Response to plant activator in Arabidopsis

To develop a screening system for plant activators, which are novel substances that protect plants by enhancing their inherent disease-resistance mechanisms, we performed analysis using an Arabidopsis microarray consisting of 1200 full-length cDNA clones representing putative defense-related and regulatory genes.　A total of 1.2K potential biotic and abiotic stress-related genes were selected from the genes covered by the Arabidopsis 7K array (RIKEN, Japan) and Arabidopsis oligo microarray (Agilent Technologies, USA) for this study. Arabidopsis wild-type plants (ecotype Columbia; Col-0) were grown in soil for 28 days in a growth chamber at 22｡C under a 12-h light/ 12-h dark cycle. Arabidopsis plants were applied a foliar spray with 5 mM SA, 0.1 mM MeJA, 1 mM ethephon, 0.5 mM BTH, 10 mM BABA and 1 mM INA. Benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester and 2,6-dichloroisonicotinic acid activated plant defense responses via the salicylic acid (SA)-dependent signaling pathway, and _-aminobutyric acid triggered a primed state in the plant that enables more efficient activation of the SA-, jasmonic acid- and ethylene-signaling pathway. These results suggest that this novel system can be used to screen for candidate plant activators. Keywords: time course, dose response A total of 1.2K potential stress-related genes that encode known or putative protein were selected for this study from the genes covered by Arabidopsis 7K array (RIKEN, Japan) and Arabidopsis oligo microarray (Agilent technologies, USA), which these genes include biotic and abiotic stress-inducible genes. Complementary DNA was synthesized and labeled with either Cy5 for the treated samples or Cy3 the untreated plants grown in parallel. No dye swaps were carried out.The microarrays were spotted using the microarray stamping machine (model SpotArray24; PerkinElmer, Wellesley, MA, USA). Hybridization was carried out in our laboratory, and hybridized chips were scanned on a ScanArray Lite scanner (PerkinElmer, Wellesley, MA, USA) and quantified using ScanArray Express ver.3 software. We calculated the median of the pixel intensities for each spot.