Sugar-Controlled Ca^<2+> Uptake and α-Amylase Secretion in Cultured Cells of Rice : (Oryza sativa L.)

概要

論文の詳細を見る
Sugar starvation-induced synthesis and extracellural liberation of α-amylase molecules in suspension-cultured cells of rice (Oryza sativa L.) required Ca^<2+> although the level of translatable α-amylase mRNA was not affected in the presence of Ca^<2+>. Sugar depletion markedly stimulated Ca^<2+> uptake by rice cells and sucrose supplementation reduced it. Immunohistochemical and electron probe microanalyzer studies indicated an apparent resemblance between the distribution pattern of Ca^<2+> and that of α-amylase molecules induced in the sugar-depleted cells. Ca^<2+> uptake was reduced by sucrose, maltose, fructose, and glucose similarly at more than 5 mM, but was unaffected by mannitol (88 mM), 6-deoxy-D-glucose (10 mM), and 3-O-methyl-D-glucose (10mM). Furthermore, an effective Ca^<2+> channel blocker, La^<3+> significantly inhibited the Ca^<2+> uptake and the synthesis and extracellural liberation of α-amylase molecules in the absence of sucrose, while a general P-type ATPase inhibitor, vanadata greatly stimulated both in the presence of sucrose. We concluded that, by controlling the Ca^<2+> uptake, metabolic sugars regulate the protein synthesis and posttranslational secretory processes of α-amylase molecules in rice cells.
日本植物生理学会の論文