Use of transcriptomics to analyze chloroplast processes in Arabidopsis.

The vast majority of the several thousands of chloroplast proteins are encoded by nuclear genes. Regulation of their expression involves control of their transcription, and thus requires the transmission of information from chloroplast to nucleus (retrograde signalling). The most powerful approach to the analysis of the transcriptional regulation of chloroplast functions involves RNA hybridization to microarrays representing almost all nuclear genes of Arabidopsis thaliana, followed by statistical data analysis. This chapter provides detailed protocols for the preparation of RNA for microarray experiments, in particular the widely used Affymetrix ATH1 array. Finally, the use of the publicly available program Robin for statistical data analysis, as well as approaches to confirm microarray data, is introduced.