When it comes to building blocks of life, protein has always gotten a lot of credit, and sugar has often gone under appreciated. Although sugar can fuel our bodies, and even rockets, there’s more to sugar than the energy it can provide or its sweet taste. Sugar helps living things survive extreme conditions, benefits the environment and even plays a part in reproduction.
1. Sugar helps cells survive dehydration
The sugar called trehalose can help some living things survive long periods without water, even if their cells are completely dried out. These living things are called extremophiles and they can withstand extreme temperatures or even water scarcity. And when they do have water, it can simply bring them back to life.
Water provides stability to living cells by keeping their shape. It also helps to stabilize the microscopic machinery of our cells — large protein molecules with complex shapes — so that they can function properly.
Extreme conditions, like lack of water or high heat, can damage these large protein molecules. The conditions can alter their shapes and stop the proteins from doing what they are supposed to do. However, because of the structure of the sugar trehalose — with a pair of glucose rings linked by a flexible, stable bond — it can take the place of water and interact with complex molecules in the cell to help them keep their shape. In fact, we make use of trehalose’s stabilizing abilities for food and vaccine preservation.
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Most of the time, when plants, bacteria, fungi or animals have this special ability to cope without water, they need to have high levels of trehalose in their cells. But tardigrades — the most extreme of the extremophiles (they can even survive in space) — do not, because they’ve evolved to use trehalose in another way.
Tardigrades have a special protein that helps protect other molecules in their cells from damage that extreme conditions can cause. In a recent study, researchers showed that the sugar trehalose and this unique protein work together — in ways that we don’t completely understand yet — to provide better protection than either trehalose on its own, or the special protein on its own.
2. Sugar is Good for our Environment
The sugar trehalose also helps plants survive changing or extreme conditions. Trehalose is not only found in plant cells where it is used for protection, but also in the soil around plant roots, which is called a rhizosphere.
Similar to how plants “breathe in” the carbon dioxide that we breathe out, and we breathe in the oxygen that plants “breathe out,” soil contains bacteria that live in symbiosis with plants. And the relationship is a close one. Scientists think that the trehalose that soil bacteria produces can act as a signal molecule. When the sugar triggers the plant to produce substances, it helps the plant better tolerate the changing conditions.
Sugar can also help plants underwater. Tons of the sugar sucrose is found under the sea where seagrasses grow. Seagrasses can take in vast amounts of carbon dioxide and lock away carbon that would otherwise return to the environment. The carbon is used in part to produce sucrose, which the seagrasses deposit into the sediment where they grow. Scientists estimate that there are several hundred thousand to over one million U.S. tons of sucrose stashed away under seagrass meadows.
3. Helping Flowers Bloom
Another way sugar can help plants is through reproduction. Although reproduction is an ability that all living things have, sugar plays an important role in the beauty and fragrance of flowers.
In plants, like in all other organisms, passing genes on to a new generation is an important part of the life cycle. And flowers are nothing more than the reproductive organs of the plant. As with most cycles, timing is everything. Flowering plants must be in sync with the environment around them so that they try to reproduce only when they are likely to be successful. But, in addition to cues like the season, time-of-day and temperature, which tell plants what is happening around them, cells use sugar to communicate within the plant. Sugar triggers metabolic pathways that to signal when to stop growing and start flowering.
From extremes to helping a flower bloom, life sure seems to depend on sugar.