Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biology

Supervisor

Tian, Lining

2nd Supervisor

Henry, Hugh

Co-Supervisor

Abstract

Despite evidence that specific histone deacetylases (HDACs) play important roles in the abiotic stress responses of plants, their roles in the stress responses of monocot plants remain largely unexplored. I investigated a HDAC gene, Bradi3g08060 (BdHD1), in the monocot Brachypodium distachyon (Brachypodium). The Brachypodium BdHD1-overexpression (OE) plants displayed a hypersensitive phenotype to abscisic acid (ABA) and exhibited higher survival under drought conditions. Conversely, the BdHD1-RNAi plants were insensitive to ABA and had low survival under drought stress. Based on ChIP-Seq at the genome-wide level, overexpressing BdHD1 led to lower H3K9 acetylation at the transcriptional start sites of 230 genes than in wild type plants under the drought treatment. I validated the ChIP-Seq data for 10 transcription factor genes from the 230 drought-specific genes. These genes exhibited much lower expression in BdHD1-OE compared to the wild type plants under drought stress. I further identified an ABA-inducible transcription factor gene, BdWRKY24 and analysis showed this gene was repressed in BdHD1-OE plants but highly expressed in BdHD1-RNAi plants under drought stress. These results indicate that BdHD1 plays a positive role in ABA sensitivity and drought stress tolerance, and they provide a link between the role of BdHD1 and the drought stress response at a genome-wide level in Brachypodium.

Available for download on Wednesday, July 01, 2020

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