Rhizoctonia solani as a potato pathogen : Variation of isolates in Finland and host response

Rhizoctonia solani is a soil inhabiting basidiomycetous fungus able to induce a wide range of symptoms in many plant species. This genetically complex species is divided to 13 anastomosis groups (AG), of which AG-3 is specialized to infect potato. However, also a few other AGs are able to infect or live in close contact with potato. On potato, R. solani infection causes two main types of diseases including stem canker observed as a dark brown lesions on developing stems and stolons, and black scurf that develops on new tubers close to the time of harvest. These disease symptoms are collectively called a ‘Rhizoctonia disease complex’. Between the growing seasons R. solani survives in soil and plant debri as sclerotia or as the sclerotia called black scurf on potato tubers which when used as seed offer the main route for dispersal of the fungus to new areas. The reasons for the dominance of AG-3 on potato seem to be attributable to its highly specialization to potato and its ability to infect and form sclerotia efficiently at low temperatures. In this study, a large nationwide survey of R. solani isolates was made in potato crops in Finland. Almost all characterized isolates belonged to AG-3. Additionally, three other AGs (AG-2-1, AG-4 and AG-5) were found associated with symptoms on potato plants but they were weaker pathogens on potato than AG-3 as less prone to form black scurf. According to phylogenetic analysis of the internal transcribed sequences (ITS) of the ribosomal RNA genes the Finnish AG-3 isolates are closely related to each other even though a wide variation of physiological features was observed between them. Detailed analysis of the ITS regions revealed single nucleotide polymorphism in 14 nucleotide positions of ITS-1 and ITS-2. Additionally, compensatory base changes on ITS-2 were detected which suggests that potato-infecting R. solani AG-3 could be considered as a separate species instead of an AG of R. solani. For the first time, molecular defence responses were studied and detected during the early phases of interaction between R. solani AG-3 and potato. Extensive systemic signalling for defence exploiting several known defence pathways was activated as soon as R. solani came into close contact with the base of a sprout. The defence response was strong enough to protect vulnerable sprout tips from new attacks by the pathogen. These results at least partly explain why potato emergence is eventually successful even under heavy infection pressure by R. solani.

Nitrogen dynamics and nitrogen use efficiency of spring cereals under Finnish growing conditions

Nitrogen (N) is one of the main inputs in cereal cultivation and as more than half of the arable land in Finland is used for cereal production, N has contributed substantially to agricultural pollution through fertilizer leaching and runoff. Based on this global phenomenon, the European Community has launched several directives to reduce agricultural emissions to the environment. Trough such measures, and by using economic incentives, it is expected that northern European agricultural practices will, in the future, include reduced N fertilizer application rates. Reduced use of N fertilizer is likely to decrease both production costs and pollution, but could also result in reduced yields and quality if crops experience temporary N deficiency. Therefore, more efficient N use in cereal production, to minimize pollution risks and maximize farmer income, represents a current challenge for agronomic research in the northern growing areas. The main objective of this study was to determine the differences in nitrogen use efficiency (NUE) among spring cereals grown in Finland. Additional aims were to characterize the multiple roles of NUE by analysing the extent of variation in NUE and its component traits among different cultivars, and to understand how other physiological traits, especially radiation use efficiency (RUE) and light interception, affect and interact with the main components of NUE and contribute to differences among cultivars. This study included cultivars of barley (Hordeum vulgare L.), oat (Avena sativa L.) and wheat (Triticum aestivum L.). Field experiments were conducted between 2001 and 2004 at Jokioinen, in Finland. To determine differences in NUE among cultivars and gauge the achievements of plant breeding in NUE, 17-18 cultivars of each of the three cereal species released between 1909 and 2002 were studied. Responses to nitrogen of landraces, old cultivars and modern cultivars of each cereal species were evaluated under two N regimes (0 and 90 kg N ha-1). Results of the study revealed that modern wheat, oat and barley cultivars had similar NUE values under Finnish growing conditions and only results from a wider range of cultivars indicated that wheat cultivars could have lower NUE than the other species. There was a clear relationship between nitrogen uptake efficiency (UPE) and NUE in all species whereas nitrogen utilization efficiency (UTE) had a strong positive relationship with NUE only for oat. UTE was clearly lower in wheat than in other species. Other traits related to N translocation indicated that wheat also had a lower harvest index, nitrogen harvest index and nitrogen remobilisation efficiency and therefore its N translocation efficiency was confirmed to be very low. On the basis of these results there appears to be potential and also a need for improvement in NUE. These results may help understand the underlying physiological differences in NUE and could help to identify alternative production options, such as the different roles that species can play in crop rotations designed to meet the demands of modern agricultural practices.

Genetic Diversity and Adaptation of Date Palm (Phoenix dactylifera L.)

Acquiring sufficient information on the genetic variation, genetic differentiation, and the ecological and genetic relationships among individuals and populations are essential for establishing guidelines on conservation and utilization of the genetic resources of a species, and more particularly when biotic and abiotic stresses are considered. The aim of this study was to assess the extent and pattern of genetic variation in date palm (Phoenix dacttylifera L) cultivars; the genetic diversity and structure in its populations occurring over geographical ranges; the variation in economically and botanically important traits of it and the variation in its drought adaptive traits, in conservation and utilization context. In this study, the genetic diversity and relationships among selected cultivars from Sudan and Morocco were assessed using microsatellite markers. Microsatellite markers were also used to investigate the genetic diversity within and among populations collected from different geographic locations in Sudan. In a separate investigation, fruits of cultivars selected from Sudan, involved morphological and chemical characterization, and morphological and DNA polymorphism of the mother trees were also investigated. Morphological and photosynthetic adjustments to water stress were studied in the five most important date palm cultivars in Sudan, namely, Gondaila, Barakawi, Bitamoda, Khateeb and Laggai; and the mechanism enhancing photosynthetic gas exchange in date palm under water stress was also investigated. Results showed a significant (p < 0.001, t-test) differentiation between Sudan and Morocco groups of cultivars. However, the major feature of all tested cultivars was the complete lack of clustering and the absence of cultivars representing specific clones. The results indicated high genetic as well as compositional and morphological diversity among cultivars; while, compositional and morphological traits were found to be characteristic features that strongly differentiate cultivars as well as phenotypes. High genetic diversity was observed also in different populations. Slight but significant (p < 0.01, AMOVA) divergence was observed for soft and dry types; however, the genetic divergence among populations was relatively weak. The results showed a complex genetic relationships between some of the tested populations especially when isolation by distance was considered. The results of the study also revealed that date palm cultivars and phenotypes possess specific direct or interaction effects due to water availability on a range of morphological and physiological traits. Soft and dry phenotypes responded differently to different levels of water stress, while the dry phenotype was more sensitive and conservative. The results indicated that date palm has high fixation capacity to photosynthetic CO2 supply with interaction effect to water availability, which can be considered as advantageous when coping with stresses that may arise with climate change. In conclusion, although a large amount of diversity exists among date palm germplasm, the findings in this study show that the role of biological nature of the tree, isolation by distance and environmental effects on structuring date palm genome was highly influenced by human impacts. Identity of date palm cultivars as developed and manipulated by date palm growers, in the absence of scientific breeding programmes, may continue to mainly depend on tree morphology and fruit characters. The pattern of genetic differentiation may cover specific morphological and physiological traits that contribute to adaptive mechanisms in each phenotype. These traits can be considered for further studies related to drought adaptation in date palm.

Vadelman (Rubus idaeus) kasvunsäätö proheksadioni-kalsiumin avulla

Vadelman (Rubus idaeus L.) viljelyala on kasvanut Suomessa voimakkaasti viimeisten viiden vuoden aikana. Vuonna 2005 vadelmaa viljeltiin 473 hehtaarilla. Vadelman satoindeksi on alhainen. Sen pääverso on pitkä, mikä hankaloittaa hoitotoimenpiteitä. Kasvin satoisimmat silmut ovat pääverson kärjessä, joten latvontaa ei kannata tehdä. Suomessakin haluttaisiin kehittää vadelman kasvihuonetuotantoa satokauden pidentämiseksi. Kasvihuonetuotannossa vegetatiivisen kasvun säätäminen on vielä tärkeämpää kuin avomaan viljelyssä. Proheksadioni-kalsium (ProCa) on gibberelliinisynteesi-inhibiittori, jonka on havaittu lyhentävän nivelvälejä sekä lisäävän versojen ja lehtien hiilihydraattipitoisuutta mm. omenalla (Malus domestica Borkh.). Tämän Helsingin yliopiston soveltavan biologian laitoksella toteutetun tutkimuksen tarkoituksena oli selvittää, miten ProCa vaikuttaa kahden kesävadelmalajikkeen ensimmäisen vuoden versojen vegetatiiviseen kasvuun ja edelleen sadontuottokykyyn. Tässä pro gradu -työssä tutkittiin ProCa:n vaikutusta kahden kesävadelmalajikkeen vegetatiiviseen kasvuun, satopotentiaaliin sekä versojen ja silmujen hiilihydraattipitoisuuksiin kesällä 2005 ja talvella 2006. Koetaimina oli 120 Tulameen-lajikkeen ja 150 Glen Ample -lajikkeen tainta. Taimet käsiteltiin kesäkuussa ja käsittely uusittiin osalle taimista neljän viikon kuluttua ensimmäisestä käsittelystä. Koekäsittelyitä oli neljä: ProCa 100 ppm, ProCa 200 ppm, ProCa 100 ppm + ProCa 100 ppm ja ProCa 200 ppm + ProCa 200 ppm. Kontrollikäsittelyitä oli kaksi: vesi sekä vesi + vesi. Kesän aikana havainnoitiin pääverson pituuskasvua ja nivelien määrää. Kesän kasvatuskauden päätyttyä Glen Ample -lajikkeen silmujen ja versojen liukoiset hiilihydraatit ja tärkkelys määritettiin entsymaattisesti. Kylmävarastoinnin jälkeen (71 vrk) tammikuussa 2006 taimet siirrettiin hyötöön kasvihuoneeseen. Hyödön aikana havainnoitiin silmujen puhkeamista ja kukintaa. Hyödön päättyessä hanka- ja pääversojen kuivapaino sekä hankaversojen pituus mitattiin. Kesän 2005 aikana ProCa lyhensi uusien nivelvälien pituuksia väliaikaisesti 1 4 viikon kuluttua käsittelystä. Nivelien lukumäärässä ei tapahtunut suuria muutoksia. Tulameen-lajikkeella kasvu kiihtyi käsittelyn vaikutuksen loputtua. Nivelvälien lyhentymisen takia pääverson kokonaispituus jäi kontrolliin verrattuna 35 % lyhyemmäksi Glen Ample -lajikkeella (ProCa 200 + ProCa 200) ja 14 % lyhyemmäksi Tulameen-lajikkeella samalla käsittelyllä. Myös käsittely ProCa 200 vähensi pääverson pituutta 6 % kontrolliin verrattuna Tulameen-lajikkeella. ProCa-käsittely lisäsi versojen ja silmujen hiilihydraattipitoisuuksia, mutta tuloksissa oli paljon hajontaa. Glen Ample -lajikkeella kaksinkertaiset käsittelyt vähensivät puhjenneiden silmujen osuutta 8 15 päivän kuluttua hyödön aloittamisesta 24 29 %, mutta käsittelyiden väliset erot tasoittuivat hyödön loppuun mennessä. Lisäksi kaksinkertaiset ProCa-käsittelyt vähensivät kukkien määrää 29 44 % 33 65 päivää hyödön alusta, mutta erot tasoittuivat hyödön loppuun mennessä. Käsittelyt eivät vaikuttaneet Tulameen-lajikkeen silmujen puhkeamiseen ja kukintaan. Satopotentiaalissa ei ollut eroa ProCa-käsittelyiden välillä kummallakaan lajikkeella. Glen Ample -lajikkeella hankaversojen kokonaismäärä väheni 27 32 % kasveilla, joita oli käsitelty kaksi kertaa ProCa:lla. Hankaversot olivat kuitenkin vastaavasti 29 43 % pidempiä. Tulameen-lajikkeella ProCa 100 -käsittely vähensi hankaversojen määrää 15 %, mutta hankaversojen pituuteen käsittelyillä ei ollut vaikutusta. Käsittelyillä ei ollut vaikutusta hankaversojen nivelvälien pituuteen kummallakaan lajikkeella. Tutkimuksen perusteella kesällä annetulla ProCa-käsittelyllä voidaan lyhentää pääverson pituutta, mutta satopotentiaaliin käsittelyllä ei ole vaikutusta. Käsittelyajankohta on kriittinen, koska kukkasilmujen kehitys näyttäisi häiriintyvän, jos ruiskutus tehdään loppukesällä.

Valikoivan metsästyksen vaikutus hirven ikärakenteeseen ja vasatuottoon Savonrannan ja Sodankylän riistanhoitoyhdistysten alueilla

Suomen hirvenmetsästykseen omaksuttiin 1970-luvun alussa valikoivan metsästyksen periaatteet, joiden tavoitteena oli maksimoida vasatuotto hirvikannan ikärakennetta muuttamalla. Metsästysstrategiassa tapahtui huomattava muutos, kun hirvisaaliin vasaosuutta lisättiin selvästi. Tämän seurauksena naarashirvien keski-ikä ja vasatuotto kohosivat. Vasojen suuri osuus saaliissa oli keskeinen tekijä hirvikannan rajuun kasvuun. Tämän opinnäytetyön tavoitteena oli selvittää saaliin vasaosuuden vaikutusta hirven ikärakenteeseen ja vasatuottoon Savonrannan ja Sodankylän riistanhoitoyhdistysten alueilla. Tutkimusalueet valittiin hyvin erilaisten hirvisaaliin vasaosuuksien perusteella, sillä Savonrannan vuosien 1994-2003 saaliin vasaosuuden keskiarvo oli 50,1 % ja Sodankylän 19,6 %. Tutkimuksen ennakko-olettamuksena oli, että erilaisten saaliin vasaosuuksien pitäisi vaikuttaa aikuistuvan ikäluokan suhteellisen osuuden kautta hirvipopulaation keski-ikään ja sitä kautta vasatuottoon. Ikärakenteen osalta tutkittiin naaraiden, valtasonnien eli 6,5-9,5-vuotiaiden uroshirvien ja vähintään 8-piikkisten urosten ikärakennetta. Tutkimus rakentui hirven iänmääritysaineiston ympärille, joka kerättiin Savonrannan ja Sodankylän riistanhoitoyhdistysten hirvenmetsästäjien avustuksella vuosina 2003 ja 2004. Iänmääritysaineistossa oli yhteensä 244 hirveä. Näistä oli naaraita 152 ja uroksia 92 kpl. Hirven ikärakennetietojen saamiseksi suoritti tutkimuksen tekijä iänmäärityksen hammasnäytteistä. Iänmääritys tehtiin hammassementtikerroksiin perustuvaa menetelmää käyttäen, jota varten sahattiin poikittaisia hammasleikkeitä hirven ensimmäisestä etuhampaasta (I1). Tutkimuksen aineistoon kuuluivat myös Savonrannan ja Sodankylän hirvihavaintokorttien perusteella saadut vasatuottotiedot vuosilta 1995- 2004 ja Riistawebin saalistiedot vuosilta 1994-2003. Tutkimuksen perusteella hirvisaaliin vasaosuus vaikuttaa Savonrannan ja Sodankylän riistanhoitoyhdistysten naaraiden ikärakenteeseen. Kaksivuotisesta aineistosta saatiin Savonrannan naaraiden keski-iäksi 6,40 vuotta. Sodankylän naaraiden keski-ikä oli 5,09 vuotta. Myös naaraiden ikäjakaumat olivat hyvin erilaiset. Hirvisaaliin vasaosuus ei sen sijaan vaikuta Savonrannan ja Sodankylän valtasonnien ja vähintään 8-piikkisten urosten ikärakenteeseen. Savonrannan valtasonnien keski-ikä oli 7,21 vuotta ja Sodankylän 7,07 vuotta. Savonrannan vähintään 8-piikkisten urosten keski-ikä oli 5,82 vuotta ja Sodankylän 5,91 vuotta. Tutkimuksella saatiin selville saaliin ikärakenne, elävän hirvikannan ikärakenteen tutkiminen vaatii laajempia tutkimuksia. Hirvisaaliin vasaosuus vaikuttaa Savonrannan ja Sodankylän riistanhoitoyhdistysten vasatuottoon. Naaraiden ikärakenteen erot näkyivät osaltaan hirvihavaintokorttien ja näytenaaraiden perusteella lasketuissa vasatuottotiedoissa. Saaliin vasaosuus vaikuttaa välillisesti hirven vasatuottoon, sillä se vaikuttaa ensin naaraiden ikärakenteeseen, joka vaikuttaa edelleen vasatuottoon.

Tracking and identifying wastewater toxicants and assessing their biodegradation products

Screening of wastewater effluents from municipal and industrial wastewater treatment plants with biotests showed that the treated wastewater effluents possess only minor acute toxic properties towards whole organisms (e.g. bacteria, algae, daphnia), if any. In vitro tests (sub-mitochondrial membranes and fish hepatocytes) were generally more susceptible to the effluents. Most of the effluents indicated the presence of hormonally active compounds, as the production of vitellogenin, an egg yolk precursor protein, was induced in fish hepatocytes exposed to wastewater. In addition, indications of slight genotoxic potential was found in one effluent concentrate with a recombinant bacteria test. Reverse electron transport (RET) of mitochondrial membranes was used as a model test to conduct effluent assessment followed by toxicant characterisations and identifications. Using a modified U.S. EPA Toxicity Identification Evaluation Phase I scheme and additional case-specific methods, the main compound in a pulp and paper mill effluent causing RET inhibition was characterised to be an organic, relatively hydrophilic high molecular weight (HMW) compound. The toxicant could be verified as HMW lignin by structural analyses using nuclear magnetic resonance. In the confirmation step commercial and in-house extracted lignin products were used. The possible toxicity related structures were characterised by statistical analysis of the chemical breakdown structures of laboratory-scale pulping and bleaching effluents and the toxicities of these effluents. Finally, the biological degradation of the identified toxicant and other wastewater constituents was evaluated using bioassays in combination with chemical analyses. Biological methods have not been used routinely in establishing effluent discharge limits in Finland. However, the biological effects observed in this study could not have been predicted using only routine physical and chemical effluent monitoring parameters. Therefore chemical parameters cannot be considered to be sufficient in controlling effluent discharges especially in case of unknown, possibly bioaccumulative, compounds that may be present in small concentrations and may cause chronic effects.

Nutrition and Nutritional Care of Elderly People in Finnish Nursing Homes and Hospitals

Background: Malnutrition is a common problem for residents of nursing homes and long-term care hospitals. It has a negative influence on elderly residents and patients health and quality of life. Nutritional care seems to have a positive effect on elderly individuals nutritional status and well-being. Studies of Finnish elderly people s nutrition and nutritional care in institutions are scarce. Objectives: The primary aim was to investigate the nutritional status and its associated factors of elderly nursing home residents and long-term care patients in Finland. In particular, to find out, if the nursing or nutritional care factors are associated with the nutritional status, and how do carers and nurses recognize malnutrition. A further aim was to assess the energy and nutrient intake of the residents of dementia wards. A final objective was to find out, if the nutrition training of professionals leads to changes in their knowledge and further translate into better nutrition for the aged residents of dementia wards. Subjects and methods: The residents (n=2114) and patients (n=1043) nutritional status was assessed in all studies using the Mini Nutritional Assessment test (MNA). Information was gathered in a questionnaire on residents and patients daily routines providing nutritional care. Residents energy and nutrient intake (n=23; n=21) in dementia wards were determined over three days by the precise weighing method. Constructive learning theory was the basis for educating the professionals (n=28). A half-structured questionnaire was used to assess professionals learning. Studies I-IV were cross-sectional studies whereas study V was an intervention study. Results: Malnutrition was common among elderly residents and patients living in nursing homes and hospitals in Finland. According to the MNA, 11% to 57% of the studied elderly people suffered from malnutrition, and 40-89% were at risk of malnutrition, whereas only 0-16% had a good nutritional status. Resident- and patient-related factors such as dementia, impaired ADL (Activities of Daily Living), swallowing difficulties and constipation mainly explained the malnutrition, but also some nutritional care related factors, such as eating less than half of the offered food portion and not receiving snacks were also related to malnutrition. The intake of energy and some nutrients by the residents of dementia wards were lower than those recommended, although the offered food contained enough energy and nutrients. The proportion of residents receiving vitamin D supplementation was low, although there is a recommendation and known benefits for the adequate intake of vitamin D. Nurses recognized malnutrition poorly, only one in four (26.7%) of the actual cases. Keeping and analysing food diaries and reflecting on nutritional issues in small group discussions were effective training methods for professionals. The nutrition education of professionals had a positive impact on the energy and protein intake, BMIs, and the MNA scores of some residents in dementia wards. Conclusions: Malnutrition was common among elderly residents and patients living in nursing homes and hospitals in Finland. Although residents- and patient related factors mainly explained malnutrition, nurses recognized malnutrition poorly and nutritional care possibilities were in minor use. Professionals nutrition education had a positive impact on the nutrition of elderly residents. Further studies describing successful nutritional care and nutrition education of professionals are needed.

Effect of phenolic-rich plant materials on protein and lipid oxidation reactions

The antioxidant activity of natural plant materials rich in phenolic compounds is being widely investigated for protection of food products sensitive to oxidative reactions. In this thesis plant materials rich in phenolic compounds were studied as possible antioxidants to prevent protein and lipid oxidation reactions in different food matrixes such as pork meat patties and corn oil-in water emulsions. Loss of anthocyanins was also measured during oxidation in corn oil-in-water emulsions. In addition, the impact of plant phenolics on amino acid level was studied using tryptophan as a model compound to elucidate their role in preventing the formation of tryptophan oxidation products. A high-performance liquid chromatography (HPLC) method with ultraviolet and fluorescence detection (UV-FL) was developed that enabled fast investigation of formation of tryptophan derived oxidation products. Byproducts of oilseed processes such as rapeseed (Brassica rapa L.), camelina (Camelina sativa) and soy meal (Glycine max L.) as well as Scots pine bark (Pinus sylvestris) and several reference compounds were shown to act as antioxidants toward both protein and lipid oxidation in cooked pork meat patties. In meat, the antioxidant activity of camelina, rapeseed and soy meal were more pronounced when used in combination with a commercial rosemary extract (Rosmarinus officinalis). Berry phenolics such as black currant (Ribes nigrum) anthocyanins and raspberry (Rubus idaeus) ellagitannins showed potent antioxidant activity in corn oil-in-water emulsions toward lipid oxidation with and without β-lactoglobulin. The antioxidant effect was more pronounced in the presence of β-lactoglobulin. The berry phenolics also inhibited the oxidation of tryptophan and cysteine side chains of β-lactoglobulin. The results show that the amino acid side chains were oxidized prior the propagation of lipid oxidation, thereby inhibiting fatty acid scission. In addition, the concentration and color of black currant anthocyanins decreased during the oxidation. Oxidation of tryptophan was investigated in two different oxidation models with hydrogen peroxide (H2O2) and hexanal/FeCl2. Oxidation of tryptophan in both models resulted in oxidation products such as 3a-hydroxypyrroloindole-2-carboxylic acid, dioxindolylalanine, 5-hydroxy-tryptophan, kynurenine, N-formylkynurenine and β-oxindolylalanine. However, formation of tryptamine was only observed in tryptophan oxidized in the presence of H2O2. Pine bark phenolics, black currant anthocyanins, camelina meal phenolics as well as cranberry proanthocyanidins (Vaccinium oxycoccus) provided the best antioxidant effect toward tryptophan and its oxidation products when oxidized with H2O2. The tryptophan modifications formed upon hexanal/FeCl2 treatment were efficiently inhibited by camelina meal followed by rapeseed and soy meal. In contrast, phenolics from raspberry, black currant, and rowanberry (Sorbus aucuparia) acted as weak prooxidants. This thesis contributes to elucidating the effects of natural phenolic compounds as potential antioxidants in order to control and prevent protein and lipid oxidation reactions. Understanding the relationship between phenolic compounds and proteins as well as lipids could lead to the development of new, effective, and multifunctional antioxidant strategies that could be used in food, cosmetic and pharmaceutical applications.