Maize non-chromosomal stripe (NCS) plants are defective plants with mutations within mitochondrial DNA (mtDNA). NCS mutants are known to synthesize several stress proteins in response to defective mitochondria. The purpose of my study was to discover which other proteins have altered expression in the mutants. Changes in RNA levels can indicate which proteins differ in expression. Using microarrays, this study compares the RNAs of the NCS2 mutant to those of a normal relative. Many differences in RNA levels were observed. Results are still being analyzed to determine how many of the apparent differences are statistically significant.