Xylella fastidiosa
A Microbial Biorealm page on the genus Xylella fastidiosa
Classification
Higher order taxa
Bacteria; Proteobacteria; Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae
Species
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NCBI: Taxonomy |
Xylella fastidiosa
Description and significance
Xylella fastidiosa is a rod-shaped, gram-negative pathogenic bacterium that infects plants, causing a variety of diseases in over 100 plants species, including grapevine, citrus, almonds, and many other species of economic importance. Among the diseases it causes are Pierce's Disease in grapevine, citrus variegated chlorosis in oranges, and leaf scorch diseases in almond, coffee, and oleander. It was first discovered associated with Pierce's Disease (of Southern California grapevines) in 1973, and first grown in culture in 1978. It was then identified as the agent that causes CVC in 1993, and disease first noticed in Brazil in 1987. X. fastidiosa exclusively colonizes the xylem, the water-conducting systems of plants, forming biofilms, and is transmitted from plant to plant by xylem-feeding leafhopper insects, including the glassy-winged sharpshooter. It poses a serious agricultural and economic threat, as it is responsible for major crop losses globally, and is included in the Federal government's Agricultural Select Agent list. Because of is public importance as an economic threat, genomic studies of different host plant stains have been underway in an attempt to gain insight into virulence factors, and consequently the development of microbiological control and disease management strategies.
Genome structure
The genome sequences of four strains of X. fastidiosa have been sequenced to date: X. fastidiosa 9a5c, X. fastidiosa Ann-1, X. fastidiosa Dixon, and X. fastidiosa Temecula-1. There are 1,579 homologous genes in all four strains, accounting for approximately 76.2% of the genome size. All pocess pathogenicity(virulence) related genes involved in the colonization of their plant host, including a 7kb conserved gene cluster encoding proteins associated with pili biogenesis, and function in attachment to the host, as well as genes for the type II secretion system, which is involved in exporting exoenzymes that degrade plant cell walls, allowing them to colonize. X. fastidiosa also pocess a gene whose protein product is an exopolysaccharide similar to the xantham gum produced by Xanthomonas campestris. At least 83 genes are bacteriophage-derived, and include virulence-associated genes.
The genome of X. fastidiosa 9a5c, first isolated in 1992 from infected twigs derived from Valencia oranges from Brazil and the cause of citrus variegated chlorosis in oranges, consists of a circular chromosome that is 2,679,306 base pairs long. It has 2,766 protein-coding regions. It also contains two circular plasmids: pXF1.3, and pXF51. pXF1.3 is 1,286 base pairs long, with 2 protein-coding regions. pXF51 is 51,158 base pairs long, with 64 protein-coding regions. Most of the genes on this plasmid aid in metabolism, but does contain 1 virulence-associated protein.
The genome of X. fastidiosa Ann-1, a strain associated with oleander leaf scorch disease, consists of a linear chromosome that is 5,115,342 base pairs long, with 4,660 protein-coding regions. It has no plasmids.
The genome of X. fastidiosa Dixon, a strain that causes almond leaf scorch, consists of a linear chromosome that is 2,622328 base pairs long, with 2,358 protein-coding regions. It has no plasmids.
The genome of X. fastidiosa Temecula-1, first isolated in 1998 from an infected California grapevine and the cause of Pierce's disease of grapevines, consists of a circular chromosome that is 2,519,802 base pairs long. It has 2,034 protein-coding regions. It also contains 1 circular plasmid, pXFPD1.3, that is 1,346 base pairs long, and has 2 protein coding regions.
Two strains of X. fastidiosa, M12 and M23, are currently being sequenced for comparative genome analysis.
Cell structure and metabolism
Xylella fastidiosa is a gram-negative, biofilm-forming, rod-shaped bacterium with dimensions of 0.25 to 0.35 µm in radius and 0.9 to 3.5 µm in length. It possesses two types of polar pili: type I pili 0.4 to 1.0 µm in length, and type IV pili 1 to 6 µm in length. Both types of pili are positioned at the same pole, and aid in xylem attachment, biofilm formation, and twitching motility. X. fastidiosais a nutritionally fastidious aerobe that grows in the highly specialized environment of the xylem fluid, which contains the lowest concentration of organic energy sources of all plant tissues.
Ecology
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Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Application to Biotechnology
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Current Research
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References
Bhattacharyya, A., Stilwagen, S., Ivanova, N., D'Souza, M., Bernal, A., Lykidis, A., Kapatral, V., Anderson, I., Larsen, N., Los, T., Reznik, G., Selkov, E.G., Walunas, T.L., Feil, H., Feil, W.S., Purcell, A., Lassez, J., Hawkins, T.L., Haselkorn, R., Overbeek, R., Predki, P.F., Kyrpides, N.C. "Whole-genome comparative analysis of three phytopathogenic Xylella fastidiosa strains". Proceedings of the National Academy of Sciences of the U.S.A. 2002. Volume 99. p.12403-12408.
Doddapaneni, H., Yao, J. Lin, H., Walker, M.A., and Civerolo, E.L. "Analysis of the genome wide variations among multiple strains of the plant pathogenic bacterium Xylella fastidiosa". BMC Genomics. 2006. Volume 7. p.225
De La Fuente, L., Montanes, E., Meng, Y., Li, Y., Burr, T.J., Hoch, H.C., Wu, M. "Assessing adhesion forces of type I and type IV pili of Xylella fastidiosa bacteria by use of a microfluidic flow chamber". Applied and Environmental Microbiology. 2007. Volume 73. p. 2690-2696.
Hopkins, D.L. "Xylella fastidiosa: xylem-limited bacterial pathogen of plants". Annual Review of Phytopathology. 1989. Volume 27. p. 271-90.
Schuenzel, E.L., Scally, M., Stouthamer, R., Nunney, L. " A multigene phylogenetic study of clonal diversity and divergence in North American strains of the plant pathogen Xylella fastidiosa". Applied Environmental Microbiology. 2005 Volume 71. p. 3832-3839.
Simpson, A.J., Reinach, F.C., Arruda, P., Abreu, F.A., Acencio, M., Alvarenga, R., Alves, L.M.C., Araya, J.E, Baia, G.S., Baptista, C.S, Barros, M.H., Bonaccorsi, E.D., Bordin, S., Bové, J.M., Briones, M.R.S., Bueno, M.R.P., Camargo, A.A., Camargo, L.E.A., Carraro, D.M., Carrer, H., Colauto, N.B., Colombo, C., Costa, F.F., Costa, M.C.R, Costa-Neto, C.M., Coutinho, L.L., Cristofani, M., Dias-Neto, E., Docena, C., El-Dorry, H., Facincani, A.P., Ferreira, A.J.S., Ferreira, V.C.A., Ferro, J.A., Fraga, J.S., França, S.C., Franco, M.C., Frohme, M., Furlan, L.R., Garnier, M., Goldman, G.H., Goldman, M.H.S., Gomes, S.L., Gruber, A., Ho, P.L., Hoheise, J.D., Junqueira, M.L., Kemper, E.L., Kitajima, J.P., Krieger, J.E., Kuramae, E.E., Laigret, F., Lambais, M.R., Leite, L.C.C., Lemos, E.G.M., Lemos, M.V.F., Lopes, S.A., Lopes, C.R., Machado, J.A., Machado, M.A., Madeira, A.M.B.N., Madeira, H.M.F., Marino, C.L., Marques, M.V., Martins, E.A.L., Martins, E.M.F., Matsukuma, A.Y., Menck, C.F.M., Miracca, E.C., Miyaki, C.Y., Monteiro-Vitorello, C.B., Moon, D.H., Nagai, M.A., Nascimento, A.L.T.O., Netto, L.E.S., Nhani, A., Nobrega, F.G., Nunes, L.R., Oliveira, M.A., de Oliveira, M.C., de Oliveira, R.C., Palmieri, D.A., Paris, A., Peixoto, B.R., Pereira, G.A.G., Pereira, H.A., Pesquero, J.B.Jr., Quaggio, R.B., Roberto, P.G., Rodrigues, V., de M. Rosa, A.J., de Rosa, V.E., de Sá, R.G., Santelli, R.V., Sawasaki, H.E., da Silva, A.C.R., da Silva, A.M., da Silva, F.R., Silva, W.A., da Silveira, J.F., Silvestri, M.L.Z., Siqueira, W.J., de Souza, A.A., de Souza, A.P., Terenzi, M.F., Truffi, D., Tsai, S.M., Tsuhako, M.H., Vallada, H., Van Sluys, M.A., Verjovski-Almeida, S., Vettore, A.L., Zago, M.A., Zatz, M., Meidanis, J., and Setuba, J.C. "The genome sequence of the plant pathogen Xylella fastidiosa". Nature. 2000. Volume 406. p. 151-157.
Xylella fastidiosa Genome Project: http://aeg.lbi.ic.unicamp.br/xf/
Edited by Kathryn Thompson, student of Rachel Larsen and Kit Pogliano, UCSD
