Cloning and characterization of a novel invertase from the obligate biotroph Uromyces fabae and analysis of expression patterns of host and pathogen invertases in the course of infection.
Invertases are key enzymes in carbon partitioning in higher plants. They gain additional importance in the distribution of carbohydrates in the event of wounding or pathogen attack. Although many researchers have found an increase in invertase activity upon infection, only a few studies were able to determine whether the source of this activity was host or parasite. This article analyzes the role of invertases involved in the biotrophic interaction of the rust fungus Uromyces fabae and its host plant, Vicia faba. We have identified a fungal gene, Uf-INV1, with homology to invertases and assessed its contribution to pathogenesis. Expression analysis indicated that transcription began upon penetration of the fungus into the leaf, with high expression levels in haustoria. Heterologous expression of Uf-INV1 in Saccharomyces cerevisiae and Pichia pastoris allowed a biochemical characterization of the enzymatic activity associated with the secreted gene product INV1p. Expression analysis of the known vacuolar and cell-wall-bound invertase isoforms of V. faba indicated a decrease in the expression of a vacuolar invertase, whereas one cell-wall-associated invertase exhibited increased expression. These changes were not confined to the infected tissue, and effects also were observed in remote plant organs, such as roots. These findings hint at systemic effects of pathogen infection. Our results support the hypothesis that pathogen infection establishes new sinks which compete with physiological sink organs.
Voegele
Ralf T
RT
Phytopathologie, Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany. Ralf.Voegele@uni-konstanz.de
Wirsel
Stefan
S
Möll
Ulla
U
Lechner
Melanie
M
Mendgen
Kurt
K
D001487:Basidiomycota / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D005656:Fungal Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008954:Models, Biological; D010802:Phylogeny; D010843:Pichia / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000201:enzymology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D031307:Vicia faba / Q000201:enzymology / Q000382:microbiology*; D043324:beta-Fructofuranosidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
D005656:Fungal Proteins; D010940:Plant Proteins; D043324:beta-Fructofuranosidase