Characterising the insecticidal capability of Pseudomonas fluorescens from the Fragaria x ananassa leaf endosphere

Abstract

Drosophila Suzukii is a major pest to the berry industry in the Pacific Northwest, resulting in a need for cost effective solutions that are safe for the surrounding ecosystem. Natural biocontrol strategies can offer a more efficient and pest-specific control measure than traditional pesticides. Plant symbiotic Pseudomonas fluorescens are known to express the insecticidal fitD toxin which makes them an ideal candidate for a biocontrol solution. Based on this, we hypothesise that P. fluorescens strains found in the fruiting bodies, leaves, and stems of strawberry and blackberry plants will express the insecticidal fitD gene. We isolated a bacterial strain from the strawberry leaf endosphere, named SL1 and confirmed it is a member of the genus Pseudomonas by 16S rRNA sequencing. Whole genome sequencing of Pseudomonas sp. SL1 and subsequent assembly and polishing returned a genome of 6.8 Mbps. We were unable to locate the fitD gene in this assembled genome using Prokka or BlastKOALA but were able to find the response regulator gene gacA, responsible for encoding virulence factors in Pseudomonas species. This process allowed for the development of a detailed approach towards isolating and characterising possible insecticidal endophytic species of Pseudomonas from above-ground plant tissues.