Peanuts love warmth, taste delicious, produce their own nitrogen, and can save the world from hunger. For these reasons, plenty of research has been taking place to improve peanut agriculture around the world. One major problem facing peanut farmers is that peanuts dread the cold. They dread the cold so much that they will die if temperatures persist below 12°C (Zhang et al., 2019).
Contrary to the conventional approach of bundling peanuts up in snow suits, scientists are currently developing a new cryophobia-curing solution. Chinese researchers are currently considering modifying the peanut genome to create a GMO capable of surviving the cold (Zhang et al., 2019)! Indeed, the thermophilic tropical peanut may one day be cultivated in fields throughout the northern United States, Europe, and the Himalayas.
The Problem
Why do we need peanuts to grow in northerly climates anyway? Don’t peanuts grow just fine where they are? The answer is no. The need to develop cold-tolerant peanuts does not stem from our interest in growing them in Canada or Norway, but due to problems growing them where they are already grown (Zhang et al., 2019).
Peanut-producing countries like China and India are faced with periodic droughts that decimate entire peanut crops (Zhang et al., 2019). As a solution, farmers in northeastern China now sow their peanuts earlier in the year to ensure their crop can be harvested before the summer drought (Zhang et al., 2019). Unfortunately, peanuts cannot germinate below temperatures of 12°C, and grow optimally at 28°C. Hence, early seed-sowing can have disastrous effects on germination and therefore yield (Zhang et al., 2019). Additionally, temperatures below 12°C irreversibly damage peanut seedlings potentially decimating crops (Zhang et al., 2019).
Why can’t peanuts handle the cold?
To give a human comparison, our immune system’s reaction to certain viral infections can be deadlier than the virus itself. Similarly, a plant’s physiological response to cold stress is deadlier than the cold.
The mechanisms involved in the cold stress response occur in the peanut cell. Firstly, the cell membrane, an elastic balloon that holds the cell contents together, accidentally releases various molecules from the cell (Huang et al., 2015). This leads to the loss of salts, sugars, and enzymes from the cell (Huang et al., 2015; Kumar et al., 2015). Due to the loss of these essential molecules, the metabolism of the cells becomes compromised causing the plant to lose its ability to photosynthesize or respire (Huang et al., 2015; Kumar et al., 2015). This response is physiologically equivalent to a human being unable to breathe or eat! The photosystems, the electrical unit that converts the Sun’s energy into sugars, become inactivated (Zhang et al., 2019). This prevents the plant from being able to generate its own food in the form of carbohydrates (Zhang et al., 2019).
If all of that wasn’t bad enough, the poor peanut plant begins to produce reactive oxygen species (ROS) as a byproduct of the stress reactions. ROS is a form of oxygen that can cause damage to biological molecules. The buildup of ROS in cells can cause cell death and eventually death of the plant (Zhang et al., 2019; Huang et al., 2015; Kumar et al., 2015.
The Solution
The interactions between the DNA, how those DNA molecules produce proteins, and how those proteins interact with each other are immensely complex and have not been fully understood (Wang et al., 2015). To illustrate the complexity of cold-tolerance in plants, a recent study on soybean identified 39 different proteins that are overproduced in a soybean strain with advanced antioxidative responses in relation to cold-tolerance (Tian et al., 2015). The scientific community has not even begun to remotely understand how these proteins work, let alone their importance in cold-tolerance.
While understanding 39 different genes and their protein products may take decades, some scientists have suggested creating cold-tolerant GMOs known to have a role in cold-tolerance genes (Zhang et al., 2019). FAD genes are a diverse set of genes that have a role in the characteristic taste of peanuts (Wang et al., 2015; Tovuu et al., 2016). Promisingly, a few studies have shown at least three of these genes to play a role in plant cold-tolerance (Tovuu et al., 2016).
A study in rice found that the FAD genes prevent the cell membrane from losing vital molecules, keeps photosynthesis active in the cold, and enhances the removal of harmful ROS molecules (Tovuu et al., 2016). This gene has not been studied in the context of cold tolerance in peanuts, but some researchers believe that adding these genes to the genome of peanuts can create a cold-tolerant peanut.
Perhaps one day peanuts will be cultivated in temperate agricultural fields throughout the world. Our grandchildren may be fortunate enough to live in a world where locally grown peanuts are available in farmers’ markets throughout Canada.