Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2011
Publication Date: 12/1/2011
Citation: Manthey, J.A., Narciso, J.A. 2011. Detection of fluorescent compounds in citrus leaf cankers. Proceedings of Florida State Horticultural Society. 124:227-231. Interpretive Summary: Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) has tremendous potential to seriously damage citrus production, especially for the fresh fruit market in Florida. Xcc is typically spread by wind and rain and enters into stomates and sites of tissue damage. The chemical ecologies of cankers in greenhouse-grown grapefruit leaves were investigated. This study showed the presence of newly formed compounds following infection by Xcc, and these compounds may be associated with plant defense mechanisms against pathogens.
Technical Abstract: Citrus canker caused by the pathogenic bacterium, Xanthomonas citri subsp. citri (Xcc), poses a serious threat to citrus production in Florida, especially for the fresh fruit market. Xcc causes severe damage to fruit, stem, and leaf tissues, and although much has been learned about the complex interactions between the infecting bacteria and these citrus plant tissues, there still remains much to be learned about the chemical responses in host trees to this infection. To address this issue, initial investigations were made of the changes in the phytochemical compositions of canker-infected leaves of greenhouse-grown grapefruit trees. These changes were monitored by HPLC-fluorescence spectroscopy, where particular attention was given to the detection of coumarins (C) and furanocoumarins (FC). Such analyses showed that physical abrasion of grapefruit leaves dramatically decreased the levels of certain Cs and FCs, and that subsequent Xcc infections triggered the production of other Cs and FCs.