Putative Transcriptional Regulation of HaWRKY33-AOA251SVV7 Complex-Mediated Sunflower Head Rot by Transcriptomics and Proteomics

<i>HaWRKY33</i> is induced by salicylic acid and participates in the disease resistance signaling pathway of sunflower rust disease; however, the transcriptional regulatory mechanism of this protein against <i>Sclerotinia sclerotiorum</i> in sunflowers remains unclear. Given this, we conducted a survey of 426 sunflower accessions at the natural disease nursery in Gannan County and identified a single dominant physiological race, MCG1, using simple sequence repeat methods. Additionally, we performed indoor inoculation tests using this dominant race and obtained disease-resistant varieties, W227 and BC2202-03, as well as susceptible varieties, N241 and Z155. Further, we inoculated the above resistant and susceptible combination materials with MCG1 and conducted transcriptomic analysis and RT-qPCR validation. Through KEGG analysis, we found that <i>HaWRKY33</i> is involved in the plant-pathogen interaction pathway, suggesting that <i>HaWRKY33</i> may regulate sunflower defense responses against <i>Sclerotinia sclerotiorum</i> through the plant-pathogen interaction pathway. Finally, yeast two-hybrid screening and AI prediction using AlphaFold 3 revealed strong interactions between ARG-189 and GLU-344 amino acids in the HaWRKY33-AOA251SVV7 proteins, indicating that the HaWRKY33-AOA251SVV7 pattern regulates the sunflower defense response against <i>Sclerotinia sclerotiorum</i> in a transcriptional complex form. In summary, these results provide new insights into the disease resistance mechanisms of sunflowers against <i>Sclerotinia sclerotiorum</i> and promote the development of molecular breeding for sunflower resistance to <i>Sclerotinia sclerotiorum</i>.