title: Genetic alteration of UDP-rhamnose metabolism in Botrytis cinerea leads to the accumulation of UDP-KDG that adversely affects development and pathogenicity.
abstract: Botrytis cinerea is a model plant-pathogenic fungus that causes grey mould and rot diseases in a wide range of agriculturally important crops. A previous study has identified two enzymes and corresponding genes (bcdh, bcer) that are involved in the biochemical transformation of uridine diphosphate (UDP)-glucose, the major fungal wall nucleotide sugar precursor, to UDP-rhamnose. We report here that deletion of bcdh, the first biosynthetic gene in the metabolic pathway, or of bcer, the second gene in the pathway, abolishes the production of rhamnose-containing glycans in these mutant strains. Deletion of bcdh or double deletion of both bcdh and bcer has no apparent effect on fungal development or pathogenicity. Interestingly, deletion of the bcer gene alone adversely affects fungal development, giving rise to altered hyphal growth and morphology, as well as reduced sporulation, sclerotia production and virulence. Treatments with wall stressors suggest the alteration of cell wall integrity. Analysis of nucleotide sugars reveals the accumulation of the UDP-rhamnose pathway intermediate UDP-4-keto-6-deoxy-glucose (UDP-KDG) in hyphae of the Δbcer strain. UDP-KDG could not be detected in hyphae of the wild-type strain, indicating fast conversion to UDP-rhamnose by the BcEr enzyme. The correlation between high UDP-KDG and modified cell wall and developmental defects raises the possibility that high levels of UDP-KDG result in deleterious effects on cell wall composition, and hence on virulence. This is the first report demonstrating that the accumulation of a minor nucleotide sugar intermediate has such a profound and adverse effect on a fungus. The ability to identify molecules that inhibit Er (also known as NRS/ER) enzymes or mimic UDP-KDG may lead to the development of new antifungal drugs.
authors.affiliation: Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Liang
authors.initials: L
authors.lastname: Ma
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Omar
authors.initials: O
authors.lastname: Salas
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Bowler
authors.affiliation: Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Liat
authors.initials: L
authors.lastname: Oren-Young
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA.|Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Maor
authors.initials: M
authors.lastname: Bar-Peled
authors.affiliation: Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Sharon
mesh_terms: D020171:Botrytis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D002244:Carbon / Q000494:pharmacology; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D007887:Fabaceae / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D017353:Gene Deletion; D005800:Genes, Fungal; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000235:genetics*; D025282:Mycelium / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology; D012210:Rhamnose / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects; D014530:Uridine Diphosphate / Q000378:metabolism*; D014539:Uridine Diphosphate Sugars / Q000378:metabolism*
chemical_list: D014539:Uridine Diphosphate Sugars; C022183:UDP-rhamnose; D014530:Uridine Diphosphate; D002244:Carbon; D012210:Rhamnose
keywords: Botrytis cinerea; NRS/ER; UDP-4-keto-6-deoxy-glucose (UDP-KDG); UDP-Glc-4,6-dehydratase; UDP-rhamnose; fungal nucleotide sugar metabolism; fungal virulence and pathogenicity