Production: Adriana Toca
How do plants know when it’s time to bloom? Like animals, plants also have an internal clock that prepares internal cellular mechanisms in anticipation of upcoming environmental changes. This ensures that plants only perform specific tasks at the most appropriate time. For example, during the day, they photosynthesize, extracting energy from sunlight. However, completely different processes occur at night in the absence of sunlight. Many plants grow significantly larger than during the day. Therefore, to tell the difference between day and night, plants have special receptors in their cells that can detect sunlight and start and stop metabolic processes as needed.
One of these processes is what we know as putting flowers, or flourishing. Researchers at Martin Luther Halle-Wittenberg University (MLU) have identified two genes that are key to this process. The ELF3 and GI genes control the plants’ internal clock, which monitors the length of daylight and determines when is the right time to bloom. The findings could help breed plants that are better suited to their environments.
Flowers are involved in the sexual reproduction of plants, but not all plants have flowers. Due to their function, flowers only appear at a certain moment in the life cycle of plants that we call angiosperms (with seeds contained in fruits).
Through circadian mechanisms, plants can anticipate certain regularities in their environment , such as the alternation of day and night, and adjust accordingly. This also includes flowering at the right time. Plants are oriented to the ratio between the hours of sunlight and darkness. Some plants only bloom when the days are particularly long. Others only bloom when nights exceed a certain period of time. Different species of plants bloom at different times of the year, when the days have different lengths.
An example of this annual adaptation is the arrival of spring. The mechanism responsible for flowers emerging in spring is known as vernalization, and that it occurs at the exact time is essential for pollination to take place. According to a study carried out by scientists at the University of Texas (USA), plants recognize this season because they “remember” that they have just gone through a long cold period thanks to a long RNA molecule called COLDAIR. According to the authors of the research, this molecule creates a cellular memory for plants after 30 to 40 days of cold. At that point, a gene called FLC, which has been dedicated to suppressing flower production during fall and winter, is silenced, and the plant prepares to flower.
As we can see, the amount of light is not the only external source of information for the circadian clock in plants. The ambient temperature also changes throughout the day and year. In future research, scientists will try to understand how temperature influences the flowering of plants and whether temperature can compensate for the lack of information about light.
Most plants have adapted to their original environment in such a way that they require a specific ratio of hours of sunlight to darkness to flourish. The new findings could allow plants designed to flourish elsewhere and produce good yields.
