Trehalose Induces the ADP-Glucose Pyrophosphorylase Gene,ApL3, and Starch Synthesis in Arabidopsis

Abstract

In Arabidopsis, genes encoding functional enzymes for the synthesis and degradation of trehalose have been detected recently. In this study we analyzed how trehalose affects the metabolism and development of Arabidopsis seedlings. Exogenously applied trehalose (25 mm) strongly reduced the elongation of the roots and, concomitantly, induced a strong accumulation of starch in the shoots, whereas the contents of soluble sugars were not increased. When Arabidopsis seedlings were grown on trehalose plus sucrose (Suc), root elongation was restored, but starch still accumulated to a much larger extent than during growth on Suc alone. The accumulation of starch in the shoots of trehalose-treated seedlings was accompanied by an increased activity of ADP-glucose pyrophosphorylase and an induction of the expression of the ADP-glucose pyrophosphorylase gene, ApL3. Even in the presence of 50 mm Suc, which itself also slightly induced ApL3, trehalose (5 mm) led to a further increase in ApL3 expression. These results suggest that trehalose interferes with carbon allocation to the sink tissues by inducing starch synthesis in the source tissues. Furthermore, trehalose induced the expression of the ␤-amylase gene, AT-␤-Amy, in combination with Suc but not when trehalose was supplied alone, indicating that trehalose can modulate sugar-mediated gene expression.

Differential Pattern of Expression and Sugar Regulation of Arabidopsis thaliana ADP-glucose Pyrophosphorylase-encoding Genes

“…Coordinated sugar transcriptional regulation of several starch biosynthetic genes has been suggested by numerous works (19). Induction of several ADP-Glc PPase-encoding genes has been reported in different species including Arabidopsis (16,(25)(26)(27)(28). We show that, under physiological conditions, only two ADP-Glc PPaseencoding genes, ApL3 and ApL4, are controlled by sugars (Figs.…”

“…5), suggesting that different signaling pathways may be involved in the transcriptional control of ApL3 and ApL4 by sugars. To date, trehalose-regulated expression of ApL3 has been shown (28), but no data regarding ApL4 regulation have been published. Trehalose feeding rescues the phenotype of the adg2-1 mutant lacking ApL1 (17), and it was proposed that under these conditions, APL3 would substitute for APL1.…”

“…With regard to the starch synthesis pathway, it has been shown that sugars mediate the induction of several genes of the pathway (20 -23), including some genes encoding for ADP-Glc PPase (24 -26), and also trigger the redox regulation of ADP-Glc PPase activity (12,13). Induction of ApL3 mRNA levels in response to sucrose (15,27) and trehalose (28) has been described in Arabidopsis leaves and seedlings. However, information concerning the effect of sugars on the expression of the other ADP-Glc PPase genes from Arabidopsis is scarce.…”

Categories of Resistance to Greenbug (Homoptera: Aphididae) Biotype I in <B> <I>Aegilops tauschii</I> </B> Germplasm

“…Singh et al (2011) suggested that TPS11 provides a threshold level of 'signaling' trehalose that is essential for regulating Arabidopsis defense against GPA, including the up-regulation of PAD4 expression and full extent of starch accumulation. Trehalose application promotes starch accumulation in Arabidopsis leaves (Wingler et al, 2000;Kolbe et al, 2005;Singh et al, 2011). As shown in other studies, the ability of trehalose to promote starch accumulation in GPAinfested plants could be due to the inhibition of starch turnover (Ramon et al, 2007) and/or the redox activation of AGPase, a key enzyme in starch synthesis, by trehalose-6-phosphate (Paul et al, 2008).…”

Raising salinity tolerant rice: recent progress and future perspectives

“…Trehalose has been shown to stabilize dehydrated enzymes, proteins and lipid membranes efficiently, as well as protect biological structures from damage during desiccation. In the plant kingdom, most species do not seem to accumulate detectable amounts of trehalose, with the exception of highly desiccation-tolerant resurrection plant, Selaginella lepidophylla (Wingler, 2002). In bacteria and yeast, trehalose is synthesized in a two-step process: trehalose-6-phosphate is first formed from UDP-glucose and glucose-6-phosphate in a reaction catalyzed by trehalose-6-phosphate synthase (TPS).…”