Deg/HtrA proteases are important factors of the cellular protein quality control system, but little is know about their function in mitochondria. DEG10 loss-of-function mutants were impaired in root elongation at elevated temperature and reduced seed set in field trials. This study analysed the root proteome of two DEG10 loss-of-function mutants, deg10-1 and deg10-2, in comparison to wild type and the catr3-1 mutant (which is a second mutation in deg10-1).