A systematic review of Bruchid resistance in common bean: Genetic mechanisms and breeding implications for Africa

Background: Bruchids (Acanthoscelides obtectus and Zabrotes subfasciatus) are responsible for severe post-harvest losses in common bean (Phaseolus vulgaris L.). Understanding the genetic mechanisms and molecular markers of resistance is critical for breeding durable cultivars, especially in Africa. Methods: This systematic review followed PRISMA guidelines. The protocol was registered on OSF before implementation. Ten databases and repositories were searched for peer-reviewed and gray literature evaluating cultivars, landraces, wild derivatives, or interspecific lines. Eligible studies reported genetic mechanisms, molecular markers, or breeding strategies for bruchid resistance. Results: Twenty-nine studies met inclusion criteria. Most identified resistance at the APA locus on chromosome Pv04, involving arcelins, phytohemagglutinin, and α-amylase inhibitors, which confer strong antibiosis. Additional loci on Pv03 and Pv07, together with seed-coat traits, contributed complementary non-APA resistance. Validated protein markers and SNPs linked to these loci were reported. Breeding approaches included backcrossing and interspecific introgression. Conclusions: Marker-assisted selection offers opportunities to pyramid multiple resistance genes into farmer-preferred germplasm. However, progress is constrained by limited germplasm diversity, inconsistent bioassays, and poor characterization of non-APA mechanisms. Greater emphasis on diverse African germplasm and standardized assays is needed to accelerate the breeding of resistant cultivars.