Transcriptome profiling uncovers the defense response of Sunflower to Phomopsis stem canker causing fungus Diaporthe helianthi

Using transcriptomics, an investigation was conducted to analyze the interaction between sunflower plants and D. helianthi, recognized as one of the predominant species causing PSC within the U.S. Three cultivated sunflower genotypes, PI 561918, PI 509062, and PI 552934 (susceptible check), were planted in a randomized complete block design and were inoculated with three isolates of D. helianthi at vegetative growth stages (V4-V5) using the mycelial contact method. The inoculated stems were sampled at 0- and 72-hours post-inoculation (hpi.). The expression analysis revealed the upregulation of 125, 120, and 88 genes, as well as the downregulation of 124, 157, and 176 genes in PI 552934, PI 561918, and PI 509062, respectively, in response to infection by all three D. helianthi isolates at 72 hpi. To validate the expression levels of differentially expressed genes (DEGs), reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was employed on a set of randomly selected DEGs.