Pea apoplastic Cu/Zn-SOD responsive to pathogenic signal molecules

Abstract

We previously reported that O₂^- was generated in isolated pea cell walls in response to the elicitor and suppressors that are secreted by a pea pathogen, Mycosphaerella pinodes. In this report, we show that the activity of superoxide dismutase (SOD) in the apoplastic fluid and isolated cell walls of pea seedlings is regulated by the fungal signal molecules. Pharmacological test and internal amino acid sequencing indicated that the SOD is Cu/Zn-type. At the levels of mRNA and protein of PsCu/Zn-SOD1 also responded to the elicitor and suppressors. The SOD activity of recombinant PsCu/Zn-SOD1 was regulated directly by the pathogen's signal molecules, indicating that this protein is able to recognize and respond to the pathogen's signal molecules in the most exterior compartment of plants.