Genome-wide assessment of genetic diversity and selective signatures in sunflower (Helianthus annuus L.) using a 10 K...

Sunflower (Helianthus annuus L.) is a valuable oilseed crop with significant economic importance. Enhancing breeding strategies in this species heavily relies on genetic diversity and molecular tools. Among these tools, SNP-based genotyping has proven to be an effective method for exploring genomic variation and understanding population structure in plants. This study aimed to evaluate the genetic diversity, population structure, and identify genomic regions under selection within a panel of sunflower inbred lines. A 10 K SNP (single-nucleotide polymorphism) array was employed to examine genetic variation among 94 sunflower inbred lines. The results showed that SNPs were unevenly distributed across the 17 sunflower chromosomes, with a higher density observed in telomeric regions. The average transition-to-transversion ratio was 3.75, confirming the reliability and quality of the genotypic data. Analysis of population structure revealed two distinct subgroups, as supported by the results from STRUCTURE, PCoA, and WPGMA methods. AMOVA revealed that 16% of total genetic variance occurred among populations (Fst = 0.156), and overall genetic diversity was moderate to high (PPL = 92.94%). A total of 283 potential genes were linked to genomic areas that were under selection. Functional enrichment analysis revealed significant involvement of these genes in proteasome activity and pyruvate metabolism pathways. The findings validate the presence of considerable genetic diversity and moderate genetic differentiation within the studied sunflower germplasm. This study reports, for the first time, the use of the Fst statistic to identify pathways that contribute to population differentiation and are under selection pressure in a panel of sunflower inbred lines. These results provide valuable insights that could inform future sunflower breeding efforts through marker-assisted selection and offer insights into the genetic mechanisms underlying adaptation and population divergence in sunflower.