Cloning And Expression Pattern Analysis Of Topoisomerase Ⅰ Gene ZmTop1from Maize(Zea Mays L.)

Maize is an important food crop worldwide. Maize also serves as valuable forage, biofuel and economic crops. Maize plays a vital role in the national economy. Topoisomerase I is a ubiquitous and essential enzyme in nature. Despite the biological importance, molecular cloning of Top1has not yet been reported in cereal crops. Herein, we presented the isolation and characterization of ZmTop1in maize. Moreover, expression patterns of ZmTopl gene were surveyed under various abiotic stresses and plant hormones using semi-quantative real-time PCR (sqRT-PCR) and quantative real-time PCR (qRT-PCR). Main results were as followings.1) A total of15exons and14introns spanned5325bp genomic region of the maize topoisomerase I gene ZmTopl. The full-length3265bp cDNA of maize Top1contained an open reading frame (ORF) of2715bp encoding904amino acids with four characterized regions.2) The deduced amino acid sequence showed homology with Topo I proteins from other plants. Based on the human Topo I information,3D structure of maize topoisomerase I was built. Totally,169putative cis-elements that are involved in hormone and light signalling responses, abiotic stress adaption were identified in the promoter region of ZmTopl. Subcellular location in silico showed the position of Topo I in maize nuclei.3) ZmTopl gene constitutively expressed in maize leaves, roots, tassels, ears and stems.4) Transcript leves of ZmTopl in maize leaves and roots altered under various abiotic treatment times. Expression pattern of ZmTopl gene in maize leaves was relatively constant under a certain concentration hormone stimulation. Contrarily, expression levels of ZmTopl in maize roots reached highest at2and24hour after treatment. Expression of ZmTop1in maize leaves significantly reduced with different concentration hormone treatment. However, Expression of ZmTop1in maize roots largely increased.