Constitutive Expression of <i>VvAATP</i> Increases Starch Content in Transgenic <i>Arabidopsis</i>

Abstract

Abstract:A plastidic ATP/ADP transporter (AATP) plays a crucial role in importing ATP from the cytosol into plastids, leading to the increase the ATP supply to facilitate anabolic synthesis in heterotrophic plastids of dicotyledonous plants. The regulatory role of the grapevine VvAATP gene in increasing starch accumulation has not been investigated. In this study, the VvAATP gene was successfully isolated from grapevine and transformed into Arabidopsis. Constitutive expression of VvAATP significantly increased starch accumulation in transgenic Arabidopsis plants. Real-time quantitative PCR analysis showed that constitutive expression of VvAATP up-regulated the expression of the genes related to starch biosynthesis pathway, including phosphoglucomutase, ADP-glucose pyrophosphorylase (AGPase), granule-bound starch synthase (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE) genes, in transgenic Arabidopsis plants. Meanwhile, enzymatic analyses indicated that the major enzymes (AGPase, GBSS, SSS and SBE) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to the wild-type (WT). These results indicate that VvAATP may improve starch content of Arabidopsis by up-regulating the expression of the related genes and increasing the activities of the major enzymes invovled in starch biosynthesis. All these findings suggest that the VvAATP gene may be applied for increasing starch accumulation of plants in the future.