KAIST

< (Upper Left) Dr. Moonyoung Kang, (From Left) Professor Sang-Gyu Kim, Dr. Yuri Choi >

Morning-blooming morning glories and flowers that release fragrance at night seem as if they know the time. A KAIST research team has uncovered, at the molecular level, the principle by which plants precisely control the timing of flower opening and scent emission through a “biological clock” aligned with insect behavior. This study suggests potential applications in technologies for controlling flowering time and fragrance.

KAIST (President Kwang Hyung Lee) announced on the 27th of March that a research team led by Professor Sang-Gyu Kim of the Department of Biological Sciences has discovered that genes regulated by the plant biological clock integratively control both the timing of flower opening and the circadian rhythm of scent emission.

Plants are known to have physiological processes regulated by a “biological clock” that allows them to perceive time according to a daily cycle. However, the exact process by which flowers open and how this process is connected to biological clock genes has not yet been fully elucidated.

The research team conducted their study using Nicotiana attenuata (coyote tobacco), a plant that opens its flowers widely at night and emits fragrance. Native to desert regions of Utah, USA, this plant is characterized by opening its flowers and releasing scent at night to attract nocturnal pollinators.

Inspired by such phenomena, the biologist Linnaeus proposed the idea of a “flower clock,” suggesting that if plants that bloom and close at different times were gathered together, one could tell the time based solely on their flowering states.

Previous studies mainly focused on analyzing changes in gene expression related to flower development, but research directly identifying the phenomenon of flower opening and the genes controlling it has been limited. To overcome these limitations, the research team analyzed mutants with altered biological clock genes and investigated, through molecular biological approaches, how flower opening and scent emission are regulated.

< A comparison of wild-type plants and COL5 (a specific circadian clock gene) mutant plants >

As a result, the team confirmed that specific biological clock genes play a key role in controlling both the timing of flower opening and the rhythm of scent emission. This demonstrates that plants make precise use of their biological clock to open flowers and attract pollinators at the most advantageous times for survival and reproduction.

< AI-generated image (the rhythmic behavior of coyote tobacco flowers regulated by the COL5 gene) >

This study is meaningful in that it presents a gene regulatory network controlling flower opening and scent emission from the perspective of the biological clock. It is also expected to provide important clues for understanding plants’ time-regulation strategies and their ecological interactions.

Professor Sang-Gyu Kim stated, “This study provides insight into how the plant biological clock links and regulates the timing of flower opening and scent emission,” adding, “It is expected to serve as an important foundation for understanding how plants optimize their reproductive strategies through interactions with the environment.”

This research, with Dr. Yuri Choi and Dr. Moonyoung Kang from the Department of Biological Sciences as co-first authors, was published on January 29 in the international journal The Plant Cell.
※ Paper title: ”CONSTANS-LIKE 5 facilitates flower opening and scent biosynthesis in Solanaceae” https://doi.org/10.1093/plcell/koag016

This research was supported by the National Research Foundation of Korea’s Synthetic Biology Core Technology Development Program, the Mid-career Researcher Program, and the Rural Development Administration’s Next-Generation Crop Breeding Technology Development Program.