Requirement of Salicylic Acid for the Induction of Systemic Acquired Resistance

Abstract

It has been proposed that salicylic acid acts as an endogenous signal responsible for inducing systemic acquired resistance in plants. The contribution of salicylic acid to systemic acquired resistance was investigated in transgenic tobacco plants harboring a bacterial gene encoding salicylate hydroxylase, which converts salicylic acid to catechol. Transgenic plants that express salicylate hydroxylase accumulated little or no salicylic acid and were defective in their ability to induce acquired resistance against tobacco mosaic virus. Thus, salicylic acid is essential for the development of systemic acquired resistance in tobacco.

Compromising early salicylic acid accumulation delays the hypersensitive response and increases viral dispersal during lesion establishment in TMV‐infected tobacco

“…Previous research Gaffney et aL, 1993) pioneered the use of transgenic plants expressing constitutively salicylate hydroxylase (NahG) to establish a central role for SA in SAR and also HR-mediated resistance. However, their interpretation of local SA-mediated events was hampered by the high levels of residual SA and PR protein accumulation about lesions .…”

“…The central role of salicylic acid in SAR has recently been elegantly demonstrated by the constitutive expression of a bacterial salicylate hydroxylase (nahG) gene in transgenic tobacco using a CaMV35S promoter (35S; Gaffney et al, 1993). Salicylate hydroxylase degrades SA to catechol, thereby preventing accumulation of SA in tobacco following infection with TMV, which in turn reduced PR protein gene expression and blocked the establishment of SAR.…”

Colonization of the Arabidopsis rhizosphere by fluorescent Pseudomonas spp. activates a root-specific, ethylene-responsive PR-5 gene in the vascular bundle

“…Many SAR genes encode pathogenesis-related (PR) proteins (PRs) (Van Loon and Van Strien, 1999), some of which have been shown to possess anti-fungal activity and are thought to contribute to the induced resistant state. Arabidopsis mutants affected in SA production, and transgenic NahG plants that express the bacterial salicylate hydroxylase (nahG) gene, are incapable of developing SAR and do not show SAR gene activation upon pathogen infection, indicating that SA is a necessary intermediate in the SAR signaling pathway (Gaffney et al, 1993;Wildermuth et al, 2001;Nawrath et al, 2002). Transduction of the SA signal requires the function of the regulatory protein NPR1 (Dong, 2004;Pieterse and Van Loon, 2004).…”

Differential Activity of Peroxidase Isozymes in Response to Wounding, Gypsy Moth, and Plant Hormones in Northern Red Oak (Quercus rubra L.)

“…Wounding and herbivore damage cause rapid increases in JA (Bostock, 1999;Reymond et al, 2000), triggering systemic defenses against herbivores and necrotrophic pathogens. Infection by biotrophic pathogens can elicit rapid increases in SA (Gaffney et al, 1993;Ryals et al, 1994) and systemic expression of defenses against a range of pathogens.…”