ARS | Publication request: Evaluation of Arabidopsis thaliana as a model host for Xylella fastidiosa

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 26, 2012
Publication Date: May 3, 2012
Citation: Rogers, E.E. 2012. Evaluation of Arabidopsis thaliana as a model host for Xylella fastidiosa. Molecular Plant-Microbe Interactions. 25(6):747-754.

Interpretive Summary: Pierce’s disease of grapes and almond leaf scorch are devastating diseases caused by the bacterium Xylella fastidiosa (Xf). To date, progress in determining the mechanisms of host plant susceptibility, tolerance or resistance has been slow, due in large part to the long generation time and limited available genetic resources for grape, almond and other known hosts of Xf. The long generation time and limited genetic resources for Xylella fastidiosa compound the problem. The model plant Arabidopsis thaliana is an ideal system for rapid progress in genetic and pathological studies. There are many publically available genetic resources for Arabidopsis and it has a short generation time. This work evaluates Arabidopsis as a model host for Xf. A pin-prick inoculation method has been developed. Following infection, Xf can be detected by microscopy and polymerase chain reaction (PCR). Xf has also been re-isolated from infected Arabidopsis tissue. Timecourses following Xf growth have revealed Arabidopsis ecotypes with differing susceptibility to infection. Differences in plant gene expression before and after infection have been examined. These changes, while very different from those induced by other studied bacterial pathogens, suggest host plant responses that may be involved in limiting the growth of Xf. Such responses can be further examined in Arabidopsis and in economically important hosts like grapes and almond.

Technical Abstract: The bacterium Xylella fastidiosa (Xf) causes a number of devastating plant diseases of significant economic impact. To date, progress determining mechanisms of host plant susceptibility, tolerance or resistance has been slow, due in large part to the long generation time and limited available genetic resources for grape, almond and other known hosts of Xf. To overcome many of these limitations, Arabidopsis thaliana was evaluated as a host for Xf. A pin-prick inoculation method has been developed to infect Arabidopsis with Xf. Following infection, Xf multiplies robustly and can be detected by microscopy, PCR and isolation. The ecotypes Van-0, LL-0 and Tsu-1 all allow more growth of Xf strain Temecula than the reference ecotype Col-0. Affymetrix ATH1 microarray analysis of inoculated vs. non-inoculated Tsu-1 reveals gene expression changes that differ greatly from changes seen after infection with apoplast colonizing bacteria. Many genes responsive to abiotic stress are differentially regulated while classic pathogenesis-related (PR) genes are not induced by Xf infection.