Legume Genomics and Genetics 2025, Vol.16, No.2, 54-62 http://cropscipublisher.com/index.php/lgg 57 differences are also greater. The geographical origin can also be seen in the population structure - for example, Chinese strains and non-Chinese strains often belong to different groups, and even there are many detailed differences among local varieties native to China (Jia et al., 2024). 4.3 Evidence of domestication bottlenecks and loss of genetic diversity When it comes to the loss of genetic diversity, the situation of mung beans is actually quite typical. Throughout the entire domestication process, mung beans have experienced a distinct genetic bottleneck. The nucleotide diversity of cultivated species is much lower than that of wild species, and the number of private SV has also decreased significantly (Jia et al., 2024). Not only that, indicators such as PIC values and allelic variations are also generally low in the cultivation materials (Chen et al., 2015; Chiteri et al., 2022), indicating that the loss of diversity is not only a "reduction in quantity", but also becomes more homogeneous at the genotype level (Figure 1). The reason for this might be related to the strong selection of some domesticated traits and the restricted introduction of wild gene banks. This situation also reminds us that in the future, the improvement of mung beans may have to rely more on wild germplasm to make up for the lack of diversity. Figure 1 Mung bean iRoot ideotypes, (A) top two genotypes in the topsoil foraging and (B) top two genotypes in the steep, cheap, and deep after ranking the genotypes in the IA mung bean panel (Adopted from Chiteri et al., 2022) 5 Case Study: Key Domestication Traits Revealed by Comparative Genomics 5.1 Variations in genes related to flowering time and growth duration Not all mung bean materials can flower normally in different environments, and this actually involves variations in photoperiodic regulatory genes. Comparative genomic studies have shown that nine genes closely related to flowering time carry significant presence/absence variations (PAVs), which have been subject to selective pressure during domestication, especially those associated with early flowering traits. Early flowering is a very practical feature among mung beans that adapt to seasonal changes or differences in planting areas. The results of GWAS further indicated that the direct homologues of genes such as FERONIA receptor-like kinase and photosensitive pigment A (PhyA) are the key to the differences in flowering time, and the SNPS related to them statistically explain a large number of phenotypic differences (Liu et al., 2022; Chiteri et al., 2024). These findings provide clear genetic targets for adjusting the growth period of mung beans. 5.2 Selection signatures in genes controlling seed size and nutritional quality In fact, domestication has also left many genetic imprints on seed quality. Structural variations and the accumulation of SNPS in pathways such as fatty acid, lignin, and phenylpropanoid metabolism reflect the direction of domestication selection, and these variations affect seed composition and nutritional values (Jia et al., 2024). GWAS also verified this: homologous genes such as SWEET10 related to crude starch content and loci
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