Why Plants Keeping Time Matters - Circadian Rhythms In Plants

Plants have evolved mechanisms to anticipate and adjust to day and night cycles. These mechanisms are known as circadian rhythms and exist in the majority of life forms. Broadly these internal clocks allow for organisms to cope with the changes in environment, time keeping however is particularly important for plants because:

1 – Plants can’t move away. Therefore being able to keep up with the changes in the cycle where it’s growing allows for the plant to perform better. Research has shown that a plant with a clock better synchronised to the 24 hour cycle have enhanced photosynthetic carbon fixation and have increased survival.  Additionally research has shown that plants actually prepare to protect themselves from herbivores by accumulating chemicals all under the control of circadian rhythms. The gifs above show plant sleep movements regulated by the circadian clock. Ultimately these strategies mean they perform better.

2 – Plants can’t “see” the seasons. Therefore they have to utilise the cycles of light known as photo periods to time the changing seasons allowing for a plant to flower at the right time or germinate at the right time. The bottom right photo shows a mutant plant flowering weeks early. This literally means successfully passing on genes or not, ultimately a critical process for future offspring.

So evolutionarily speaking these two factors combined, in having a selective advantage and an advantage for reproduction means that circadian rhythms are very very important. As the plants which perform better, by being synced with the day and night cycle will have increased progeny, increased survival and increased growth.

The research into these circadian rhythms has vast applications into agriculture, food security and space travel! The genes and proteins involved in circadian rhythms are often in complex sets of pathways, the processes of which are being discovered so this field remains one to watch out for.