Polyhydroxybutyrate and trehalose: A close look at metabolites present in tomato xylem sap during Ralstonia solanacearum infection
A. MACINTYRE (1) (1) University of Wisconsin-Madison, U.S.A.

Ralstonia solanacearum (Rs), which causes bacterial wilt disease, is a xylem dwelling plant pathogen.  Plant xylem has been described as a harsh, nutrient poor environment, but Rs grows to high density there. Little is known about the metabolic strategies that enable Rs to exploit this unpromising niche. Comparative GC-MS analysis revealed that 35 metabolites were more abundant in xylem sap from infected plants than healthy plants. Interestingly, Rs grew better in filter-sterilized xylem sap from infected plants than it grew in sap from healthy plants. These results suggest that Rs manipulates the xylem environment. Among the metabolites that increased in sap from infected plants were 3-hydroxybutyrate (3HB) and trehalose which increased 10.6 and 16 fold, respectively. 3HB monomers are linked together to form poly-3-hydroxybutyrate (PHB), a bacterial storage compound synthesized when carbon is abundant but other nutrients are limited. We are testing the hypothesis that R. solanacearum uses PHB as a carbon source during bacterial wilt disease and in the soil. We also hypothesize that PHB accumulation in planta prepares R. solanacearum for escape from dying plants and survival in the soil. Trehalose plays many roles in plants and bacteria, including stress tolerance and signaling. Rs has several pathways to synthesize and degrade trehalose, and preliminary evidence suggests that one degradation pathway is highly expressed during infection. We are testing to see if trehalose produced and degraded by plants and bacteria contributes to plant resistance and/or pathogen virulence. 

Abstract Number: P9-286
Session Type: Poster