Defense-related proteins in Canavalia seeds: Implications for resistance to cowpea weevil Callosobruchus maculatus (F.)

Seeds of the genus Canavalia contain several bioactive proteins with known toxic effects, including the lectin concanavalin A, ureases, canatoxin, and vicilins. In this study, the toxicity of Canavalia gladiata (Jacq.) DC. and Canavalia rosea (Sw.) DC. seeds against the cowpea weevil, Callosobruchus maculatus (F.), was evaluated through morphological, biological, proteomic, and in silico analyses. Compared with the host species, Vigna unguiculata (L.), both Canavalia species produced larger, harder seeds with thicker seed coats and darker coloration. Oviposition by C. maculatus was reduced by 69.45% on C. rosea and 74.19% on C. gladiata , while larval penetration was completely inhibited. Larvae remained trapped within the eggs, exhibited apparent atrophy, and died without entering the seeds. Cotyledon flours from both species were toxic to larvae, reducing survival when at concentrations of 2% for C. rosea and at 10% for C. gladiata . Larval biomass was significantly reduced in artificial seeds containing 1% C. rosea flour and 2% C. gladiata flour. Furthermore, the flours of C. rosea and C. gladiata were lethal to insects at concentrations of 10% and 20%, respectively. Proteomic analysis identified 304 proteins annotated based on matches to Glycine max database entries , including defense-related proteins assigned to conserved urease and cupin protein families , such as putative β-conglycinins and basic 7S globulins . Molecular docking analyses suggested that putative urease homologs may interact with cathepsin L from C. maculatus , whereas putative β-conglycinin and basic 7S globulin homologs exhibited affinity for N -acetylglucosamine tetramers, indicating potential interactions with chitin-containing structures such as the insect peritrophic matrix. Collectively, these results indicate that C. rosea and C. gladiata possess both physical and biochemical defenses that confer resistance to C. maculatus . The identified seed proteins represent promising candidates for further investigation as bioinsecticidal agents in stored-product pest management.