Horticultural performance and QTL mapping of snap bean (

Introduction: Improving crop cultivars for use on organic farms is pertinent, as current elite germplasm is less resilient within the more variable context of organic farm environments. Although a growing number of studies have focused on organic plant breeding in cereal crops, very few have focused on vegetable crops, especially those such as snap beans ( Methods: We developed four populations of recombinant inbred lines under parallel organic and conventional management; utilizing these populations, we explored how historic breeding history influences the performance of snap bean progeny. Results: We identified significant increases in germination speed and rate, suggesting that beans bred within an organic production environment are more resilient to early-season stressors without support of chemical interventions. We also found that root branching density increased among organically-bred bean families, while root disease decreased in both the organically-bred bean families and the populations with 'OR5630' × 'Black Valentine' parentage. After developing linkage maps for each of our four populations, we identified QTL associated with days to germination, early-season vigor, root morphology, disease, days to flowering, and seed weight. Discussion: This study lays the groundwork for improving snap bean germplasm for performance in organic systems by tracking the microevolutions created through long-term selection under organic or conventional management (i.e., breeding history). By understanding these shifts, plant breeders will begin to build a toolbox of genetic information that they can leverage in modern breeding work for organic crop cultivars.