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Elucidating mechanisms that underpin aphid-plant interactions
Swiegers, Hendrik Willem. 2024. Role of strigolactones in adventitious rooting of Arabidopsis thaliana callus in vitro. Unpublished doctoral dissertation. Stellenbosch : Stellenbosch University [online]. Available: https://scholar.sun.ac.za/handle/10019.1/131923 Thesis (PhDAgric)--Stellenbosch Uni...
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Stellenbosch : Stellenbosch University
2025
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| access_status_str | Open Access |
| author | Swiegers, Hendrik Willem |
| author2 | Botha-Oberholster, Anna-Maria |
| author_browse | Botha-Oberholster, Anna-Maria Swiegers, Hendrik Willem |
| author_facet | Botha-Oberholster, Anna-Maria Swiegers, Hendrik Willem |
| author_sort | Swiegers, Hendrik Willem |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Swiegers, Hendrik Willem. 2024. Role of strigolactones in adventitious rooting of Arabidopsis thaliana callus in vitro. Unpublished doctoral dissertation. Stellenbosch : Stellenbosch University [online].
Available: https://scholar.sun.ac.za/handle/10019.1/131923
Thesis (PhDAgric)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131923 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:40:58.715Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131923 Elucidating mechanisms that underpin aphid-plant interactions Swiegers, Hendrik Willem Botha-Oberholster, Anna-Maria Foyer, Christine Hellen Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics & Institute of Plant Biotechnology. Aphids Wheat -- Diseases and pests RNA interference Genetic regulation Aphids -- Biological control Insecticides -- Mechanism of action Aphid-plant interactions -- Defenses UCTD Swiegers, Hendrik Willem. 2024. Role of strigolactones in adventitious rooting of Arabidopsis thaliana callus in vitro. Unpublished doctoral dissertation. Stellenbosch : Stellenbosch University [online]. Available: https://scholar.sun.ac.za/handle/10019.1/131923 Thesis (PhDAgric)--Stellenbosch University, 2024. ENGLISH ABSTRACT: Aphids are global pests of both crop and ornamental plants. Aphid infestations of crop plants result in yield losses through nutrient depletion and the spread of viruses. Although often effectively controlled by traditional chemical insecticides, these have deleterious effects on both the environment and human health. As such the use of insecticides have been restricted in some parts of the world. Secondly, many aphid populations have developed resistance to various insecticide classes. Host plant resistance offers an alternative to control aphid pests, however as with other control methods, aphids often overcome host resistance through the development of virulent biotypes. The aim of this project was to investigate the aphid-plant interaction by firstly examining differential gene regulation of aphid and host using virulent and avirulent Diuraphis noxia (Russian wheat aphid) biotypes feeding on a resistant Triticum aestivum (bread wheat) cultivar containing the D. noxia resistance gene, Dn7. The virulent D. noxia biotype SAMv2 exhibited distinct gene expression compared to the genealogically linked avirulent SAl, suggesting adaptations to overcome host resistance. SAMv2 upregulated transcripts implicated in detoxification (e.g. L-xylulose reductase) as well as other transcripts of unknown function. Transposable elements were highly active in all biotypes and to a lesser extent, epigenome modifying enzymes, potentially contributing to rapid adaptation to its host. T. aestivum responded to aphid feeding with jasmonic acid signalling and terpene biosynthesis. However, virulent SAMv2 appeared to modulate these defence mechanisms as monoterpenoid and diterpenoid biosynthesis were only upregulated following feeding by avirulent biotypes SAS and SAl, respectively. It was also found that the strigolactone synthesis gene, CYP711A1 was upregulated following feeding of biotype SAS. Secondly, the effect of elevated CO2 and strigolactones on Pisum sativum (pea) susceptibility to Acyrthosiphon pisum (pea aphid) were investigated. A. pisum performed better on strigolactone synthesis and signalling P. sativum mutants while [CO2] had no effect on aphid fecundity. The lower gibberellic acid levels observed in the strigolactone mutants were significantly correlated with increased A. pisum fecundity. Lastly, the function of cuticle protein, CpRRl-8, in the formation of virulence in D. noxia was also investigated. This work provides a foundation for developing more effective and sustainable aphid control strategies. Future research building on these findings will continue to uncover the dynamics of aphid-plant interactions and contribute to the development of resilient agricultural systems. AFRIKAANSE OPSOMMING: Blaasluise is wereldwye plae van beide landbou- en sierplante. Blaasluisbesmetting van landbouplante lei tot opbrengsverliese deur die uitputting van plantvoedingstowwe en die verspreiding van virusse. Alhoewel dit dikwels effektief beheer word deur tradisionele chemiese insekdoders, het hierdie middels newe-effekte op beide die omgewing en menslike gesondheid. As sodanig is die gebruik van insekdoders in sommige dele van die wereld beperk. Tweedens het baie blaasluispopulasies weerstand ontwikkel teen verskeie insekdoderklasse. Gasheerplantweerstand bied 'n alternatief vir die beheer van blaasluispeste, maar soos met ander beheermetodes, pas blaasluise dikwels aan by gasheerplantweerstand deur die ontwikkeling van virulente biotipes. Die doel van hierdie projek was om die blaasluis-plant interaksie te ondersoek deur eerstens differensiele geenregulering van blaasluis en plantgasheer te ondersoek deur virulente en avirulente Diuraphis noxia (Russiese koringblaasluis) biotipes te laat voed op 'n weerstandige Triticum aestivum (koring) kultivar wat die D. noxia-weerstandsgeen, Dn7, bevat. Die virulente D. noxia biotipe SAMv2 het duidelike geenuitdrukking verskille getoon in vergelyking met die naby verwante avirulente SAl, wat dui op aanpassings om gasheerweerstand te oorkom. SAMv2 het transkripte opgereguleer wat betrokke is by ontgifting (bv. L-xilulose reduktase), asook ander transkripte met onbekende funksie. Transponeerbare elemente was hoogs aktief in alle biotipes en tot 'n mindere mate, epigenoom-modifiserende ensieme, wat moontlik bydra tot vinnige gasheeraanpassing. T. aestivum het op blaasluisvoeding gereageer met jasmonsuur- en terpeenbiosintese. Virulente SAMv2 het egter hierdie verdedigingsmeganismes blykbaar gemoduleer aangesien monoterpeen- en diterpeenbiosintese slegs opgereguleer is na voeding deur avirulente biotipes SAS en SAl, onderskeidelik. Daar is ook bevind dat die strigolaktoon sintesegeen, CYP711A1, opgereguleer is na voeding van biotipe SAS. Tweedens is die effek van verhoogde CO2 en strigolaktoon op Pisum sativum (ertjie) se vatbaarheid vir Acyrthosiphon pisum (ertjieblaasluis) ondersoek. A. pisum het beter gevaar op strigolaktoon sintese en seintransduksie P. sativum mutante terwyl [CO2] geen effek gehad het op blaasluis vrugbaarheid nie. Die laer gibberelliensuur vlakke wat in die strigolaktoon mutante waargeneem is, was betekenisvol gekorreleer met verhoogde A. pisum vrugbaarheid. Laastens is die funksie van die kutikulaproteien, CpRRl-8, in die vorming van virulensie in D. noxia ook ondersoek. Hierdie werk verskaf 'n basis vir die ontwikkeling van meer effektiewe en volhoubare blaasluis beheerststrategiee. Toekomstige navorsing wat op hierdie bevindinge voortbou, sal voortgaan om die dinamika van blaasluis-plant interaksies te ontsyfer en bydra tot die ontwikkeling van veerkragtige landbou-stelsels. Doctoral 2025-04-25T07:20:13Z 2025-04-25T07:20:13Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131923 Stellenbosch University xxiv, 185 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Aphids Wheat -- Diseases and pests RNA interference Genetic regulation Aphids -- Biological control Insecticides -- Mechanism of action Aphid-plant interactions -- Defenses UCTD Swiegers, Hendrik Willem Elucidating mechanisms that underpin aphid-plant interactions |
| title | Elucidating mechanisms that underpin aphid-plant interactions |
| title_full | Elucidating mechanisms that underpin aphid-plant interactions |
| title_fullStr | Elucidating mechanisms that underpin aphid-plant interactions |
| title_full_unstemmed | Elucidating mechanisms that underpin aphid-plant interactions |
| title_short | Elucidating mechanisms that underpin aphid-plant interactions |
| title_sort | elucidating mechanisms that underpin aphid plant interactions |
| topic | Aphids Wheat -- Diseases and pests RNA interference Genetic regulation Aphids -- Biological control Insecticides -- Mechanism of action Aphid-plant interactions -- Defenses UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131923 |
| work_keys_str_mv | AT swiegershendrikwillem elucidatingmechanismsthatunderpinaphidplantinteractions |