Date of Award

January 2016

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Botany and Plant Pathology

First Advisor

Tesfaye Mengiste

Committee Member 1

Jin-Rong Xu

Committee Member 2

Gurmukh Johal

Committee Member 3

Steven Scofield


Arabidopsis histone acetyltransferase HLS1 has been implicated in the control of seedling development in response to ethylene. Here, we demonstrate that the loss of function hls1 mutant plants have broad effects on the plant development such as early senescence and flowering, seed insensitivity to ABA as well as plant defense responses including enhanced susceptibility to the necrotrophic pathogen Botrytis cinerea and the hemi-biotrophic pathogen Pseudomonas syringae DC3000 strain expressing the effector protein AvrRpm1 strain. We show that HLS1 modulates the expression of WRKY33 gene, a known defense regulator, as well as ABI5 in modulating ABA signaling pathway. The regulation of WRKY33 and ABI5 is through histone H3 acetylation (H3Ac) at the specific loci. Furthermore, pathogen infection enhances HLS1 association and H3Ac at WRKY33 chromatin.