Auxin-polyamine interaction with the calcium-controlled secretion of peroxidase by sugarbeet cells

Spermidine and ornithine given to normal auxin-requiring cell suspensions of sugarbeet inhibited peroxidase secretion in the absence of Ca(2+). Habituated (organogenic or not) cells did not respond. Both compounds counteracted the Ca(2+) - promoted enzyme secretion by three cell lines. Auxins (2,4-D and BSAA) did not modify the extracellular level of peroxidase activity in the absence of Ca(2+) When Ca(2+) was added, auxins increased its effect in normal cells and had practically no effect in habituated cells. The inhibitory effect of spermidine and ornithine was somewhat reduced by auxins in normal cells and increased in habituated cells. It was hypothesized that the effect of auxins did not involve the mediation of polyamines and that both types of compounds directly interacted with Ca(2+) at the membrane level.