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<p>Sesame (<i>Sesamum indicum</i> L.) is a commercially important oilseed crop whose effective utilisation in breeding depends on a thorough understanding of genetic diversity. This study evaluated 177 sesame accessions (107 indigenous breeding lines, 46 exotic breeding lines, and 24 released cultivars) for molecular and phenotypic diversity using expressed sequence tag-simple sequence repeat (EST-SSR) markers and quantitative morphological traits across two monsoon/autumn seasons (2023 and 2024). Screening of 96 EST-SSR markers yielded 29 polymorphic markers with polymorphism information content (PIC) ranging from 0.2888 (SEM-12–58) to 0.8655 (ZM_5), with a mean of 0.6089; 24 markers were highly informative (PIC &gt; 0.50) and 5 were moderately informative (0.25 &lt; PIC ≤ 0.50). Molecular variance analysis observed 95% of total genetic variation within populations and only 5% among populations (Φst = 0.048, <i>P</i> &lt; 0.001), independently supported by Shannon diversity analysis (95.79% within populations) and a high scaled overlap value (D' = 0.910), indicating extensive allele sharing among populations. Indigenous accessions exhibited comparatively higher allelic richness (Na = 7.069; I = 1.323), and this ranking remained consistent after rarefaction standardisation to n = 24, confirming that the advantage reflected genuine genetic richness rather than sampling depth alone. Permutational multivariate&#xa0;analysis of variance (PERMANOVA) on best linear unbiased estimate&#xa0;(BLUEs)-adjusted trait means distributed 92.21% of phenotypic variance within populations, with released cultivars recording the highest yield-trait means as a predictable outcome of directed selection. Principal coordinate analysis (PCoA), Bayesian clustering (K = 2; ΔK = 298.489), and unweighted pair group method with arithmetic mean (UPGMA) analysis all pointed to widespread genetic admixture across the three groups. These findings demonstrate the utility of EST-SSR markers for sesame germplasm characterisation and highlight the rich genetic potential available for integration into future breeding programmes.</p>

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Molecular and morphological diversity and population structure of sesame (Sesamum indicum L.) germplasm using expressed sequence tag-simple sequence repeat (EST-SSR) markers

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Avtar Singh,
  • Puneet Walia,
  • Sanjeet Singh Sandal,
  • Shubham Gopera

摘要

Sesame (Sesamum indicum L.) is a commercially important oilseed crop whose effective utilisation in breeding depends on a thorough understanding of genetic diversity. This study evaluated 177 sesame accessions (107 indigenous breeding lines, 46 exotic breeding lines, and 24 released cultivars) for molecular and phenotypic diversity using expressed sequence tag-simple sequence repeat (EST-SSR) markers and quantitative morphological traits across two monsoon/autumn seasons (2023 and 2024). Screening of 96 EST-SSR markers yielded 29 polymorphic markers with polymorphism information content (PIC) ranging from 0.2888 (SEM-12–58) to 0.8655 (ZM_5), with a mean of 0.6089; 24 markers were highly informative (PIC > 0.50) and 5 were moderately informative (0.25 < PIC ≤ 0.50). Molecular variance analysis observed 95% of total genetic variation within populations and only 5% among populations (Φst = 0.048, P < 0.001), independently supported by Shannon diversity analysis (95.79% within populations) and a high scaled overlap value (D' = 0.910), indicating extensive allele sharing among populations. Indigenous accessions exhibited comparatively higher allelic richness (Na = 7.069; I = 1.323), and this ranking remained consistent after rarefaction standardisation to n = 24, confirming that the advantage reflected genuine genetic richness rather than sampling depth alone. Permutational multivariate analysis of variance (PERMANOVA) on best linear unbiased estimate (BLUEs)-adjusted trait means distributed 92.21% of phenotypic variance within populations, with released cultivars recording the highest yield-trait means as a predictable outcome of directed selection. Principal coordinate analysis (PCoA), Bayesian clustering (K = 2; ΔK = 298.489), and unweighted pair group method with arithmetic mean (UPGMA) analysis all pointed to widespread genetic admixture across the three groups. These findings demonstrate the utility of EST-SSR markers for sesame germplasm characterisation and highlight the rich genetic potential available for integration into future breeding programmes.