Actinidia chinensis Planch. is a fruit tree originating from China that is abundant in the wild. Actinidia eriantha Benth. is a type of A. chinensis that has emerged in recent years. The shape of A. eriantha is an elongated oval, and the skin is covered with dense, non-shedding milk-white hairs. The mature fruit has flesh that is bright green in colour, and the fruit has a strong flavour and a grass-like smell. It is appreciated for its rich nutrient content and unique flavour. Vitamin C, sugar, and organic acids are key factors in the quality and flavour composition of A. eriantha but have not yet been systematically analysed. Therefore, we sequenced the transcriptome of A. eriantha at three developmental stages and labelled them S1, S2, and S3, and comparisons of S1 vs. S2, S1 vs. S3, and S2 vs. S3 revealed 1218, 4019, and 3759 upregulated differentially expressed genes and 1823, 3415, and 2226 downregulated differentially expressed genes, respectively. Furthermore, the upregulated differentially expressed genes included 213 core genes, and Gene Ontology enrichment analysis showed that they were enriched in hormones, sugars, organic acids, and many organic metabolic pathways. The downregulated differentially expressed genes included 207 core genes, which were enriched in the light signalling pathway. We further constructed the metabolic pathways of sugars, organic acids, and vitamin C in A. eriantha and identified the genes involved in vitamin C, sugar, and organic acid synthesis in A. eriantha fruits at different stages. During fruit development, the vitamin C content decreased, the carbohydrate compound content increased, and the organic acid content decreased. The gene expression patterns were closely related to the accumulation patterns of vitamin C, sugars, and organic acids in A. eriantha. The above results lay the foundation for the accumulation of vitamin C, sugars, and organic acids in A. eriantha and for understanding flavour formation in A. eriantha.

As the main active ingredient in Anoectochilus roxburghii, kinsenoside has important health and medical effects including hepatoprotective, anti-oxidant, and bacteriostasis, among others. In recent years, with the limited application of high-throughput technology to A. roxburghii, there has been no research on the key regulatory genes involved in the synthesis of kinsenoside. Therefore, we examined three species of A. roxburghii that are widely planted in mainland China and Taiwan Province, A. roxburghii cultivar ‘Jian ye’, Anoectochilus formosanus, and Anoectochilus burmannicus, determining the content of kinsenoside, performing transcriptomic and metabolomic sequencing, identifying UDP glycosyltransferases, and screening for UDP glycosyltransferases that may be involved in kinsenoside synthesis. The results showed that among the three species of A. roxburghii, the content of kinsenoside in A. roxburghii cv. ‘Jian ye’ was the highest. Transcriptome and metabolome data showed that A. roxburghii cv. ‘Jian ye’ and the two other species of A. roxburghii have 3702 and 5369 differentially expressed genes and 69 and 120 differentially accumulated metabolites, respectively. Meanwhile, differentially expressed genes and differentially accumulated metabolites are enriched in the glucose metabolism and hormone pathways. We also treated the A. roxburghii samples with exogenous auxin and characterized the related genes. In A. roxburghii, we identified 73 members of the UDP glycosyltransferase family. Through phylogenetic tree, transcriptome data expression profile, and qPCR analyses, we screened for members that may be involved in the synthesis of kinsenoside. In summary, the results of this study provide insights for breeding high-kinsenoside-content and high-intron varieties of A. roxburghii.

Dendrobium candidum is a traditional Chinese medicinal herb with green and red stems. D. candidum, which has red stems, is highly nutritious. However, there is a need to clarify the mechanisms of transcriptional regulation underlying anthocyanin biosynthesis in D. candidum. In this study, we found that the red stem of D. candidum has a high anthocyanin content and a wide variety of types. Cyanidin derivatives of anthocyanins were found to be responsible for red pigmentation in red leaves. An R3-MYB transcription factor, DcMYB56, which modulates anthocyanin biosynthesis, along with homologs of other plants, was isolated and identified. Compared with that in green stems, DcMYB56 expression in D. candidum red stems markedly increased. The binding of DcMYB56 to the DcCHS8, DcF3′H, DcF3′5′H, and DcANS1 gene promoters controlled DcMYB56 expression levels. The overexpression of DcMYB56 in Arabidopsis thaliana resulted in a red phenotype and substantially increased the anthocyanin content. Our findings suggest that DcMYB56 is important for anthocyanin biosynthesis, which thus sheds new light on the modulation of anthocyanin biosynthesis-associated transcription factors in D. candidum.