Plastid 2-oxoglutarate-dependent dioxygenases mediate stereoselective C14β-hydroxylation in cardenolide biosynthesis

. Our findings uncover diverse evolutionary mechanisms-such as the co-opted enzyme pair, atypical subcellular localization, and enzyme convergence at the subfamily level-that underscore the remarkable ability of plants to independently evolve complex metabolic pathways for specialized metabolism. These findings also identify enzyme classes that catalyze a rare stereo-inverted hydroxylation reaction unique to cardenolide biosynthesis.