Doctoral Thesis
Genomic characterization and functional analysis of Pseudomonas sp. MUP55 for agricultural applications
Doctor of Philosophy (PhD), Murdoch University
2025
DOI:
https://doi.org/10.60867/00000126
Abstract
This thesis investigates both pathogenic and beneficial Pseudomonas strains in agricultural contexts through genomic characterization and functional analysis. The research begins by sequencing the complete genomes of ice-nucleation-active Pseudomonas syringae strains isolated from frost-damaged crops in Australia. Genomic analysis of strains MUP32 (from pea), MUP20 (from wheat), and MUP17 (from barley) identifies ice-nucleation protein genes with 19-20 repetitive PF00818 domains.
The research then characterizes Pseudomonas sp. MUP55, a novel strain isolated from rainwater with promising biocontrol properties. Phylogenetic and genomic analyses establish MUP55 as a distinct species within the P. fluorescens group. Through metabolomic profiling and genetic characterization, Massetolide A is identified as the primary bioactive compound responsible for MUP55's antimicrobial activity against both bacterial (P. syringae, Xanthomonas campestris) and fungal (Fusarium oxysporum, Rhizoctonia solani) pathogens.
Mutant analysis shows that GacA regulation is critical for Massetolide production, with a P58L mutation abolishing synthesis and reducing biocontrol efficacy. Further investigation of the pvf cluster in MUP55 demonstrates its dual functionality in both global gene regulation and direct antimicrobial activity. Metabolomic and transcriptomic analysis of a ΔpvfC mutant showed extensive global changes in the regulation of metabolites and gene expression, with effects on specialized metabolites.
In planta experiments confirm MUP55's dual capacity to suppress pathogen growth while enhancing tomato biomass by 71.2% compared to controls. This comprehensive investigation of contrasting Pseudomonas strains enhances our understanding of plantmicrobe interactions and identifies MUP55 as a promising biocontrol agent, contributing valuable knowledge toward developing sustainable alternatives to chemical pesticides in agriculture.
Details
- Title
- Genomic characterization and functional analysis of Pseudomonas sp. MUP55 for agricultural applications
- Authors/Creators
- Hussain Alattas - Murdoch University, Food Futures Institute
- Contributors
- Daniel Murphy (Supervisor) - Murdoch University, Centre for Sustainable Farming SystemsFrancesca L Brailsford (Supervisor) - Murdoch University, Centre for Sustainable Farming SystemsColin Scott (Supervisor) - Murdoch University
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005898164107891
- Murdoch Affiliation
- School of Agricultural Sciences; Bioplastics Innovation Hub; Food Futures Institute
- Resource Type
- Doctoral Thesis
UN Sustainable Development Goals (SDGs)
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