Bacterial wilt disease changes the xylem sap metabolome
T. LOWE (1), A. Jancewicz (1), R. Mitra (2), B. Dalsing (1), P. Masson (1), C. Allen (1) (1) University of Wisconsin-Madison, U.S.A.; (2) Carleton College, U.S.A.

The bacterial plant pathogen Ralstonia solanacearum (Rs) infects xylem vessels of many plants. During infection, Rs populations exceed 109 CFU/g stem. Surprisingly, we found that Rs grows better in xylem sap harvested from Rs-infected tomato plants than in sap from healthy plants. GC/MS metabolomics revealed that Rs-infected sap was enriched in multiple sugars, amino acids, and fatty acids. Although glucose was not significantly enriched in the xylem sap from Rs-infected plants, Rs depleted glucose in ex vivo xylem sap, suggesting that glucose supports Rs growth in the plant. While most metabolites were modestly enriched in Rs-infected sap, putrescine was enriched 62-fold. We are investigating whether the host and/or Rs contribute to putrescine enrichment. We found that both the tomato host and the pathogen express putrescine biosynthesis genes during the interaction, suggesting that both partners may contribute to the increased putrescine. We will use Rs putrescine biosynthesis mutants to measure the amount of putrescine produced by the pathogen. Putrescine and related compounds are recognized as virulence factors for several animal pathogens. On the other hand, putrescine protects plants against multiple abiotic and some biotic stresses. To determine the role of putrescine in Rs-tomato interactions, we applied exogenous putrescine to plants prior to inoculation. Putrescine treatment accelerated disease development indicating that putrescine contributes to Rs virulence.

Abstract Number: P9-283
Session Type: Poster