Bioscience Methods 2024, Vol.15, No.6, 348-355 http://bioscipublisher.com/index.php/bm 350 2.2 Genetic markers used in diversity studies Several genetic markers have been employed to study the genetic diversity of sweet potato. Chloroplast simple sequence repeat (cpSSR) markers have been used to analyze the genetic diversity of sweet potato accessions, revealing polymorphisms and diversity indices that are essential for understanding the genetic makeup of the crop. Retrotransposon-based insertion polymorphism (RBIP) markers have also been utilized, providing high-throughput systems to study genetic diversity and population structure. Additionally, Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeats (ISSR) markers have been used to evaluate genetic relatedness among sweet potato germplasms, offering insights into the genetic variation present within different accessions (Murthy et al., 2021). Specific Length Amplified Fragment (SLAF) sequencing has also been employed for genome-wide assessments, using single nucleotide polymorphisms (SNPs) to evaluate genetic diversity and population structure. 2.3 Key findings from global diversity studies Global studies on sweet potato genetic diversity have yielded several key findings. The use of cpSSR markers revealed that the genetic diversity of female parents in the NAC collection is low, suggesting the need for more diverse accessions to be collected for effective germplasm management. RBIP markers have shown that sweet potato germplasms are not well evolutionarily diversified, although some geographic speciation has occurred. RAPD and ISSR markers have demonstrated high levels of polymorphism, indicating significant genetic variation among sweet potato germplasms. SLAF sequencing has provided a comprehensive genome-wide assessment, identifying three major genetic groups and highlighting the importance of within-accession diversity (Su et al., 2017). These findings underscore the importance of using diverse genetic markers to capture the full extent of genetic variation in sweet potato, which is essential for breeding and conservation efforts. 3 Meta-Analysis of Genetic Diversity Data 3.1 Statistical synthesis of diversity measures The genetic diversity of sweet potato has been assessed using various molecular markers, including retrotransposon-based insertion polymorphism (RBIP), chloroplast simple sequence repeats (cpSSR), and single nucleotide polymorphisms (SNPs). For instance, RBIP markers revealed an average polymorphism of 91.07% among 105 sweet potato germplasm resources, indicating significant genetic variability. Similarly, cpSSR markers showed polymorphisms in eight out of nine markers, with diversity indices ranging from 0.148 to 0.626 (Lee et al., 2019). SNP-based studies also demonstrated substantial genetic diversity, with mean polymorphic information content (PIC) values ranging from 0.232 to 0.251. 3.2 Key trends observed in genetic diversity studies Several key trends have emerged from genetic diversity studies in sweet potato. Firstly, the genetic diversity within sweet potato germplasms is generally high, as evidenced by the high polymorphism rates and diversity indices across different studies. Secondly, the genetic structure analyses consistently divide sweet potato accessions into distinct groups, reflecting underlying genetic differentiation. For example, RBIP and SNP analyses both identified three major groups among the studied germplasms (Su et al., 2017). Thirdly, there is a notable consensus across different analytical methods, such as UPGMA dendrograms, principal component analysis (PCA), and model-based genetic structure analyses, in grouping the germplasms. 3.3 Variability across regions and germplasm collections Genetic diversity studies have highlighted variability across different regions and germplasm collections. For instance, cpSSR marker analysis of 558 sweet potato accessions from the National Agrobiodiversity Center (NAC) revealed low genetic diversity among female parents, suggesting the need for more diverse collections. Similarly, studies on sweet potato accessions from traditional communities in Vale do Ribeira Paulista showed wide genetic diversity, with no clear grouping according to collection points (Vargas et al., 2018). These findings underscore the importance of regional and germplasm-specific studies to capture the full extent of genetic variability.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==