Legume Genomics and Genetics 2024, Vol.15, No.1, 13-22 http://cropscipublisher.com/index.php/lgg 15 2.2 Discovery of key genetic markers GWAS has achieved remarkable results in genetic research in leguminous crops, especially in identifying key genetic markers associated with important traits such as yield, disease resistance, and stress tolerance. Below are some specific examples of important genetic markers discovered through GWAS in leguminous crops, which demonstrate the scope and potential of GWAS technology in crop improvement research. GWAS studies successfully identified multiple genetic markers associated with yield-related traits such as seed size, pod number, and seed number. For example, Zhang et al. (2016) discovered several SNP markers related to soybean seed size and yield through GWAS analysis, which provides valuable genetic resources for molecular breeding of soybean yield traits. In pea (Pisum sativum), GWAS study reveals association with resistance to Fusarium oxysporum associated genetic markers. Kumar et al. (2015) reported that several SNP markers were significantly associated with Fusariu m wilt resistance in pea, and these findings can help improve disease resistance in pea through molecular marker-assisted selection (MAS). In chickpea (Cicer arietinum), GWAS analysis identified key genetic markers associated with salt tolerance. Varshney et al. (2019) conducted GWAS analysis on chickpea varieties under salt stress conditions and identified multiple SNP markers related to salt tolerance. These findings provide a molecular basis for improving the stress tolerance of chickpea. Root traits are key factors in the adaptation of leguminous crops to drought and low-fertilizer conditions. In a study of faba beans (Vicia faba), a GWAS study identified genetic markers associated with root depth and branch number, which are important for breeding crops adapted to drought conditions. Broad bean varieties are of great significance (Webb et al., 2016). The above examples demonstrate the application of GWAS in genetic research of leguminous crops. By identifying genetic markers related to key agronomic traits, GWAS provides a powerful tool for genetic improvement and molecular breeding of crops. These research results not only deepen our understanding of the genetic basis of leguminous crop traits, but also point the way for future breeding efforts, especially in improving crop yield, disease resistance and stress tolerance. 2.3 Related case analysis Genome-wide association analysis (GWAS) has achieved remarkable results in genetic research in leguminous crops, especially in identifying key genetic markers associated with important traits such as yield, disease resistance, and stress tolerance. In Adzuki Bean, the author assembled a high-quality adzuki bean genome, covering almost the entire genome sequence of adzuki bean. At the same time, the author also combined the genome with genetic linkage groups for GWAS analysis and identified more than 300 potentially important genomic loci. Aleena et al. (2022) performed single-molecule real-time (SMRT) long-read genome sequencing on the high-yielding Indian adzuki bean variety VRB3, and assembled 1287 C ontig, with an N50 of 1.71 Mb and a total length of 605.22 Mb. The authors also used optical map data (589.03 Gb) and Hi-C library sequencing data (145.40 Gb) to correct these contigs. Illumina short read (186.45 Gb) corrects bases and fills gaps. The authors also anchored the assembled scaffold through an ultra-high-density genetic linkage map (containing 25 633 SNPs). With the help of this genetic linkage map, the authors constructed 11 chromosomes with a total chromosome length of 619.01 Mb (Figure 1). The genome covers almost 99.5% of the estimated genome length and is the largest chromosome-level genome of the genus Cowpea to date. The authors also generated VRB3 transcriptome data through the Iso-Seq method, generating a total of 33 004 transcripts with a total length of 94.43 Mb. The genome sequence after masking of repetitive sequences was used to annotate non-redundant and high-confidence genes, and 37 489 protein-coding genes were finally identified. BUSCO analysis also showed that the adzuki bean genome assembly was almost complete.
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