Calcium requirement for ethylene-dependent responses involving 1-aminocyclopropane-1-carboxylic acid oxidase in radicle tissues of germinated pea seeds

The Ca 2+ requirements of ethylene-dependent responses were investigated in germinating seeds of Pisum sativum L. using 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase ( Ps-ACO1 ), ACC synthase ( Ps-ACS2 ) and class I b b b -1,3-glucanase as molecular markers. Ethylene biosynthesis and responsiveness are localized to the elongation and differentiation zones of the pea radicle. Ethylene treatment induced ectopic root hair formation in the cell elongation zone and promoted root hair elongation growth in the radicles of germinated seeds. Characterized Ca 2+ antagonists, including EGTA, lanthanum, verapamil, ruthenium red, W7, lithium and neomycin, were used to test for the involvement of the apoplastic and the intracellular Ca 2+ -pool, the