OXIDATIVE SIGNAL-INDUCIBLE1 induces immunity by coordinating N-hydroxypipecolic acid, salicylic acid, and camalexin synthesis.

Expression of OXIDATIVE SIGNAL-INDUCIBLE1 (OXI1) is induced by a number of stress conditions and regulates the interaction of plants with pathogenic and beneficial microbes. In this work, we generated Arabidopsis OXI1 knockout and genomic OXI1 overexpression lines and show by transcriptome, proteome, and metabolome analysis that OXI1 triggers ALD1, SARD4, and FMO1 expressions to promote the biosynthesis of pipecolic acid (Pip) and N-hydroxypipecolic acid (NHP). OXI1 contributes to enhanced immunity by induced SA biosynthesis via CBP60g-induced expression of SID2 and camalexin accumulation via WRKY33-targeted transcription of PAD3.