Abstract
Southern leaf blight (SLB), caused by Bipolaris maydis, poses a significant threat to maize and popcorn production. To understand the molecular mechanisms underlying SLB resistance, we conducted a high-throughput proteomic analysis comparing SLB-resistant (L66) and SLB-susceptible (L51) popcorn genotypes at four and ten days after inoculation (DAI). A total of 717 proteins were identified, with 151 differentially accumulated proteins (DAPs) between the genotypes. Eighteen DAPs exhibited the same regulatory pattern in both the SLB-resistant and SLB-susceptible genotypes at four (R4/S4) and ten (R10/S10) DAI. The protein-protein interaction (PPI) network of differentially accumulated proteins (DAPs) linked to SLB resistance and susceptibility enriched specific metabolic pathways in the SLB response, including photosynthesis, ribosome, ascorbate and aldarate metabolism, glutathione metabolism, and carbon metabolism. Proteins such as photosystem II 11 kD protein (B4FRJ4, PSB27-1), which was up-regulated at both time points (R4/S4 and R10/S10), and 60S acidic ribosomal protein P0 (A0A1D6LEZ7, RPP0B), which was unique to the resistant genotype at both time points (R4 and R10), highlighted the importance of maintaining photosynthetic efficiency and protein synthesis during pathogen attack. Additionally, dehydroascorbate reductase like-3 (B4F817, DHAR3) was consistently up-regulated at both time points in resistant genotypes, emphasizing its role in redox balance and ROS detoxification. In contrast, glyceraldehyde-3-phosphate dehydrogenase (K7UGF5, GAPC2), a glycolytic enzyme, was unique to the susceptible genotype, suggesting its involvement in managing energy metabolism under stress conditions. Our findings suggest that resistance to SLB in popcorn involves a combination of enhanced photosynthetic repair, redox homeostasis, and ribosomal protein activity, providing new potential molecular targets, such as DHAR3 and RPP0B, for genetic improvement in SLB resistance. These results offer valuable insights into breeding programs aimed at developing SLB-resistant popcorn varieties.