A Cytological Comparison of Germinating Aeciospores in the Cronartium coleosporioides Complex

Abstract

SUMMARYDifferent patterns of nuclear behavior are found in the aecial stages of members of the Cronartium coleosporioides complex. Nuclear behavior in the heteroecious members, Peridermium stalactiforme and Peridermium filamentosum, follows the classical pattern for macrocyclic rust fungi. Binucleate aeciospores produce binucleate germ tubes. The autoecious fungi Peridermium harknessii and Peridermium cerebroides are not separable from each other on a cytological basis. The spores, which are mostly binucleate, produce germ tubes that become uninucleate by septation. Meiosis was not proved. A non-Castilleja-infecting race of P. filamentosum (probably autoecious) exhibits unusual cytological variability with nuclear numbers ranging from 1 to 6 (usually 2 or 3) in spores and 1 to 16 (usually 1) in germ tube cells.