Abstract:  Polyubiquitin1 (DoUb1) in Dendrobium officinale Kimura et Migo was achieved by RACE (rapid amplification of cDNA ends). DoUb1 contained 1985 bp nucleotides with a putative open reading frame encoding 457 amino acid residues. The predicted molecular weight and theoretical isoelectric point of pI were 51 179.7 ku and 7.76 respectively. Subcellular localization analysis showed that gene product played a major role in the cytoplasm or the mitochondrial matrix. Phylogenetic analysis showed that the DoUb1 has the closest relativon with monocotyledonous plants such as Zea mays, Setaria italica and Oryza sativa. Results of real-time quantitative PCR (RT-qPCR) showed that the expression of DoUb1 was higher in roots and leaves than in stems; DoUb1 was down-regulated during drought stress and temperature stress, the expression level was reduced in the early stage of stresses and then slowly increased. For drought stress, and the expression level was at the lowest after PEG treatment for 6 h; for temperature stress, it had similar responsive characteristics to drought stress, but in the low temperature stress, the expression of DoUb1 was lower than in high temperature stress. These results showed that the gene was more sensitive to low temperature stress.

Key words: RACE, Dendrobium officinale Kimura et Migo, Polyubiquitin, RT-qPCR