PnSCR82, a small cysteine-rich secretory protein of Phytophthora nicotianae, can enhance defense responses in plants

A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts. Although several small cysteine-rich (SCR) secretory proteins, conserved in oomycete pathogens, have been identified in Phytophthora, their specific involvement in these interactions remains unknown. In this study, an SCR effector encoded by PnSCR82 in P. nicotianae was identified and shown to have similarities to P. cactorum phytotoxic protein, PcF (Phytophthora cactorum Fragaria). Agroinfection with potato virus X vector, PnSCR82, was capable of inducing plant hypersensitive cell death in Nicotiana benthamiana and Solanum lycopersicum. Real-time PCR results indicated that transiently expressed PnSCR82 in N. benthamiana leaves activated the jasmonate, salicylic acid and ethylene signaling pathways. Transient expression of PnSCR82 enhanced plant resisitance to P. capsici. In summary, our results demonstrated that P. nicotianae PnSCR82 elicits defensive responses in N. benthamiana and may potentially play a significant role in future crop protection programs.