01879naa a2200241 a 450000100080000000500110000800800410001902400490006010000220010924501000013126000090023152011590024065000220139965300270142165300130144865300190146165300140148070000170149470000220151170000230153370000220155677300590157821330422021-07-20       2021    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1590/0104-1428.088202DOI1 aLIMA, C. P. C. de  aInduction of defense in apples by sulfated and deacetylated chichá gum.h[electronic resource]  c2021  aElicitors activate the defense mechanism in plants to resist pathogens. Ulvans and glucuronans can act as elicitors, and their activity seems to be related to the sulfate groups, rhamnose and uronic acid monosaccharides. Chichá gum (CHG), which also contains rhamnose and uronic acid, was sulfated with chlorosulfonic acid/N,N-dimethylformamide and deacetylated with sodium hydroxide solution. The changes were confirmed by infrared spectroscopy. Carbon-13 NMR revealed that sulfation occurred in galactose and rhamnose units. The apples were sprayed with water (negative control), deacetylated chichá gum (DCHG), and sulfated chichá gum (SCHG). The activity of enzymes guaiacol peroxidase and polyphenol oxidases and the lignin content were compared with those under the action of a commercial elicitor, benzothiadiazole. DCHG, and especially SCHG, increased the activity of the two enzymes. Only fruits treated with SCHG showed a significant (p&lt0.05) increase in lignin content. The plant exudate can be one abundant, renewable and safe source of elicitors. Keywords: benzothiadiazole (BTH), Sterculia striata, elicitor, polysaccharide, sulfation.  aSterculia striata  aBenzothiadiazole (BTH)  aElicitor  aPolysaccharide  aSulfation1 aOSTER, A. H.1 aCAVALCANTI, F. R.1 aPAULA, R. C. M. de1 aFEITOSA, J. P. A.  tPolímerosgv. 31, n. 1, e2021010, p. 1-8, julho 2021.