The Effect of Calcium Antagonists on Auxin-induced Elongation and on the Expression of Two Auxin-Regulated Genes in Pea Epicotyls

摘要

Calcium has been implicated in various regulatory roles in plant cells including auxin-induced cell elongation. Treatment of pea epicotyl segments with the calcium chelators, EGTA and chlorotetracycline (CTC), the calcium ionophore, A23187, and channel blocker, D-600, inhibits auxin-induced cell elongation. Depletion of tissue calcium either by EGTA or EGTA and a calcium ionophore does not interfere with the induction of the early auxin inducible mRNAs pIAA4/5 and pIAA6. Similarly, an increase in cytosolic calcium with calcium and calcium ionophore neither induces the hormonally regulated mRNAs nor interferes with their induction by auxin. The calcium channel blocker, D-600, is without effect on the auxin-regulated mRNA induction. The results indicate that calcium is not involved in the rapid induction of IAA4/5 and IAA6 genes in pea tissue. However, a possible role for calcium in the translation of these mRNAs, or in the expression of other auxin-regulated genes, is not excluded.