Reaction catalyzed by phytoene desaturase (3,4-didehydrolycopene-forming) (1.3.99.30)

		+	3	acceptor	=			+	3	reduced acceptor
	all-trans-zeta-carotene	+		3 acceptor	=		all-trans-3,4-didehydrolycopene	+		3 reduced acceptor