Abstract
ABSTRACTThe plastidic thioredoxin F-type (TrxF) protein plays a key role in plant carbohydrate metabolism. In this work, a gene encoding the TrxF protein, named StTrxF, was successfully isolated from potato and transformed into Arabidopsis thaliana to obtain transgenic plants. Constitutive expression of StTrxF significantly increased the starch accumulation in the transgenic plants. Real-time quantitative polymerase chain reaction analysis showed that constitutive expression of StTrxF up-regulated the expression of the adenosine diphosphate (ADP)-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2) and soluble starch synthases (AtSSS I, AtSSS II, AtSSS III and AtSSS IV) genes involved in starch biosynthesis in the transgenic A. thaliana plants. Meanwhile, enzymatic analyses indicated that the major enzymes (AGPase and SSS) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to the wild-type. These results suggest that StTrxF may improve the starch content of A. thaliana by up-regulating the expression of the related genes and increasing the activities of the major enzymes involved in starch biosynthesis. The StTrxF gene may be applied for increasing starch accumulation of plants in the future.
Highlights
Starch, as a main source of nutrition in human and animal diet, is a major storage carbohydrate in plants, which plays a fundamentally important role in plant survival and adaptation to varying environmental conditions [1,2]
Four major enzymes are involved in starch biosynthesis: adenosine diphosphate (ADP)-glucose pyrophosphorylase (AGPase), starch synthase, starch branching enzyme and starch debranching enzyme [4,5]
The StTrxF (Genbank accession No XM_006345 713) gene was cloned by reverse transcription polymerase chain reaction (RT-PCR)
Summary
As a main source of nutrition in human and animal diet, is a major storage carbohydrate in plants, which plays a fundamentally important role in plant survival and adaptation to varying environmental conditions [1,2]. Starch is an insoluble glucan composed of two glucose polymers: amylose and amylopectin. Amylose mainly comprises linear chains that are linked by a-1,4 O-glycosidic bonds, whereas amylopectin is highly branched and contains 5%–6% a-1,6 O-glycosidic bonds to generate glucan branches of various lengths [3]. Four major enzymes are involved in starch biosynthesis: adenosine diphosphate (ADP)-glucose pyrophosphorylase (AGPase), starch synthase, starch branching enzyme and starch debranching enzyme [4,5]. Redox regulation, which has been widely researched in plant starch biosynthesis, is related to the coordination of enzymes involved in starch degradation [6,7]. The redox regulation of the AGPase [8] and b-amylase 1 (BAM1) activity [9,10] are all widely known
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