Bioscience Evidence 2024, Vol.14, No.6, 281-292 http://bioscipublisher.com/index.php/be 288 6.3 Study on genome rearrangement and metabolic adaptation of dragon fruit Dragon fruit (Hylocereus spp.) is a tropical fruit with high economic value, widely recognized for its rich nutritional content and unique antioxidant properties (Hossain et al., 2021). However, the understanding of its genome structure and evolutionary history remains limited. Zheng et al. (2021) have constructed the first chromosome-level genome assembly of dragon fruit and revealed a whole-genome duplication (WGD) event. The study found that the common ancestor of dragon fruit and other cacti experienced a WGD event, followed by significant genome rearrangements. These changes may have contributed to the adaptation of cacti to arid environments. Genes related to antioxidant defense, amino acid metabolism, and photosynthesis are enriched in dragon fruit-specific OGCs. The expansion and expression regulation of these genes contribute to enhancing the stress resistance and nutritional value of dragon fruit (Figure 3). Moreover, key genes in the betacyanin biosynthesis pathway are co-localized in a 12 Mb region on one chromosome in dragon fruit. This gene co-localization may enhance the efficiency of betacyanin biosynthesis, thereby contributing to the high antioxidant capacity of dragon fruit (Zheng et al., 2021). This research not only reveals the unique evolutionary and metabolic mechanisms of dragon fruit but also provides valuable resources for future breeding and functional gene studies based on genomic information. Figure 3 GO enrichment analysis of orthologous gene clusters (OGCs) in cactus and noncactus plants. (A) 30,457 OGCs are clustered into 12 755 cactus-specific OGCs, 6689 noncactus-specific OGCs, and 11 214 shared OGCs. (B) GO enrichment analysis was conducted with 12 775 cactus-specific OGCs as foreground, and 11 214 shared OGCs as background. The x axis shows the log10 of the adjusted P values, and the y axis shows the GO terms (only molecular function (MP) and biological process (BP) are shown) with adjusted P value < 0.01. Groups of GO terms are colored in green (group I), red (group II), purple (group III), blue (group IV), and orange (group V) (Adopted from Zheng et al., 2021) Image caption: Figure 3A categorizes 30,457 OGCs into three types: cactus-specific, non-cactus-specific, and shared OGCs. Figure 3B shows that significantly enriched GO functions in cactus-specific OGCs include ion channels (related to osmotic stress and stomatal regulation), antioxidant defense, amino acid and biosynthetic metabolism, CAM photosynthesis, and phosphorylation and methylation metabolism. This figure indicates that cactus plants have enhanced their drought resistance and environmental adaptability through the expansion of these functional genes during evolution, confirming the crucial role of these genes in drought and high-temperature conditions (Adapted from Zheng et al., 2021)
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