less affected by the virus and 36–49% survived. In group A the larval survival in the pH 3 treatment was higher than in other treatments; at the end of the larval period the difference was twofold. In group B there were no clear effects of acid rain on the susceptibility of larvae to virus. The study yielded the following new information: (1) the effect of prolonged acid rain treatment on reducing the efficacy of virus on young larvae was more distinct than in a previous study with shorter exposure to acid rain, and the difference was maintained to the end of larval period; (2) the susceptibility of older larvae to virus was not affected by acid rain treatments; (3) pH inside the needles did not explain the larval mortality caused by virus.

Little attention has been paid to the effects of pollutants via natural enemies of herbivores, and the effects on interactions among tritrophic levels (host plants - herbivores - natural enemies) have been almost totally neglected. However, the experiment by Neuvonen et al. (1990) suggested that simulated acid rain (SAR) with pH 3 applied to host trees (Scots pine, Pinus sylvestris L.) might reduce the susceptibility of young (first and second instar) European pine sawfly (Neodiprion sertifer (Fourcroy)) larvae to a nuclear polyhedrosis virus (NsNPV). On the other hand, there were no significant effects of SAR with pH 4 on the efficacy of NsNPV, and the effect of SAR was only on the timing of mortality of the larvae reared on pH 3 treated trees: all the larvae died toward the end of the larval period. These results were obtained after the host trees had been treated with SAR for only two growing seasons, which may be insufficient for the expression of many processes.

In the systemic grass endophyte associations only one fungal genotype is transmitted vertically to seed progeny, promoting stable interactions between the fungal genotype and the host lineage.

Endophytes are known to increase the resistance of their host plant to voles directly through reduced palatability

Many grass species are symbiotic with systemic, vertically-transmitted, asymptomatic Epichloe endophytic fungi. These fungi often produce alkaloids that defend the host against herbivores. We studied how environmental variables affect alkaloids in endophyte-infected tall fescue (Schedonorus phoenix) from three Northern European wild origins and the widely planted US cultivar ‘Kentucky-31’ (KY31). The plants were grown in identical common garden experiments in Finland and Kentucky for two growing seasons. Plants were left as controls (C) or given water (W), nutrient (N) or water and nutrient (WN) treatments. For 8–10 replications of each plant origin and treatment combination in both experiments, we analyzed ergot alkaloids, lysergic acid, and lolines. In Finland, tall fescue plants produced 50 % more ergot alkaloids compared to plants of the same origin and treatments in Kentucky. Origin of the plants affected the ergot alkaloid concentration at both study sites: the wild origin plants produced 2–4 times more ergot alkaloids than KY31, but the ergot alkaloid concentration of KY31 plants was the same at both locations. Overall lysergic acid content was 60 % higher in plants grown in Kentucky than in those grown in Finland. Nutrient treatments (N, WN) significantly increased ergot alkaloid concentrations in plants from Finland but not in plants from Kentucky. These results suggest that the success of KY31 in US is not due to selection for high ergot alkaloid production but rather other traits associated with the endophyte. In addition, the environmental effects causing variation in alkaloid production of grass-endophyte combinations should be taken into account when using endophyte-infected grasses agriculturally.

Ilmastonmuutos saattaa parantaa Suomen maatalouden tuotantokykyä lähitulevaisuudessa pidentyvän kasvukauden ja suuremman lämpösumman kautta. Ilmastonmuutoksen myötä säätilan vaihtelut, ääri-ilmiöt ja suurempi tauti- ja tuholaispaine saattavat kuitenkin aiheuttaa ennalta arvaamattomia haittoja maataloudelle. Myönteisistä muutoksista voidaan parhaiten hyötyä ja haasteista selviytyä varautumalla muutoksiin joustavasti. Viljelymenetelmiä ja -järjestelmiä on kehitettävä jatkuvasti, on rakennettava hälytysjärjestelmiä mm. tuholaisten massaesiintymisten tai tautiepidemioiden varalle ja huolehdittava siitä, että kasvinjalostus tuottaa jatkuvasti uusia lajikkeita uusiin oloihin. Kasvintuotannossa etenkin talvella lisääntyvä kosteus lisää vesitalouden hallintatarvetta. Kohonneet lämpötilat voivat johtaa kasvien liian nopeaan kehitysrytmiin, joka saattaa johtaa alentuneisiin satoihin. Kotieläintaloudessa vaarana ovat yleistyvät eläintaudit ja rehuissa esiintyvät homesienimyrkyt eli mykotoksiinit. Elintarviketaloudessa lämpimämpi ja kosteampi ilmasto saattaa lisätä ruoan varastointiongelmia ja uhata ruoan hygieenisyyttä ja laatua. Etenkin vieraslajien ja uusien haittamikrobien yleistymistä ja leviämistä Suomeen on seurattava ja arvioitava, miten niiden aiheuttamat haitat tulevaisuuden ilmastossa voivat muuttua ja miten muutoksiin voidaan varautua. Maatalouden ympäristönsuojelussa on varauduttava lisätoimiin, kun kasvitautien ja -tuholaisten torjunta ja lisääntyvät sateet uhkaavat lisätä torjunta-aineiden ja ravinteiden huuhtoutumista vesistöihin. Varautumisessa on tärkeää paitsi tietyn uhkan tunteminen, myös joustavuus sopeutumisessa sekä tunnettuihin että tuntemattomiin tekijöihin. Joustavuutta voidaan parantaa monipuolisella tuotannolla, jossa yksittäisen maatilan käytössä on esim. useita viljelykasvilajikkeita ja viljelykasveja yksipuolisen peltoviljelyn sijaan