Plants grow at night

Sugar tells plants the time

Not only we humans, plants also have an internal clock. But how does this clock adapt to the day-night rhythm of nature? Apparently, sugar molecules play a crucial role, as a study now shows. According to this, certain sensors in the plants register how much sugar is produced during photosynthesis. Based on this information, the internal clock is then adjusted - a finding that could also be of interest to agriculture.

Most living things adapt their behavior to the day-night rhythm - this also applies to plants. The rhythm of their internal clock determines how fast they grow, when they open their flowers or when they produce a particularly large amount of fragrances and nectar. At the same time, it helps them to organize their energy reserves so that they do not starve to death at night. This internal clock not only has to ensure that the many processes in the plant body are perfectly coordinated - but also that they run synchronously with the conditions in the environment. But how exactly does it work? To find out how the internal clock of plants ticks, Alexander Frank from the University of Cambridge and his colleagues have now examined the Arabidopsis thaliana model species, the thale cress. They wanted to know: How can the internal clock of this plant detect changes in the environment?

Sugar sensor affects watch genes

During their experiments, they found: Apparently the crucifer registers how much sugar is available in its cells. "The plant continuously measures the amount of sugar that is produced during photosynthesis and uses this information to adapt the processes in the body accordingly," explains co-author Antony Dodd from the University of Bristol. A kinase called SnRK1 is apparently decisive for this process. This enzyme acts as a sugar sensor and in turn regulates the activity of an important transcription factor that influences the PRR7 clock gene. In addition, another enzyme acts both on this transcription factor and on the kinase. This synthesizes a certain sugar, which is already known from previous studies as an important signal substance in plants - and which, among other things, influences the metabolism.

The cycle of the internal clock shifts via these three molecular components in response to the current availability of energy. "For the first time, our results decipher a mechanism in plants that shifts the circadian rhythm backwards or forwards in order to be in sync with the environment," states Dodd. According to the scientists, this finding could be of interest for agriculture. Because the internal clock also ensures, among other things, that plants mature at the correct time of year. Changes in circadian rhythms therefore play a role in domestication and the breeding of new plant varieties. “That means: The mechanism we discovered could possibly be used in the future to improve the yield of crops,” Dodd concludes.

Source: Alexander Frank (University of Cambridge) et al., Current Biology, doi: 10.1016 / j.cub.2018.05.092

3rd August 2018

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