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Title: AN EVALUATION OF GENETIC DIVERSITY OF XYLELLA FASTIDIOSA ISOLATED FROM DISEASED CITRUS AND COFFEE

Author
item QIN, XIAOTING - CHINESE ACAD. OF AGRI.SCI
item MIRANDA, VICENTE - FUNDECITRUS, BRAZIL
item Hartung, John

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2000
Publication Date: 8/1/2000
Citation: Qin, X., Miranda, V.S., Hartung, J.S. 2000. An evaluation of genetic diversity of xylella fastidiosa isolated from diseased citrus and coffee. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Strains of Xylella fastidiosa Wells et al., isolated from sweet orange trees (Citrus sinensis Osb.) and coffee trees (Coffea arabica) with symptoms of citrus variegated chlorosis and Requeima do Cafe respectively were indistinguishable based on REP-PCR and ERIC-PCR assays. These strains were also indistinguishable using a previously described PCR assay which distinguished the citrus strains from all other strains of X. fastidiosa. When comparisons were made to reference strains of X. fastidiosa isolated from other hosts using these methods, four groups were consistently identified: citrus/coffee, grapevine/almond, mulberry, and elm/plum/oak. Results from RAPD-PCR assays were consistent with these results. Two of the primers tested in RAPD-PCR were able to distinguish the coffee and citrus strains. Sequence comparisons of the 472 base pair PCR product confirmed the presence of a Cfo I polymorphism that can be used to distinguish the citrus strains from all others. No nucleotide sequence differences were present in this product amplified from X. fastidiosa from any other host. The amplification product of the coffee strains from Brazil shared the nucleotide sequence of the reference strains from the United States rather than that of the citrus strains from Brazil in spite of the fact that REP- and ERIC-PCR assays clearly showed the basic genomic organization of the coffee and citrus strains to be very similar to each other and quite different to that of strains from the United States. The ability to distinguish X. fastidiosa strains from citrus and coffee with a PCR-based assay will be useful in epidemiological and etiological studies of this pathogen in Brazil.