Transcriptome profiling of differentially expressed genes in strawberry after preharvest application of benzothiadiazole and chitosan

The application of resistance inducers exploiting natural protection of plants is an alternative approach to the use of synthetic fungicides for the control of pre- and postharvest decay of strawberries. However, the mechanisms behind the specific resistance inducer are not completely understood. The global transcriptional changes in strawberry fruits were investigated, using RNA-Seq technology, 6, 12 and 24 h after preharvest application to the canopy of benzothiadiazole and chitosan. Overall, 5,062 and 5,210 differentially expressed genes (fold change ≥ 2) were identified in the fruits treated with benzothiadiazole and chitosan, respectively, as compared with the control, only 20% of these genes being induced by both elicitors. The functional enrichment analysis highlighted different gene modulation over time for transcripts associated with photosynthesis and heat-shock proteins, according to the elicitor. Several genes associated with the plant immune system, biotic and abiotic stresses, and SAR, were elicited by the treatments. In addition, the reprogramming of protein metabolism was observed in fruits treated with both elicitors, which led to increased storage proteins. The RNA-Seq data were confirmed using RT-qPCR for 12 selected genes. This study established that the two elicitors affect cell pathways associated with plant defences in different ways, and suggests a role for chloroplasts as the primary target in the modulation of the plant defence responses, which actively communicate signals through changes in redox status. The genes identified in the present study can represent markers to better elucidate plant/ pathogen/resistance inducer interactions, and to plan innovative sustainable disease management strategies.