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United States Department of Agriculture

Agricultural Research Service

Title: The Contribution of the Pectin-Degrading Enzyme Polygalacturonase (Pg) in Transmission of Xylella Fastidiosa to Grape and Use of Pg-Inhibitor Proteins for Transgenic Resistance to Pierce's Disease

Authors
item Labavitch, John - UNIV OF CA-DAVIS
item BACKUS, ELAINE
item Morgan, David - CA DEPT OF FOOD AND AG

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: October 13, 2004
Publication Date: December 7, 2004
Citation: Labavitch, J., Backus, E.A., Morgan, D. 2004. The contribution of the pectin-degrading enzyme polygalacturonase (pg) in transmission of xylella fastidiosa to grape and use of pg-inhibitor proteins for transgenic resistance to pierce's disease. Proceedings of CDFA Pierce's Disease Control Program Research Symposium. p. 19-21.

Interpretive Summary: Previous research has shown that xylem vessel obstruction (tyloses, plant cell wall component-derived gels and bacterial extracellular polysaccharides) are early consequences of infection with Xylella fastidiosa (Xf), before bacterial populations are substantial and have spread far from the inoculation point. Also, ethylene treatment of vines also triggers vessel obstruction development and reduced water movement. This new project will study the role of GWSS cell wall-degrading salivary enzymes in cell wall breakdown, especially of pit cell membranes. Objectives are to obtain cell wall-degrading salivary enzymes from GWSS and determine whether inhibitor proteins can interfere with their role in Xf transmission and establishment.

Technical Abstract: Previous research has shown that xylem vessel obstruction (tyloses, plant cell wall component-derived gels and bacterial extracellular polysaccharides) are early consequences of infection with Xylella fastidiosa (Xf), before bacterial populations are substantial and have spread far from the inoculation point. Also, ethylene treatment of vines also triggers vessel obstruction development and reduced water movement. This new project will study the role of GWSS cell wall-degrading salivary enzymes in cell wall breakdown, especially of pit cell membranes. Objectives are to obtain polygalacturonase (PG) and other enzymes from both GWSS and Xf and determine the extent to which PG inhibitor proteins (PGIP) inhibits the PGs from the insect as well as bacteria. Preliminary work to date has shown PG to be present in low but variable amounts in GWSS salivary gland extracts. In contrast, beta-1,4-glucanase (BGase) activity has been substantial in all extracts and is being purified.

Last Modified: 9/10/2014
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