Developmental and Structural Section
Sun, Yuliang , Labavitch, John , Walker, Andy , Sun, Qiang .
Tylose development and its impact on the water conduction of Xylella fastidiosa-infected grapevines with different Pierce's disease resistance .
Grapevine Pierce's disease (PD) is a vascular disease caused by the xylem-limited bacterium Xylella fastidiosa that can ultimately lead to death of infected vines. Tyloses, outgrowths of parenchyma cells into adjacent vessel lumens, were observed in X. fastidiosa-infected grapevines; however, their potential role in determining disease resistance vs. susceptibility of infected vines is still unclear. Recently, we used grapevines with different PD resistances to study tylose development and its impact on water conduction of the infected vines. Our investigation found tylose development in X. fastidiosa-inoculated grapevines but no tyloses in buffer-inoculated control vines, showing a correlation between tylose development and pathogen infection. A comparison of tylose development among the different grapevines three months post inoculation also indicated that tyloses were abundant throughout the PD-susceptible grapevines, but they were mostly restricted to internodes nearest to the inoculation site in the PD-resistant genotypes. Vessels occluded by tyloses accounted for over 60% of the total vessels in the transverse section of most internodes in the PD-susceptible grapevines, but represented less than 15% of vessels in the PD-resistant vines. Rates of water flow were measured in stem explants 3 months after inoculation. It was found that the hydraulic conductivity of the X. fastidiosa-inoculated PD-susceptible vines was only 10% of that in control vines. In concurrence with the presence of Xylella cells in all the internodes of susceptible vines, our finding demonstrates that tylose development does not stop the systemic spread of X. fastidiosa cells in an infected susceptible vine but it does suppress water conduction in the vine by occluding many vessels, therefore contributing to PD symptom development.
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1 - University of Wisconsin-Madison, Department of Biochemistry, Madison, WI, 53715, USA
2 - University of California-Davis, Department of Plant Sciences, Davis, CA, 95616, USA
3 - University of California-Davis, Department of Viticulture and Enology, Davis, CA, 95616, USA
4 - University Of Wisconsin-Stevens Point, Department Of Biology, 237 TNR Building, 800 Reserve Street, Stevens Point, WI, 54481, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union D/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:30 PM