Dissertation
Molecular genetic analysis of two plant-specific gene families, SOFL and AHL, in Arabidopsis thaliana
Doctor of Philosophy (PhD), Washington State University
05/2015
Handle:
https://hdl.handle.net/2376/118334
Abstract
SOFL (SOB FIVE-LIKE) and AHL (AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED) are plant specific gene families in Arabidopsis. This study focuses on characterizing gene members in both families using over-expression analysis.
There are 29 AHLs in Arabidopsis but only eleven have been characterized at the molecular and genetic level. This study focused on two AHL members, AtAHL6 and AtAHL20, which belong to two different phylogenetic clades. Histochemical analysis of plants harboring proAtAHL6-GUS and proAtAHL20-GUS transcriptional fusion constructs revealed distinct expression patterns. Plants harboring the proAtAHL6-GUS construct showed GUS signal in root tips of Arabidopsis seedlings but not in rosette leaves and floral structures. ProAtAHL20-GUS seedlings revealed GUS activity in roots, hypocotyls and cotyledons. AtAHL20 was also expressed in rosette leaves and floral structures. Over-expression analysis of wild-type and aberrant versions of AtAHL6 and AtAHL20 proteins revealed that they are involved in regulation of flowering time in an opposite manner. 35S:AtAHL6 transgenic plants flowered earlier than wild-type plants in a photoperiod dependent manner. In contrast, 35S:AtAHL20 transgenic plants exhibited delayed flowering compared to wild-type plants in a photoperiod independent manner. Over-expression of AtAHL6 and AtAHL20 proteins carrying point mutations in a highly conserved motif, the AT-Hook, led to the loss of AtAHL20’s over-expression phenotype but not AtAHL6’s.
Gain-of-function and loss-of-function analyses of three founding SOFL family members; SOB5, AtSOFL1 and AtSOFL2, suggested that they are involved in cytokinin-mediated plant development. Database searches led to the retrieval of 195 sequences from dicotyledon and monocotyledon species. Arabidopsis thaliana has 11 SOFL members. Multiple sequence alignment of all SOFLs from 57 species revealed two conserved domains; SOFL-A and SOFL-B. Structure/function analysis using SOB5, AtSOFL1 and AtSOFL2 showed that these domains are important for function. Subcellular localization studies using the founding SOFL members showed that they localize in the nucleus. A sob5-2 sofl1RNAi sofl2-1 triple mutant did not show any additional phenotypes versus wild-type plants, suggesting that there is still functional redundancy among the 11 SOFLs in Arabidopsis thaliana.
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Details
- Title
- Molecular genetic analysis of two plant-specific gene families, SOFL and AHL, in Arabidopsis thaliana
- Creators
- Reuben Tayengwa
- Contributors
- Michael M Neff (Advisor)Amit Dhingra (Committee Member)Hanjo A Hellmann (Committee Member)Camille M Steber (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Program in Molecular Plant Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 129
- Identifiers
- 99900581839301842
- Language
- English
- Resource Type
- Dissertation