Abstract
Antagonistic interaction between endogenous sugar status and abscisic acid (ABA) signaling was examined in Arabidopsis. Endogenous ABA content in suspension-cultured cells and seedlings grown in the dark increased following reduction in endogenous sugar content. Expression of Arabidopsis 9-cis epoxycarotenoid dioxygenase (AtNCED ) genes, which encode key enzymes for ABA biosynthesis and ABSCISIC ACID INSENSITIVE 3 (ABI 3) which controls ABA sensitivity was enhanced by sugar starvation. GUS activity analysis in transgenic Arabidopsis carrying GUS controlled by the ABI3 promoter showed that ABI3 was expressed, when sugar was depleted and thereby leaf development was terminated, in the shoot apical meristem. We conclude that sugar depletion promotes ABA signaling to terminate leaf development in Arabidopsis seedlings. Antagonistic effects of sugar on ABA signaling in the process of vegetative quiescence processs are discussed.
