Relationship between leaf symptoms and the proportions of xylem-colonized vessels of plum, coffee and citrus colonized by Xylella fastidiosa

• Author(s): Alves, E.; Leite, Breno; Lopes, Joao; Marucci, Rosangela; Pascholati, S.;
• Abstract: Symptoms caused by Xylella fastidiosa (Xf) in host plants are often attributed to vessel obstruction. Proportion of vessels colonized by X. f. and titers of bacteria in leaf petioles of plum, coffee and citrus were correlated with simptomatology. Leaves exhibiting mild (MS) and severe (SS) symptoms were sampled from X. f.-inoculated plants. Scanning electron microscopy was used to examine vessels. Bacterial titer was determined by isolation and confirmed by PCR. The percentage of X. f.-infected vessels was influenced by the degree of symptom expression, host, and symptom expression*host interactions. Percentage of colonized vessels in petioles of coffee was higher than in petioles of plum and citrus whether trees were exhibiting MS or SS. Bacterial titer did not vary statistically among the hosts. Severity of symptoms was consistently correlated with a higher proportion of colonized vessels in coffee and plum, but not in citrus. Citrus was the lowest colonized host.
• Publication Date: Jun 2003
• Journal: Phytopathology