Molecular Plant Breeding 2025, Vol.16, No.2, 133-145 http://genbreedpublisher.com/index.php/mpb 135 The sweetness and texture of sweet potato are influenced by genes involved in sucrose metabolism and starch degradation. The Ibβfruct2-1 gene, which encodes a vacuolar invertase, is a negative regulator of starch content and positively influences glucose content, thereby affecting sweetness (Zhang et al., 2023). Additionally, genetic variations in starch biosynthesis and sucrose metabolism genes contribute to differences in starch properties and sweetness among sweet potato varieties (Zhang et al., 2020a). 3.2 Beta-carotene biosynthesis genes Beta-carotene biosynthesis in sweet potato is governed by several genes in the carotenoid pathway. The Orange gene and phytoene synthase are key regulators, with phytoene synthase being the rate-limiting enzyme in carotenoid biosynthesis (Gemenet et al., 2019). Differential expression of these genes has been observed in orange-fleshed sweet potato varieties, contributing to higher beta-carotene content (Shekhar et al., 2015). Beta-carotene is a precursor of vitamin A, and its biosynthesis in sweet potato is crucial for addressing vitamin A deficiency. The high beta-carotene content in orange-fleshed sweet potato varieties, regulated by genes such as phytoene synthase and the Orange gene, enhances the nutritional value of the crop and provides significant health benefits (Gemenet et al., 2019; Lamaro et al., 2023). These genes are targets for breeding programs aimed at biofortification to improve vitamin A content in sweet potato (Zeist et al., 2022). 3.3 Anthocyanin and flavonoid pathway genes Anthocyanin and flavonoid biosynthesis in sweet potato is controlled by specific genes that influence pigmentation and antioxidant properties. Comparative studies have shown that orange-fleshed sweet potato (OFSP) varieties have higher levels of flavonoids and anthocyanins compared to white-fleshed varieties, indicating tight regulation of these biosynthetic pathways (Shekhar et al., 2015). These compounds contribute to the antioxidant properties of sweet potato, enhancing its nutritional and medicinal value. The presence of anthocyanins and flavonoids in sweet potato not only affects pigmentation but also provides significant health benefits due to their antioxidant properties. These compounds help in scavenging free radicals, thereby reducing oxidative stress and contributing to the medicinal value of sweet potato (Shekhar et al., 2015; Lamaro et al., 2023). The genetic regulation of these pathways is crucial for developing sweet potato varieties with enhanced nutritional profiles. 3.4 Protein and amino acid content genes Protein synthesis in sweet potato is regulated by various genes, with cultivar-specific expression patterns influencing the overall protein content. Studies have shown that orange-fleshed sweet potato varieties exhibit higher levels of total protein compared to white-fleshed varieties, suggesting differential gene expression related to protein synthesis (Shekhar et al., 2015). The protein content in sweet potato significantly impacts its nutritional value. Higher protein levels, as observed in certain orange-fleshed varieties, enhance the overall nutritional profile of the crop, making it a more valuable food source. Understanding the genetic basis of protein synthesis in sweet potato can aid in breeding programs aimed at improving its nutritional quality. 4 Key Genes Influencing Yield 4.1 Genes regulating root development Root development is crucial for nutrient uptake and overall plant health, directly impacting yield. In sweet potato, genes such as IbBBX24 and IbPRX17 have been shown to play significant roles in root development under stress conditions. The IbBBX24 transcription factor activates the expression of the class III peroxidase gene IbPRX17, enhancing root development and stress tolerance by scavenging reactive oxygen species (ROS) (Zhang et al., 2021). Additionally, genes involved in root cell elongation and division, as identified in comparative transcriptome analyses of deep-rooting and shallow-rooting potato genotypes, also contribute to root development and drought tolerance (Qin et al., 2022).
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