Cloning and characterization of uridine diphosphate glucose dehydrogenase gene from Ipomoea batatas

In order to study the structure and expression patterns of uridine diphosphate glucose dehydrogenase (UDPGH) genes in Ipomoea batatas, the transcriptome database of this plant constructed in our lab was first analyzed to screen UDPGH contigs. It was found that there were 23 UDPGH contigs of different sizes in the transcriptome database. Primers were designed to amplify the coding regions of UDPGH, and five UDPGH-coding genes (named IbUDPGH1-IbUDPGH5) were cloned and sequenced. Open reading frames of all the UDPGH were 1443 bp in length, and their identity was more than 97 and 99% at the nucleotide and protein level, respectively. Homology comparison among different plant UDPGH showed that the identity ranged from 73 to 95% at the nucleotide level and from 84 to 95% at the protein level. The results of digital gene expression profile analysis (DGE) displayed that IbUDPGH1 had the highest expression in the tuberous roots, lower in the young and mature leaves, and the lowest in stems and fibrous roots, while IbUDPGH2 and IbUDPGH5 had the highest transcript level in stems, lower in roots, and very low in leaves. The rest genes were expressed at a low level in different tissues. Semi-quantitative RT-PCR results were similar to above data from the DGE. These results imply that the high expression of UDPGH might make large contribution to the accumulation of cell wall polysaccharides in sweet potato stems and roots.