Pseudomonas chlororaphis PA23 biocontrol of Sclerotinia sclerotiorum on canola: understanding populations and enhancing inoculation

Abstract
Pseudomonas chlororaphis strain PA23 has demonstrated biocontrol of Sclerotinia sclerotiorum (Lib.) de Bary, a fungal pathogen of canola (Brassica napus L.). The objectives of this research were two-fold: to optimize PA23 phyllosphere biocontrol and to investigate PA23’s influence in the rhizosphere. PA23 demonstrated longevity when inoculated on B. napus under greenhouse conditions. Carbon source differentially effected growth rate and antifungal metabolite production of PA23 in culture. Carbon source did not have a significant effect on in vivo biocontrol. PA23 demonstrated biocontrol ability of the fungal root pathogens Rhizoctonia solani J.G. Kühn and Pythium ultimum Trow in radial diffusion assays. PA23’s ability to promote seedling root growth was demonstrated in sterile growth pouches, but in a soil system these results were reversed. This research is essential for developing PA23 into an effective biocontrol agent in the phyllosphere and it opens the door for use of PA23 as a rhizosphere seed treatment.
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Keywords
Pseudomonas chlororaphis PA23, Sclerotinia sclerotiorum, canola
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