Streptomyces sädebakteerien kilpailusuhteet ja vaikutus perunaruven taudinaiheuttajiin

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http://urn.fi/URN:NBN:fi:hulib-201507211621
Title: Streptomyces sädebakteerien kilpailusuhteet ja vaikutus perunaruven taudinaiheuttajiin
Author: Ojanperä, Taru
Other contributor: Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Soveltavan biologian laitos
University of Helsinki, Faculty of Agriculture and Forestry, Department of Applied Biology
Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten, Institutionen för tillämpad biologi
Publisher: Helsingfors universitet
Date: 2008
Language: fin
URI: http://urn.fi/URN:NBN:fi:hulib-201507211621
http://hdl.handle.net/1975/7946
Thesis level: master's thesis
Discipline: Växtpatologi
Plant pathology
Kasvipatologia
Abstract: Perunaruven aiheuttajat S. scabies, S. turgidiscabies ja S. aureofaciens aiheuttavat lähinnä laadullisia tappioita muodostaen perunan mukuloihin rupea. Pahimmillaan taudinaiheuttajat hidastavat perunan taimettumista, lisäävät pienten mukuloiden määrää sekä vähentävät satoa. Viljelytekniset keinot eivät ole aina tehokkaita eivätkä kemialliset keinot ole Suomessa sallittuja. Työssä selvitettiin Streptomyces-kantojen ominaisuuksia biologisen torjunnan lähtökohdista. Tavoitteena oli selvittää Suomesta eristettyjen Streptomyces–sädebakteerien kykyä estää perunarupibakteerien kasvu eri pH-olosuhteissa. Tutkimuksiin valittiin sekä rupea aiheuttavia että rupea aiheuttamattomia kantoja. Lisäksi tutkittiin Streptomyces–sädebakteerien kykyä estää harmaahilseen ja perunaseitin taudinaiheuttajien (Ritzoctonia solani ja Helmintosporium solani) kasvua. Maljakokeissa tutkittiin sieni- ja sädebakteerikantojen keskinäisiä kilpailusuhteita. Kasvihuonekokeissa tutkittiin sädebakteerien asettumista perunan juuristoon. Tutkituilta kannoilta löytyi hyviä biologisen torjuntaeliön ominaisuuksia. Streptomyces-kannat estivät toistensa kasvua. Kantojen estovaikutukset eivät liittyneet ruvenaiheuttamiskykyyn. Kaikki testatut kannat estivät harmaahilseen ja perunaseitin taudinaiheuttajien kasvua, mutta kannat S. griseoviridis ja kanta 16IV osoittautuivat erityisen tehokkaiksi estäjiksi. Kaikki kannat kasvoivat pH-oloissa välillä 5.5–8.0. Tunnistamaton Streptomyces-kanta 16IV kasvoi heikosti pH:ssa 5.5 ja yllättäen happamiin olosuhteisiin sopeutunut pohjanrupibakteerikanta (S. turgidiscabies) kasvoi erinomaisesti myös pH:ssa 8.0. Kaikki testatut sädebakteerikannat asuttivat perunan juuren. Tutkimuksissa löytyi potentiaalisia kantoja lisätutkimuksiin biologisen torjunnan agentiksi. Lisäkokeita tarvitaan mm. perunan juurenasutuksesta ja kantojen estovaikutuksista juuristo-oloissaThe causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions. The causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions.
Subject: potato scab
Streptomyces
biological control
silver scurf
stem cancer
black scurf
Streptomyces
biologinen torjunta
harmaahilse
perunaseitti


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