title: New Insights into the Life Cycle of the Wheat Powdery Mildew: Direct Observation of Ascosporic Infection in Blumeria graminis f. sp. tritici.
abstract: Although Blumeria graminis is an intensively studied pathogen, an important part of its life cycle (namely, the way ascospores initiate primary infections on cereal leaves) has not yet been explored in detail. This study reports, for the first time, the direct observation of this process in B. graminis f. sp. tritici using light and confocal laser-scanning microscopy. All the germinated ascospores produced a single germ tube type both in vitro and on host plant surfaces; therefore, the ascosporic and conidial germination patterns are markedly different in this fungus, in contrast to other powdery mildews. Germinated ascospores penetrated the epidermal cells of wheat leaves and produced haustoria as known in the case of conidial infections. This work confirmed earlier studies reporting that B. graminis chasmothecia collected from the field do not contain mature ascospores, only asci filled with protoplasm; ascospore development is induced by moist conditions and is a fast process compared with other powdery mildews. Although ascosporic infections are frequent in B. graminis f. sp. tritici in the field, as shown by this study and other works as well, a recent analysis of the genomes of four isolates revealed the signs of clonal or near-clonal reproduction. Therefore, chasmothecia and ascospores are probably more important as oversummering structures than genetic recombination factors in the life cycle of this pathogen.
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Tünde
authors.initials: T
authors.lastname: Jankovics
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Komáromi
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Fábián
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Jäger
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Gyula
authors.initials: G
authors.lastname: Vida
authors.affiliation: First and sixth authors: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), P.O. Box 102, H-1525 Budapest, Hungary; second, third, fourth, and fifth authors: Agricultural Institute, Centre for Agricultural Research, MTA, Brunszvik 2, H-2462 Martonvásár, Hungary; and sixth author: University of Pannonia, Georgikon Faculty, Institute of Plant Protection, Deák Ferenc u. 57, H-8360 Keszthely, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Kiss
mesh_terms: D001203:Ascomycota / Q000166:cytology* / Q000235:genetics / Q000502:physiology; D002523:Edible Grain / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D013172:Spores, Fungal / Q000166:cytology* / Q000235:genetics / Q000502:physiology; D014908:Triticum / Q000382:microbiology*