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United States Department of Agriculture

Agricultural Research Service

Research Project: EPIDEMIOLOGY AND MANAGEMENT OF XYLELLA FASTIDIOSA (XF) AND OTHER EXOTIC AND INVASIVE DISEASES AND INSECT PESTS Title: Effects of Grape Xylem Sap and Cell Wall Constituents on In Vitro Growth, Biofilm Formation, and Cellular Aggregation of Xylella fastidiosa

Authors
item Cheng, Davis
item Lin, Hong
item Walker,, M. Andrew - UC DAVIS
item Stenger, Drake
item Civerolo, Edwin

Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2009
Publication Date: May 8, 2009
Citation: Cheng, D.W., Lin, H., Walker,, M., Stenger, D.C., Civerolo, E.L. 2009. Effects of Grape Xylem Sap and Cell Wall Constituents on In Vitro Growth, Biofilm Formation, and Cellular Aggregation of Xylella fastidiosa. European Journal of Plant Pathology. 125:213-222.

Interpretive Summary: Most cultivated grapevines are susceptible to Pierce’s disease (PD); however, related grape species V. arizonica, V. shuttleworthii, V. simpsonii, V. smalliana, and Muscadinia rotundifolia are PD resistant. In this study, we investigated the effect of culture media amended with xylem sap from PD resistant and susceptible grapes or with several cell-wall constituents on growth and gene expression of the bacterium Xylella fastidiosa (Xf), the causal agent of PD. Bacteria grew better on media containing xylem sap from PD-susceptible plants than on media supplemented with xylem sap from PD-resistant plants. Culturing Xf on media supplemented with purified cell-wall constituents such as cellulose, xylan, laminarin, and glucan promoted bacterial growth whereas other cell-wall constituents, such as lichenan, strongly suppressed growth. Disease-related Xf genes were expressed differentially in response to growth on media amended with xylem sap from PD-resistant compared to PD-susceptible plants. Analysis of xylem sap protein also revealed differential expression by resistant and susceptible host genotypes in response to Xf infection. This study suggests that differences in xylem sap composition and cell wall properties among PD-resistant and -susceptible grapes may affect Xf pathogenesis.

Technical Abstract: Pierce’s Disease (PD) of grapevines is caused by the xylem-limited bacterium Xylella fastidiosa (Xf). Most Vitis vinifera-based cultivars are susceptible to PD; however, related grape species V. arizonica, V. shuttleworthii, V. simpsonii, V. smalliana, and Muscadinia rotundifolia are PD resistant. In this study, we investigated the effect of media amended with xylem sap from PD resistant and susceptible grapes or with several cell-wall constituents on bacterial growth, biofilm formation, and virulence-related gene expression. Media containing xylem sap from PD-susceptible plants provided better support for bacterial growth and biofilm formation than media supplemented with xylem sap from PD-resistant plants. Culturing Xf on media containing various purified cell-wall constituents demonstrated that cellulose, xylan, laminarin, and glucan promoted bacterial growth whereas lichenan strongly suppressed growth. However, only xylan, laminarin and k-carrageenan promoted biofilm formation in vitro. Reverse transcription-polymerase chain reaction assays revealed differential expression of Xf genes encoding glucanase, protease, and a number of virulence-related products in response to growth on media amended with xylem sap from PD-resistant compared to PD-susceptible plants. Analysis of xylem sap protein also revealed differential expression by resistant and susceptible host genotypes in response to Xf infection. This study suggests that differences in xylem sap composition and cell wall properties among PD-resistant and -susceptible grapes may affect Xf pathogenesis.

Last Modified: 10/25/2014
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