ARS | Publication request: Role of metabolism in ABA homeostasis during potato tuber dormancy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 2008
Publication Date: April 1, 2009
Citation: Suttle, J.C., Destefano-Beltran, L. 2009. Role of Metabolism in ABA Homeostasis During Potato Tuber Dormancy [abstract]. American Journal of Potato Research. 86(2): 159.

Technical Abstract: Endogenous hormones play a essential role in the regulation of potato tuber dormancy. Abscisic acid has been shown to be critically involved in tuber dormancy induction and maintenance. Genes encoding enzymes catalyzing the terminal steps of ABA synthesis and metabolism have been cloned from tuber tissues and potential regulatory steps have been identified (Plant Mol. Biol. 61: 687, 2006). In potato tubers, ABA is metabolized primarily via oxidation to phaseic acid (PA) and ultimately accumulates as dihydro-phaseic acid and glucose ester. The rate-limiting step of this pathway is catalyzed by ABA-8'-hydroxylase, a cytochrome P-450 mixed-function oxidase. Six StCYP707a genes encoding this enzyme have been cloned from tuber tissues and three have been shown to be enzymatically active when expressed in yeast cells. In vitro enzyme activity is completely inhibited by a variety of P-450 mixed function oxidase inhibitors. Application of these inhibitors to developing microtubers results in a pronounced increase in endogenous ABA content. These results suggest that one or more of these enzymes plays a critical role in ABA homeostasis during tuber dormancy and may therefore be candidates for targeted breeding and/or directed gene manipulation to reduce postharvest losses due to uncontrolled sprouting. (Poster, Physiology, PAA membership #1977)