title: The monosaccharide transporter gene, AtSTP4, and the cell-wall invertase, Atbetafruct1, are induced in Arabidopsis during infection with the fungal biotroph Erysiphe cichoracearum.
abstract: Powdery mildew fungi are biotrophic pathogens that form a complex interface, the haustorium, between the host plant and the parasite. The pathogen acts as an additional sink, competing with host sinks, resulting in considerable modification of photoassimilate production and partitioning within the host tissue. Here, we examine the factors that may contribute to these changes. We show for the first time in one biotrophic interaction (Arabidopsis/Erysiphe cichoracearum) all of the following responses: Glc uptake in host tissues is enhanced after fungal infection; this coincides with the induction of expression of the monosaccharide transporter gene, Arabidopsis sugar transport protein 4 (AtSTP4), in infected leaves; invertase activity and transcript levels for a cell wall invertase, Atbetafruct1, increase substantially in Arabidopsis during attack by this pathogen. Before infection, Arabidopsis plants transformed with an AtSTP4 promoter-beta-glucuronidase construct show expression mainly in sink tissues such as roots; after infection, AtSTP4 expression is induced in the mature leaves and increases over the 6-d time period. Sections of infected leaves stained for beta-glucuronidase show that AtSTP4 expression is not confined to infected epidermal cells but is also evident in a wider range of cells, including those of the vascular tissue. The results are discussed in relation to the possible coordinated expression of hexose transporters and cell wall invertase in the host response to powdery mildew infection.
authors.affiliation: School of Biological Sciences, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, United Kingdom.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Fotopoulos
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Gilbert
authors.forename: Jon K
authors.initials: JK
authors.lastname: Pittman
authors.forename: Alison C
authors.initials: AC
authors.lastname: Marvier
authors.forename: Aram J
authors.initials: AJ
authors.lastname: Buchanan
authors.forename: Norbert
authors.initials: N
authors.lastname: Sauer
authors.forename: J L
authors.initials: JL
authors.lastname: Hall
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Williams
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics*; D001203:Ascomycota / Q000472:pathogenicity*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002473:Cell Wall / Q000187:drug effects / Q000201:enzymology; D005033:Ethylmaleimide / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics*; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D010695:Phlorhizin / Q000494:pharmacology; D010935:Plant Diseases; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D043324:beta-Fructofuranosidase
chemical_list: D029681:Arabidopsis Proteins; D009004:Monosaccharide Transport Proteins; C103791:STP4 protein, Arabidopsis; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D002731:4-Chloromercuribenzenesulfonate; D010695:Phlorhizin; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; D005947:Glucose; D005033:Ethylmaleimide