Phytoalexins in Citrus sinensis (L.) Osbeck (Orange Pear) associated with the bacterium Xanthomonas citri subsp. citri: identification, quantification by "headspace" and HS-SPME-MDGC/GCMS and effect of some natural compounds on the growth of the pathogen

• Grant number: 14/18872-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2015
• End date: September 20, 2015
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: João Batista Fernandes
• Grantee: Edenilson dos Santos Niculau
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Citrus canker, caused by Xanthomonas citri subsp. citri (Xac), is a disease that causes serious problems to the global citrus production, especially the orange crop. An alternative to inhibiting the growth of this bacterium may be the use of natural antimicrobial compounds in pathossystem Orange Pear-Xac. During part of the doctoral thesis of Edenilson dos Santos Niculau, it was detected some phytoalexins derived from benzene (benzaldehyde, methyl salicylate, 1-phenyl ethyl acetate, 2-phenyl ethyl acetate, benzyl acetate, phenyl methanol, methyl benzoate and ethyl benzoate) in leaf from Orange Pear by Solid Phase Microextraction (HS-SPME) associated to monoquadrupole GC-MS, leading to the hypothesis that the plant produces these compounds to try to protect against bacteria. Probably, plant produce them at low levels. With the recent acquisition and installation of MDGC/GCMS triple quadrupole system in DQ UFSCar, will be possible to confirm and identify those and other phytoalexins that probably may be co-eluted, with use of manual HS-SPME and headspace autosampler AOC- 5000 Plus. Their techniques will enable effective quantify them because of the high selectivity of MRM experiments of the type (Multiple Reaction Monitoring). In addition, some phytoalexins identified, as well other compounds isolated by the group PN UFSCar will be evaluated in vitro against the Xac with goal to verify if they inhibit the growth of bacteria. Thus, this postdoctoral project will contribute for the understanding of interaction orange pear-Xac and consequently to control the citrus canker disease.