Genetic characterization of two phototropism mutants of Phycomyces with defects in the genes madI and madJ.

Two Phycomyces genes, madI and madJ, which are involved in phototropism, were characterized by recombination and complementation analyses. The madI gene was located on linkage group IV of the genetic map of Phycomyces, 27 map units away from the gene carA. Complementation and recombination studies involving the genes madD, madE, madF, and madG, in combination with previous genetic studies, show that the recently isolated mad-407 mutation defines a novel behavioural gene, madJ, of Phycomyces. A regulatory role of the madJ gene product in the light-sensory transduction pathway is suggested.