Didymium Iridis Reproductive Systems: Additions and Meiotic Drive

ABSTRACT

Three heterothallic Mexican isolates (Mex 1, Mex 2, and Mex 3) of Didymium iridis belong to the reproductively isolated A5 mating series of this morphospecies. This was unexpected in that the sole previous A5 isolate was from Georgia and the Mexican isolates were collected in southern Mexico adjacent to the Central American A1 series region. The Mexican isolates were also unusual in that mating alleles did not generally segregate in a normal 1:1 ratio. The A5³ or A5⁴ 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 Central American A1 mating series. Each of these isolates was collected as a haploid selfed plasmodium which contained a single mating type respectively designated A1¹³ and A1¹⁴. Four nonheterothallic isolates from California (Ca 8), Guatemala (Gua 1), Japan (Jap 1) and South Africa (SA 2) were also investigated.

Key Words:

• apomixes
• Didymium iridis
• heterothallism
• mating types
• meiotic drive