TY  - THES
AB  - The biosynthesis of flavonoids in Arabidopsis thaliana can be interpreted as a model system for the regulation of gene expression and metabolism in plants. The flavonoids can be subdivided into flavonols, anthocyanins and proanthocyanidins. A majority of the transcription factors, which are involved in the developmental and tissue specific accumulation of these metabolites, is well known. In this work a number of regulators of the flavonoid metabolism was analysed in detail. Each of these regulators was mainly involved in the biosynthesis of one of the three subclasses of flavonoids. Either new functions of the regulators could be observed or tools for further investigations concerning their functions were generated.
The C2H2 zinc finger protein TT1 was analysed as an example for a regulator of the seed coat specific proanthocyanidin accumulation. A stable knock out of the tt1 gene was generated using a transposon insertion line and the previously assumed tt1 knock out phenotype was confirmed. A number of new TT1 alleles was identified by the TILLING method. Those alleles are now available for the molecular characterisation of TT1. Moreover five homologues of TT1, which form the WIP gene family in A. thaliana together with TT1, were analysed concerning expression profiles, intracellular localisation, knock out and overexpression phenotypes and possible target genes. In tt1 proanthocyanidins are mainly found in the micropylar and chalazal area of the seeds. To analyse this tissue specific accumulation in more detail, a population of EMS mutagenised tt1 plants was generated. This population is available now for further investigations, which could lead to new insights in the molecular function of TT1 or in the different regulation of gene expression in the micropylar and chalazal areas of the seed. The PFG genes encode the R2R3-MYB transcription factors MYB11, MYB12 and MYB111, which are flavonol specific regulators. They are known to activate some genes, which are encoding enzymes of the flavonoid metabolism, like for example CHS and FLS. There were hints for further candidate target genes, resulting from ATH1 gene chip analysis. In this work three of these candidate target genes could be confirmed experimentally by using co-transfection assays. Besides R2R3-MYB transcription factors R3-MYB proteins are found in A. thaliana. An involvement in processes leading to the determination of the cell identity of trichomes and root hairs has been shown for several R3-MYBs. In this work a negatively regulating effect of the R3-MYB protein MYBL2 on the activation of the DFR gene, which is involved in anthocyanin formation, has been shown. This is the first known example of an R3-MYB gene, which is involved in flavonoid metabolism in plants.
DA  - 2008
KW  - Zinkfinger
KW  - WIP-Proteine
KW  - Sekundärmetabolit
KW  - Flavonoide
KW  - Proanthocyanidine
KW  - Anthocyane
KW  - Ackerschmalwand
KW  - Flavonoidstoffwechsel
KW  - Samen
KW  - Transkriptionsfaktor
LA  - ger
PY  - 2008
TI  - Untersuchungen zu Regulatoren der Flavonoidbiosynthese in Arabidopsis thaliana : eine Studie zu neuen Funktionen bekannter Proteinklassen
UR  - https://nbn-resolving.org/urn:nbn:de:hbz:361-12918
Y2  - 2024-11-22T04:33:13
ER  -