Comparative analysis between the genomes of the phytopathogens Xylella fastidiosa and Xanthomonas axonopodis pv. citri

Author(s)

Leandro Marcio Moreira

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2002-11-04

Examining board members

Ana Claudia Rasera da Silva; Carlos Frederico Martins Menck; Glaucia Mendes Souza

• Advisor: Ana Claudia Rasera da Silva
• Field of knowledge: Biological Sciences - Biochemistry
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS
• Location: Universidade de São Paulo. Biblioteca do Conjunto das Químicas; CQ T/574.88; M838L

Abstract

Xylella fastidiosa (Xf) and Xanthomonas axonopodis pv. citri Xac are gram negative gamma proteobacteria, responsible for great economical losses in the Brazilian citrus sector. With their sequenced and annotated genomes, we have done a comparative analysis between their genetic composition and life habitat. Xac displays a genome of 5.2Mb against 2. 7Mb of Xf. This reflects the number of genes (4432 against 2838) which results in a greater metabolic complexity of Xac, characterized by: a wide range of genes of cell wall degradation (44), biosynthesis of proteases (92), many genes of regulatory functions (296), a complex energy metabolism (209), chemotatic (absent in Xf) and secretory systerns (presence of types I, II, III and IV, type II in duplicate), besides a great number of genes involved in iron acquisition (65), make of Xac a pathogen of high invasive power and of quick spreading and virulence. In the other hand Xf, due to the lack of the complexity just cited, seems to have its resources adapted to the habitat in which it lives, as for example a large number of genes involved in pili biosynthesis, that associated with gum biosynthesis, favor its adhesion to the salivary glands of the vector (sharpshooter) and the formation of cellular agglomerations responsible for the blockage of the vessels which leads to the pathologies resulted from this event. (AU)