ABA Catabolism and Mode of Action of Diniconazole
The level of ABA in any particular tissue of a plant is determined by the rate of its biosynthesis and catabolism.
However catabolism of ABA is predominant in germinating seeds [33]. There are several metabolic pathways of
ABA catabolism [22], of which oxidative pathway is the major one leading to the formation of PA that is triggered
by hydroxylation at C-8’ by the enzyme - ABA 8’-hydroxylase to produce 8’-hydroxy ABA [13]. Diniconazole
is an inhibitor of the ABA-catabolizing enzyme, i.e. ABA 8’-hydroxylase, resulting in accumulation of
free ABA in the cell. It is evident from the present study that diniconazole inhibits the formation of bound form of ABA in a concentration dependant manner and subsequently the amount of free ABA increased in the cotyledonary
tissues.