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Background and Aims The tree peony (Paeonia suffruticosa Andr.) has been widely cultivated as a field plant, and petal blotch is one of its important traits, which not only promotes proliferation but also confers high ornamental value. However, the regulatory network controlling blotch formation remains elusive owing to the functional differences and limited conservation of transcriptional regulators in dicots. Methods We performed phylogenetic analysis to identify MYB44-like transcription factors in P. suffruticosa blotched cultivar 'High noon' petals. A candidate MYB44-like transcription factor, PsMYB44, was analysed via expression pattern analysis, subcellular localization, target gene identification, gene silencing in P. suffruticosa petals and heterologous overexpression in tobacco. Key Results A blotch formation-related MYB44-like transcription factor, PsMYB44, was cloned. The C-terminal of the PsMYB44 amino acid sequence had a complete C2 motif that affects anthocyanin biosynthesis, and PsMYB44 was clustered in the MYB44-like transcriptional repressor branch. PsMYB44 was located in the nucleus, and its spatial and temporal expression patterns were negatively correlated with blotch formation. Furthermore, a yeast one-hybrid assay showed that PsMYB44 could target the promoter of the late anthocyanin biosynthesis-related dihydroflavonol-4-reductase (DFR) gene, and a dual-luciferase assay demonstrated that PsMYB44 could repress PsDFR promoter activity. On the one hand, overexpression of PsMYB44 significantly faded the red colour of tobacco flowers and decreased the anthocyanin content by 42.3 % by downregulating the expression level of the tobacco NtDFR gene. On the other hand, PsMYB44 -silenced P. suffruticosa petals had a redder blotch colour, which was attributed to the fact that silencing PsMYB44 redirected metabolic flux to the anthocyanin biosynthesis branch, thereby promoting more anthocyanin accumulation in the petal base. Conclusion These results demonstrated that PsMYB44 negatively regulated the biosynthesis of anthocyanin by directly binding to the PsDFR promoter and subsequently inhibiting blotch formation, which helped to elucidate the molecular regulatory network of anthocyanin-mediated blotch formation in plants. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is an ornamental plant with huge potential in the international flower market. Similar to the flowers of most other ornamental plants, the top sellers of P. lactiflora are those with red or pink flowers. However, most studies on flower colors have focused on the novel colors and have neglected the most common red flowers. In this study, a red cultivar of P. lactiflora ('Dafugui') and a pink cultivar ('Qingwen') were selected in order to study the discrepancy in the red color of the flowers. The results demonstrate that these two cultivars have the same compositions as anthocyanins, flavones, and flavonols but different contents. 'Dafugui' was found to have a high accumulation of upstream substances due to the higher expression of the early genes encoding phenylalanine ammonialyase (PlPAL) and flavonoid 3′-hydroxylase (PlF3′H). Moreover, the anthocyanidin synthase gene (PlANS) and UDP-glucose flavonoid 3-O-glucosyltransferase gene (PlUF3GT) encoding enzymes catalyze these upstream substances into anthocyanins, resulting in more redness in 'Dafugui' than in 'Qingwen'. Our study thus provides a better understanding of the anthocyanin accumulation and coloring mechanism of P. lactiflora and can serve as a theoretical basis for breeding more red flowers using genetic engineering techniques to cater to consumers' preferences. [ABSTRACT FROM AUTHOR]

The heart is the central organ of the circulatory system, and its proper development is vital to maintain human life. As fetal heart development is complex and poorly understood, we use single-cell RNA sequencing to profile the gene expression landscapes of human fetal hearts from the four-time points: 8, 10, 11, 17 gestational weeks (GW8, GW10, GW11, GW17), and identified 11 major types of cells: erythroid cells, fibroblasts, heart endothelial cells, ventricular cardiomyocytes, atrial cardiomyocytes, macrophage, DCs, smooth muscle, pericytes, neural cells, schwann cells. In addition, we identified a series of differentially expressed genes and signaling pathways in each cell type between different gestational weeks. Notably, we found that ANNEXIN, MIF, PTN, GRN signalling pathways were simple and fewer intercellular connections in GW8, however, they were significantly more complex and had more intercellular communication in GW10, GW11, and GW17. Notably, the interaction strength of OSM signalling pathways was gradually decreased during this period of time (from GW8 to GW17). Together, in this study, we presented a comprehensive and clear description of the differentiation processes of all the main cell types in the human fetal hearts, which may provide information and reference data for heart regeneration and heart disease treatment. [Display omitted] • Gene expression map of human fetal hearts from the four-time points were identified. • Dynamic alteration of cell subpopulations and gene expression during heart development. • ANNEXIN, MIF, PTN, GRN, OSM signalling pathways are crucial in heart development. [ABSTRACT FROM AUTHOR]

Daminozide is a plant growth retardant that inhibits 2-oxoglutarate-dependent dioxygenase activity in the gibberellin biosynthesis pathway, but few studies have focused on its effect on the flavonoid biosynthesis pathway involved in flower color. In the present study, the effect of daminozide on the regulation of flower color was investigated. An herbaceous peony (Paeonia lactiflora Pall.) cultivar ‘Fenzhu Pan’ was used as the material and treated with daminozide. Color parameters of petals were measured; flavonoid composition and content as well as flavonoid biosynthetic gene expression were monitored. The results showed that daminozide treatment caused less red coloration in herbaceous peony. The content of total anthocyanins was decreased by 23%, and the content of total anthoxanthins was increased by 8%; thus, it appeared that less red coloration in daminozide-treated flowers was associated with restricted anthocyanin accumulation. Furthermore, the gene expression patterns of flavonoid 3′-hydroxylase, dihydroflavonol 4-reductase and anthocyanidin synthase were lower after daminozide treatment, which could decrease anthocyanin accumulation and lead to less red coloration in flowers. These findings would improve our understanding of daminozide regulation of flower color in herbaceous peony. [ABSTRACT FROM AUTHOR]