Bacteria causing important diseases of citrus utilise distinct modes of pathogenesis to attack a common host

ADRIÁN ALBERTO VOJNOV; ALEXANDRE MORAIS DO AMARAL; JOHN MAXWELL DOW; PEDRO CASTAGNARO; MARÌA ROSA MARANO5

APPLIED MICROBIOLOGY AND BIOTECHNOLOGY

SPRINGER

Año: 2010 vol. 87 p. 467 - 477

0175-7598

In this review, we summarize the current knowledge on three pathogens that exhibit 43 distinct tissue specificity and modes of pathogenesis in citrus plants. Xanthomonas 44 axonopodis pv. citri causes canker disease and invades the host leaf mesophyll tissue 45 through natural openings and can also survive as an epiphyte. X. fastidiosa and Ca. 46 Liberibacter are vectored by insects and proliferate in the vascular system of the host, 47 either in the phloem (Ca. Liberibacter) or xylem (X. fastidiosa) causing variegated 48 chlorosis and huanglongbing diseases, respectively. Ca. Liberibacter can be found 49 within host cells and is thus unique as an intracellular phytopathogenic bacterium. 50 Genome sequence comparisons have identified groups of species-specific genes that 51 may be associated with the particular lifestyle, mode of transmission or symptoms 52 produced by each phytopathogen. In addition, components that are conserved among 53 bacteria may have diverse regulatory actions underpinning the different bacterial 54 lifestyles; one example is the divergent role of the Rpf/DSF cell-cell signalling system 55 in X. citri and X.fastidiosa. Biofilm plays a key role in epiphytic fitness and canker 56 development in X. citri and in the symptoms produced by X. fastidiosa. Bacterial 57 aggregation may be associated with vascular occlusion of the xylem vessels and 58 symptomatology of variegated chlorosis