Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences



Committee Chair

Keqiang Wu


This report describes AtHD2C as a regulator of the ABA controlled events. AtHD2C is a member of the HD2-type histone deacetylase family. Results indicated an overall physiological significance for the HD2 proteins as well as a possible involvement in embryo development. In continuum with this, seeds overexpressing AtHD2C were insensitive to ABA, NaCl and mannitol at germination. This phenotype was supported by ABA-responsive gene expression patterns in the transgenic plants that implicated a negative role for AtHD2C in ABA response regulation in this developmental window. Additionally, the AtHD2C transcript accumulation was down-regulated by ABA that was reflected by the down-regulation of AtHD2C promoter driven GUS. In contrast to its function in the germination-post germination phase, AtHD2C seemed to play a positive role in ABA response regulation during the vegetative stage. AtHD2C overexpressing mature plants were able to survive extreme osmotic shock and drought conditions. The expression of AtHD2C promoter driven GUS in all vegetative tissues confirmed the presence of AtHD2C in this stage. The predominantly closed stomata and up-regulated ABA-responsive genes support the stress-tolerant phenotype of the 35S:AtHD2C transgenic plants. The information obtained from this investigation delineates a dual role for the AtHD2C in the regulation of the ABA response signaling in two developmental stages. (Abstract shortened by UMI.).