CAAT box-derived polymorphism (CBDP) marker system exhibited a clear classification pattern in a global mini core collection of Aegilops tauschii Coss. populations

In this study, the population structure and genetic diversity of Aegilops tauschii individuals were investigated using CAAT box-derived polymorphism markers. Fifteen primers produced one hundred forty-nine amplification fragments, out of which one hundred forty were polymorphic, yielding a polymorphism rate of 94%. Total amplified fragments (TAF) per primer varied from 8 to 13, with polymorphic fragments ranging from 8 to 12. The mean resolving power (RP) was 12.07, while the average polymorphism information content (PIC) and marker index (MI) were 0.37 and 3.44, respectively. Analysis of molecular variance revealed that 85% of the total genetic variation occurred within three geographical regions (Central and Inner Asia (CI), Caucasus and Caspian Region (CC), and the Middle East (MED)), whereas 58% of the variance was partitioned among countries. The CI region displayed the highest genetic diversity, evidenced by the greatest number of effective alleles, gene diversity, percentage of polymorphic loci, and Shannon’s diversity index. At the country level, China and Afghanistan exhibited the highest diversity parameters. Principal coordinates analysis (PCoA) explained 30.25 and 57.60% % of the total variance and delineated three major geographic clusters corresponding to CI, CC, and MED. Cluster analysis corroborated these distinct regional patterns with minimal overlap among groups. Bayesian population structure analysis further supported these findings by assigning accessions to three primary subpopulations (K = 3) and revealing finer substructure at K = 9. Overall, our results demonstrate the effectiveness of CBDP markers for evaluating genetic diversity and geographic structuring in Ae. tauschii, providing valuable insights for its conservation and breeding.