RNA and mRNA Nitration as a Novel Metabolic Link in Potato Immune Response to .

Peroxynitrite (ONOO) exhibits a well-documented nitration activity in relation to proteins and lipids; however, the interaction of ONOO with nucleic acids remains unknown in plants. The study uncovers RNA and mRNA nitration as an integral event in plant metabolism intensified during immune response. Using potato- systems and immunoassays we documented that potato immunity is accompanied by two waves of boosted ONOO formation affecting guanine nucleotides embedded in RNA/mRNA and protein tyrosine residues. The early ONOO generation was orchestrated with an elevated level of protein nitration and a huge accumulation of 8-nitroguanine (8-NO-G) in RNA and mRNA pools confirmed as a biomarker of nucleic acid nitration. Importantly, potato cells lacking ONOO due to scavenger treatment and attacked by the pathogen exhibited a low level of 8-NO-G in the mRNA pool correlated with reduced symptoms of programmed cell death (PCD). The second burst of ONOO coincided both with an enhanced level of tyrosine-nitrated proteins identified as subtilisine-like proteases and diminished protease activity in cells surrounding the PCD zone. Nitration of both RNA/mRNA and proteins NO/ONOO may constitute a new metabolic switch in redox regulation of PCD, potentially limiting its range in potato immunity to .