Plant Gene and Trait 2025, Vol.16, No.4, 182-193 http://genbreedpublisher.com/index.php/pgt 187 4.3 Pre-breeding approaches to broaden genetic bases Pre-breeding is a preparation step before formal breeding. It often uses distant hybridization or mutation to introduce useful traits from wild species or underused germplasm into breeding materials (Silva et al., 2017). Many wild relatives of dragon fruit and some underutilized germplasms contain valuable trait genes. For example, the wild species S. setaceus is drought- and disease-resistant and grows vigorously, but its fruits are small and it has low self-pollination success. However, its resistance genes can be introduced into cultivated dragon fruit through hybridization. Figure 2 Molecular characterization of HpDof1.7 and HpDof5.4 (Adopted from Mou et al., 2022) Image caption: (A) Expression patterns of HpDof1.7 and HpDof5.4 during pitaya maturation. (B) Subcellular localization assay of HpDof1.7 and HpDof5.4. Bars=50 μm. (C) Transcriptional activation assay of HpDof1.7 and HpDof5.4 in yeast cells. (D) Schematic representation of reporter and effector vectors constructed for transcriptional activity analysis. (E) Transcriptional activity analysis of HpDof1.7 and HpDof5.4 in vivo. The data are normalized to a value of 1 for the 62SK-BD group. 62SK-BD-VP16 served as positive control. Each value represents means±SE of six biological replicates (*P<0.05, **P<0.01, compared to 62SK-BD) (Adopted from Mou et al., 2022) The Tel-Zur team in Israel crossed H. polyrhizus with S. setaceus and obtained the first-generation (F1) hybrids. They then backcrossed them with cultivated types and developed new varieties with larger fruits and some resistance. In South America, a cactus genus called Stenocereus produces fruits with excellent flavor and high
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