Genetic Dissection of Adaptation Traits in Apricot Through GWAS and QTL Analyses

Understanding the genetic basis of adaptation traits including chilling requirements, flowering and fruiting is essential for developing apricot cultivars adapted to changing climatic conditions and for extending the apricot production calendar. The objective of this study is to detect and finely identify marker−trait associations linked to these adaptation traits including chilling requirements in apricot, using an R-based workflow developed with agroclimatic functions. In this study, high-density GBS-based linkage maps previously developed for two biparental populations (‘Bergeron’ × ‘Currot’ and ‘Goldrich’ × ‘Currot’) were used to analyze the genetic basis of key adaptation traits, including chilling requirement (CR), blooming date (BD), fruit development period (FDP), and ripening time (RT), through Genome-Wide Association (GWAS) and Quantitative Trait Locus (QTL) analyses. Phenotypic evaluation over eight years revealed wide variability across genotypes and strong correlations between CR and BD, particularly when using Chill Portions as a metric. Genome-wide association and QTL mapping consistently identified major loci on linkage group (LG) 1 for BD and CR, and on LG4 for FDP and RT, explaining up to 59% of phenotypic variance. The candidate gene (qMD4.1 ANAC072), upon analysis, revealed the involvement of epigenetic regulators, cold-responsive proteins, and transcription factors, offering plausible functional links between genotype and phenotype. These findings provide novel insights into the genetic control of dormancy and phenological traits in apricot and represent a valuable genomic resource for marker-assisted breeding programs aimed at improving climatic resilience and extending the harvest.