Tree peony (Paeonia section Moutan DC.) is known for its excellent ornamental and medicinal values. In 2011, seeds from P. ostii have been identified as novel resource of α-linolenic acid (ALA) for seed oil production and development in China. However, the molecular mechanism on biosynthesis of unsaturated fatty acids in tree peony seeds remains unknown. Therefore, transcriptome data is needed to better understand the underlying mechanisms. In this study, lipid accumulation contents were measured using GC-MS methods across developing tree peony seeds, which exhibited an extraordinary ALA content (49.3%) in P. ostii mature seeds. Transcriptome analysis was performed using Illumina sequencing platform. A total of 144 million 100-bp paired-end reads were generated from six libraries, which identified 175,874 contigs. In the KEGG Orthology enrichment of differentially expressed genes, lipid metabolism pathways were highly represented categories. Using this data we identified 388 unigenes that may be involved in de novo fatty acid and triacylglycerol biosynthesis. In particular, three unigenes (SAD, FAD2 and FAD8) encoding fatty acid desaturase with high expression levels in the fast oil accumulation stage compared with the initial stage of seed development were identified. This study provides the first comprehensive genomic resources characterizing tree peony seeds gene expression at the transcriptional level. These data lay the foundation for further understanding of molecular mechanism responsible for lipid biosynthesis and the high unsaturated fatty acids (especially ALA) accumulation. Meanwhile, it provides theoretical base for potential oilseed application in the respect of n-6 to n-3 ratio for human diets and future regulation of target healthy components of oils.

Benzenoids/phenylpropanoids, the second most diverse group of plant volatiles, exhibit significant structural diversity and play crucial roles in attracting pollinators and protecting against pathogens, insects, and herbivores. This review summarizes their complex biosynthetic pathways and regulatory mechanisms, highlighting their links to plant growth, development, hormone levels, circadian rhythms, and flower coloration. External factors like light, humidity, and temperature also influence their biosynthesis. Their ecological value is discussed, offering insights for enhancing floral scent, pollinator attraction, pest resistance, and metabolic engineering through genetic modification.

Xibei tree peony is a distinctive cultivar group that features red–purple blotches in petals. Interestingly, the pigmentations of blotches and non-blotches are largely independent of one another. The underlying molecular mechanism had attracted lots of attention from investigators, but was still uncertain. Our present work demonstrates the factors that are closely related to blotch formation in Paeonia rockii ‘Shu Sheng Peng Mo’. Non-blotch pigmentation is prevented by the silencing of anthocyanin structural genes, among which PrF3H, PrDFR, and PrANS are the three major genes. We characterized two R2R3-MYBs as the key transcription factors that control the early and late anthocyanin biosynthetic pathways. PrMYBa1, which belongs to MYB subgroup 7 (SG7) was found to activate the early biosynthetic gene (EBG) PrF3H by interacting with SG5 member PrMYBa2 to form an ‘MM’ complex. The SG6 member PrMYBa3 interacts with two SG5 (IIIf) bHLHs to synergistically activate the late biosynthetic genes (LBGs) PrDFR and PrANS, which is essential for anthocyanin accumulation in petal blotches. The comparison of methylation levels of the PrANS and PrF3H promoters between blotch and non-blotch indicated a correlation between hypermethylation and gene silencing. The methylation dynamics of PrANS promoter during flower development revealed a potential early demethylating reaction, which may have contributed to the particular expression of PrANS solely in the blotch area. We suggest that the formation of petal blotch may be highly associated with the cooperation of transcriptional activation and DNA methylation of structural gene promoters.

Waterlily (Nymphaea spp.), a perennial herbaceous aquatic plant, is divided into two ecological groups: hardy waterlily and tropical waterlily. Although the hardy waterlily has no attractive blue flower cultivar, its adaptability is stronger than tropical waterlily because it can survive a cold winter. Thus, breeding hardy waterlily with real blue flowers has become an important target for breeders. Molecular breeding may be a useful way. However, molecular studies on waterlily are limited due to the lack of sequence data. In this study, six cDNA libraries generated from the petals of two different coloring stages of blue tropical waterlily cultivar Nymphaea ‘King of Siam’ were sequenced using the Illumina HiSeq™ 2500 platform. Each library produced no less than 5.65 Gb clean reads. Subsequently, de novo assembly generated 112,485 unigenes, including 26,206 unigenes annotated to seven public protein databases. Then, 127 unigenes could be identified as putative homologues of color-related genes in other species, including 28 up-regulated and 5 down-regulated unigenes. In petals, 16 flavonoids (4 anthocyanins and 12 flavonols) were detected in different contents during the color development due to the different expression levels of color-related genes, and four flavonols were detected in waterlily for the first time. Furthermore, UA3GTs were selected as the most important candidates involved in the flavonoid metabolic pathway, UA3GTs induced blue petal color formation in Nymphaea ‘King of Siam’. This study will improve our understanding of the molecular mechanism of blue flowers in waterlily and provide the basis for molecular breeding of blue hardy waterlily cultivars.

Flavones are important secondary metabolites found in many plants. InLoniceraspecies, flavones contribute both physiological and pharmaceutical properties. However, flavone synthase (FNS), the key enzyme responsible for flavone biosynthesis, has not yet been characterized inLoniceraspecies. In this study,FNSIIgenes were identified fromLonicera japonicaThunb. andL. macranthoidesHand.-Mazz. In the presence of NADPH, the recombinant cytochrome P450 proteins encoded byLjFNSII-1.1,LjFNSII-2.1andLmFNSII-1.1converted eriodictyol, naringenin and liquiritigenin to the corresponding flavones directly. The different catalytic properties between LjFNSII-2.1 and LjFNSII-1.1 were caused by a single amino acid substitution at position 242 (glutamic acid to lysine). A methionine at position 206 and a leucine at position 381 contributed considerably to the high catalytic activity of LjFNSII-1.1. In addition, LjFNSII-1.1&2.1 and LmFNSII-1.1 also biosynthesize flavones that were further modified byO-glycosylation in transgenic tobacco. The expression levels of theFNSIIgenes were consistent with flavone accumulation patterns in flower buds. Our findings suggested that the weak catalytic activity of LmFNSII-1.1 and the relatively low expression ofLmFNSII-1.1in flowers might be responsible for the low levels of flavone accumulation in flower buds ofL. macranthoides.