This study investigates the APA gene family, responsible for encoding α-amylase inhibitor, phytohemagglutinin, and arcelin proteins in common beans (Phaseolus vulgaris), specifically examining its role in preventing insect herbivory species such as Zabrotes subfasciatus and Acanthoscelides obtectus. The researchers analyzed linkage disequilibrium (LD) between microsatellite markers at the APA locus and bruchid resistance in 105 genotypes. They discovered variability in microsatellite allele diversity among the eight APA-linked markers and identified two markers within the APA locus as diagnostic for bruchid resistance or susceptibility , as well as for different arcelin alleles. The study found that Arc1 provides higher resistance levels than Arc5 (accessions purified as highly resistant G12882B for Arc1 and G2771A for Arc5), and introgression of the APA gene-family from wild beans confers resistance in cultivated beans. LD around the APA locus is intermediate compared to other genomic regions, with the highest LD observed within the APA locus itself. The study concludes that the APA locus is a crucial genetic determinant of bruchids resistance, emphasizing the importance of LD and association studies for understanding the introgression of arcelin and maintaining resistance in common bean cultivation. Functionally, the APA proteins are though to provide resistance to bruchids through antibiosis by reducing larval development as well as insect fertility and growth.

The accessions identified in the genebank with high resistance are: G12882, G12952, G2771 and G24584. Those with intermediate resistance include G12866. On the other hand, susceptible accessions are G12922 and G11051.