Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2002
Publication Date: N/A
Technical Abstract: To test for possible sexual reproduction of the barley speckled leaf blotch pathogen Septoria passerinii, a putative mating-type locus was cloned and compared to that of its close relative Mycosphaerella graminicola. Sequence anaysis of the corresponding region from S. passerinii confirmed that it is homologous to the mating-type locus of M. graminicola and contained MAT-1 and MAT-2 idiomorphs of approximately 3 kb. A multiplex PCR test was developed that allowed rapid identification of the mating types of isolates of S. passerinii. Both mating types were present in approximately equal frequencies in fields in MN and ND, often among multiple isolates from the same leaves. Analyses with isozyme and RAPD markers revealed that each isolate had a unique genotype. The common occurrence of both mating types on the same leaf and high levels of genotypic diversity indicate that sexual reproduction probably plays an integral role in the life cycle of S. passerinii and may be much more important than believed previously in this and possibly other "asexual" species of Septoria.