A novel spectral marker-based diversity assessment of sesame germplasm

Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy provides a rapid, reproducible, and non-destructive analytical platform for profiling biochemical variation in biological samples. In this study, we demonstrate its application for diversity assessment in sesame (Sesamum indicum L.) seed oils, highlighting its potential as a methodological tool for high-throughput biochemical phenotyping. Spectral fingerprints were acquired from 64 genotypes and analysed using principal component analysis, hierarchical clustering, and K-means clustering. The first two principal components captured 73% of the total spectral variance, while clustering methods consistently separated genotypes into distinct groups, reflecting underlying biochemical polymorphisms. Key wavenumbers, 3888, 3757, 3564, 3294, 3132, 2902, 2470, 1850, 1685, 1436, 1350, 989, 888, and 788 cm^-1, were identified as major contributors to diversity, serving as spectral markers for oil quality and compositional analysis. The clustering of genotypes was further supported by band ratio analysis highlighting differences in unsaturation and esterification patterns among clusters. Beyond sesame, the workflow established here underscores the analytical capacity of ATR-FTIR, coupled with chemometric approaches, for capturing subtle biochemical variation across complex biological matrices. These results position ATR-FTIR as a broadly applicable method for biochemical screening and diversity studies in plant-derived and other biological systems.