Genetic Analysis of Redundant and Diverged MADS-box Genes Involved in Floral Development in Petunia hybrida
In case you object to the disclosure of your thesis, you can contact email@example.com
[S.l. : s.n.]
Number of pages
RU Radboud Universiteit Nijmegen, 18 december 2006
Promotor : Gerats, A.G.M.
Display more detailsDisplay less details
Flowers play a central role in angiosperm biology. Genetic studies of floral mutants in Arabidopsis and Antirrhinum laid the basis for the ABC model. Most of these genes are MADS-box genes and their proteins act as transcription factors in binding DNA as dimers. In Petunia, B-class genes are duplicated. PhGLO1 and PhGLO2 belong to the GLO/PI lineage; PhDEF and PhTM6 belong to the DEF/AP3 lineage. Functional analysis has been performed by creating single, double and triple mutant combinations with available transposon insertion alleles of phglo1, phglo2, phtm6, and phdef (EMS). Single and double mutants were also crossed with the A-function mutant blind. Expression of B- and C-class genes in wild-type and various mutant flowers was determined by real-time PCR, a yeast two-hybrid assay was performed, in situ localization for the PhGLO2 and PhTM6 transcripts, and an RNAi strategy was applied to downregulate PhTM6. PhTM6 was also overexpressed in wild-type and phdef mutant backgrounds. Overall, petal development in Petunia is controlled by the concerted action of PHDEF/PHGLO1 and PHDEF/PHGLO2 heterodimers. Function, regulation and interaction of PHTM6 are different compared to the known euAP3-type DEF/AP3-like proteins. Our results indicate that PHDEF/PHGLO2, PHDEF/PHGLO1 and PHTM6/PHGLO2 heterodimers are sufficient to determine stamen identity. Expression maintenance of PhDEF, PhGLO1, and PhGLO2 is interdependent in the second whorl. Our results also indicate PHDEF and PHTM6 act redundantly in maintaining PhGLO1 and PhGLO2 expression in the third whorl. These results show that PHDEF and PHTM6 proteins have functionally diverged and are differently regulated. PHDEF functions as a classical euAP3 type protein in the determination of petals and stamens. PHTM6, as a B-type protein, is only involved in conferring stamen identity. Noteworthy, ectopic expression of PhTM6 is able to restore petal development in a phdef mutant background and it also induces development of ectopic petals in wild-type flowers
Upload full text
Use your RU credentials (u/z-number and password) tolog in with SURFconextto upload a file for processing by the repository team.