Legume Genomics and Genetics 2025, Vol.16, No.2, 54-62 http://cropscipublisher.com/index.php/lgg 55 Chen et al., 2022; Chiteri et al., 2024). These tools do not make research more complicated; instead, they make breeding more directional and efficient. This study systematically compared the genomes of wild and cultivated mung beans to clarify the genetic basis of domestication, trait selection and adaptation, including characterizing genomic diversity and population structure, identifying key gene and structural variations related to domestication and agronomic traits, and assessing the genetic improvement potential of wild germplasm. This study aims to provide fundamental knowledge for breeding mung bean varieties with strong stress resistance, high yield and rich nutrition by integrating comparative genomics, thereby promoting sustainable agriculture and food security. 2 Genome Structure and Conserved Features Analysis 2.1 Comparison of genome size and chromosome-level structure The recently completed intergranular telomere to telomere (T2T) genome assembly of mung bean cultivated varieties now presents a comprehensive set of data: a genome size of approximately 500 Mb, distributed across 11 chromosomes, with a total of 28 740 protein-coding genes annotated. Nearly half (49.17%) of the regions were repetitive sequences, especially the long-terminal repetitive retrotransposon (LTR-RT) accounted for a large proportion. However, if mung beans are compared with their close relatives, such as adzuki beans, their collinearity in chromosomal structure is still very high, basically in a one-to-one correspondence. This stable structure also indicates from the side that the chromosomal arrangement within the genus Vigna has not been much "disturbed" and is relatively conserved (Liu et al., 2022). 2.2 Identification of conserved gene families and homologous gene clusters In fact, it is not only the structural aspect that shows a conservative trend, but also the gene family has a similar tendency. In the comparative analysis of mung beans and other dicotyledonous plants, 32 253 orthogonal groups were identified, among which 87.4% of the mung bean coding genes were classified into a certain gene family. Among these families, 1 532 are unique to mung beans and mainly participate in biological processes such as starch and sucrose metabolism, amino acid synthesis, and ribosome assembly. Of course, not all families remained unchanged. Some expanded, while others shrank. Tandem repeats contribute significantly to expansion, especially in plant-pathogen interactions and secondary metabolism. Transcription factor families like NAC and BBX are typical examples that are highly conserved among various species. They are not only conserved but also often undergo purification selection. Most of the retained ones have practical effects on development or stress responses (Yin et al., 2021; Tariq et al., 2022; Yin et al., 2024). 2.3 Differences in structural variations (deletions, inversions, duplications) The difference in structural variation (SV) between wild mung beans and cultivated mung beans can actually be seen through comparison, especially after conducting an integrated analysis of multiple germplasms. It's not to say that all variations are related to domestication, but the absence, inversion and repetition of some key regions are very likely to have accumulated gradually during the process of artificial selection. And don't forget that transposition factors like LTR-RT, these "moving" genetic elements, have been secretly causing trouble all along. Their amplification may not only affect the expression activity near the genes, but even lead the entire genome to evolve in another direction. Take those genes that regulate flowering time or color for example. PAV events occur particularly frequently. This is likely not a coincidence but the result of long-term selection. As for the expansion of gene families, fragment duplication is one of the driving forces, which has been mentioned in many studies. But then again, although there are many repeated genes, most of them are not messed up - their functions are rather stable because they are basically still under the pressure control of purified selection (Jia et al., 2024). 3 Gene Family Evolution and Functional Divergence 3.1 Comparative analysis of gene family expansion and contraction Gene families do not exist statically, especially in mung beans, where their expansion and contraction are particularly obvious. Comparative genomic data show that among 32 253 orthogonal groups, 2 218 families experienced expansion and another 1 093 shrank (Liu et al., 2022; Tariq et al., 2022; Yin et al., 2024). The most
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