METABOLIC FINGERPRINTING OF ACS7 MUTANT AND WILD-TYPE Arabidopsis thaliana UNDER SALT STRESS BY ULTRA PERFORMANCE LIQUID CHROMATOGRAPHY COUPLED WITH QUADRUPOLE/TIME OF FLIGHT MASS SPECTROMETRY

The metabolic fingerprints of the acs7 mutant and wild-type (WT) of the model plant Arabidopsis thaliana with and without salt stress were compared by ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-QTOF MS). Separations were performed on C-18 column (2.1 mm x 100 mm, 1.7 mu m). A linear gradient elution of acetonitrile and 0.1% formic acid solution was used at a flow rate of 0.4 mL/min. Principal components analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were combined for the data treatment. A clear discrimination was obtained by both PCA and PLS-DA. The acs7 salt-treated group was closer to the control group samples than the WT salt-treated group samples. Several potential stress-induced ions were revealed as markers of salt stress. The markers 12-oxophytodienoic acid (OPDA), arabidopside A, sinapoyl malate, linolenic acid, and abscisic acid were identified by the accurate mass (from TOF MS). Linolenic acid and OPDA are the biosynthetic precursors of jasmonic acid (JA) by the octadecanoid pathway. The JA content determination results indicated that salt stress increased the JA levels in the leaves of the WT plant, but there was no significant increase in the JA content of acs7 after salt treatment. These data suggested the responses to salt stress of the acs7 mutant and WT A. thaliana were different in the octadecanoid pathway.