title: Different Gene Expressions of Resistant and Susceptible Hop Cultivars in Response to Infection with a Highly Aggressive Strain ofVerticillium albo-atrum.
abstract: Verticillium wilt has become a serious threat to hop production in Europe due to outbreaks of lethal wilt caused by a highly virulent strain ofVerticillium albo-atrum. In order to enhance our understanding of resistance mechanisms, the fungal colonization patterns and interactions of resistant and susceptible hop cultivars infected withV. albo-atrumwere analysed in time course experiments. Quantification of fungal DNA showed marked differences in spatial and temporal fungal colonization patterns in the two cultivars. Two differential display methods obtained 217 transcripts with altered expression, of which 84 showed similarity to plant proteins and 8 to fungal proteins. Gene ontology categorised them into cellular and metabolic processes, response to stimuli, biological regulation, biogenesis and localization. The expression patterns of 17 transcripts with possible implication in plant immunity were examined by real-time PCR (RT-qPCR). Our results showed strong expression of genes encoding pathogenesis-related (PR) proteins in susceptible plants and strong upregulation of genes implicated in ubiquitination and vesicle trafficking in the incompatible interaction and their downregulation in susceptible plants, suggesting the involvement of these processes in the hop resistance reaction. In the resistant cultivar, the RT-qPCR expression patterns of most genes showed their peak at 20 dpi and declined towards 30 dpi, comparable to the gene expression pattern ofin plantadetected fungal protein and coinciding with the highest fungal biomass in plants at 15 dpi. These expression patterns suggest that the defence response in the resistant cultivar is strong enough at 20 dpi to restrict further fungus colonization.
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Sara
authors.initials: S
authors.lastname: Cregeen
authors.affiliation: Slovenian Institute for Hop Research and Brewing, Cesta ŽalskegaTabora 2, SI-3320 Žalec, Slovenia.
authors.forename: Sebastjan
authors.initials: S
authors.lastname: Radisek
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Mandelc
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Natasa
authors.initials: N
authors.lastname: Stajner
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Jernej
authors.initials: J
authors.lastname: Jakse
authors.affiliation: Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Branka
authors.initials: B
authors.lastname: Javornik
keywords: Colonization; Differential gene expression; Hops; RT-qPCR; Verticillium wilt