Disease relevance of ICS1

• Some bacteria such as Pseudomonas aeruginosa synthesize SA using isochorismate synthase (ICS) and pyruvate lyase [1].

High impact information on ICS1

• We developed a software package called InterMap and used it to automatically delimit Eds16 to a 7-cM interval on chromosome 1 [2].
• Isochorismate synthase is required to synthesize salicylic acid for plant defence [1].
• Here we show, by cloning and characterizing an Arabidopsis defence-related gene (SID2) defined by mutation, that SA is synthesized from chorismate by means of ICS, and that SA made by this pathway is required for LAR and SAR responses [1].
• This systemic up-regulation is missing in the SAR-defective SA pathway mutants sid2 and npr1, as well as in the defense mutant ndr1, indicating a close correlation between systemic FMO1 expression and SAR establishment [3].
• Double-mutant analysis revealed that edr2-mediated resistance is suppressed by mutations that inhibit salicylic acid (SA)-induced defense signaling, including npr1, pad4 and sid2, demonstrating that edr2-mediated disease resistance is dependent on SA [4].

Chemical compound and disease context of ICS1

• By fusing the two bacterial genes pchA and pchB from Pseudomonas aeruginosa, which encode isochorismate synthase and isochorismate pyruvate-lyase, respectively, we have engineered a novel hybrid enzyme with salicylate synthase (SAS) activity [5].

Biological context of ICS1

• Furthermore, plants expressing a nahG transgene or treated with a phenylalanine ammonia lyase (PAL) inhibitor showed enhanced symptoms, suggesting that SA synthesized via PAL, and not via isochorismate synthase (ICS), mediates lesion development [6].
• Glycerol increased SA levels and induced pathogenesis-related gene expression in all but sid2, nahG, fad7, and fad7 fad8 plants [7].

Associations of ICS1 with chemical compounds

• These data indicate that local resistance to B. cinerea requires ethylene-, jasmonate-, and SA-mediated signaling, that the SA affecting this resistance does not require ICS1 and is likely synthesized via PAL, and that camalexin limits lesion development [6].
• Growing fungal colonies of both Uromyces spp., indicative of a successful biotrophic relationship between plant and fungus, formed in NahG plants, but only U. vignae formed growing colonies in the sid2 mutants and cycloheximide-treated wild-type plants [8].
• These results suggest that the ozone-induced expression of FAD7 gene requires SA, but not ethylene, JA, NPR1 and SID2 [9].
• ISR was blocked in Arabidopsis mutants npr1-1, eds5/sid1, and sid2, indicating that components of the pathway from isochorismate and a functional NPR1 play a crucial role in the K165-mediated ISR [10].
• AtICS1 acts as a monofunctional isochorismate synthase (ICS), catalyzing the conversion of chorismate to isochorismate (IC) in a reaction that operates near equilibrium (K(eq) = 0.89) [11].

Other interactions of ICS1

• Furthermore, in the sid2 mutant which lacks an enzyme required for SA biosynthesis, the expression of FAD7 was induced by ozone exposure [9].

Analytical, diagnostic and therapeutic context of ICS1

• All three mutants have reduced levels of salicylic acid after infection. eds16 was mapped to the lower arm of chromosome I and found by complementation tests to be allelic to the salicylic acid-deficient mutant sid2 [12].

References