Transcriptome profile analysis of European plum response to fungal Monilinia fructigena pathogen

The European plum is a commercially important stone fruit worldwide, belonging to Prunus genus, Rosacea family. The main criteria for plum breeding are fruit quality, productivity, nourishment value and disease resistance. The most important diseases affecting stone fruits are caused by fungal pathogens of the genus Monilinia, with Monilinia fructigena being the most common species in Europe. These pathogens cause brown rot, blossom blight and twig canker, which results in considerable losses in stone fruit production. The knowledge of molecular mechanisms that determine plant response to pathogens is essential for controlling the effects of the disease. The underlying genes and molecular mechanisms involved in the postharvest response of plum to M. fructigena infection have yet to be identified. Fruits of the ‘Victoria’ plum were collected at the Institute of Horticulture of the Lithuanian Research Centre for Agriculture and Forestry orchards. The fruits were wounded and artificially injected with the pathogen. During this study, the dynamics of the plum's transcriptomic response to M. fructigena infection was observed by analysing gene expression levels at three postinfection stages: 24, 48, and 72 hours. The highest number of differentially expressed genes (DEGs) was shown after 72 h of infection compared to the control. The number of up-regulated DEGs in the 72h infected sample was significantly higher than in the 24h and 48h exposed fruit samples, showing the tendency to involve more genes in the response to prolonged exposure to the pathogen. The plum initiates complex defence responses to the M. fructigena infection. According to Gene Ontology enrichment analysis, the highest number of infection-related pathways were activated after 24h of infection. As the duration of the infection increases, infection-related pathways decrease. The comparative transcriptome analysis of the European plum allows us to understand the molecular mechanisms behind pathogen-infection responses. This information is essential for European plum breeding programs to develop fungi resistant varieties in the future.