Reference gene selection for real-time quantitative polymerase chain reaction normalization in Swingle citrumelo under drought stress

We describe the first systematic evaluation of reference genes for use in real-time quantitative polymerase chain reaction (qPCR) for water deficit stress studies in the citrus rootstock Swingle citrumelo. The expression levels of seven reference genes cyclophilin (CYP), cathepsin (CtP), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), elongation factor 1 alpha (EF1 alpha), beta-tubulin (TUB), and ADP ribosylation factor (ADP) during drought stress were tested using geNorm and NormFinder programs. Results from four experimental conditions indicated that EF1 alpha and ADP were the most stable reference genes. Relative expression levels of Delta 1-pyrroline-5-carboxylate synthetase (P5CS) was used for reference gene validation. (C) 2010 Elsevier Inc. All rights reserved.