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dc.contributor.advisorVan der Westhuizen, A. J.
dc.contributor.authorMohase, Lintle
dc.date.accessioned2018-05-11T06:52:55Z
dc.date.available2018-05-11T06:52:55Z
dc.date.issued1998-11
dc.identifier.urihttp://hdl.handle.net/11660/8272
dc.description.abstractEnglish: Features of the upstream defense response in the interaction between wheat (Triticum aestivum L.) and the Russian wheat aphid (RWA) (Diuraphis noxia, Mordvilko) were investigated. The study was conducted in an attempt to shed light on the eliciting and signal transduction events of the defense mechanism. It was found that the intercellular wash fluid (IWF) of infested resistant wheat plants (Tugela Dn 1), injected intercellularly into susceptible (Tugela) and resistant (Tugela Dn 1) plants had much higher eliciting activity than the IWF of infested susceptible plants. The eliciting activity was measured in terms of the expression of downstream defense related peroxidase and β-1,3-glucanase activities. The defense related enzymes were differentially induced to higher levels in the resistant than susceptible plants. Fractionation of the IWF of infested resistant plants by C-18 reverse-phase and con A binding chromatography revealed the elicitor to be a glycoprotein capable of inducing both local and systemic defense responses. The signaling role of salicylic acid (SA) in mediating the downstream defense responses was also investigated. RWA infestation induced differential accumulation of SA to higher levels in the resistant (421-fold) than susceptible (78-fold) plants. The increase in the activity of the defense related peroxidase in infested resistant plants correlated well with the increase in SA content. Intercellular application of H202 induced a 65% increase in SA content only in the resistant plants. As SA was accumulating, catalase activity was declining. In addition, intercellularly applied SA also inhibited catalase activity by 49%. The results from this study indicated that the intercellular glycoproteins from infested resistant plants can act as elicitors of the downstream defense responses and that SA is most probably a signaling molecule in mediating these responses.en_ZA
dc.description.abstractAfrikaans: In 'n poging om meer lig te werp op die elisiterings- en seintransduksiemeganismes van die verdedigingsmeganisme van koring, Triticum aestivum L., teen die Russiese koringluis (RKL), Diuraphis noxia Mordvilko, is aspekte van die stroomop verdedigingsrespons ondersoek. Deur middel van intersel1ulêre toediening aan weerstandbiedende (Tugela Dn 1) en vatbare (Tugela) koringplante is dit vasgestel dat die intersel1ulêre wasvloeistof (IWV) van geïnfesteerde weerstandbiedende koring (Tugela Dn 1) baie hoër elisiteringsaktiwiteite as die IWV van geïnfesteerde vatbare koring (Tugela) bevat het. Die elisiteringsaktiwiteit is bepaal in terme van die uitdrukking van stroomaf verdedigingsverwante peroksidase- en β-1,3-glukanase-aktiwiteite. Hierdie aktiwiteite is deur die IWV van geïnfesteerde weerstandbiedende plante selektief tot hoër vlakke in weerstandbiedende as in vatbare plante geïnduseer. 'n Glikoproteïen met lokale sowel as sistemiese elisiteringsvermoëns is deur middel van C-18 omgekeerde fase en kon. Abindingschromatografie uit die IWV van geïnfesteerde weerstandbiedende koringplante geïsoleer. Die rol van salisielsuur (SA) in die seinmeganisme wat aanleiding tot die stroomafverdedigingsresponse gee, is ook ondersoek. RKL-infestering het differensiële akkumulering van SA tot hoër vlakke in weerstandbiedende (421-voud) as in vatbare (78-voud) plante geïnduseer, Die toename in verdedigingsverwante peroksidase-aktiwiteit in geïnfesteerde weerstandbiedende plante het goed met die toename in salisielsuurinhoud gekorreleer. Intersellulêre H202 -toediening het 'n 65% toename in SA-inhoud slegs in weerstandbiedende plante geïnduseer, Endogene SAakkumulering het met 'n afuame in katalase-aktiwiteit gepaard gegaan. Hierbenewens het intersel1ulêre toegediende SA, katalase-aktiwiteit met 49% gerem. Die resultate van hierdie studie het aangetoon dat intersel1ulêre glikoproteïene van geïnfesteerde weerstandbiedende plante kan as elisitore van die stroomaf verdedigingsrespons optree en dat SA heel moontlik die seinmolekuul is wat hierdie respons uitlok.en_ZA
dc.description.sponsorshipNMDS (Lesotho Government)en_ZA
dc.description.sponsorshipThe May and Stanley Smith Charitable Trust Funden_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectWheat -- Biotechnologyen_ZA
dc.subjectWheat -- Disease and pest resistanceen_ZA
dc.subjectPlant cellular signal transductionen_ZA
dc.subjectDissertation (M.Sc. (Botany and Genetics))--University of the Free State, 1998en_ZA
dc.titleEliciting and signal transduction events of the Russian wheat aphid resistance response in wheaten_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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