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Summary The biosynthesis of specialized metabolites is strictly regulated by environmental inputs such as the day–night cycle, but the underlying mechanisms remain elusive. InPetunia hybridacv. Mitchell flowers, the biosynthesis and emission of volatile compounds display a diurnal pattern with a peak in the evening to attract nocturnal pollinators.Using petunia flowers as a model system, we found that chromatin level regulation, especially histone acetylation, plays an essential role in mediating the day–night oscillation of the biosynthetic gene network of specialized metabolites.By performing time‐course chromatin immunoprecipitation assays for histone modifications, we uncovered that a specific group of genes involved in the regulation, biosynthesis, and emission of floral volatile compounds, which displays the greatest magnitude in day–night oscillating gene expression, is associated with highly dynamic histone acetylation marks H3K9ac and H3K27ac. Specifically, the strongest oscillating genes featured a drastic removal of histone acetylation marks at night, potentially to shut down the biosynthesis of floral volatile compounds during the morning when they are not needed. Inhibiting daytime histone acetylation led to a compromised evening induction of these genes.Overall, our study suggested an active role of chromatin modification in the diurnal oscillation of specialized metabolic network.
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Cell‐type‐aware regulatory landscapes governing monoterpene indole alkaloid biosynthesis in the medicinal plant Catharanthus roseus
Summary In plants, the biosynthetic pathways of some specialized metabolites are partitioned into specialized or rare cell types, as exemplified by the monoterpenoid indole alkaloid (MIA) pathway ofCatharanthus roseus(Madagascar Periwinkle), the source of the anticancer compounds vinblastine and vincristine. In the leaf, theC. roseusMIA biosynthetic pathway is partitioned into three cell types with the final known steps of the pathway expressed in the rare cell type termed idioblast. How cell‐type specificity of MIA biosynthesis is achieved is poorly understood.We generated single‐cell multi‐omics data fromC. roseusleaves. Integrating gene expression and chromatin accessibility profiles across single cells, as well as transcription factor (TF)‐binding site profiles, we constructed a cell‐type‐aware gene regulatory network for MIA biosynthesis.We showcased cell‐type‐specific TFs as well as cell‐type‐specificcis‐regulatory elements. Using motif enrichment analysis, co‐expression across cell types, and functional validation approaches, we discovered a novel idioblast‐specific TF (Idioblast MYB1,CrIDM1) that activates expression of late‐stage MIA biosynthetic genes in the idioblast.These analyses not only led to the discovery of the first documented cell‐type‐specific TF that regulates the expression of two idioblast‐specific biosynthetic genes within an idioblast metabolic regulon but also provides insights into cell‐type‐specific metabolic regulation.
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- Award ID(s):
- 2309665
- PAR ID:
- 10574943
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 245
- Issue:
- 1
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 347-362
- Size(s):
- p. 347-362
- Sponsoring Org:
- National Science Foundation
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