Spinach (Spinacia oleracea L. ) is a major leafy vegetable valued for its nutritional content and commercial importance. The timing of bolting, defined as the transition from vegetative to reproductive growth, is a critical factor determining harvest period and leaf quality. In this study, the objectives were to identify genomic regions associated with bolting variation and assess genomic prediction (GP) accuracy for molecular breeding. Evaluation of bolting in a panel of 295 United States Department of Agriculture (USDA) accessions revealed a bimodal distribution reflecting contrasting bolting phenotypes. Whole-genome resequencing (WGR) yielded 16, 563 high-quality SNPs. A multi-model GWAS approach identified seven significant loci distributed across chromosomes 2, 4, and 6. A major-effect locus was identified on chromosome 6 (~13. 54 Mb), where the lead SNP, SOVchr6₁3545882, exceeded the significance threshold with a peak −log 10 (P) value of 8. 66. Consistently identified across multiple robust models, this SNP explained 21. 18% of the phenotypic variance (PVE). Within this interval, candidate genes SOV6g004520 (cysteine-rich receptor-like kinase) and SOV6g004560 (PPR protein) were prioritized due to their established roles in floral transition pathways. GP analysis further indicated a predominantly additive genetic architecture, with the rrBLUP model achieving a peak predictive accuracy of r ≈ 0. 39. A prioritized set of only six significant GWAS-derived SNPs (m6) achieved accuracy levels equivalent to the whole-genome panel. The genomic regulation of bolting identified through this analysis establishes a foundation of validated resources for the development of spinach cultivars with optimized reproductive timing.
Alkabkabi et al. (Mon,) studied this question.