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Zheng, Renwei

University of British Columbia

Seeds hold immense biological and economic importance as they safeguard and perpetuate plant life. Successful seed development and seedling establishment rely on a series of physio-morphological transformations. Transcription factors (TFs) form an intricate network to tightly regulate gene expression throughout various stages of seed development. The master TFs LEAFY COTYLEDON 1 (LEC1), ABA INSENSITIVE 3 (ABI3), FUSCA 3 (FUS3), and LEC2, collectively known as LAFL, possess significant functions in seed development and maturation. Transcriptional repressors VIVIPAROUS1/ABI3-LIKE1 (VAL1) and VAL2 inhibit the expression of LAFL genes, and their double mutants val1 val2 lead to delayed germination and derepression of the LAFL. VAL proteins recruit Polycomb Repressive Complex 1 (PRC1) and PRC2 to repress target genes epigenetically. A novel transcriptional co-repressor, Arabidopsis thaliana SEED DORMANCY 4-LIKE (AtSDR4L), and its paralog Dynamic Influencer of Gene expression 1 (DIG1), are expressed in maturing seeds and young seedlings. Notably, mutations in AtSDR4L resemble to val1 val2 mutants at the phenotypic and molecular level. However, little is known about the mechanistic connection between AtSDR4L, DIG1, and the VALs. In this study, the protein-protein interactions between AtSDR4L, DIG1 and VAL1, VAL2 were investigated. Yeast Two-Hybrid (Y2H) results corroborate a direct interaction between DIG1 and VAL2, which is dependent on the beta barrel structure of DIG1 and N-terminal of VAL2. However, no strong interaction was observed between AtSDR4L and VALs (Chapter 2). To verify the DIG1-VAL2 interaction, a Bimolecular Fluorescence Complementation (BiFC) assay was performed, (Chapter 3). Complementation lines of AtSDR4L were developed and examined, suggesting that the functional fragment is located at the N-terminus (Chapter 4). In summary, a direct interaction was observed between DIG1 and VAL2, which facilitates the recruitment of PRC1 and PRC2 to repress target gene expression. Investigations of the functional domains of DIG1, AtSDR4L, and VAL2 contribute to a better understanding of the mechanisms underlying their actions, thereby providing a pathway for further exploration into the intricate network of transcriptional regulation during seed development.

Text

2024-11-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86397

Botany

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/