INDUCTION OF AGGREGATION IN VITRO OF XYLELLA FASTIDIOSA CELLS BY DIVALENT IONS

• Author(s): Andersen, Peter; Kitajima, Elliot; Leite, Breno;
• Abstract: Xylella fastidiosa (Xf) aggregates within xylem vessels. Aggregation is followed by biofilm formation and ultimately vessel plugging. Characteristic Pierce`s disease (PD) symptoms are visualized right after vessel plugging. Nutritional and water stress are the most common deficiencies and may result in leaf yellowing, leaf scorching and interveinal chlorosis. We hypothesize that xylem fluid chemical composition strongly influences aggregation and biofilm formation. Divalent ion availability is dissimilar in susceptible and resistant plants. In order to clarify these findings, we assayed aggregation of Xf in (different concentrations of MgCl)2 (and CaCl)2 (20, 50 and 100 mg/L) with two)(Xf) PD strains (UCLA and STL). Our results indicate that calcium or magnesium induced approximately a 10-fold increase in aggregation of Xf cells. Controls were treated with deionized water. Aggregation of UCLA cells was greater than for STL cells either with calcium or magnesium treatments. However, calcium and magnesium induced aggregation. These results support the hypothesis that divalent ion availability is important in determining PD susceptibility and or resistance.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium