The Role of Calcium in Mediating SIIAAs Expression in Tomato Pedicel Explants

In order to illuminate the effect of calcium on the IAA signal transduction, we studied the expression of eight SlIAA genes which were up-regulated by calcium during the abscission after short-term (1 h) and long-term (16 h) treatments with calcium, IAA and calcium inhibitors. The results indicated that calcium induced SIIAAs expression in 1 h at low concentration, EGTA affected little SIIAAs expression; it also increased IAA-induced transcript level of SIIAAs, TFP (named trifluoperazine) decreased most SIIAAs expression below the level of calcium combined with IAA-induced expression, except for SlIAA17. Long-term treatment of calcium or calcium inhibitors suppressed some SIIAAs expression, whereas TFP enhanced all SIIAAs expression. Interestingly, SlIAA29 was induced by most treatments excluding 16 h EGTA.