Project description:Despite an ever-increasing interest for the use of pectin-derived oligogalacturonides (OGs) as biological control agents in agriculture, very little information exists, mainly for technical reasons, on the nature and activity of the OGs that accumulate during pathogen infection. Here we developed a sensitive OG profiling method, which revealed unsuspected features of the OGome generated during infection of Arabidopsis thaliana with the fungus Botrytis cinerea. Indeed, most OGs were acetyl- and methylesterified, and 80 % of them were produced by fungal pectin lyases (PNL), not polygalacturonases (PG). PG products did not accumulate as larger size OGs but were converted into oxidized GalA dimers. Finally, the comparison of the OGomes and transcriptomes of leaves infected with B. cinerea mutants with reduced pectinolytic activity but with decreased or increased virulence respectively, identified novel candidate OG elicitors. In conclusion, OGome analysis provides new insights into the enzymatic arms race between plant and pathogen and facilitates the identification of novel defense elicitors.
Project description:Botrytis cinerea, the causal agent of gray mold, is a necrotrophic fungus that can infect a wide variety of plant species and plant tissues. During infection, this pathogen modulates the pH of its environment by secreting organic acids or ammonia. Deletion of the gene encoding the pH-responsive transcription factor PacC revealed the importance of this regulator in different steps of the infection process and particularly in the secretion of organics acids, reactive oxygen species and plant cell wall degrading enzymes. This study aimed to identify the regulatory networks controlled by this fungus-specific transcription factor when the fungus is placed under acidic or alkaline conditions.
Project description:To investigate plant-fungus interactions in early stage of infection, we analyzed response of rice against Magnaporthe grisea infection deficient mutants. In M. grisea, Mgb1 and Mst12 are essential for development of infection structures. Deletion of MGB1 results in defect in appresorium formation, and MST12, in penetration peg development. Analysis of gene expression profiles in rice by microarray revealed the mutant-specific and R gene dependent gene expression, strongly suggesting that gene-for-gene interaction commences before the penetration into rice cell. Keywords: disease state analysis