DIDYMIUM-IRIDIS REPRODUCTIVE SYSTEMS - ADDITIONS AND MEIOTIC DRIVE

Three heterothallic Mexican isolates (Mex 1, Mex 2, and Mex 3) of Didy mium iridis belong to the reproductively isolated A5 mating series of this morphospecies. This was unexpected in that the sole previous A5 i solate was from Georgia and the Mexican isolates were collected in sou thern Mexico adjacent to the Central American Al series region. The Me xican isolates were also unusual in that mating alleles did not genera lly segregate in a normal 1:1 ratio. The A5(3) or A5(4) mating types, when present in a plasmodium, caused the partial or total elimination of the other mating allele during growth or sporulation. Isolates from Guatemala (Gua 2) and Panama (Pan 8) were found to belong to the Cent ral American Al mating series. Each of these isolates was collected as a haploid selfed plasmodium which contained a single mating type resp ectively designated A1(13) and A1(14). Four nonheterothallic isolates from California (Ca 8), Guatemala (Gua 1), Japan (jap 1) and South Afr ica (SA 2) were also investigated.