Dissecting Vegetative Period Into Its Phenotypic and Genotypic Components Allows Environment-Specific Breeding in...

In legumes, flowering time is regulated by genes responsive to temperature and photoperiod, presenting challenges for high-latitude lentil producers who must adapt cultivars to short growing seasons and extended daylight hours. Therefore, prolonged vegetative periods are favored in those areas. To address this, we studied a recombinant inbred line (RIL) population, derived from a cross between the adapted cultivar CDC-Milestone and the non-adapted line ILL8006, to investigate phenology-related traits under long-day conditions in western Canada. Significant variation in days to emergence (DTE), days to flowering (DTF), and days to pod maturity (DTM) enabled analysis of the vegetative (VegP) and reproductive (RepP) periods within the population. We constructed a high-density genetic linkage map using molecular markers linked to genes in the Lcu.2RBY reference genome, identifying quantitative trait loci (QTLs) for those traits across four site-years in Saskatchewan. Differential expression analysis of known flowering time genes enhanced interpretation of the QTL results for flowering time. Three major DTE QTLs (qDTE2/3.II, qDTE2/3.III, and qDTE2/3.IV) on chromosome 2 explained 16%-28% phenotypic variability, depending on the environment, with in silico analysis identifying six curated genes as putative candidates within that region. A key DTF QTL (qDTF6.I) on chromosome 6 accounted for 23%-56% of phenotypic variability, harboring a homolog of the FLOWERING LOCUS T gene, whose role was explored alongside other candidate genes. Dissecting the vegetative period into DTE and DTF revealed distinct genetic controls for each trait, enabling breeders to combine early or late emergence and flowering to optimize adaptation and yield in diverse agroclimatic conditions.