Fluoride-induced inhibition of starch biosynthesis in developing potato, Solanum tuberosum L., tubers is associated with pyrophosphate accumulation
1991
Viola, R. | Davies, H.V.
Pretreatment of discs excised from developing tubers of potato (Solanum tuberosum L.) with 10 millimolar sodium fluoride induced a transient increase in 3-phosphoglycerate content. This was followed by increases in triose-phosphate, fructose 1,6-bisphosphate and hexose-phosphate (glucose 6-phosphate + fructose 6-phosphate + glucose 1-phosphate). The effect of fluoride is attributed to an inhibition of glycolysis and a stimulation of triose-phosphate recycling (the latter confirmed by the pattern of 13C-labeling [NMR] in sucrose when tissue was supplied with [2-13C]glucose). Fluoride inhibited the incorporation of [U-14C] glucose, [U-14C]sucrose, [U-14C]glucose 1-phosphate, and [U-14C] glycerol into starch. The incorporation of [U-14C]ADPglucose was unaffected. Inhibition of starch biosynthesis was accompanied by an almost proportional increase in the incorporation of 14C into sucrose. The inhibition of starch synthesis was accompanied by a 10-fold increase in tissue pyrophosphate (PPi) content. Although the subcellular localization of PPi was not determined, a hypothesis is presented that argues that the PPi accumulates in the amyloplast due to inhibition of alkaline inorganic pyrophosphatase by fluoride ions.
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