Responses of sunflower induced by Sclerotinia sclerotiorum infection

Sunflower (Helianthus annuus) can be infected by the fungal pathogen Sclerotinia sclerotiorum, but its susceptibility varies depending on the cultivars. The aim of this study was to characterize and compare the biochemical responses between the R and the S sunflower cultivars after inoculation with S. sclerotiorum. The biochemical activities were detected by measuring necrotic cell, callose deposition, soluble protein content, as well as ROS accumulation at the infection site. Antioxidant enzymatic activities, the transcripts of ROS related genes and marker genes in pathways of salicylic acid (SA) and jasmonic acid (JA) were also quantified to characterize the responses. Results showed that compared to the S cultivar, the R cultivar was characterized having reduced number of necrotic cell, more callose deposition on the cell wall, increased soluble protein content, higher levels of H2O2 and ROS scavenger enzyme activities, and upregulated transcript profile of marker genes of both SA and JA pathways.