P-223 - Investigating the soybean-Cercospora sojina interaction: insight into the role of the phytohormone signaling pathways and age-related resistance

Frogeye leaf spot (FLS) is an important soybean disease caused by the hemibiotrophic fungus Cercospora sojina. Phytohormone signaling plays a critical role in the plant immune system by inducing molecular responses that can determine resistance or susceptibility. They are also involved in age-related resistance (ARR) as plant tissues mature. However, they have not been explored as potential means to improve FLS resistance in soybeans. Therefore, the objective of this study is to elucidate the role of phytohormone pathways during FLS disease development and ARR. FLS resistant and susceptible soybean cultivars were inoculated with C. sojina. Non-inoculated plants were used as controls. The second trifoliate (V2) was collected at 24, 48, 72, and 336 hours post-inoculation (hpi). The third trifoliate (V3) was also collected at 336 hpi. V2 samples were used to quantify hormone marker gene expression via RT-qPCR. V3 and V2 samples (336hpi) were used to conduct RNAseq analysis. RT-qPCR results showed that salicylic acid (SA) signaling is likely important for resistance during early (biotrophic) infection. V2 leaves developed smaller and fewer lesions compared to V3 leaves in the susceptible genotype and RNAseq results suggested that SA-related genes may be involved in ARR. An RNAseq experiment is currently underway to elucidate the mechanisms underlying ARR during FLS-early infection. Together, these results will shed light onto the molecular pathways involved in FLS resistance.