Unlike many isoprenoids, this hormone is not synthesized from mevalonic acid; rather, its precursors are synthesized by the MEP pathway.
The biosynthesis of this hormone has been studied with the fungi Cercospora rosicola and Cercospora cruenta. The cytochrome P450 CYP707A encodes an enzyme that catabolizes this hormone in Arabidopsis. Unlike many isoprenoids, this hormone is not synthesized from mevalonic acid; rather, its precursors are synthesized by the MEP pathway. This hormone is derived from IPP and DMAPP and its immediate precursors include xanthoxin and a namesake aldehyde. It is predominantly catabolized by a namesake 8-prime hydroxylase. It was first identified by Frederick Addicott and associates. This hormone is present in high levels in severe drought conditions because it triggers the closing of stomata. It is antagonistic to auxins and gibberellins. For 10 points, identify this plant hormone that promotes seed dormancy and inhibits growth.
The biosynthesis of this hormone has been studied with the fungi Cercospora rosicola and Cercospora cruenta.
abscisic acid [or ABA; or abscisin II; or dormin; prompt on abscisate]