Is AtGSTF2 involved in lumichrome perception and transport?

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dc.contributor.advisorHills, Paul Normanen_ZA
dc.contributor.authorWarren, Kyleen_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Department of Genetics & Institute of Plant Biotechnology.en_ZA
dc.date.accessioned2024-02-29T15:15:25Z
dc.date.accessioned2024-04-26T20:18:36Z
dc.date.available2024-02-29T15:15:25Z
dc.date.available2024-04-26T20:18:36Z
dc.date.issued2024-03
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: A number of exudates from plant growth-promoting rhizobacteria (PGPR) have been increasingly studied and used as an alternative way of promoting plant health and growth. One such exudate is lumichrome, a signal molecule which has been shown to elicit a growth response across multiple species. Recent studies have identified some of the molecular mechanisms which underpin this growth response, however, to date it remains unknown how lumichrome is perceived and transported in planta. It was proposed that the Arabidopsis Glutathione S-Transferase (GST) AtGSTF2 may act as either a receptor or a transporter of lumichrome, as a previous study had found lumichrome was able to bind to AtGSTF2 with high affinity when the Arabidopsis gene was overexpressed in Escherichia coli. Consequently, AtGSTF2 overexpressor (OE) and knockout (KO) lines were generated in Arabidopsis thaliana to test whether these lines would show enhancements or reductions in the growth effects of lumichrome, and to gain additional insight into the role of AtGSTF2 in Arabidopsis. It was determined that overexpression of AtGSTF2 did not affect the growth response of treated plants to lumichrome, although it was found that the OE plants had increased overall plant growth and differences in a number of physiological responses in comparison to untreated wild-type plants. Previous studies had shown no obvious phenotypic effects from AtGSTF2 overexpression under normal growth conditions, although the plants had increased tolerance to phenolic stress; however, this study showed that overexpression of AtGSTF2 resulted in an increase in both fresh and dry biomass, an increase in the number of leaves, increased starch and sugar levels, as well as higher stomatal conductance and transpiration rates than wild-type plants. However, in both OE lines generated, lumichrome treatment reduced plant biomass, whilst leaf number was also reduced following lumichrome treatment in one of the two OE lines. RT-qPCR analysis showed decreased expression of AtGSTF2 in wild-type plants following lumichrome treatment, however, increased expression compared to wild-type controls was seen in growth-related genes XTH9 and CYCA1 and the jasmonate-related gene JAL34. However, lumichrome-treatment of OE plants resulted in significant differences in expression patterns for the lumichrome- responsive genes studied compared to its effects on the transcripts in wild-type plants, as the overexpression of AtGSTF2 appeared to decrease ACO1 and CYCA1 expression. Overexpression of AtGSTF2 increased plant growth in comparison to the wild-type plants, suggesting that AtGSTF2 plays a critical role in development. In summary, the evidence from this study revealed no correlations between lumichrome-related growth or gene expression responses and AtGSTF2 expression, suggesting that AtGSTF2 is most likely not involved in either lumichrome perception or transport. Despite being one of the most widely studied phi-class GSTs, little is known about the functions of AtGSTF2. This study proposes that AtGSTF2 plays a more important role in plant growth than previously thought, and it is recommended that future studies should focus on the role of AtGST2 in plant growth and development.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: 'n Aantal eksudate van plantgroeibevorderende risobakterieë (PGBR) is al hoe meer bestudeer en gebruik as 'n alternatiewe manier om plantgesondheid en -groei te bevorder. Een so 'n eksudaat is lumichrome, 'n seinmolekule wat getoon is om 'n groeireaksie oor verskeie spesies te ontlok. Onlangse studies het sommige van die molekulêre meganismes geïdentifiseer wat hierdie groeireaksie onderlê, maar tot op hede bly dit onbekend hoe lumichrome waargeneem en vervoer word in planta. Daar is voorgestel dat die Arabidopsis Glutathione S- Transferase (GST) AtGSTF2 as óf 'n reseptor óf 'n vervoerder van lumichrome kan optree, aangesien 'n vorige studie bevind het lumichrome kon met hoë affiniteit aan AtGSTF2 bind wanneer die Arabidopsis-geen in Escherichia coli ooruitgedruk was. Gevolglik is AtGSTF2-ooruitdrukking (OE) en uitklop- (KO)-lyne in Arabidopsis thaliana gegenereer om te toets of hierdie lyne verbeterings of vermindering in die groei-effekte van lumichrome sal toon, en om addisionele insig te verkry in die rol van AtGSTF2 in Arabidopsis. Daar is vasgestel dat ooruitdrukking van AtGSTF2 nie die groeirespons van behandelde plante op lumichrome beïnvloed het nie, alhoewel daar gevind is dat die OE-plante se algehele plantgroei verhoog was en dat daar verskille in 'n aantal fisiologiese responsies in vergelyking met onbehandelde wildtipe plante was. Vorige studies het geen ooglopende fenotipiese effekte van AtGSTF2-ooruitdrukking onder normale groeitoestande getoon nie, alhoewel die plante verdraagsaamheid vir fenoliese stres verhoog het; hierdie studie het egter getoon dat ooruitdrukking van AtGSTF2 'n toename in beide vars en droë biomassa tot gevolg gehad het, 'n toename in die aantal blare, verhoogde stysel- en suikervlakke, sowel as hoër stomatale geleiding en transpirasietempos as wilde-tipe plante. In beide OE-lyne wat gegenereer is, het lumichromebehandeling egter plantbiomassa verminder, terwyl blaargetal ook verminder was na lumichromebehandeling in een van die twee OE-lyne. RT- qPCR analise het verminderde uitdrukking van AtGSTF2 in wilde-tipe plante getoon na lumichrome behandeling, maar verhoogde uitdrukking in vergelyking met wilde-tipe kontroles is gesien in groeiverwante gene XTH9 en CYCA1 en die jasmonaatverwante geen JAL34. Lumichrome-behandeling van OE-plante het egter gelei tot beduidende verskille in uitdrukkingspatrone vir die lumichrome-responsiewe gene wat bestudeer is in vergelyking met die effekte daarvan op die transkripsies in wildtipe plante, aangesien die ooruitdrukking van AtGSTF2 blykbaar ACO1 en CYCA1 uitdrukking verminder het. Ooruitdrukking van AtGSTF2 het plantegroei verhoog in vergelyking met die wilde-tipe plante, wat daarop dui dat AtGSTF2 'n kritieke rol in ontwikkeling speel. Samevattend, die bewyse van hierdie studie het geen korrelasies tussen lumichrome-verwante groei- of geenuitdrukking-reaksies en AtGSTF2-uitdrukking aan die lig gebring nie, wat daarop dui dat AtGSTF2 heel waarskynlik nie betrokke is by óf lumichrome-persepsie óf vervoer nie. Ten spyte daarvan dat dit een van die mees bestudeerde phi-klas GST's is, is min bekend oor die funksies van AtGSTF2. Hierdie studie stel voor dat AtGSTF2 'n belangriker rol in plantgroei speel as wat voorheen gedink is, en dit word aanbeveel dat toekomstige studies moet fokus op die rol van AtGST2 in plantgroei en -ontwikkeling.en_ZA
dc.description.versionMastersen_ZA
dc.format.extent84 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130512
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshPlant growth-promoting rhizobacteriaen_ZA
dc.subject.lcshArabidopsis thaliana -- Effect of stress on -- Genetic aspectsen_ZA
dc.subject.lcshArabidopsis Glutathione S-Transferaseen_ZA
dc.subject.lcshGrowth (Plants) -- Regulationen_ZA
dc.subject.lcshGlutathione transferaseen_ZA
dc.subject.lcshOverexpression (Genetics)en_ZA
dc.subject.lcshLumichrome -- Treatmenten_ZA
dc.titleIs AtGSTF2 involved in lumichrome perception and transport?en_ZA
dc.typeThesisen_ZA
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