Constitutive expression of SlTrxF increases starch content in transgenic Arabidopsis

Abstract

The plastidic thioredoxin F-type (TrxF) protein plays an important role in plant saccharide metabolism. In this study, a gene encoding the TrxF protein, named SlTrxF, was isolated from tomato. The coding region of SlTrxF was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana. The transgenic Arabidopsis plants exhibited increased starch accumulation compared to the wild-type (WT). Real-time quantitative PCR analysis showed that constitutive expression of SlTrxF up-regulated the expression of ADP-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2) and soluble starch synthase (AtSSS I, AtSSS II, AtSSS III and AtSSS IV) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses showed that the major enzymes (AGPase and SSS) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to WT. These results suggest that SlTrxF may improve starch content of Arabidopsis by regulating the expression of the related genes and increasing the activities of the major enzymes involved in starch biosynthesis.

StTrxF, a potato plastidic thioredoxin F-type protein gene, is involved in starch accumulation in transgenic Arabidopsis thaliana

“…SSS can be grouped into four types, SSS I, SSS II, SSS III and SSS IV [3][4][5]. A large body of evidence has illustrated that up-regulation of these genes could increase starch accumulation in plants [5,[18][19][20][21][31][32][33][34][35]. In our study, a significant increase of SSS activity was also observed in transgenic plants ( Figure 5).…”

Constitutive expression of StAATP, a potato plastidic ATP/ADP transporter gene, increases starch content in transgenic Arabidopsis

“…SS can be grouped into five types, granulebound starch synthase (GBSS) and four types of soluble starch synthases (SSS): SSS I, SSS II, SSS III and SSS IV [5,6,31]. A large body of evidence has illustrated that up-regulation of these genes can increase starch accumulation in plants [30][31][32][33][34][35][36]. In our study, systematic upregulation of these genes (AtGBSS I, AtGBSS II, AtSSS I, AtSSS II, AtSSS III, AtSSS IV, AtSBE I and AtSBE II) involved in the starch biosynthesis pathway was observed in transgenic plants ( Figure 6).…”

NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves

“…Interestingly, the ability of Arabidopsis SSI to be redox-activated was confirmed, with Trx f being the most effective activator in vitro [37]. Supporting this idea, Arabidopsis plants overexpressing Trx f from different species displayed increased SS expression and activity [73,74].…”