CONSTANS-LIKE 5 facilitates flower opening and scent biosynthesis in Solanaceae

🥈 Top 2% JournalJan 28, 2026The Plant cell

CONSTANS-LIKE 5 helps flower opening and scent production in nightshade plants

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

Flowers of the coyote tobacco open at night and close in the morning over a two-day cycle, synchronized with scent emission.

The transcription factor CONSTANS-LIKE 5 (COL5) is identified as a key regulator of flower opening and scent emission.
Mutants lacking COL5 show incomplete flower opening and do not emit the major floral scent, benzylacetone.
Overall plant growth and floral development are not affected in col5 mutants.
Silencing the COL5 gene in the large white petunia also results in similar flower and scent emission deficiencies.
These findings indicate that COL5 plays a crucial role in coordinating circadian rhythms in floral processes.

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Flowers of the coyote tobacco (Nicotiana attenuata) exhibit a distinct diurnal rhythm: they open at night, close the following morning, and repeat this movement over two days, synchronized with nighttime scent emission. While circadian clock components like LATE ELONGATED HYPOCOTYL (LHY) and ZEITLUPE (ZTL) are known to regulate floral rhythms in N. attenuata, the molecular mechanism underlying these processes remains largely unknown. Here, we identify the transcription factor CONSTANS-LIKE 5 (COL5) as a key regulator of flower opening and scent emission in N. attenuata and the large white petunia (Petunia axillaris). We screened for genes in N. attenuata corolla displaying (1) diurnal rhythms, (2) altered expression in ZTL mutants, and (3) co-regulation with EMISSION OF BENZENOIDS II. Using this multifaceted strategy, we found that col5 mutants exhibited incomplete flower opening and lacked emission of the major floral scent, benzylacetone, without affecting overall plant growth and floral development. Silencing the orthologous gene in P. axillaris produced similar phenotypes, confirming a conserved role for COL5 in facilitating flower opening and scent emission. These results demonstrate that COL5 coordinates circadian-regulated floral rhythms, advancing our understanding of the molecular basis underlying floral rhythms.

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