Sorghum (Sorghum bicolor) is one of the most important monocot crops cultivated worldwide and is known for its versatility as a food, forage, and bioenergy crop. Sugarcane aphid (SCA; Melanaphis sacchari Zehntner) is considered a major threat to sorghum production, which severely damages the plant by sucking sap from leaves, thereby reducing its photosynthetic ability. Although several studies have been focused on the identification of sorghum-resistant varieties to SCA, very little is known about how sorghum mounts direct defenses against SCA. In the current study, we screened a panel of sorghum nested association mapping (NAM) founder lines to identify and characterize sorghum resistance mechanisms to SCA. We found SC265 genotype demonstrates a combination of antibiosis- and antixenosis-mediated resistance mechanisms to SCA. Furthermore, phytohormonal analysis suggests that the higher constitutive and SCA feeding-induced levels of salicylic acid in SC265 can provide defenses against aphids. Proteome profiling of SC265 after SCA infestation at days 1 and 7 revealed the suppression of plant defense-related proteins and upregulation of plant defense and signaling-related proteins, respectively. Proteomic data were validated using the electrical penetration graph technique by assessing the feeding behavior of SCA on control and SCA-infested plants. Results from this work will help us to better understand the sorghum defense signaling mechanisms against phloem-feeding insects.
