A stop-gained mutation in a Peroxiredoxin gene may underlie the low-chill phenotype of the apricot spontaneous mutant 'Bulida Precoz'

1.Somatic mutations in clonally propagated fruit trees, known as "bud sports," are a primary source of new and agronomically valuable traits. This study addresses the study of Bulida Precoz, a spontaneous somatic variant of the Bulida apricot characterized by an early flowering (low-chill) phenotype. The main objective of this work was to design and implement a comprehensive bioinformatic workflow to identify the specific somatic mutation(s) responsible for this significant developmental change, using whole-genome sequencing (WGS) data. A comparative genomics approach was employed, analyzing the genomes of four biological replicates from the Bulida Precoz mutant and four from the original Bulida wild-type. The analysis was centered on a specialized somatic variant-calling workflow using GATK Mutect2, chosen for its high sensitivity in detecting low-frequency mutations. The results were cross-validated against an independent analysis using the germline caller GATK HaplotypeCaller. The final candidates were functionally annotated to predict their biological impact on gene function. This work establishes a solid foundation for future experimental validation and provides valuable molecular targets that could be used in marker-assisted breeding programs aimed at developing new apricot cultivars better adapted to climates with mild winters.