title: Changes in carbohydrate metabolism in Plasmopara viticola-infected grapevine leaves.
abstract: The oomycete Plasmopara viticola is responsible for downy mildew, a severe grapevine disease. In infected grapevine leaves, we have observed an abnormal starch accumulation at the end of the dark period, suggesting modifications in starch metabolism. Therefore, several complementary approaches, including transcriptomic analyses, measurements of enzyme activities, and sugar quantification, were performed in order to investigate and to understand the effects of P. viticola infection on leaf starch and-to a larger extent-carbohydrate metabolism. Our results indicate that starch accumulation is associated with an increase in ADP-glucose pyrophosphorylase (AGPase) activity and modifications in the starch degradation pathway, especially an increased α-amylase activity. Together with these alterations in starch metabolism, we have observed an accumulation of hexoses, an increase in invertase activity, and a reduction of photosynthesis, indicating a source-to-sink transition in infected leaf tissue. Additionally, we have measured an accumulation of the disaccharide trehalose correlated to an increased trehalase gene expression and enzyme activity. Altogether, these results highlight a dramatic alteration of carbohydrate metabolism correlated with later stages of P. viticola development in leaves.
authors.affiliation: Universite de Bourgogne Plante Microbe Environnement, Dijon Cedex, France.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Gamm
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Héloir
authors.forename: Richard
authors.initials: R
authors.lastname: Bligny
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vaillant-Gaveau
authors.forename: Sophie
authors.initials: S
authors.lastname: Trouvelot
authors.forename: Gérard
authors.initials: G
authors.lastname: Alcaraz
authors.forename: Patrick
authors.initials: P
authors.lastname: Frettinger
authors.forename: Christophe
authors.initials: C
authors.lastname: Clément
authors.forename: Alain
authors.initials: A
authors.lastname: Pugin
authors.forename: David
authors.initials: D
authors.lastname: Wendehenne
authors.forename: Marielle
authors.initials: M
authors.lastname: Adrian
mesh_terms: D050260:Carbohydrate Metabolism; D002734:Chlorophyll / Q000378:metabolism; D004798:Enzymes / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D006601:Hexoses / Q000032:analysis / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009868:Oomycetes / Q000254:growth & development* / Q000472:pathogenicity; D010788:Photosynthesis / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D013213:Starch / Q000032:analysis / Q000378:metabolism*; D014199:Trehalose / Q000378:metabolism; D027843:Vitis / Q000201:enzymology / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism; D001614:beta-Amylase / Q000235:genetics / Q000378:metabolism
chemical_list: D004798:Enzymes; D006601:Hexoses; D011134:Polysaccharides; D018749:RNA, Plant; D002734:Chlorophyll; D013213:Starch; D014199:Trehalose; D051599:Glucose-1-Phosphate Adenylyltransferase; D000516:alpha-Amylases; D001614:beta-Amylase