Summary: Quercus dentata Thunb., a dominant forest tree species in northern China, has significant ecological and ornamental value due to its adaptability and beautiful autumn coloration, with color changes from green to yellow into red resulting from the autumnal shifts in leaf pigmentation. However, the key genes and molecular regulatory mechanisms for leaf color transition remain to be investigated. First, we presented a high‐quality chromosome‐scale assembly for Q. dentata. This 893.54 Mb sized genome (contig N50 = 4.21 Mb, scaffold N50 = 75.55 Mb; 2n = 24) harbors 31 584 protein‐coding genes. Second, our metabolome analyses uncovered pelargonidin‐3‐O‐glucoside, cyanidin‐3‐O‐arabinoside, and cyanidin‐3‐O‐glucoside as the main pigments involved in leaf color transition. Third, gene co‐expression further identified the MYB‐bHLH‐WD40 (MBW) transcription activation complex as central to anthocyanin biosynthesis regulation. Notably, transcription factor (TF) QdNAC (QD08G038820) was highly co‐expressed with this MBW complex and may regulate anthocyanin accumulation and chlorophyll degradation during leaf senescence through direct interaction with another TF, QdMYB (QD01G020890), as revealed by our further protein–protein and DNA–protein interaction assays. Our high‐quality genome assembly, metabolome, and transcriptome resources further enrich Quercus genomics and will facilitate upcoming exploration of ornamental values and environmental adaptability in this important genus.

Color change during flower opening is common; however, little is understood on the biochemical and molecular basis related. Lilac (Syringa oblata), a well-known woody ornamental plant with obvious petal color changes, is an ideal model. Here, we presented chromosome-scale genome assembly for lilac, resolved the flavonoids metabolism, and identified key genes and potential regulatory networks related to petal color change. The genome assembly is 1.05 Gb anchored onto 23 chromosomes, with a BUSCO score of 96.6%. Whole-genome duplication (WGD) event shared within Oleaceae was revealed. Metabolome quantification identified delphinidin-3-O-rutinoside (Dp3Ru) and cyanidin-3-O-rutinoside (Cy3Ru) as the major pigments; gene co-expression networks indicated WRKY an essential regulation factor at the early flowering stage, ERF more important in the color transition period (from violet to light nearly white), while the MBW complex participated in the entire process. Our results provide a foundation for functional study and molecular breeding in lilac.

Tree peony (Paeonia suffruticosa), as a popular ornamental plant worldwide, has a unique floral fragrance, and it is important in the pollination, ornamental, food, and fragrance product industries. However, the underlying molecular mechanisms for the synthesis of floral fragrance terpenoids in tree peony are not well understood, constraining their exploitation. P. suffruticosa ‘Oukan’ produces strong floral fragrance terpenoids with high ornamental value and excellent stress resistance and is considered a valuable model for studying tree peony floral fragrance formation. Based on transcriptome data analysis, the PsHMGR1 and PsTPS1 genes associated with floral terpene synthesis were cloned. Then, PsHMGR1 and PsTPS1 were functionally characterized by amino acid sequence analysis, multiple sequence alignment, phylogenetic tree construction, qRT-PCR, and transgenic assay. PsHMGR1 contains two transmembrane structures and a conserved HMG-CoA_reductase_class I domain, and PsTPS1 belongs to TPS-a subfamily. The qRT-PCR analysis showed that the expression levels of PsHMGR1 and PsTPS1 increased and then decreased at different flower development stages, and both were significantly higher in flowers than in roots, stems, and leaves. In addition, the linalool content in PsHMGR1 transgenic lines was significantly higher than that of WT. Germacrene D, which was not found in WT, was detected in the flowers of PsTPS1 transgenic lines. These results indicate that PsHMGR1 and PsTPS1 promote terpene synthesis in plants and provide ideas for the molecular mechanism of enhancing terpene synthesis in tree peony floral fragrance.