Plants are amazing organisms that can convert light energy into chemical energy through photosynthesis.
But what happens when the days get shorter and the sunlight becomes scarce? How do plants adjust to the changing seasons and maintain their growth and survival?
Scientists from Michigan State University have discovered some of the secrets that plants use to cope with shorter days and less sunlight.
Plants increase their photosynthetic efficiency and reduce their respiration rate
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The researchers studied a plant called Camelina sativa, a model oilseed crop, using mass spectrometry and metabolomics techniques.
They compared the growth and metabolism of plants that were grown under long-day conditions (16 hours of light and 8 hours of dark) and short-day conditions (8 hours of light and 16 hours of dark).
They found that the short-day plants had a higher photosynthetic rate and a lower respiration rate than the long-day plants.
This means that the short-day plants were able to capture more light energy and use less of it for their own maintenance.
They also invested more energy in their shoots, where photosynthesis takes place, and less in their roots, where respiration occurs.
The researchers explained that this is an adaptive mechanism that plants have developed to deal with shorter days and less sunlight.
By increasing their photosynthetic efficiency and reducing their respiration rate, plants can optimize their energy balance and avoid carbon starvation during the longer night.
Plants store more sugar as starch and slow down their metabolite exchange
Another way that plants cope with shorter days and less sunlight is by storing more sugar as starch during the day and using it as a source of energy during the night.
The researchers found that the short-day plants had higher levels of starch in their leaves than the long-day plants.
Starch is a complex carbohydrate that can be broken down into simple sugars when needed. By storing more starch, plants can ensure that they have enough energy to sustain their growth and metabolism during the dark period.
The researchers also found that the short-day plants had lower levels of metabolites in their vacuoles than the long-day plants.
Vacuoles are large compartments in plant cells that store various substances, such as sugars, amino acids, organic acids, and ions.
The exchange of metabolites between the vacuoles and other cellular compartments is regulated by transporters, which are proteins that move substances across membranes.
The researchers suggested that by slowing down the metabolite exchange, plants can maintain their carbon balance and prevent the accumulation of toxic compounds during the night.
Implications for crop improvement and climate change
The findings of the study reveal some of the intricate and fine-tuned systems that plants have to deal with varying day lengths, which could help to develop new crop varieties that can grow in a wider range of climates.
For example, by manipulating the genes that control the photosynthetic rate, the respiration rate, the starch synthesis, and the metabolite transport, it may be possible to create plants that can produce more biomass and oil under different light conditions.
The study also has implications for understanding how plants will respond to climate change, which is expected to affect the length and intensity of daylight in different regions of the world.
By studying how plants adapt to shorter days and less sunlight, the researchers hope to gain insights into how plants will cope with the changing environment and how to mitigate the negative impacts of climate change on plant productivity and food security.
The study was published in the journal Plant Physiology and was led by Tom Sharkey, a University Distinguished Professor in the Department of Biochemistry and Molecular Biology, and Yair Shachar-Hill, a professor in the Department of Plant Biology, at Michigan State University.
The research was supported by the U.S. Department of Energy and the National Science Foundation.
