Bioscience Methods 2024, Vol.15, No.6, 348-355 http://bioscipublisher.com/index.php/bm 351 3.4 Impact of breeding practices on diversity levels Breeding practices have a significant impact on the genetic diversity of sweet potato. Long-term self-retention and selective breeding can lead to reduced genetic variability within germplasm collections. For example, the analysis of molecular variance (AMOVA) indicated higher intergroup genetic variation (53%) than intrapopulation variation, suggesting limited evolutionary diversification due to breeding practices (Table 1) (Meng et al., 2021). Conversely, the development of core germplasm sets, as seen in studies using CoreHunter software, helps maintain genetic diversity while minimizing redundancies. These practices are crucial for ensuring the sustainability and improvement of sweet potato breeding programs. Table 1 AMOVA results of 105 sweet potato germplasms with the K = 3 model (Adopted from Meng et al., 2021) Source df Sum of squares Mean of squares Estimated variance Percentage of total variance (%) AMOVA statistics Value P Among groups 2 225.601 112.800 3.698 53 Within groups 102 339.371 3.327 3.327 47 PhiPT4 0.526 0.001 Total 104 564.971 7.026 100 4 Implications for Breeding 4.1 Insights for improving genetic traits The genetic diversity within sweet potato cultivars offers significant insights for improving various genetic traits. For instance, the identification of heat-tolerant cultivars and breeding lines, as well as traits predictive of heat tolerance such as canopy temperature depression, chlorophyll content, and storage root-flesh color, provides a foundation for breeding programs aimed at enhancing heat resilience (Heider et al., 2020). Additionally, the study of genetic variability and trait interrelationships, such as the positive phenotypic correlation between fresh weight of tubers per plant and the number of tubers per plant, days to maturity, and vine internode length, can guide the selection of genotypes with desirable yield traits (Solankey et al., 2015). 4.2 Role of diversity in disease resistance, yield, and stress tolerance Genetic diversity plays a crucial role in enhancing disease resistance, yield, and stress tolerance in sweet potato. For example, the presence of natural fungicides and insect repellents like chlorogenic acids and coumarins in the storage root periderm can reduce post-harvest losses and insect damage, thereby improving overall crop resilience (Lebot et al., 2021). Furthermore, the identification of genotypes with high resistance to sweet potato virus disease (SPVD) and other biotic stresses through genotype-by-environment interaction analysis underscores the importance of genetic diversity in breeding for disease resistance (Ngailo et al., 2019). The study of drought tolerance mechanisms and the selection of drought-tolerant genotypes based on physiological and biochemical traits also highlight the role of genetic diversity in stress tolerance (Sapakhova et al., 2023). 4.3 Breeding strategies based on diversity findings Breeding strategies can be significantly informed by findings on genetic diversity. The use of simple sequence repeat (SSR) markers to determine genetic diversity and resistance responses to various stresses can aid in the selection of parents for breeding and the design of effective crossing schemes (Carputo et al., 2013; Bhardwaj et al., 2023). The integration of metabolite profiling to differentiate chemotypes and assist in the selection of parents with desirable traits, such as high chlorogenic acid content, can enhance the efficiency of breeding program. Additionally, the application of advanced genomic tools, such as genome editing and genomic selection, can leverage the genetic diversity within sweet potato to develop varieties with improved biotic and abiotic stress tolerance (Tiwari et al., 2022). 4.4 Enhancing breeding programs using genetic diversity data The comprehensive analysis of genetic diversity data can enhance breeding programs by providing a deeper understanding of the genetic makeup of breeding materials. For instance, the molecular characterization of breeding clone banks and the identification of core sets of clones can facilitate the long-term conservation of
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