|Lee, Xiaoyun -|
|Armstrong, Donald -|
|Reimmann, Cornelia -|
Submitted to: Environmental Microbiology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2012
Publication Date: February 28, 2013
Citation: Lee, X., Azevedo, M.D., Armstrong, D.J., Banowetz, G.M., Reimmann, C. 2013. The Pseudomonas aeruginosa oxyvinylglycine L-2-amino-4-methoxy-trans-3-butenoic acid inhibits growth of Erwinia amylovora and acts as a weak seed germination-arrest factor. Environmental Microbiology Reports. 5:83-89. Interpretive Summary: Soil bacteria can produce compounds that have practical utility in agriculture. One strain of Pseudomonas produces a compound called GAF is a vinylglycine that inhibits germination of many invasive weeds and inhibits the growth of the plant pathogen that causes fire blight disease in apples and pears. Another Pseudomonas has been discovered which produces a vinylglycine (AMG) with structural similarity to GAF. This study compared the effects of GAF and AMG on weed seed germination and inhibition of the fire blight pathogen. AMG had less seed germination inhibition activity than GAF, but appeared to have greater activity in inhibiting the fire blight pathogen.
Technical Abstract: The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid (AMB) is demonstrated to share biological activities with 4-formylaminooxyvinylglycine, a related molecule produced by Pseudomonas fluorescens WH6. We found that culture filtrates of a P. aeruginosa strain overproducing AMB weakly interfered with seed germination of the grassy weed Poa annua and strongly inhibited growth of Erwinia amylovora, the causal agent of the devastating orchard crop disease known as fire blight. Interestingly, AMB was active even against a 4-formylaminooxyvinylglycine-resistant isolate of E. amylovora, suggesting that the molecular targets of the two oxyvinylglycines in Erwinia do not, or not entirely, overlap. The AMB biosynthesis and transport genes are shown to be organized in two separate transcriptional units, ambA and ambBCDE, which were sucessfully expressed from IPTG-inducible tac promoters in the heterologous host Pseudomonas fluorescens CHA0. Engineered AMB production enabled this well-known biocontrol strain to become inhibitory for E. amylovora and to weakly interfere with seed germination of P. annua. We conclude that AMB production requires no additional genes besides ambABCDE and we speculate that their expression in marketed fire blight biocontrol strains could potentially contribute to disease control.