Expression changes of stress-induced peroxidase (swpa2 and swpa4) and storage root-specific sporamin (spo-A and spo-B) genes were examined using qRT-PCR after treatment with wounding and bacterial pathogens on leaves of sweetpotato (Ipomoea batatas) plants. As a result of examining the expression change in the wounding treatment condition for 48 hours after treatment, which is a representative physical stress, the expression of all genes increased after 12 hours of wounding treatment, but the expression pattern of each gene group showed distinct differences thereafter. Expression levels of swpa2 and swpa4 strongly increased up to 36 or 48 hours after wounding treatment, whereas spo-A and spo-B expression levels strongly decreased after 24 or 36 hours after wounding treatment. Peroxidase and sporamin genes are involved in the early response after wounding treatment and, in particular, the peroxidase swpa2 and swpa4 genes are also involved in the late response after wounding treatment. Gene expression analysis after infection with P. chrysanthemi, which causes softness in sweetpotato, showed that the swpa2 and swpa4 genes were weakly induced after 8 hours and then strongly induced after 20 hours during pathogen infection. Expression of the spo-A gene was weakly induced in the pathogen-treated group after 20 hours, whereas spo-B showed an expression pattern similar to that of the peroxidase genes. The above results indicate that expression of the stress-induced peroxidase gene used in this study is induced not only by abiotic stress but also by biological stress caused by bacterial pathogen invasion and that peroxidase plays an important function in the initial defense response.

Abstract
Introduction
Materials and Methods
    1. Plant materials
    2. Wounding and bacterial pathogen treatments
    3. Gene expression analysis
    4. Statistical analyses
Results and Discussion
    1. Comparative analysis of gene expression in planttissues and cultured cells
    2. Comparative analysis of gene expression inwound treatment conditions
    3. Comparative analysis of gene expression duringbacterial pathogen infection conditions
Acknowledgments
References

• Jung-Wook Yang(Researcher, Department of Crop Cultivation & Environment, Research National Institute of Crop Science, Rural Development Administration)
• Ju Hwan Kim(Research professor, Department of Pharmacology, College of Medicine, Dankook University)
• Kang-Lok Lee(Professor, Department of Biology Education, IALS, Gyeongsang National University)
• Ki Jung Nam(Professor, Department of Biology Education, IALS, Gyeongsang National University)
• Yun-Hee Kim(Professor, Department of Biology Education, IALS, Gyeongsang National University) Corresponding author