The plant hormone abscisic acid (ABA) is an important signaling molecule, both during normal processes of growth and development and in responding to environmental stresses such as drought. Many of the responses to ABA involve changes in the expression of particular genes. Some genes are stimulated by the presence of ABA, while other genes are repressed. In cereal grains, the protein kinase, PKABA1, acts as an intermediate in the ABA-signaling pathway. Specifically, the action of PKABA1 brings about an ABA-induced repression of several seed-expressed genes. To understand the precise role of PKABA1 in ABA-signaling, it is necessary to identify proteins that act in concert with PKABA1. Two such proteins, TaABF and TaWD40, have recently been identified and will be the focus of this project. TaABF belongs to the ABF family of transcription factors, a type of protein that binds to DNA sequences and regulates gene activity. To confirm the biological role of TaABF in cells that are responding to ABA, aleurone cells of barley grains will be induced to both overproduce and underproduce TaABF, and the effects on ABA signaling will be observed. In addition, the interaction between PKABA1 and TaABF will be characterized by binding assays, and the ability of PKABA1 to phosphorylate TaABF will be assessed. To confirm that TaABF functions as a transcription factor in modulating gene activity, its DNA-binding properties will be assayed. The biological role of TaWD40 will be assessed in experiments similar to those proposed for TaABF. Broader Impacts: This work will lead to a better understanding of how plants respond to ABA. Such knowledge will support the future development of practical solutions to a number of agricultural problems, such as protection of crop plants from stresses in the field, preharvest sprouting of cereals, and the control of weedy species with strong seed dormancy. The project will contribute to education by involving undergraduate students. The techniques used and the results obtained from the research program will be incorporated into courses taught by the PI so that many students not directly involved in the project will also benefit. The PI's extensive involvement with Introductory Biology courses and with programs for the mentoring of minority students will lead to recruitment of students from groups traditionally underrepresented in the sciences.
