The monosaccharide transporter gene, AtSTP4, and the cell-wall invertase, Atbetafruct1, are induced in Arabidopsis during infection with the fungal biotroph Erysiphe cichoracearum.
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.
Fotopoulos
Vasileios
V
School of Biological Sciences, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, United Kingdom.
Gilbert
Martin J
MJ
Pittman
Jon K
JK
Marvier
Alison C
AC
Buchanan
Aram J
AJ
Sauer
Norbert
N
Hall
J L
JL
Williams
Lorraine E
LE
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
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