Salicylic acid and wounding induce defense‐related proteins in Chinese cabbage

The response of plants to pathogens and wounding is dependent upon very sensitive perception mechanisms. Although genetic approaches have revealed a variety of resistance genes that activate common defense responses, defense‐related proteins are not well characterized in plants. Therefore, we used a proteomic approach to determine which defense‐related proteins are induced by salicylic acid (SA) and wounding in Chinese cabbage. We found that SA and wounding induce pathogenesis‐related protein 1a (PR1a) at both protein and mRNA levels using proteomics and Northern blot analysis, respectively. This indicates that our proteomic approach is useful for identifying defense‐related proteins. We also identified several other proteins that are induced by SA or wounding. Among the seven SA‐induced proteins identified, four may be defense‐related, including defense‐related protein, phospholipase D (PLD), resistance protein RPS2 homolog, and L‐ascorbate peroxidase. Out of the six wounding‐induced proteins identified, three may be defense‐related: heat shock cognate protein 70 (HSC70), polygalacturonase, and peroxidase P7. The precise functions of these proteins in plant defense responses await further study. However, identification of the defense‐related proteins described in this study should allow us to better understand the mechanisms and signal transduction pathways involved in defense responses in Chinese cabbage.