Abstract
Elicitors 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<0.05) increase in lignin content. The plant exudate can be one abundant, renewable and safe source of elicitors.
Highlights
Elicitors are molecules capable of induce defense responses
The sulfation of Chichá gum (CHG) was based on the method reported by Pires et al (2013)[13], with several modifications. 1 g sample of the polysaccharide and 50 mL of DMF were placed in a round-bottom flask (250 mL)
A yield exceeding 100% is justified because hydrogen atoms (1.0 g mol-1) in the molecular structure are replaced by SO3Na groups (103.1 g mol‒1) during the sulfation process
Summary
Elicitors are molecules capable of induce defense responses Because these molecules can protect plants against pathogens, they are promising for reducing the use of agrochemicals[1]. The most promising algae-derived polysaccharides for defense induction in plant tissue are ulvans and glucuronans, which are widely available due to the abundance of green algae[3,4]. According El Modafar et al (2012)[6] the ability of ulvans to induce plant defense may be related to the presence of rhamnose and sulfate groups. Three polysaccharide subunits are reportedly related to the elicitation of apples defenses: rhamnose, uronic acid, and sulfate groups. The objective of this work is to deacetylate and sulfate (for the first time) CHG, characterize the derivatives, and evaluate the ability of these polysaccharides to enhance the protection of “Pink Lady” apples against pathogens. Equation 1 was used to calculate the degree of sulfation (DS):
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
