Selective inhibition of Erwinia amylovora by the herbicidally active germination-arrest factor (GAF) produced by Pseudomonas bacteria

Abstract

Aims: The germination‐arrest factor (GAF) produced by Pseudomonas fluorescens WH6, and identified as 4‐formylaminooxyvinylglycine, specifically inhibits the germination of a wide range of grassy weeds. This study was undertaken to determine whether GAF has antimicrobial activity in addition to its inhibitory effects on grass seed germination. Methods and Results: Culture filtrate from Ps. fluorescens WH6 had little or no effect on 17 species of bacteria grown in Petri dish lawns, but the in vitro growth of Erwinia amylovora, the causal agent of the disease of orchard crops known as fire blight, was strongly inhibited by the filtrate. The anti‐Erwinia activity of WH6 culture filtrate was shown to be due to its GAF content, and a commercially available oxyvinylglycine, 4‐aminoethoxyvinylglycine (AVG), exhibited anti‐Erwinia activity similar to that of GAF. The effects of GAF on Erwinia were reversed by particular amino acids. Conclusions: The biological properties of GAF include a rather specific antimicrobial activity against Erw. amylovora. This may be a general property of oxyvinylglycines as AVG exhibited similar activity. The ability of particular amino acids to reverse GAF inhibition is consistent with a potential effect of this compound on the activity of aminotransferases. Significance and Impact of the Study: The results presented here demonstrate a novel antimicrobial activity of oxyvinylglycines and suggest that GAF and/or GAF‐producing bacteria may have potential for the control of fire blight.

Indole-3-acetic acid (IAA) producing Pseudomonas isolates inhibit seed germination and α-amylase activity in durum wheat (Triticum turgidum L.)

“…For example, some of the bacteria in this group are known to be pathogenic (Hirano & Upper, 2000), while others are known to be involved in disease suppression (Halgren et al, 2011). In addition, some members of this group of bacteria appear to increase seed germination (Selvakumar et al, 2009), while others exert inhibitory effects on seed germination (McPhail et al, 2010;Lee et al, 2013).…”

Pseudomonas fluorescens SBW25 produces furanomycin, a non-proteinogenic amino acid with selective antimicrobial properties

“…tomato DC3000 harbors its own antibacterial properties [24], we chose Dickeya dadantii 1447, a pathovar that causes bacterial soft rot of corn, to use in following antibiotic activity in subsequent purification work. The bacterial plant pathogens inhibited by SBW25 culture filtrate included Erwinia amylovora, which is also selectively inhibited by culture filtrate from P. fluorescens WH6 [25]. However, unlike WH6, SBW25 culture filtrate did not inhibit the germination of Poa annua in our standard germination arrest assay [10].…”

“…For example, FVG and MVG selectively inhibit the growth of Erwinia amylovora , the causal agent of fireblight, an important disease of roseaceous orchard crops [25,37]. MVG also inhibits growth of Acanthamoeba castellanii [38] and Bacillus sp.…”

“…A 300-μL aliquot of the diluted culture was spread onto the surface of a 925 Minimal Medium plate (100 × 15 mm, containing 25 mL of medium). The 925 Minimal Medium [43] was prepared with the modifications described by Halgren et al [25]. After spreading the bacterial lawn, central wells were punched in the agar with a No.…”

Draft Genome Sequences of Seven 4-Formylaminooxyvinylglycine Producers Belonging to the Pseudomonas fluorescens Species Complex

“…One compound that contributes to the utility of P. fluorescens is the nonproteinogenic amino acid 4-formylaminooxyvinylglycine (FVG) (5, 6). FVG has both herbicidal and antimicrobial properties (7, 8). The activity, production, and regulation of FVG have been studied in the sequenced strain P. fluorescens WH6 (9–12).…”