Development of a Nested Association Mapping (NAM) population for untangling complex traits in lentil (Lens culinaris Medik.)

Understanding the genetic basis of complex traits remains a key challenge in crop improvement. This study aimed to develop a structured, multi-parental mapping population to enhance the resolution of quantitative trait dissection, based on the hypothesis that a Nested Association Mapping (NAM) design would enable the detection of minor-effect loci often overlooked by traditional biparental or diversity panel-based approaches. A lentil (Lens culinaris Medik.) NAM population was developed by crossing the Canadian cultivar CDC Redberry with 32 diverse genotypes sourced globally from three major lentil-growing macro-environments: Northern temperate, Mediterranean, and South Asia. The resulting recombinant inbred lines were phenotyped for key phenological traits, days to emergence (DTE), flowering (DTF), and maturity (DTM), under field conditions, and genotyped using exome capture sequencing. Genome-wide association studies for DTF identified 14 significant loci across six chromosomes, including the known FTb locus and novel associations near AP3a, HUB2a, and PIF6 genes. These results demonstrate the utility of the NAM design in detecting both major and minor-effect loci that underlie complex trait variation. To our knowledge, this is the first publicly available NAM population in lentil. It provides a high-resolution, globally representative platform for trait discovery, pre-breeding, and collaborative genetic improvement of this nutritionally and agronomically important legume.