RNA editing in plant mitochondria: assays and biochemical approaches.

To analyze the C-to-U conversion of RNA editing in plant mitochondria, complementary methods are required, which include in vivo, in organello, and in vitro approaches. The major obstacle for in vitro assays is the generally observed fragility of the activity in mitochondrial lysates and the corresponding low activity. If seen at all, this activity is often in the range of a few percent conversion of the added templates. We have developed a sensitive assay system using mismatch analysis that allows detection of such low conversion rates. With this assay mitochondrial lysate preparations could be established from pea shoots and cauliflower inflorescences, which can be employed for the in vitro analysis of specificity requirements and biochemical parameters of RNA editing in plant mitochondria.