Molecular Plant Breeding 2024, Vol.15, No.6, 351-361 http://genbreedpublisher.com/index.php/mpb 352 various environmental stresses (e.g., drought and disease resistance) while identifying key genetic markers associated with target traits that can provide guidance for breeding programs, and also discusses the significance of genetic research in improving sweet potato varieties with the expectation of enhancing food security and improving nutritional outcomes. 2 Genetic Diversity and Evolutionary Background 2.1 Origin and domestication of sweet potato The sweet potato (Ipomoea batatas) was domesticated in Central and South America before being introduced to Africa, where it is now widely cultivated across tropical regions (Glato et al., 2017). The domestication process involved significant genetic changes, including the integration of Agrobacterium T-DNA sequences into the sweet potato genome, which suggests that plant-microbe interactions played a crucial role in its domestication. This natural genetic modification may have provided traits that were selected for during the domestication process, highlighting the complex evolutionary history of this crop (Kyndt et al., 2015). 2.2 Genetic diversity among different cultivars Genetic diversity in sweet potato varies significantly across different regions and cultivars. For instance, in West Africa, genetic diversity is structured into five distinct groups, each associated with specific climatic conditions and morphological traits (Glato et al., 2017). Similarly, a study in Puerto Rico revealed high levels of genetic diversity among local landraces, commercial cultivars, and accessions from the USDA repository, indicating a rich genetic pool that can be leveraged for crop improvement (Rodríguez-Bonilla et al., 2014). The genetic variability among sweet potato genotypes is also evident in traits such as tuber yield, carotene content, and vine length, which are crucial for effective crop improvement (Solankey et al., 2015). 2.3 Evolutionary traits that have enabled adaptation Several evolutionary traits have enabled the sweet potato to adapt to diverse environmental conditions. The presence of Agrobacterium T-DNA sequences in the sweet potato genome is a notable example, as these sequences are expressed and may confer advantageous traits that were selected during domestication (Kyndt et al., 2015). Additionally, the genetic diversity structured along climatic gradients in West Africa suggests that certain genetic groups are better adapted to specific environmental conditions, such as tropical humid or Sahelian climates (Glato et al., 2017). The ability of sweet potato to thrive under different climatic conditions is further supported by the identification of expression quantitative trait loci (eQTLs) that regulate gene expression in storage roots, which can influence key agronomic traits (Zhang et al., 2020). These evolutionary adaptations highlight the sweet potato’s resilience and potential for further genetic improvement to enhance climate resilience and food security (Hancock, 2005; Pironon and Gomez, 2020). 3 Genomic Tools and Resources 3.1 Advances in sequencing technologies for sweet potato Recent advancements in sequencing technologies have significantly enhanced our understanding of the sweet potato genome. High-throughput sequencing methods, such as Illumina paired-end RNA-Sequencing, have been employed to generate comprehensive transcriptomic data. For instance, Illumina sequencing produced 48.7 million 75 bp paired-end reads, which were de novo assembled into 128 052 transcripts, providing a robust resource for gene expression analysis in sweet potato (Tao et al., 2012). Additionally, single-molecule real-time sequencing has been utilized to identify full-length cDNAs and alternative splicing events, further enriching the genomic data available for this hexaploid crop (Ding et al., 2019). These technologies have enabled the identification of numerous differentially expressed genes and alternative splicing events, which are crucial for understanding the genetic basis of traits such as stress tolerance and metabolic processes (Ding et al., 2019; Arisha et al., 2020). 3.2 Overview of available genomic databases and resources The accumulation of sequencing data has led to the development of extensive genomic databases and resources for sweet potato. For example, the de novo transcriptome assembly from Illumina sequencing has provided a comprehensive set of annotated transcripts, including those involved in viral genomes, starch metabolism, and
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