Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/19/2004
Publication Date: 4/17/2004
Citation: Ware, S., Verstappen, E.C., Cavaletto, J.R., Goodwin, S.B., Waalwijk, C., Kema, G.H. 2004. Identification of the teleomorph of septoria passerinii, the barley speckled leaf pathogen [abstract]. Fungal Genetics Conference Proceedings. p. 94.
Technical Abstract: Septoria passerinii causes speckled leaf blotch on barley. Although S. passerinii is considered to be asexual, mating-type idiomorphs were recently identified. In addition, both mating type idiomorphs were commonly found among isolates from single leaves, suggesting that sexual recombination of S. passerinii in field conditions may be common. We were therefore interested in discovering the possible sexual stage of S. passerinii. Using the M. graminicola in vitro crossing method, isolates of S. passerinii with opposite mating types were inoculated on the susceptible barley cultivar Topper 33. From one of these combinations (P71 x P83), approximately 80 ascospores were found that morphologically resembled ascospores of the very closely related species, Mycosphaerella graminicola. Seventeen viable two-celled ascospores could be isolated, and conidial growth of these isolates on PDA plates, as well as in liquid culture, was identical to the parental isolates. The 17 progeny isolates were inoculated onto the barley cv. Topper 33, and all 17 produced septoria speckled leaf blotch symptoms. RAPD and AFLP analyses of the progeny and parental isolates (P71 and P83) clearly indicated a segregating population of the hitherto unknown teleomorph of S. passerinii. Based on the pathogenicity tests and genotypic data, we conclude that Septoria passerinii, formerly known as an asexual pathogen, has an active teleomorph. An active teleomorph has important implications for resistance breeding and understanding the population dynamics of this pathogen.