Discovery of Pseudomonas Natural Products Involved in the Biological Control of Potato Pathogens

Moffat, Alaster (2021) Discovery of Pseudomonas Natural Products Involved in the Biological Control of Potato Pathogens. Doctoral thesis, University of East Anglia.

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Potato common scab and late blight, caused by Streptomyces scabies and Phytophthora infestans, respectively, are serious diseases affecting one of the world’s largest and most important food crops. The lack of stable interventions has shifted recent focus toward biological control (biocontrol) methods. Pseudomonas isolates have shown significant promise as bacterial biocontrol agents, occurring in soils worldwide with high inter-strain diversity and potential for natural product biosynthesis. This thesis details investigations into the biosynthetic potential of environmental Pseudomonas strains isolated from a potato field, with a focus on discovering novel natural products active against plant pathogens. Investigations focused on a strain showing strong biocontrol phenotypes, Ps652. Initially, this strain showed strong inhibition of phytopathogens but with few biosynthetic gene clusters (BGCs) identified by common methods. A variety of methods were used to identify the determinants of the strong biocontrol phenotype shown by this strain, including activity-guided isolation of natural products and transposon mutagenesis. 3,7-dihydroxytropolone (3,7-HT) is reported here as being produced by a Pseudomonas isolate for the first time. 3,7-HT shows improved activity towards Streptomyces scabies compared to 7-hydroxytropolone, but does not fully explain activity of Ps652 against P. infestans. Additionally, investigations were made into putative RiPP BGCs containing DUF692 proteins in environmental Pseudomonas isolates Ps706 and Ps708. These BGCs appeared associated with phytopathogen inhibition in previous work, and were studied here using bioinformatics, gene deletions, and heterologous expression approaches.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 10 Mar 2022 11:28
Last Modified: 10 Mar 2022 11:28


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