Regulation of Salicylic Acid and N-Hydroxy-Pipecolic Acid in Systemic Acquired Resistance

Abstract

In plants, salicylic acid (SA) is a central immune signal that is involved in both local and systemic acquired resistance (SAR). In addition to SA, several other chemical signals are also involved in SAR and these include N-hydroxy-pipecolic acid (NHP), a newly discovered plant metabolite that plays a crucial role in SAR. Recent discoveries have led to a better understanding of the biosynthesis of SA and NHP and their signaling during plant defense responses. Here, I review the recent progress in role of SA and NHP in SAR. In addition, I discuss how these signals cooperate with other SAR-inducing chemicals to regulate SAR.

Keywords: N-hydroxy-pipecolic acid; pipecolic acid; salicylic acid; systemic acquired resistance.

Fig. 1

Salicylic acid and N-hydroxypipecolic acid are required for systemic acquired resistance. Abbreviations used are isochosrismate synthase (ICS), avrPphB susceptible 3 (PBS3), EPS1 chorismate mutase (CM), phenylalanine ammonia lyase (PAL), abnormal inflorescence meristem1 (AIM1) benzoic acid 2-hydroxylase (BA2H), AGD2-like defense response protein 1 (ALD1), SAR-deficient 4 (SARD4), flavin-dependent monooxygenase 1 (FMO1), and UDP-glycosyltransferase 76B1 (UGT76B1).