Abstract: Two types of FNR genes（Root-type Ferredoxin-NADP+ oxidoreductase，RFNR and Leaf-type Ferredoxin-NADP+ oxidoreductase，LFNR）were cloned from‘Little Cherry’Oncidium. The bioinformatics analysis showed that they both belonged to the FNR-like super-family with flavin adenine dinucleotide（FAD）and nicotinamide adenine dinucleotide（NAD）functional domains and they were conservative in the evolution process，but exhibited significant differences in the composition of amino acids，protein structure and configurations. The RFNR was more conservative than LFNR. The results of FNR protein localization showed their encoded proteins were found mainly in the chloroplasts. The real-time fluorescence quantitative PCR expression analysis showed that LFNR and RFNR had organ-specific expression，i.e. LFNR was mainly in the leaf and RFNR in the root. The soft rot induced the down-regulation of LFNR gene and the up-regulation of RFNR gene. Both LFNR and RFNR showed up-regulation in response to the treatments of high salt concentration and high temperature and RFNR showed more quickly and higher levels of response，as well as both responded slightly to salicylic acid（SA）treatment. When treated with methyl jasmonate（MeJA），both LFNR and RFNR exhibited single-peak expression. There were similar and different expression characteristics under various stress conditions in two types of FNR in Oncidium，which implied different molecular mechanisms in responding to different stresses.

Key words: Oncidium, FNR（Ferredoxin-NADP+ oxidoreductase）, stress, subcellular localization, gene expression