Ciereszko I, Kleczkowski LA
Expression of several genes involved in sucrose/starch metabolism as affected by different strategies to induce phosphate deficiency in Arabidopsis
Acta Physiologiae Plantarum: 2005 27:147-155
The effects of inorganic phosphate (Pi) deficiency on expression of genes encoding ADP-glucose pyrophosphorylase small and large subunits (ApS and ApL1, ApL2, ApL3 genes), UDP-glucose pyrophosphorylase (Ugp gene), sucrose synthase (Sus]), Soluble and insoluble acid invertases (Invand Invcw) and hexokinase (Hxk1 gene), all involved in carbohydrate metabolism, were investigated in Arabidopsis thaliana (L.) Heynh. We used soil-grown pho mutants affected in Pi status, as well as wild-type (wt) plants grown under Pi deficiency conditions in liquid medium, and leaves of wt plants fed with D-mannose. Generally, ApS, ApL1, Ugp and Inv genes were upregulated, although to a varied degree, under conditions of Pi-stress. The applied conditions had differential effects on expression of other genes Studied. For instance, Susl was downregulated in phol (Pi-deficient) mutant, but was unaffected in wt plants grown in liquid medium under P-deficiency. Mannose had distinct coil contration-dependent effects on expression of genes under Study, possibly reflecting a dual role of mannose as a sink for Pi and as glucose analog. Feeding- Pi (at up to 200 mM) to the detached leaves of wt plants strongly affected the expression of ApL1, ApL2, Sus1 and Inv genes, possibly due to an osmotic effect exerted by Pi. The data Suggest that ADP-glucose and UDP-glucose pyrophosphorylases (ent, 0 zymes indirectly involved in Pi recycling) as well as invertases (sucrose hydrolysis) are transcriptionally regulated by Pi-deficiency, which may play a role in homeostatic mechanisms that acclimate the plant to the Pi-stress conditions.
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