Isolation and characterization of sexual sporulation mutants of Aspergillus nidulans.

K. Swart, D. van Heemst, M. Slakhorst, F. Debets and C. Heyting

Author address: 

Department of Plant Sciences, Wageningen University, 6703 HA Wageningen, The Netherlands.


For the genetic dissection of sexual sporulation in Aspergillus nidulans, we started a collection of ascosporeless mutants. After mutagenization of conidiospores with high doses of UV, we isolated 20 mutants with defects in ascospore formation. We crossed these mutants in two successive rounds with the wildtype strain. Eighteen of the 20 isolated mutants produced progeny with the original mutant phenotype in these crosses, and these mutants were further analyzed. All 18 analyzed mutations were recessive to wildtype. We assigned them to 15 complementation groups, based on crosses between mutants. The mutants could be classified as follows according to their cytological phenotype: (1) no croziers; (2) arrest at pre-karyogamy; (3) arrest in early meiotic prophase; (4) arrest in late meiotic prophase; (5) arrest in meiotic metaphase I; (6) defective post meitotic mitosis and/or deliniation of ascospores; and (7) slow progression through the post meiotic stages of ascospore formation. A large proportion of the mutants, namely 11 out of 18, arrested in meiotic prophase or metaphase I. We discuss a possible approach for isolating the wildtype aleles of the genes that carry the sexual sporulation mutations

abstract No: 


Full conference title: 

21st Fungal Genetics Conference
    • Fungal Genetics Conference 21st (2000)