Design of bioactive peptides by amino acid combination strategy against peanut southern blight caused by Sclerotium rolfsii.

BACKGROUND: Peanut southern blight, caused by Sclerotium rolfsii Sacc., is a destructive soil-borne disease that severely threatens peanut yield and production safety. In response to the growing demand for environmentally compatible fungicides with low resistance risk, bioactive peptides have emerged as promising alternatives for disease management. RESULTS: In this study, two novel peptides, wmz-1 and wmz-2, were designed using an amino acid combination strategy, and their bioactivities were systematically evaluated. Although both peptides exhibited moderate in vitro inhibition rates of 28.48% and 26.46% against S. rolfsii at 400 mg L-1, they showed superior in vivo performance in pot experiments. At 200 mg L-1, wmz-1 demonstrated protective and curative efficacies of 62.79% and 65.68%, respectively, whereas wmz-2 achieved 53.74% and 46.06%, respectively. To investigate the discrepancy between in vitro and in vivo activity, their effects on peanut plants were further examined. The results showed that both wmz-1 and the amino acid combination significantly promoted plant growth and enhanced the activities of defense-related enzymes, thereby providing experimental evidence supporting the involvement of plant growth promotion and induced defense responses. Moreover, both peptides exhibited low cytotoxicity toward human LO2 liver cells. CONCLUSION: These findings highlight the potential of wmz-1 and wmz-2 as effective, low-toxicity and environmentally friendly biopesticide candidates for the sustainable management of peanut southern blight, providing a theoretical basis for further development of peptide-based fungicides. © 2026 Society of Chemical Industry.