Project description:Phytoalexins are abundant in edible crucifers and have important biological activities, yet no dedicated gene for their biosynthesis is known. Here, we report two new cytochromes P450 from the non-model plant Brassica rapa (Chinese cabbage) that catalyze unprecedented S-heterocyclizations in cyclobrassinin and spirobrassinin biosynthesis. Our results reveal the first genetic and biochemical insights into the biosynthesis of a prominent pair of dietary metabolites, and have important implications for pathway discovery across >20 recently sequenced non-model crucifers. Leaf mRNA profiles of four conditions (Pseudomonas syringae pv. maculicola, flg22, and their respective mock treatments) were tested in triplicate.
Project description:Expression profiling of wild-type plants and mutants with defects in key components of the defense signaling network was used to model the Arabidopsis network 24 hours after infection by Pseudomonas syringae pv. maculicola strain Psm ES4326. Results using the Affymetrix ATH1 array revealed that expression levels of most pathogen-responsive genes were affected by mutations in coi1, ein2, npr1, pad4, or sid2. These five mutations defined a small number of different expression patterns displayed by the majority of pathogen-responsive genes. P. syringae pv. tomato strain Pst DC3000 elicited a much weaker salicylic acid response than Psm ES4326. Additional mutants were profiled using a custom array. Profiles of pbs3 and ndr1 revealed major effects of these mutations and allowed PBS3 and NDR1 to be placed between the EDS1/PAD4 node and the SA synthesis node in the defense network. Comparison of coi1, dde2, and jar1 profiles showed that many genes were affected by coi1, but very few were affected by dde2 or jar1. Profiles of coi1 plants infected with Psm ES4326 were very similar to those of wild-type plants infected with bacteria unable to produce the phytotoxin coronatine, indicating that essentially all COI1-dependent gene expression changes in this system are caused by coronatine.
Project description:Expression profiling of wild-type plants and mutants with defects in key components of the defense signaling network was used to model the Arabidopsis network 24 hours after infection by Pseudomonas syringae pv. maculicola strain Psm ES4326. Results using the Affymetrix ATH1 array revealed that expression levels of most pathogen-responsive genes were affected by mutations in coi1, ein2, npr1, pad4, or sid2. These five mutations defined a small number of different expression patterns displayed by the majority of pathogen-responsive genes. P. syringae pv. tomato strain Pst DC3000 elicited a much weaker salicylic acid response than Psm ES4326. Additional mutants were profiled using a custom array. Profiles of pbs3 and ndr1 revealed major effects of these mutations and allowed PBS3 and NDR1 to be placed between the EDS1/PAD4 node and the SA synthesis node in the defense network. Comparison of coi1, dde2, and jar1 profiles showed that many genes were affected by coi1, but very few were affected by dde2 or jar1. Profiles of coi1 plants infected with Psm ES4326 were very similar to those of wild-type plants infected with bacteria unable to produce the phytotoxin coronatine, indicating that essentially all COI1-dependent gene expression changes in this system are caused by coronatine. This experiment consists of three biological replicates. For each genotype, two leaves per plant were pooled from three pots to prepare total RNA.