Screening and verification of reference genes for analysis of gene expression in winter rapeseed (Brassica rapaL.) under abiotic stress

Winter rapeseed (Brassica rapaL.) is the main oilseed crop in northern China and can safely overwinter at 35 (i.e., Tianshui, China) to 48 degrees north latitude (i.e., Altai, Heilongjiang, Raohe, and Xinjiang, China). In order to identify stable reference genes to understand the molecular mechanisms of stress tolerance in winter rapeseed, internal reference genes of winter rapeseed under four abiotic stresses were analyzed using GeNorm, NormFinder, BestKeeper, and RefFinder software. The most stable combinations of internal reference genes were beta-actinandSANDin cold-stressed leaves,beta-actinandEF1ain cold-stressed roots,F-boxandSANDin high temperature-stressed leaves, andPP2AandRPLin high temperature-stressed roots,SANDandPP2Ain NaCl-stressed leaves,RPLandUBCin NaCl-stressed roots,RPLandPP2Ain PEG-stressed leaves, andPP2AandRPLin PEG-stressed roots. Expression profiles ofPXG3were used to verify these results. The stable reference genes identified in this study are useful tools for identifying stress-responsive genes to understand the molecular mechanisms of stress tolerance in winter rapeseed.