Sequence 38 from Patent WO2004063358. Sequence 38 from Patent WO2004063359. METHOD FOR THE GENETIC MODIFICATION OF ORGANISMS OF THE GENUS BLAKESLEA,CORRESPONDING ORGANISMS, AND THE USE OF THE SAME. METHOD FOR PRODUCING CAROTENOIDS OR THEIR PRECURSORS USINGGENETICALLY MODIFIED ORGANISMS OF THE BLAKESLEA GENUS,CAROTENOIDS OR THEIR PRECURSORS PRODUCED BY SAID METHOD ANDUSE THEREOF. Method for the genetic modification of organisms of the genus Blakeslea, corresponding organisms, and use of the same. Method for producing carotenoids or their precursors using genetically modified organisms of the Blakeslea genus, carotenoids or their precursors produced by said method and use thereof.