Identification of valid reference genes for quantitative RT-PCR inCaragana microphyllaunder salt and drought stresses

Caragana microphyllais a leguminosae plant and grows mainly in semi-arid areas of northwest China and Mongolia. However, the lack of studies onC. microphyllareference genes limits the accurate understanding of the molecular biology mechanisms in this crop under abiotic stresses. In this study, we selected nine candidate genes from salt-treatedC. microphyllatranscriptome data and evaluated their stability by using geNorm, NormFinder, BestKeeper, and RefFinder in salt and drought conditions. In addition, the relative expressions of Delta 1-pyrroline-5-carboxylate synthase 2 (P5CS2) and Catalase 2 (CAT2) were examined to confirm the stability of the candidate reference genes. As a results, glyceraldehyde-3-phosphate dehydrogenase C2 (GAPC2) and 26S proteasome regulatory subunit (RPN5) were the most stable in both salt and drought treatments. The relative expression ofP5CS2andCAT2also showed more stable levels in normalization byGAPC2andRPN5than the most unstable gene,Ubiquitin 4(UBQ4). Therefore, it is believed that these candidate reference genes selected and validated in our study could be used to study the molecular biological study of response to salt and drought stress inC. microphylla.