Functional metabolomics as a tool to analyze Mediator function and structure in plants.

Area of Science:

• Plant molecular biology
• Gene regulation
• Biochemistry

Background:

• Mediator is a crucial multiprotein complex regulating eukaryotic gene transcription.
• It comprises four modules: Head, Middle, Tail, and Kinase.
• Mediator transmits signals from regulators to RNA polymerase II.

Purpose of the Study:

• To determine Mediator subunit localization and activities in Arabidopsis.
• To identify novel roles of Mediator subunits in plant development and stress responses.
• To analyze metabolomic and transcriptomic data from Mediator mutants.

Main Methods:

• Metabolome and transcriptome analyses of Arabidopsis Mediator mutants.
• Multivariate statistical analysis and heat-map visualization of metabolite profiles.
• Comparative analysis with yeast Mediator subunit localization.

Main Results:

• Distinct metabolite profiles were observed for different Mediator subunit mutants.
• Metabolite profiles clustered according to known yeast subunit localizations, aiding plant subunit assignment.
• Mutations in med18 and med25 affected gene expression and metabolite levels, explaining observed phenotypes.
• med18 mutants showed induced phytoalexin levels post-pathogen exposure.

Conclusions:

• Mediator subunits exhibit specific localization within plant Mediator complex modules.
• Individual Mediator subunits play significant roles in Arabidopsis development.
• Mediator subunits are involved in distinct signaling pathways controlling development and pathogen tolerance.