Impact of light and nitrogen supply on biosynthesis and action of metabolic regulators of systemic acquired resistance in Arabidopsis
Z. AJAMI-RASHIDI (1), J. Zeier (1), K. Gruner (1) (1) Heinrich Heine Universität, Germany

Systemic acquired resistance (SAR) is induced by a localized leaf inoculation with pathogenic microbes and constitutes a state of elevated, broad spectrum disease resistance within the entire plant foliage. SAR establishment and the associated priming of defense responses are regulated by the non-protein amino acid pipecolic acid (Pip) via salicylic acid (SA)-dependent and -independent pathways. Besides Pip and SA, a number of other potential SAR signals, such as methyl salicylate (MeSA), glycerol-3-phosphate (G3P), DIR1 and azelaic acid (AzA), have been proposed. The aim of this study is to investigate whether light, the plant’s nitrogen supply, and the timing of pathogen inoculation during a day can affect the biosynthesis and regulatory action of SAR-related metabolites. We show that the biosynthesis of Pip and its regulatory role in defense priming are positively influenced by light. Similarly, adequate N supply stimulates pathogen-induced Pip accumulation and is a prerequisite for effective SAR induction. Our data suggest that AzA, DIR1 and MeSA are not essential for SAR establishment, irrespective of the time of day when the inducing inoculation occurs. Moreover, interactions between the pathogen-inducible Pip and the G3P signalling pathways seem to exist, but the mechanisms underlying this interplay still need to be elucidated. Our study provides the framework for future studies on how plants adapt SAR and defense priming responses to changing environmental conditions.

Abstract Number: P18-658
Session Type: Poster