Stresses that target mitochondrial function lead to altered transcriptional responses for 100-1000s of genes genome wide, and are signalled via retrograde signalling pathways within the cell. rao1 mutants contain a mutation in a gene encoding a Cyclin-Dependant Kinase E;1 and cannot induce stress responsive genes (such as the mitochondrial alternative oxidase 1a) in response to mitochondrial dysfunction. We sought to define the global gene network regulated through RAO1 function in response to mitochondrial stress (mimicked through treatment of plants with antimycin A - a specific inhibitor of complex III in the mitochondrial electron transfer chain). We have defined global stress responses that are positively and negatively mediated by RAO1 function, as well as global stress responses to antimycin A treatment that are regulated independently of RAO1. We used Affymetrix microarray to characterise global gene expression profiles for mutant plants with compromised mitochondrial retrograde signalling under stress (rao1 mutants), to define the genome wide transcriptional network regulated through RAO1 function. rao1 and wild type 14-day-old seedlings (the optimal stage as defined by forward genetic screens that identifed rao1 mutants) grown on GamborgB5 plates were treated by spraying plants with 50 µM antimycin A (an elicitor of mitochondrial retrograde signalling) while mock control samples were sprayed with deionised water. Samples were collected after 3hr of treatment for global expression profiling.