1887

Abstract

WH6 secretes a germination-arrest factor (GAF) that we have identified previously as 4-formylaminooxyvinylglycine. GAF irreversibly inhibits germination of the seeds of numerous grassy weeds and selectively inhibits growth of the bacterial plant pathogen . WH6-3, a mutant that has lost the ability to produce GAF, contains a Tn insertion in a gene that has been described previously in some strains of as encoding a transmembrane regulator. As in these other pseudomonads, in WH6, occurs immediately downstream of , which encodes a protein homologous to extracytoplasmic function (ECF) sigma factors. These two genes have been proposed to function as a dicistronic operon. In this study, we demonstrated that deletion of in WT WH6 had no effect on GAF production. However, deletion of in the WH6-3 mutant overcame the effects of the Tn insertion in and restored GAF production in the resulting double mutant. Complementation of the double mutant with suppressed GAF production. This overall pattern of regulation was also observed for the activity of an AprX protease. Furthermore, reverse transcription quantitative real-time PCR analysis demonstrated that alterations in GAF production were mirrored by changes in the transcription of two putative GAF biosynthetic genes. Thus, we concluded that PrtI exerted a negative regulatory effect on GAF production, although the mechanism has not yet been determined. In addition, evidence was obtained that the transcription of and in WH6 may be more complex than predicted by existing models.

Funding
This study was supported by the:
  • USDA CSREES Grass Seed Cropping Systems for Sustainable Agriculture Special Grant Program
  • Oregon State University Agricultural Research Foundation
  • Agriculture and Food Research Initiative (Award 2012-67012-19868)
  • General Research Funds
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2014-11-01
2024-03-29
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