The role of Pseudomonas secondary metabolism in potato scab biocontrol

Lead Research Organisation: John Innes Centre
Department Name: Contracts Office


We will examine the role of several Pseudomonas secreted natural products (NPs) in S. scabies killing, and confirm their importance for scab suppression in planta. Specifically, we will complete the following experiments:
1. We will complete the bioinformatic analysis of our pre- and post-irrigation phenotypic and genomic soil Pseudomonas isolate datasets. This will enable us to more fully explore the relationship between different NP gene clusters and S. scabies/G. graminis var. tritici suppression, and the impact of irrigation on the distribution of NP clusters in the Pseudomonas population. This bioinformatic analysis will inform the experimental work below.
2. We will produce gene deletions in the NP loci of several scab-suppressive Pseudomonas isolates, and examine the effects of these mutations on S. scabies and G. graminis var. tritici suppression, and other relevant phenotypes (i.e. growth rate and swarming motility) in lab assays. MS/MS analysis of bacterial extracts will confirm the abolition of NP production in the mutant strains.
3. We will extract novel cyclic lipopeptides and other secreted NPs from Pseudomonas cultures using well-established protocols, and examine their effects on S. scabies and fungal growth in laboratory assays. Where particularly interesting molecules are identified, we will attempt to purify these in sufficient quantities to enable their structural determination by NMR.
4. We will determine the impact of Pseudomonas natural product production on suppression of potato scab in planta, testing whether scab symptoms can be effectively suppressed by the addition of Pseudomonas isolates, and whether NP operon deletion ameliorates this protection. We will also examine the impact of adding purified NPs on scab suppression.
The work described in this project will establish the importance of cyclic lipopeptides and potentially other NP loci in the suppression of an economically important crop disease.


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