The biocontrol agent Pseudomonas chlororaphis PA23 primes Brassica napus defenses through distinct gene networks

BMC Genomics

Research Article

Michael G. Becker¹  Ian J. Girard¹  Jenna L. Millar¹  Mark F. Belmonte¹  Kelly A. Duke²  Teresa R. de Kievit²  W. G. Dilantha Fernando³ 

[1] Department of Biological Sciences, University of Manitoba, R3T 2N2, Winnipeg, MB, Canada;Department of Microbiology, University of Manitoba, R3T 2N2, Winnipeg, MB, Canada;Department of Plant Science, University of Manitoba, R3T 2N2, Winnipeg, MB, Canada;

关键词: Biocontrol;    Brassica napus;    Chloroplast;    Pseudomonas chlororaphis;    Reactive oxygen species;    RNA-seq;    Sclerotinia sclerotiorum;    Systemic acquired resistance;   

DOI  :  10.1186/s12864-017-3848-6

 received in 2016-08-09, accepted in 2017-03-27,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundThe biological control agent Pseudomonas chlororaphis PA23 is capable of protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. While we have elucidated bacterial genes and gene products responsible biocontrol, little is known about how the host plant responds to bacterial priming on the leaf surface, including global changes in gene activity in the presence and absence of S. sclerotiorum.ResultsApplication of PA23 to the aerial surfaces of canola plants reduced the number of S. sclerotiorum lesion-forming petals by 91.1%. RNA sequencing of the host pathogen interface showed that pretreatment with PA23 reduced the number of genes upregulated in response to S. sclerotiorum by 16-fold. By itself, PA23 activated unique defense networks indicative of defense priming. Genes encoding MAMP-triggered immunity receptors detecting flagellin and peptidoglycan were downregulated in PA23 only-treated plants, consistent with post-stimulus desensitization. Downstream, we observed reactive oxygen species (ROS) production involving low levels of H2O2 and overexpression of genes associated with glycerol-3-phosphate (G3P)-mediated systemic acquired resistance (SAR). Leaf chloroplasts exhibited increased thylakoid membrane structures and chlorophyll content, while lipid metabolic processes were upregulated.ConclusionIn addition to directly antagonizing S. sclerotiorum, PA23 primes the plant defense response through induction of unique local and systemic defense networks. This study provides novel insight into the effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as an alternative to chemical pesticides for protection of important crop systems.

【 授权许可】

CC BY   
© The Author(s). 2017