Effect of NCED3 gene estradiol-induced expression on ABA biosynthetic genes and metabolic enzyme gene expression.

There has been a heated debate on the existence of positive feedback regulation in endogenous ABA signaling system.By estradiol-induced gene expression system,the over-expression of key enzyme NCED3 gene in ABA synthesis is given.It is found the over-expression of key enzyme NCED3 gene has increased the level of endogenous ABA,thus enchanced the ABA synthase gene ZEP,AAO3 expression level,and also activated CYP707A3 metabolic enzyme gene expression.Studies have shown that endogenous ABA signaling level is controlled collaboratively by both positive and negative feedback regulation.