Ulvan, a Sulfated Polysaccharide from Green Algae, Activates Plant Immunity through the Jasmonic Acid Signaling Pathway
Biochemical analysis and biological activity of fractions from green algae Ulva spp. (a) Size exclusion chromatography of the high molecular mass compounds present in the ethanol-insoluble fraction recovered from the crude extract. Fractionation was followed by glucuronic measurement. (b) FITR spectra of the 600–400 kDa fraction. The peaks at 847, 1052, 1256, 1641, and 3446 cm-1 are respectively generated by the bending vibration of C–O–S in axial position, the stretching vibration of C–O, S–O, C=O, and C–OH, all linkages being present in the constitutive dimer -D-glucuronosyl-(1,4)--L-rhamnose-3-sulfate. (c) Biological activity of the crude extract and fractions. GUS activity was measured on P1Lox::GUS transgenic tobacco 3 days after infiltration in leaves of the various samples (1 mgml-1) as indicated. Means, for each treatment compared to the control mean using a Student’s t-test. Treatment associated to a or was marked, respectively, by * or **.
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