Molecular Plant Breeding 2024, Vol.15, No.6, 351-361 http://genbreedpublisher.com/index.php/mpb 356 6 Case Studies 6.1 Examples of specific sweet potato cultivars adapted to harsh environments Several studies have identified sweet potato cultivars that exhibit remarkable adaptability to harsh environmental conditions. For instance, in Tanzania, the genotypes G2 (Resisto × Ukerewe), G3 (Ukerewe × Ex-Msimbu-1), G4 (03-03 x SPKBH008), G12 (Ukerewe × SPKBH008), and G18 (Resisto × Simama) have shown high yields, high dry matter content, and resistance to sweet potato virus disease (SPVD) across diverse environments (Ngailo et al., 2019). Similarly, in Indonesia, the genotypes Ayamurasaki, Beniazuma, Awachy2, 15(112), Awachy4, Awachy5, 80(109), 54(160), and 35(180) have been identified as specifically adapted to marginal lands based on Finlay-Wilkinson analysis (Mustamu et al., 2018). In Colombia, the genotype 0113-672COR was selected for the Caribbean region due to its superior multi-trait performance and stability across multiple environments (Rosero et al., 2023). Additionally, a study in Cameroon identified high-yielding and stable sweet potato clones suitable for major cultivation areas, despite the significant genotype-by-environment interactions observed (Ngeve, 2004). These examples highlight the potential of specific sweet potato cultivars to thrive in challenging environments, contributing to food security and agricultural sustainability. 6.2 Insights from recent studies on gene-environment interactions Recent studies have provided valuable insights into the gene-environment interactions that influence sweet potato adaptation. For instance, a transcriptomic analysis of the US-bred cultivar Beauregard and the Ugandan landrace Tanzania under dehydration stress identified approximately 4 000 to 6 000 differentially expressed genes in each cultivar, with many genes associated with drought response (Lau et al., 2018). This study highlighted the genotype-specific responses to drought stress, which can inform the development of drought-tolerant cultivars. Another study emphasized the importance of understanding the genetic mechanisms underlying drought tolerance. It reviewed the physiological, metabolic, and genetic modifications that sweet potato plants employ to respond to water stress, such as activating antioxidants and accumulating stress proteins (Sapakhova et al., 2023). These modifications can serve as indicators for selecting drought-tolerant genotypes. Furthermore, a study on the ecophysiological and morpho-agronomic parameters of sweet potato genotypes from different altitudes revealed significant variability in their responses to low-altitude conditions. Genotypes with greater soil coverage efficiency and leaf size exhibited better photosynthetic performance and water use efficiency, which are crucial for root formation under low-altitude environments (Figure 3) (Burbano-Erazo et al., 2020). These findings underscore the complex interactions between genetic traits and environmental factors in sweet potato adaptation. Figure 3 Relationship between genotypes with storage roots and without storage roots according to Pn and altitude. Pn: Net photosynthetic rate; masl: meters above sea level (Adopted from Burbano-Erazo et al., 2020)
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