Legume Genomics and Genetics 2026, Vol.17, No.1, 1-13 http://cropscipublisher.com/index.php/lgg 6 certain traits and making the individuals more genetically similar to each other (Falconer and Mackay, 1996). This higher heritability within a population is present in Table 2. The investigation of intracultivar variation in soybeans has disclosed several key insights that have implications for soybean breeding and cultivation. The potential for selection within a cultivar stands out as a promising avenue for enhancing desirable traits while maintaining the overall genetic elite background of the cultivar. This potential for selection within a soybean cultivar also raises important considerations in the context of plant variety protection. To qualify for protection under plant variety protection laws, a new cultivar must typically meet the criteria of Distinctness, Uniformity, and Stability (DUS). Another perspective that emerges when considering intracultivar variation is the multiline cultivars. This strategy aims to enhance yield stability and bolster resilience against both biotic and abiotic stresses. For several soybean breeding programs, the bulk method is commonly employed to manage segregating populations through to the F3 or F4 generations. This approach is also used during the evaluation of progenies within families. As a result, the cultivars that are developed under these conditions are, in essence, a composite of multiple lines rather than a single, pure line (Tokatlidis, 2015). Studies using multiline approach has demonstrated that such cultivars are markedly stable (Carneiro et al., 2019) and effective in reducing the severety of asian soybean rust (ASR) (Vilela et al., 2024). 3.2 Molecular data Phenotypic variation within cultivars has Several studies have demonstrated intracultivar variation using molecular tools. Yates et al. (2012) (Yates et al., 2012) used SSR markers to analyze three soybean cultivars and confirmed heterogeneity in protein and oil content, as well as in fatty acid composition, as previously reported by Fasoula and Boerma (2005). The majority of intracultivar SSR variation was attributed to residual heterozygosity, resulting in allele polymorphism. Additionally, Achard et al. (2020), employed SNP markers to assess intracultivar variation in a study involving 36 cultivars and 5 346 SNPs, revealing heterogeneity levels ranging from 0 to 10%. Mihelich et al. (2020), conducted a heterogeneity analysis of 20.087 Glycine max and Glycine soja accessions from the USDA Soybean Germplasm Collection (SGC). The study identified high probability intervals of heterogeneity in 4% of the collection, corresponding to 870 accessions. However, the 'Williams 82' soybean accession showed no evidence of heterogeneity, in contrast to the within 'Williams 82' variation reported by Haun et al. (2011). The researchers proposed three explanations for the absence of intra-accession variation in 'Williams 82': a genetic bottleneck causing a specific population homogeneity distinct from other varieties; sampling of genetically identical individuals or derivation from a single, non-representative plant. This lack of heterogeneity in 'Williams 82' suggests that similar processes could have also obscured the true genetic diversity in other accessions within the SGC. In this study, genotypic variation is consistent with phenotypic variation. Progeny derived from P98Y11 and NA5909 exhibited significant variations for PH, FM, and DF in multi-environment analysis. So, a considerable genetic diversity was found for a within P98Y11 and NA5909 population analysis, indicating substantial genetic diversity in these populations. Furthermore, at an individual level, they displayed considerable variation for yield and plant height. Cultivars 97R73 and P98Y11 were grouped together because they both originated from the same breeding company (Corteva-Pioneer). Even though they have different maturity groups, the genetic background could be similar. In contrast, the cultivars NA5909 and NS7000 IPRO exhibit differences, and despite both originating from the same breeding company (Syngenta-Nidera), this variation may be due to the cultivars being derived from different relative maturity groups (RMGs). These findings agree with those reported by Mendonça et al. (2022), indicating that varieties from the same breeding company, particularly those from identical RMGs, have substantial genetic similarity. The PCA analyses revealed six major clusters corresponding to the origins of the progenies from previous cultivars. A distinct separation of cultivars 97R73 and P98Y11 from the others corroborates with the dendrogram
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