Abstract
Systemic acquired resistance (SAR), one of plant defense systems, is induced by pathogen infection through salicylic acid (SA) accumulation. SAR has been well characterized and set of pathogenesis-related (PR) genes has been identified as SAR marker genes. The induction of disease resistance by high temperature treatment has been reported in cucumber, in which SA is likely to take part. To investigate the detailed mechanism of this resistance, effects of high temperature treatment in Arabidopsis were examined. The treatment induced the expression of PR genes, the accumulation of SA, and disease resistance to Pseudomonas syringae pv. tomato DC3000. The High temperature treatment induced the expression the isochorismate synthase 1 (ICS1) gene, encoding an SA biosynthetic enzyme. Analyses using the sid2 (SALICYLIC ACID INDUCTION DEFICIENT2) mutant defective in ICS1 and NahG transgenic plants expressing SA degrading enzyme, indicated that high temperature-induced disease resistance required SA biosynthesis.
