Tree Genetics and Molecular Breeding 2024, Vol.14, No.6, 295-303 http://genbreedpublisher.com/index.php/tgmb 298 Figure 1 Genes involved in the betalain biosynthesis cascade (Adopted from Chen et al., 2021) Image caption: A The development of ‘Guanhuabai’ (GHB) and ‘Guanhuahong’ (GHH) pitaya pulp. B The betacyanin and betaxanthin contents of ‘GHB’ and ‘GHH’ pitaya pulp. C The expression profiles of genes related to betalain biosynthesis according to the RNA-Seq datasets of ‘GHB’ and ‘GHH’ pitaya pulp. The gene IDs are in brackets. Spon, spontaneous. Bar =2 cm (Adopted from Chen et al., 2021) 5 Case Study: Biochemical Characterization of Four Genotypes from Three Species of Pitaya (Hylocereus spp.) 5.1 Selection criteria for the case study A case study was selected to analyze the biochemical characteristics of four genotypes of pitaya, it was observed that DGF4 demonstrated significant advantages in total phenol, flavonoid, and β-carotene content, with notably high antioxidant activity in the peel. DGF2 exhibited outstanding performance in antioxidant activity and xanthophyll content, while DGF3 led in carotenoid and xanthophyll accumulation. These results provide a scientific basis for evaluating the nutritional value and functional properties of different dragon fruit genotypes, offering valuable references for breeding and cultivar selection, particularly for enhancing fruit antioxidant capacity and nutritional composition. 5.2 Biochemical characteristics and antioxidant capacity of different dragon fruit genotypes This study systematically compared the biochemical characteristics of four different genotypes (DGF1, DGF2, DGF3, and DGF4) of three Hylocereus spp. species, focusing on total phenol content (TPC), total flavonoid content (TFC), total carotenoid content (TCC), β-carotene, xanthophyll, and color parameters (L, a, b, hue, and chroma). In terms of total phenol content, the DGF4 genotype showed significant advantages, with phenolic content in the peel and pulp reaching 161.3 mg GAE 100 g⁻¹ and 130.0 mg GAE 100 g⁻¹, respectively, far exceeding the other genotypes. This was followed by DGF3, while DGF1 and DGF2 exhibited relatively lower phenolic content, indicating that DGF4 might possess stronger antioxidant potential (Abirami et al., 2021). For total flavonoid content, DGF4 demonstrated the highest flavonoid content in the peel, reaching 508.2 mg RE 100 g⁻¹, while its pulp flavonoid content also surpassed other genotypes at 258.2 mg RE 100 g-1. In contrast, DGF2 had the lowest flavonoid content. Flavonoids, as natural antioxidants, contribute significant nutritional value, and the high levels observed in DGF4 further enhance its functional importance. Additionally, carotenoid content analysis revealed that DGF3 had the highest total carotenoid content in the pulp (33.8 µg 100 g-1), while DGF2 exhibited the highest value in the peel (24.3 µg 100 g-1). For β-carotene, both DGF4 and DGF2 displayed high accumulation, particularly in the pulp, with values of 55.9 µg 100 g-1 and 53.2 µg 100 g-1, respectively. These results highlight the nutritional superiority of these two genotypes as excellent sources of vitamin A precursors (Abirami et al., 2021).
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