Proteomic characterization of tissue expansion of rice scutellum stimulated by abscisic acid.

We found that appropriate treatment with a highly potent and long-lasting abscisic acid analog enhanced the tissue expansion of scutellum during early seedling development of rice, accompanied by increases of protein and starch accumulation in the tissue. A comparative display of the protein expression patterns in the abscisic acid analog-treated and non-treated tissues on two dimensional gel electrophoretogram indicated that approximately 30% of the scutellar proteins were induced by abscisic acid. The abscisic acid-induced proteins included sucrose metabolizing, glycolytic, and ATP-producing enzymes. Most of these enzyme proteins also increased during the seedling growth. In addition, the expression of some isoforms of UDP-glucose pyrophosphorylase, 3-phosphoglycerate kinase, and mitochondrial ATP synthase beta chain was stimulated in the scutellum, with suppressed expression of alpha-amylase. We concluded that abscisic acid directly and indirectly stimulates the expression of numerous proteins, including carbohydrate metabolic enzymes, in scutellar tissues.