Isolation and Characterization of a Nitric Oxide-induced Gene in Sweetpotato

Abstract

A new nitric oxide-induced (NOI) gene was isolated by screening ESTs from a cDNA library of dehydration-treated fibrous roots of sweetpotato (Ipomoea batatas). The 720 bp cDNA fragment, IbNOI, was sequenced, from which a 77 amino acid residue protein was deduced. A search of the protein BLAST database identified significant similarity to other plant NOI protein sequences. Quantitative RT-PCR analysis revealed diverse expression patterns of IbNOI in various tissues of the intact sweetpotato plant, and in leaves exposed to different stresses. The IbNOI gene was highly expressed in storage roots and suspension-cultured cells. In leaf tissues, IbNOI showed strong expression during sodium nitroprusside (SNP)-induced NO accumulation and chemical stress treatments. Expression of IbNOI was also induced under various abiotic stress conditions, such as dehydration, salt, and bacterial pathogen infection. These results suggest that IbNOI is involved in plant responses to diverse abiotic stresses and pathogen infection through a NO-related pathway.