Use of a Pressure Chamber to Isolate and Detect Xylella fastidiosa in Xylem Exudates of Grapevines

¹ College of Life Sciences, Hunan Normal University, Changsha, 410081, ChinaCenter for Viticulture Science, Florida A&M University, Tallahassee, FL 32307.
² Center for Viticulture Science, Florida A&M University, Tallahassee, FL 32307.

email: Jiang.Lu{at}famu.edu

Xylella fastidiosa (Xf), a xylem-limited bacterium, is the causal agent of many plant diseases, including Pierce’s disease (PD) of grapevine. Reliable detection of PD depends upon accurate and repeatable methods to isolate and identify Xf in grapevines. A pressure chamber was used to extrude xylem fluids from grapevine shoots. Xf was isolated from xylem exudates of infected shoots, while Xf was not found in xylem exudate from healthy shoots on the same plant. Polymerase chain reaction detected Xf in bacterial suspensions from xylem exudates using either immunocapture or centrifugation to avoid or eliminate polymerase inhibitors. Pressure chamber extraction followed by centrifugation of xylem exudate provides a simple, rapid, and efficient protocol for isolation and detection of Xf. This procedure would greatly aid epidemiological studies of PD that involve large numbers of plant samples.

Note:
Acknowledgments: The authors thank Dr. Shuqiu Zhang for helpful discussions and the suggestion of using a pressure chamber in the experiment during her visiting study at Florida State University and the members of the Center for Viticulture Science for the fieldwork.

Key words: grape, PCR, pressure chamber, Xylella fastidiosa, xylem exudates