Maatalous- metsätieteellinen tiedekunta


Recent Submissions

  • Keriö, Susanna (Helsingin yliopisto, 2015)
    During their life, conifers are attacked by fungal pathogens and insects. In the European forests, Heterobasidion annosum sensu stricto (s.s.) attacks Scots pine (Pinus sylvestris) roots, whereas Heterobasidion parviporum causes the majority of decay in Norway spruce (Picea abies), both causing severe economic losses. Another significant health problem of Scots pine is caused by Hylobius abietis, the large pine weevil, which damages newly established Scots pine stands. Several defence reactions in trees are activated upon fungal infection and insect attack, but these reactions have not been comprehensively studied in conifers. In this dissertation, the responses of mature Norway spruce and Scots pine trees to Heterobasidion spp. inoculation, and the responses of Scots pine saplings to Hylobius abietis feeding were studied. Also the ability of homokaryotic Heterobasidion spp. isolates to infect mature conifer hosts and elicit defensive responses was investigated. Terpene and transcript profiles of Scots pine to H. annosum s.s. and H. abietis challenge were studied, and a customised oligonucleotide microarray with 36.5K cDNA elements designed based on the P. taeda transcriptome was used to study the Scots pine transcriptome. The used homokaryotic Heterobasidion spp. isolates were able to colonize and evoke defence responses in the host trees with varying levels of susceptibility. Insect feeding and fungal inoculation induced terpene production in Scots pine. The results indicated that high accumulation of terpenes is not necessarily an effective defence against H. annosum, but δ-3-carene might be associated with higher tolerance to H. annosum in Scots pine. Only few genes related to terpene synthesis were induced in response to H. annosum infection and weevil feeding. Induction of genes related to biotic and abiotic stress responses indicated a wide transcriptomic reprogramming in response to fungal infection and weevil feeding. Genes related to signal perception and defence responses were induced especially in the trees less susceptible to H. annosum inoculation. In addition to these genes, Scots pine δ-3-carene synthases are promising candidates for further research on the Scots pine resistance to H. annosum.
  • Purkamo, Lotta (Helsingin yliopisto, 2015)
    Microbial life in the deep subsurface contributes significantly to overall biomass on Earth. Although the microbial communities inhabiting the deep subsurface are abundant, little is known about their diversity, activity, interactions and role in global biogeochemical cycles. The diversity of microbial life in the deep terrestrial subsurface of the Fennoscandian shield was studied with molecular biological methods. The Outokumpu Deep Drill Hole provides access to crystalline bedrock fluids that are estimated to be tens of millions of years old. Characterization of the indigenous bacterial and archaeal communities in addition to microbial communities with important functional properties in bedrock fluids was done from a depth range of 180 m to 2300 m. Microbial community profiling and assessment of possible functional processes was done with molecular fingerprinting, cloning and sequencing methods combined with suitable statistical and bioinformatics analyses. Low cell numbers but high diversity was characteristic to the microbial communities of the Outokumpu deep subsurface. The microbial communities in the fracture zones had in general fewer cells than those in the mixed fluids of the drill hole. Comamonadaceae, Peptococcaceae and Anaerobrancaceae were prevalent bacterial members of the microbial communities in the fracture fluids. Archaea were a minority in microbial communities. Sulfate-reducing bacteria and methanogens were detected at several depths. Microbial communities resembled those detected from other deep Fennoscandian Shield subsurface sites. Furthermore, sulfate reducing communities and archaeal communities resembled those found from the deep subsurface of South Africa. Investigation on carbon assimilation strategies of the microbial communities revealed that mainly heterotrophic Clostridia were responsible for CO2 fixation in this habitat. Representatives of Burkholderiales and Clostridia formed the core microbial community and these were also identified to be the keystone genera. The microbial communities of Outokumpu fractures share similarity with those of serpentinization-driven ecosystems. Energy and carbon substrates formed in serpentinization reactions of ophiolitic rocks in Outokumpu may sustain the microbial communities in this deep subsurface environment.
  • Aalto, Juho (Helsingin yliopisto, 2015)
    Boreal forests are the most significant source of volatile organic compounds (VOCs) in Northern Europe, emissions originating both from trees and forest floor. The VOCs are reactive trace gases that participate in chemical reactions in the atmosphere, thus affecting aerosol formation and climate. The overall aim was to characterize the temporal and spatial variability of VOC emissions and explain the processes and phenomena affecting those. Extensive field measurements were used, including both gas chromatograph and mass spectrometer as VOC analyzers. A dynamic enclosure method was utilized in measuring VOC fluxes from the forest floor and emissions from Scots pine shoots. The genetic background determines the blend of terpenoids emitted by Scots pine, thus having effect on the atmospheric composition. Forest floor and soil also has substantial effect on VOC fluxes on the ecosystem scale. In addition to the considerable spatial variation in VOC fluxes from the forest floor, there is variation of VOC emissions from Scots pine shoots; differences were associated with needle age, seasonality and growth processes. New foliage dominates the VOC emissions from Scots pine foliage during spring and early summer, when growth processes release significant amounts of VOCs, especially monoterpenes. Scots pine shoots are a strong source of monoterpenes during the early stages of photosynthetic recovery; these periods last from a couple of days to about one week and are likely related to the protection of evergreen foliage against photo-oxidative stress. The studies challenge the presumption of constant emission capacities, which is currently a common presumption in VOC emission inventories. Atmospheric concentrations of VOCs result from an output of the existing sources and their seasonal and spatial variation; this underlines the relevance and importance of details on large a scale. The findings provide new opportunities for developing VOC emissions models based on underlying physico-chemical processes.
  • Immonen, Aino-Maria (Helsingin yliopisto, 2015)
    This study investigates the manifestation of emotional influences in the context of two different instances of consumer food choice: price vs. ethicality trade-off decisions in everyday food purchase decision contexts, and the acceptance of genetically modified food products. This study has a particular emphasis on the intricacies that can be uncovered in the emotional influences, by putting focus on the unique compositions and motivational properties of different discrete emotions, and the anomalies and tensions that emerge when mixtures of emotions are experienced. The theoretical background of this study draws from emotion literature, previous research on consumer emotions, and consumer food choice. As a result of a literature review on these topics, this study proposes four key conceptual dimensions that need to be identified and defined in order to gain a better understanding of the role of discrete emotions in particular contexts of consumer food choice. The empirical investigation of this study was conducted with a quantitative approach. Two sets of consumer data (N = 855; 267) were acquired by means of survey questionnaires. The data were analysed with SPSS- and LISREL-softwares by using correlation analysis, analysis of variance, analysis of multiple mediation, moderation analysis, and structural equation modelling. The findings indicate that the salience of an explicit price vs. ethicality trade-off in food purchase decisions induces mixed consumer emotions. This emotionally ambivalent experience has an attenuating effect on the favourability of consumer responses to ethical food purchases with a premium price, but also to unethical food purchases that appeal to consumers with a low price. The findings also indicate that the specific combinations of discrete positive and negative emotions that arise in response to the two types of price vs. ethicality trade-offs are qualitatively distinct. This notion allows for identifying discrete emotional drivers that motivate and inhibit ethical and unethical food purchase decision-making among consumers, particularly when ethical product characteristics are being evaluated against the product price. The findings in the second empirical context of this study outline two distinguishable consumer response patterns to genetically modified (GM) food products, which are intertwined with consumers fearful and angry responses to the genetic modification of food (the GM of food). The findings indicate that the fear and anger that consumers experience towards the GM of food are rooted in different types of substantive concerns, and fearful and angry consumers have a preference for distinct modes of coping with the perceived threat of GM food products. The findings have implications for disentangling the nuances of the affectively toned consumer opposition that exists towards the GM of food and GM food products, and for interpreting their distinct impacts on the prospects of GM foods in the consumer market.
  • Korpunen, Heikki (Helsingin yliopisto, 2015)
    Finnish forest industry purchases 50 million cubic meters of wood annually. This means that the economic importance of the business is significant to forest owners. Sawmills, pulp and paper industry, and energy production are most common targets of the wood raw material. It is in mutual interest of both forest owners and the industry that the wood is allocated to right use according to the highest possible value-adding. The path of wood from forest to customers can be described as a value chain where the links are formed of harvesting and forwarding, long distance transportation, wood processing and energy use, and delivery to final customers. This dissertation focuses on the links of wood processing and energy use of the wood value chain by modelling production and costs of sawmill, pulp mill, paper mill, and combined heat and power (CHP) plant. The modelling was done by using activity-based costing (ABC), where the production is divided into processes and the production costs of each process are allocated to products or services according to resource consumption. Finally, all process costs are summed for total production costs of each cost object. The production and cost models were tested with virtual mills. The processes, the resources and the necessary cost factors of production were determined for test calculations. Finally, the capital, the labor, and the energy costs were allocated to the cost objects, which were both the raw materials and the end products. When comparing different mills and their production processes, it was noticed clearly that drying was an expensive process in sawmilling, pulping and papermaking. When focusing on cost factors of each mill, it was noteworthy that the sawing pattern affects the costs of a sawmill, energy production affects the costs of pulp and paper industry, and, likewise the utilization rate affects the combined heat and power plant. Profitability analyses were also made on the pulp mill, the paper mill and the CHP plant in varied market situations. One key finding was that in papermaking, the change of market price of paper was more significant to economics of the mill than a similar change in the market price of energy. The results of this dissertation can be used in estimating the economic performance of forest industry. Process-based approach helps in finding possible bottlenecks and in developing the production systematically. The findings of this study can also be used in finding the most profitable route for wood from the forest to customers.
  • Klimeski, Aleksandar (Helsingin yliopisto, 2015)
    Deterioration in the quality of surface waters worldwide is associated with losses of phosphorus (P) from diffuse sources. Controlling such losses is rather difficult, but their significance in reducing the effects of eutrophication is crucial. Phosphorus losses from diffuse sources represent a significant share of total P transfers to surface waters. Researchers have studied and implemented numerous methods to curb non-point P losses during the past decades, but such studies have generally been insufficient to change the impact of agriculture on the course of surface waters eutrophication. For example, even though inputs of P and nitrogen (N) into the Baltic Sea have significantly decreased over the past two decades, the Baltic Sea still represents a eutrofied body of water. To further reduce P losses from agriculture, current P abatement methods must be amended with additional techniques. One such technique involves the use of P-retaining materials as filters placed in ditches within agricultural areas. This study encompasses a set of laboratory, meso- and large-scale set-ups to identify potential P-retaining materials available in Finland for the treatment of agricultural runoff. The laboratory studies investigated the P retention potential of fresh and weathered Ca-rich (Sachtofer PR®, steel slag, Filtra P®, Filtralite P®) as well as Fe-rich materials (mine drainage residual - MDR) in flow-through tests when applying a high influent P concentration of 50 mg/l. The weathering process served to leach out soluble species such as Ca2+ and OH-, thus mimicking aged filters. In addition, desorption/dissolution tests involved the placement of P-saturated materials in solutions of variable pH as well as one-month extraction with large volumes of water. Sachtofer PR®, steel slag, Filtra P® and MDR retained relatively large amounts of P, varying between 12 and 24 mg P/g material. As desorption/dissolution tests show, two distinct mechanisms controlled the materials retention of P: precipitation of Ca-phosphates and sorption of P onto Fe-hydroxide surfaces. As the most promising material, Sachtofer PR® was further employed in meso- (20 kg) and large-scale (7 tons) filters that treated influents with significantly lower P concentrations, up to 6 mg/l and 0.25 mg/l, respectively. The feed solution in the meso-scale filter alternated between P-enriched tap and river waters, whereas the large filter treated agricultural runoff from 17 ha of cropland. As the application of Sachtofer was scaled up, and influent P concentration declined, cumulative P retention decreased from 19 mg P/g in the laboratory to 0.06 mg P/g in the field. The meso-scale experiment indicated that the P removal efficiency decreased also due to the presence of dissolved organic carbon (DOC) in the influents; the filter retained about 10% of the total amount of DOC added to the system. As for the large filter, the formation of preferential water pathways resulting from material decomposition and freezing-thawing cycles greatly reduced its efficiency. Moreover, in high flow conditions during spring snowmelts or high rainfalls, the large filter treated only a small portion of the incoming flow; the estimated treated flow during the entire test period was about 20%. Maintaining a low effluent limit is rather challenging, and such techniques should instead serve to remove a significant part (e.g., 30-40%) of the dissolved mass of P in agricultural runoff. To justify the potential P recovery from spent filters and to ensure cost-efficiency, the P-retaining material should reach a significant P saturation. In addition, P removal structures should be coupled with other best management practices to minimize losses of P from agriculture. Keywords: P-retaining materials, P retention, precipitation, sorption, upscaled application, dissolved organic carbon, material alteration, preferential flows, high flows, filters, permeable reactive barriers
  • Jokela, Venla (Helsingin yliopisto, 2015)
    Timothy (Phleum pratense L.) is one of the most important forage grass species grown at high latitudes. Its sward canopy structure determines the quantity and quality of the silage yield. Nonetheless, processes behind the transition to flowering, as well as the formation of stems and the connection with forage quality have not been studied in detail for timothy. Seven experiments were conducted to explore the effect of vernalization, photoperiod and gibberellin treatments on flowering and canopy structure in different cultivars or accessions. In addition, the expression of key regulator genes, VRN1 and VRN3, as well as the flowering repressors VRN2 and MADS10 were studied, and the connection between these and flowering induction and stem formation was revealed. Results showed that photoperiod is the most important regulator of flowering in timothy. In addition, vernalization response was reported in most of the tested accessions, which was seen as faster flowering. It was found that the application of GA3 could not replace the LD requirement for flowering. Moreover, results showed that the requirement for flowering and stem elongation vary. Flowering is also associated with decreased digestibility of grass stems. Our results showed, however, that flowering induction was not required for the development of the lignified sclerenchyma ring in developing stems, but rather lignin accumulation was as a result of stem elongation and requirements for mechanical support. At molecular level, novel vernalization-related partial cDNAs were identified through sequencing. Both PpVRN1 and PpVRN3 homologs induced the transition to reproductive development, but PpVRN3 was required for flowering. These results support the theory of universal flowering-promoting system between species. The expression of the putative repressor homolog, PpMADS10, was connected to the developmental stage of the apex. Results obtained in this thesis shed new light on the regulation of flowering and canopy structure in timothy. It is concluded that large variation exists among accessions in their responses to vernalization and photoperiod. This information can be utilized in breeding for high-yielding new cultivars for different growing conditions at high latitudes and for different harvesting strategies.
  • Epie, Kenedy Etone (Helsingin yliopisto, 2015)
    The increasing use of fossil fuel is plagued with problems leading to interest in alternative sources of energies. Bioenergy or biomass energy remains today s important renewable energy source that can contribute to reducing the overall consumption of fossil fuel and can move energy systems towards sustainability and supply security. However, doubts on sustainability impede the acceptance of bioenergy. Hence, the sustainable cropping of reed canary grass (Phalaris arundinacea L., RCG), an established perennial energy grass, was studied. Important sustainability criteria were considered, namely; land use, biomass productivity, emission of greenhouse gas nitrous oxide (N2O) and biodiversity. The general aim of the study was to develop farming methods that would provide biomass feedstock of RCG in a sustainable manner. Field and glasshouse experiments were carried out at the University of Helsinki, Finland, during 2008 to 2013. The suitability of problematic acid sulphate soils managed with raised water tables for cropping RCG was investigated in lysimeter experiments. Growth parameters were measured and biomass yield and energy qualities were determined. In field conditions with soils classified as Gleyic Stagnosol, RCG was supplied with N from inorganic fertilizer and N fixed into soil by intercropped legume galega (Galega orientalis Lam.) and its biomass yields and mineral element composition and other energy qualities were determined. Gases were collected from these fields using closed chambers and greenhouse gas N2O emissions were analysed by gas chromatography. The crop and crop mixture effects on earthworm communities were determined by the extraction of earthworms using mustard oil and manual separation from soil. Reed canary grass grew well in acid sulphate soils and even performed better by producing more biomass with better quality when the water table was raised to reduce acidity and to avoid environmental hazards. Carbon was also sequestered into the soil by RCG root biomass. In the field experiment, RCG galega mixtures produced equally good biomass yields and of better energy quality than the fertilized RCG counterpart. The annual cumulative emissions of N2O from mixtures were marginally lower than those from fertilized RCG soils. Although fertilized RCG produced twice as much biomass and correspondingly higher nitrogen and energy yields, its low emission of N2O per ton of dry matter or per unit of harvestable bioenergy was not significantly different from that of the mixtures. Mixtures also enhanced earthworm abundance and species numbers compared to pure RCG stands. Therefore cropping an RCG galega mixture for biofuel may supply a good quantity of biomass feedstock, result in lower N2O gas fluxes, and sustain earthworm biodiversity but requires management to maintain grass as the major component. Using managed acid sulphate soils for perennial energy cropping will help to reduce the tension between food and energy crop production over arable land and may improve the negative perception of bioenergy as a whole. A 25% Galega- 75% RCG mix has the potential to replace N fertilizer input during energy crop cultivation, meaning reduced cost of production and more income for energy crop farmers. Moreover soil macrofauna diversity will be conserved. With reduced N2O gas emission, this grass-legume mixture could make a significant contribution in mitigating climate change and its effects. All these will come a long way to help in making bioenergy more sustainable.
  • Ramos Diaz, Jose Martin (Helsingin yliopisto, 2015)
    Amaranth (Amaranthus caudatus), quinoa (Chenopodium quinoa) and kañiwa (Chenopodium pallidicaule) have been cultivated in the Andean region of South America since Pre-Hispanic times. They are regarded as formidable nutritious alternatives due their high content of protein (rich in lysine), dietary fibre and bioactive compounds such as tocopherols, phenolic compounds and folate. Despite this, the academic research conducted on their utilisation for human consumption is relatively low. Conversely, lupine (Lupinus angustifolius) is a well-known legume used for animal feed in most of the Nordic countries. The aim of this research was to incorporate amaranth, quinoa, kañiwa and lupine to corn-based snacks, and study their physical, chemical and sensory properties. A co-rotating twin screw extruder was used to obtain corn-based extrudates containing amaranth, quinoa, kañiwa and lupine. In preliminary studies (incorporation up to 20% of solids), Box-Behnken experimental design with three predictors was used: water content of mixture (WCM, 15-19%), screw speed (SS, 200-500 rpm) and temperature of the die (TEM, 150-170 °C). Subsequent studies were conducted using partial least squares regression (PLSR) and L-partial least squares regression (L-PLSR) with nine predictors: Grain type, grain content (20-50% of solids), temperature of die (140-160 °C), screw speed (200-500 rpm), water content of mixture (WCM, 14-18%) as well as contents of protein, ash, fibre and sum content of main fatty acids of blend. In general, WCM and screw speed had the greatest importance for response variables such as torque and pressure at the die during extrusion, sectional expansion index (SEI), stiffness and water content of extrudate; the content of protein and dietary fibre in the blend was particularly relevant during the extrusion of extrudates containing kañiwa and lupine. Regarding the most expanded extrudates, those containing 20, 35 and 50% amaranth, quinoa or kañiwa presented comparable SEIs and stiffness while those containing above 20% lupine suffered from structural collapse. Extrusion reduced the content of fatty acids and tocopherols in the solids but it had a slight effect on the content of total phenolic compounds and folate. In sensory studies, extrudates with higher contents of amaranth, quinoa and kañiwa were rated less crispy, less crunchy and less adhesive with less hard particles. Temporal analysis showed that with increasing contents of amaranth, quinoa and kañiwa, crispiness and crunchiness became the most dominant attributes during mastication while the dominance of roughness reduced considerably. Porosity and wall thickness, measured by X-ray microtomography, were linked to the perception of crispiness and crunchiness, respectively. In storage, whole extrudates containing 20% amaranth, quinoa or kañiwa and exposed to RH of 76% presented the lowest formation of hexanal compared to milled extrudates exposed to RH of 11%. This study showed that expanded corn-based extrudates containing up to 50% amaranth, quinoa and kañiwa and at most 20% lupine of solids can maintain key mechanical and textural properties as well as added nutritional value. This study applied successfully PLSR and L-PLSR modelling techniques to study the incorporation of amaranth, quinoa, kañiwa and lupine to corn-based snacks. This research has expanded the knowledge linked to the development of gluten-free extrudates with added nutritional value.
  • Haltia, Emmi (Helsingin yliopisto, 2015)
    Environmental quality has a direct effect on citizens welfare. To quantify this effect, the four articles of this thesis analyse Finnish citizens willingness to pay (WTP) for increased forest conservation using the contingent valuation (CV) and choice experiment (CE) methods. These methods are based on neo-classical welfare economics augmented with the choice process framework originating from psychology and behavioural economics. Using the CV method, we analyse how WTP is affected by respondents uncertainty, by the share of nonrespondents and by the considerably high share of yes responses at the highest proposed costs to households. The CE data are used to study the effects of different conservation programme characteristics on WTP. The results show that Finnish citizens support increased forest conservation. The median WTP in the contingent valuation was 72 EUR, i.e. 50% of respondents supported increased conservation if the costs per household did not exceed 72 EUR. The mean WTP estimates were sensitive to modelling assumptions and assumptions concerning the nonrespondent preferences. This emphasises the need for careful sensitivity analyses when results are used for welfare measurement and policy planning. Respondents choices in the valuation questions were affected by the household costs of conservation and other socioeconomic characteristics. The results suggest that the choices in valuation tasks are affected by economic and psychological factors. The study gives important insights into the choice behaviour and lower and upper bound estimates of WTP. These estimates are somewhat lower than those in comparable earlier Finnish studies. In CV, respondents seemed insensitive to programme size while the extent of the proposed project had a significant effect on the choices in CE.
  • Chen, Hongxin (Helsingin yliopisto, 2015)
    The basidiomycete white-rot fungus Heterobasidion annosum sensu stricto (s.s.) is one of the most severe conifer pathogens in the Northern Hemisphere. It can live as a saprotroph on dead wood tissues or a necrotroph on living trees. Taking advantage of a sequenced genome from a closely related species, Heterobasidion irregulare, we performed an in-depth transcriptomic analysis of this fungus under various abiotic stresses (temperature stress, osmotic stress, oxidative stress, and nutrient starvation) and during saprotrophic growth on pine bark, sapwood, and heartwood. The results unraveled potential regulatory mechanisms to overcome these conditions. Based on the specific induction in the microarray, cerato-platanins were selected for further study in the interactions between H. annosum s.s. and Pinus sylvestris. As the first step, a genome-wide bioinformatic study of the cerato-platanin family in Dikarya was therefore conducted. The results suggested that they exist in both Ascomycota and Basidiomycota, but were lost in early branches of jelly fungi as well as in some groups with yeast or yeast-like forms in their life cycles. The ancestor of the Dikarya possessed multiple copies of cerato-platanins, which sorted differently in Ascomycota and Basidiomycota, and this gene family might have expanded in Basidiomycota. To gain insight into the role of cerato-platanins as potential virulence factors in H. annosum s.s., we performed the functional study of HaCPL2 by using a recombinant protein produced in Pichia pastoris. Interestingly, HaCPL2 was able to induce cell death in both host (P. sylvestris) and non-host (Nicotiana tabacum) plants. Besides cell death symptoms, HaCPL2 retarded apical root growth of P. sylvestris seedlings and induced phytoalexin production in N. tabacum. Defense-related gene expression was also upregulated in both plants after HaCPL2 treatment. This study has provided valuable information about potential gene regulatory mechanisms in H. annosum s.s. that mediate stress adaptation and growth in different pine wood compartments. Moreover, we propose that HaCPL2, a cerato-platanin protein, could act as an effector and contribute to the virulence in the H. annosum s.s.–P. sylvestris pathosystem. This furthers our understanding of Heterobasidion pathogenesis and provides a future target for disease control.
  • Kymäläinen, Maija (Helsingin yliopisto, 2015)
    The need to replace fossil fuels with renewable energy sources has become an increasingly important field of research and development in order to combat the global climate change. Wood is a well utilised and much studied source of energy that has some inherent problematic characteristics common to all lignocellulosic biomass. Moisture affects the entire supply chain of wood fuels negatively by complicating transport, handling, storage, and combustion. During storage, the wood takes up moisture, which leads to fungal deterioration and consequently losses of heating value. The problem has been addressed by reducing the hygroscopicity of wood through the thermal pre-treatment process of torrefaction. In addition to hydrophobicity, torrefaction leads to other beneficial characteristics that are expected to improve the performance of lignocellulosic biomass in logistics and combustion. Due to hydrophobicity the material is said to be resistant to fungal degradation and subsequent dry matter losses. The combustion would be efficient without the need to evaporate water that can form up to 60% of untreated woody biomass. However, only few studies exist, and the material s performance in storage has been pointed out as an important research area. To tackle this challenge, this thesis aimed to provide much needed answers related to the storage properties of torrefied wood and charcoal, most importantly the effect of moisture. This thesis is made up of four studies, in which the sorption properties and fungal degradation of torrefied spruce and birch, as well as charcoal produced from the same feedstock, were investigated. In one experiment torrefied pellets and steam explosion pellets were compared with the undensified material. It was found that the pyrolysed material adsorbed only minor amounts of water vapour both in laboratory experiments as well as in an outside storage trial. The hydroxyl group accessibility and the particle size of the material were also reduced. However, although the capillary absorption was slower, the capacity for water uptake was increased. This led to high moisture contents during the storage trials. It was also shown that the material can serve as the sole carbon source and is therefore subjected to fungal degradation. The degradation was slow, but significant dry matter losses were recorded from certain samples in laboratory conditions. Furthermore, the fungal activity increased the material s moisture content. The torrefied material hosted abundant fungal flora following outside storage trials, and many of the identified genera were known allergens. Also it was shown that torrefied pellets do not tolerate contact with water. Many of the properties of torrefied wood are favourable in terms of easier handling and improved combustion behaviour. However, the results presented in this thesis show that the storage of the material may not be as easy as speculated. The torrefied wood, whether as chips or pellets, should be stored in covered areas and direct contact with water should be avoided. The working safety issues should be carefully addressed to avoid unnecessary exposure and accidents when handling the pre-treated material.
  • Zou, Ling (Helsingin yliopisto, 2015)
    Factors limiting barley yield have been reduced since the Green Revolution globally. Nevertheless, higher yields are pursued with the pressure to feed the increasing human population and domestic animals. However, sustainability can be impaired by the cereal monocultures, in particular, cereal-specific pathogen inocula can increase at the cost of diversity of soil microfauna. Use of pesticides has selected for resistance in weeds and pathogens. Use of mineral fertilizers has resulted in waste of resources and pollution. In Finland, about half of the arable land is used for continuous cereal production, and barley (Hordeum vulgare), as an important source for food and feed, is the most cultivated cereal crop. In this dissertation, research focused on evaluating the effects of various rotation crops on weeds, pathogenic fungi, soil fertility and yield of subsequent barley. The competitive ability of six crops, namely buckwheat (Fagopyrum esculentum), caraway (Carum carvi), faba bean (Vicia faba), hemp (Cannabis sativa), common vetch (Vicia sativa) and white lupin (Lupinus albus) with weeds was evaluated in glasshouse and field experiments. In the glasshouse experiment, couch grass (Elymus repens) grown with buckwheat accumulated the least dry matter. Activated charcoal was used to exclude the effect of root exudates from donor crops. The results indicated that activated charcoal incorporated in the soil deactivated buckwheat root exudates that apparently inhibited the growth of couch grass. In the field experiment, buckwheat s fast growth and formation of effective leaf area inhibited growth of weeds most effectively among the crops tested. The effect of turnip rape [Brassica rapa L. ssp. oleifera (DC.) Metzg.] on several soil pathogenic fungi was evaluated in a field trial in two growing seasons involving five different cultivation regimes: mixed culture of barley and turnip rape, turnip rape sown after barley, and turnip rape incorporated as green manure either in autumn or in spring, with continuous barley monoculture as a control. Soil fungal community structure was monitored with capillary-based LH PCR of the ITS region using primers ITS1F/ITS4. The mixed culture and sowing turnip rape after barley did not significantly decrease the relative abundance of Fusarium spp. Incorporation of turnip rape plants into the soil, as a source of organic matter and nutrients, was associated with a low relative abundance of Fusarium spp. Fungal diversity was the lowest and the relative abundance of Fusarium spp. the highest in continuous barley. Higher fertilizer application and organic matter incorporation, leading to high fungal diversity, seemed more important in affecting Fusarium spp. than the allelochemicals of turnip rape, as turnip rape extracts did not detectably inhibit the growth of F. culmorum in an in vitro test. In growth media of different nutrient levels, 10 g soil were suspended in 100 mL sterile water, then 400 μL of the suspended solution was spread on the media of each nutrient level with four replicates. The number of fungal colonies was counted. The soil Fusarium CFU count was higher on nutrient-poor growth medium than on rich medium, supporting the results of field experiments. Results of sequencing indicated that Penicillium spp. might also tolerate low nutrient availability. In two experiments that ran 2010-2012 and 2011-2013, faba bean, turnip rape and barley were sown as first crops and their residues were tilled into the soil after harvest in blocks in the first year. In the following year, barley, buckwheat, caraway, faba bean, hemp and white lupin were sown in each block and incorporated either at flowering stage (except barley) or after harvest. Barley yield and grain protein concentration were determined. Mineral N concentrations in the plough layer two months after incorporation of crops and before sowing barley in the following spring were determined. In the third year, all the plots were sown with barley. The beneficial effect of faba bean and turnip rape, as first crops, on yields and grain protein concentration of barley was still detectable in the third year. Barley yields after white lupin, faba bean and hemp, as second crops, were higher than in continuous barley. Barley grain protein concentration was increased after faba bean. In contrast, barley yield and grain protein concentration were not improved after buckwheat and caraway. Incorporation of plants at flowering stage posed a risk of increased N leaching, suggesting that incorporation of plants should be delayed or catch crops should be used during winter to reduce N leaching. The response of barley yields to increased mineralized N from green manure or residues after harvest of rotation crops was significant only in the first experiment conducted in 2010-2012 suggesting that increased mineral N in the plough layer has minor influence on barley yield. Thus, rotation with faba bean, white lupin and hemp was beneficial to barley grain yield. In addition, barley grain protein concentration was increased after rotation with faba bean. Weed growth was most strongly suppressed by buckwheat as a complement to current weed management regime, but, rotation with buckwheat and incorporation of its residues did not improve the yield of the successive barley. The effect of glucosinolates of turnip rape on soil-borne pathogens was outweighed by high fungal bio-diversity suggesting that allelochemicals released from plants sown at a realizable density in the field are unlikely to control pathogens. Maintaining high microbial diversity through sufficient nutrient input is crucial to control pathogenic Fusarium spp. populations.
  • Zhang, Yanlei (Helsingin yliopisto, 2015)
    Type 2 diabetes occurs as a consequence of aging, family history, physical inactivity, unhealthy diet and obesity and it is an increasing public health problem worldwide. The condition is associated with high rates of mortality from co-morbid cardiovascular diseases and poor health-related quality of life (HRQoL). A large proportion of individuals with type 2 diabetes are not diagnosed for up to a decade after onset unless a screening programme has been implemented. The estimated prevalence of undiagnosed diabetes in China accounts for about 60-70% of the diabetes population. Diabetes education that is targeted at the general population is the key to increase public knowledge and awareness and is a fundamental building block for addressing the diabetes epidemic. Screening for identifying undiagnosed diabetes could lead to earlier identification and intervention, and postpone or prevent the onset of diabetes and its complications. However, there is a paucity of study on the impact of education and screening programmes on HRQoL, lifestyle modification of the targeted population, and the cost-effectiveness of such programmes. The objectives of this study were to investigate 1) the cost and effectiveness of a population-based education programme to increase public knowledge and awareness of diabetes; 2) the cost-effectiveness of two different screening tools for undiagnosed diabetes; 3) impact of type 2 diabetes and its complications on individuals HRQoL; 4) impact of a screening programme on individuals overall HRQoL, depression dimension and lifestyle modification. This study was based on data analyses of two population-based diabetes surveys conducted in 2006 (Survey A) and 2009 (Survey C), and a dataset of diabetes high-risk population identified through the Qingdao Diabetes Prevention Program (QD-DPP) between 2007 and 2010 in Qingdao, China (Survey B). The same stratified, random cluster sampling method was used in Surveys A and C to recruit a representative sample of the general population who had lived in Qingdao city for at least five years. A total of 5355 individuals in Survey A and 5110 in Survey C aged 35-74 years participated in the surveys. A total of 3108 rural participants who did not have diabetes at baseline in 2009 were invited for a re-examination and 1782 individuals attended the follow-up survey. A standard 2h 75g oral glucose tolerance test was administrated to all participants in both surveys. Diabetes education and health promotion information and activities under the framework of QD-DPP were given via printed and audio-visual media, the internet, free distribution of information booklets and diabetes risk score (DRS) flyers that targeted the entire population of 1.94 million who lived in the intervention areas. An adult with a DRS more or as much as 14 was considered at high-risk for diabetes and invited to a nearby community clinic for a free capillary blood glucose test. The proportions of participants who correctly marked obesity, physical inactivity and positive family history of diabetes as the risk factors of diabetes were doubled in both urban and rural populations, irrespective of age and gender during the QD-DPP education campaign period. The cheapest way to inform 1000 individuals about type 2 diabetes was to distribute DRS flyers (¥54, ¥ = Chinese yuan), followed by the newspapers articles (¥77), booklets (¥313) and by radio programmes (¥375) (1 ≈7¥, for the year 2015). The fasting capillary glucose (FCG) test and Chinese DRS questionnaire were used as the first-line screening tools and these were evaluated for detecting undiagnosed diabetes in primary care settings. The sensitivity of FCG and DRS was 65.1% and 65.8%, whereas their respective specificity was 72.4% and 55.2%. The costs per undiagnosed diabetes identified at the optimal cut-off values of 6.1 mmol/l for FCG and 14 for DRS were ¥674 and ¥844, respectively. The area under curve (AUC) was higher for FCG than for DRS (75.3% vs. 63.7%, p less than 0.001). People with previously known type 2 diabetes reported that the symptomatic comorbidities had a strong negative impact on HRQoL; no significant difference was detected between people without diabetes and with newly diagnosed diabetes. The screening and labelling as pre-diabetes or normoglycaemia had no adverse impact on the participants overall HRQoL and depression. An improvement in lifestyle as measured by the frequency of physical activity and vegetable intake was observed at 3 years post screening in both groups. In conclusion, the QD-DPP education campaign efficiently increased public knowledge and awareness of diabetes. The DRS questionnaire is a simple, non-invasive and reliable first-line screening tool to identify undiagnosed diabetes at primary care settings. The diabetes screening programme in Qingdao generated positive changes towards a healthy lifestyle and did not result in any harm to the participants.
  • Détry, Nicolas (Helsingin yliopisto, 2015)
    Oxidoreductases are found in all living organisms and play essential roles in housekeeping, perception of environmental stress, plant-pathogen interactions, defense reactions, and pathogenicity. In particular, laccase, peroxidases and NADPH oxidase, have been implicated in virulence of phytopathogenic fungi in pathogenicity. Despite its relevance towards plant microbe interaction, the identification and comparative analysis of fungal peroxidase-encoding genes at the genomic level have been limited by the lack of a bioinformatics platform as well as paucity of information on transcript profiling of potential candidate oxidoreductase genes. In this project, one of the primary tasks addressed was the construction and development of a new fungal peroxidase database (fPoxDB). The availability of fPoxDB platform facilitated comparative and evolutionary studies of fungal peroxidases at the genomic level. The database contains 6,113 peroxidase genes of 25 gene families from 331 genomes. The archived genes were subjected to pre-computational analyses using eight different bioinformatic tools: SignalP 3.0, SecretomeP 1.0f, TargetP 1.1b, predictNLS, ChloroP 1.1, TMHMM 2.0c, PSortII, and InterPro Scan. Similarity search tools including HMMER, ClustalW, Blast, and BlastMatrix are provided on the platform. A web interface enables researchers to browse the database via either species or class . Graphics support the work and enhance user-friendliness. Retrieved data can be exported to other family web-systems including the comparative fungal genomics platform (CFGP). In parallel to the above study, the second project was focused on in silico comparative analysis fungal NADPH oxidase (Nox) genes sequences. Nox proteins are transmembrane enzymes found in most eukaryotic organisms and influence many biological processes by generating reactive oxygen species (ROS). In fungi, Nox enzymes play roles in pathogenicity, such as the weakening of plant cell walls by ROS. The enzymes exhibit high sequence similarities to the ferric-reductases (Fre) and ferric-chelate reductases (FRO) proteins, which are involved in reduction of Fe3+ to Fe2+ for iron uptake. A total of 34 eukaryotic genomes, covering 28 fungal, one Oomycota, three animal and two plant species, were subjected to bioinformatic analysis. The results indicate that the properties of fungal Nox genes differ from those of the human and plants, providing novel insights that will enable more accurate identification and characterization of the fungal genes. In the third project, as not much is known is about precise role of oxidoreductase encoding genes in pathogenesis, we explored expression profiling of a typical oxidoreductase gene, laccase, in Heterobasidion conifer pathosystem. Laccases are multi-copper oxidoreductases catalyzing the oxidation of phenolic substrates, and they play diverse roles in plants and fungi. In fungi, laccase have been shown to be involved in pathogenicity, as well as in lignin degradation. To understand the potential roles of laccases of the forest pathogen Heterobasidion annosum, a total of 18 laccase genes was identified in this fungus and phylogenetically analyzed. The expression levels of the genes, and laccase activities, during growth of H. annosum on its host in the presence or absence of additional carbon source, such as glucose and sucrose, were investigated. Based on increased transcript expression levels eight laccases were considered to be potentially involved in H. annosum virulence. In summary, we provide the research community with a database dedicated to fungal peroxidases, and our in silico analysis affords new insights in the structure of fungal NADPH oxidases. Lastly, we present experimental evidence that some H. annosum laccases might be involved in virulence during infection of non-suberized Scots pine seedlings.