A new WRKY transcription factor gene was isolated by ESTs screening from a cDNA library of suspension cultured cells of Sweet potato (Ipomoea batatas). The 2,285 bp cDNA fragment, IbWRKY, was sequenced, from which a 505 amino acid residue protein was deduced. A search of the protein BLAST database identified significant similarity to other plant WRKY31 protein sequences. RT-PCR analysis showed expression patterns of IbWRKY31 in various intact tissues and suspension cultured cells of Sweet potato, and in leaves exposed to different stresses. The IbWRKY31 gene was highly expressed in suspension cultured cells. In leaf tissues, IbWRKY31 showed strong expression during salicylic acid and methyl jasmonate treatments. Expression of IbWRKY31 was also induced under various abiotic stress and pathogen infection conditions, such as wounding, H2O2, MV, PEG, NaCl, and bacterial pathogen infection. These results suggest that IbWRKY31 is involved in plant responses to various stress conditions, such as abiotic stresses and pathogen infection through a defense signaling pathway.

Abstract
Introduction
Materials and Methods
    1. Plant materials
    2. Analysis of nucleotide and protein sequences
    3. Stress treatment
    4. Gene expression analysis
Results
    1. Isolation and sequence analysis of the IbWRKY31
    2. Differential expression of IbWRKY31 in intactSweet potato tissues and suspension cultured cells
    3. Differential responses of Sweet potato IbWRKY31to phyto-hormone and chemical stresses
    4. Differential expression of IbWRKY31 in responseto wounding and pathogen infection
Discussion
References

• Dong-Hwan Shim(Department of Forest Genetic Resources, National Institute of Forest Science)
• Yun-Hee Kim(Department of Biology Education, IALS, Gyeongsang National University) Corresponding author