XVI International Botanical Congess

A gene encoding a conventional kinesin in the filamentous ascomycete, Nectria haematococca, was cloned, sequenced and mutated. The mutant underwent normal mitosis, but exhibited abnormal growth, morphogenesis and organelle distribution. A gene encoding cytoplasmic dynein was also cloned, sequenced and mutated. Mitotic nuclei in this mutant had few or no astral microtubules, anaphase B spindles elongated at half the normal rate, and active spindle pole body motility and nuclear migration did not occur, resulting in nonuniform distribution of post- mitotic nuclei. This mutant also had small Spitzenkorper, grew at only 33% the normal rate, and its hyphae were spiral and highly branched. Two genes encoding kinesin-related proteins have been cloned and sequenced, and one has been successfully mutated. We are examining this mutant for a mitotic phenotype.