Both cDNA and DNA clones of PtDof1 （GenBank Accession No. FJ402844 and FJ402845） were isolated from plants grown in tissue culture ofPopulus tornentosa. The DNA sequence is 1597 bp including two exons and one intron. The cDNA is 969 bp in length with a 765 bp open reading frame which is capable of encoding 255 amino acids. The deduced amino acids sequence of the PtDofl protein shares 65%, 56% and 55% identity with Vitis vinifera （CAO48618）, Nicotiana tabacum （CAA08755） and Glycine max （ABI 16022） Dof protein by blast analysis in GenBank. Phylogenic analysis suggests PtDof1 gene could belong to the Dofgene family. PtDofl protein contains an unusual conserved single zinc finger with the pattern of C-X2-C-X21-C-X2-C, which may play a functional role in tissue-specific expression and possibly the auxin response of endogenous plant genes.
GA 20-oxidase, the most important limiting enzyme, can catalyze a series of oxidization of GA biosynthesis pathway from GA12 to GA9 and from GA53 to GA20 in the higher plants. This paper reviews the studies on the characters of GA 20-oxidase, the gene and the protein of GA 20-oxidase and the regulation of GA 20-oxidase gene expression in recent years. At the same time, the prospects for the gene transformation of GA 20-oxidase in agriculture, forestry and horticulture are also discussed.
Li Wei Chen Xiaoyang Li Hui Guo HaiCollege of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, P. R. China
