Ascospore progenies from two crosses between a wild single-ascospore
strain and two mutants of Phaeosphaeria nodorum were
obtained in vitro. Cultural characters, sensitivity to carbendazim
(MBC), nitrate utilization, mating type, esterase zymograms and
aggressiveness of these progenies and parents were compared and differences
were detected between the ascospores. The single-ascospore strains from each single ascus could always be grouped into four pairs using a combination of markers. Recombinations
were observed between nitrate non-utilizing phenotype and mating type or
esterase patterns for one cross. For the other cross,
recombinations between MBC resistance and esterase patterns were detected. The values of aggressiveness in each progeny were
distributed along a wide range confirming the polygenic character of aggressiveness
in P. nodorum. No close relationship was
observed between in vitro conidiogenesis, the intensity of leaf
necrosis and the fertile pycnidia production on leaf lesions.