Tomatoes at the forefront of the food revolution

At first glance, this plant was like any other plant grown in the corner of offices or on the windowsill of university laboratories. But this particular tomato that was grown at the University of Minnesota in 2018 was different. A plump plant with long leaves and small red fruits was a characteristic of the wild species of tomato plant native to Peru and Ecuador, and the grape tomato (scientific name). Solanum pimpinellifolium) And is also called red raisin tomato. However, a closer look revealed the plant’s uniqueness.

This particular plant was denser than wild tomatoes and had fewer branches and more fruits. The fruits were also slightly darker than usual, indicating an increase in lycopene. Lycopene is an antioxidant that has been linked to a reduced risk of cancer and heart disease. In fact, the plant was designed that way.

The plant was created by a geneticist named Thomas Sarmak and colleagues using a Crisper gene modification. Crisper is a Nobel Prize-winning technology that acts as a cutting and pasting tool for genetic material. This technology is transforming agriculture and helping to create agricultural products for the future. Cold is a perfect tomato that is easy to grow, nutritious and delicious, but more adaptable to climate change. “The ideal plant can withstand a variety of stresses such as heat, cold, salinity and drought, as well as pests,” he says.

Climate change is a problem for many crops, and tomatoes are no exception. Tomatoes do not like heat and grow best at 18 to 25 degrees Celsius. Problems begin outside this temperature range: pollen does not form well and the flowers do not turn into fruit as they should. When the temperature reaches above 35 ° C, the yield decreases.

A 2020 study found that by the middle of the 21st century, up to 66 percent of California’s long-growing tomato fields may no longer have the right temperature to grow this crop. Other modeling studies show that by 2050, large plots of land in Brazil, Black Africa, India, and Indonesia will no longer have the right climate to grow tomatoes.

Wild tomato / Solanum pimpinellifolium

Solanum pimpinellifolium is a wild tomato found in Peru and Ecuador, and its fruits are about the size of a goat.

However, as the average temperature rises, areas that were previously very cold may become suitable for growing tomatoes. However, observations in Italy indicate that severe weather events in these areas should also be considered. The 2019 growing season in northern Italy was weak due to hail, strong winds, unusually heavy rainfall, frost and unprecedented heat. The result of these conditions was stress on tomato plants and poor harvest.

There are other problems. Water scarcity forces farmers to use lower quality irrigation water, which is often salty and leads to soil salinity. Commercial tomato cultivars do not like this situation. At the same time, rising ozone levels make tomatoes more vulnerable to diseases such as bacterial leaf spot.

All of the above is worrying, especially given that tomatoes are currently the largest horticultural crop in the world. Man produces 182 million tons of tomatoes each year, which is equivalent to the weight of approximately 32 large pyramids of Giza. In addition, our appetite for tomatoes is growing rapidly. Over the past 15 years, global tomato production has increased by more than 30%.

Tomato is also a favorite fruit of man, it is also a typical product: it grows fast, it is easy to grow and reproduce, and its genetic manipulation is relatively simple. “Compared to other plant species, there is more funding for tomato research to develop resources such as genomic sequencing, genetic engineering and gene editing,” said Joyce Van Eck, a plant geneticist at Cornell University in New York. All in all, this makes tomatoes great for exploring new gene editing technologies like Crisper that could bring us climate-friendly products in the near future.

Crisper is a molecular tool that scientists have taken from bacteria and modified it (when bacteria are attacked by viruses, they take and cut viral DNA to prevent an attacker from replicating inside them and thus repelling it). they do).

Crisper, which has been used in plants since 2013, helps researchers modify the genome with great precision to obtain the desired traits. You can insert useful genes, delete unwanted genes, and create targeted mutations.

In (non-human) animals, crisper is used to study models of human disease as well as to improve livestock, and can even potentially be used to revive extinct species. In plants, this technology can help create better, tastier, more nutritious and more resilient crops.

The first step is to find the right genes for targeting. “The plant geneticist at the University of Wakeningen in the Netherlands,” says Richard Weiser.

We need to identify the genes responsible for or involved in the ability to tolerate biological and non-biological stress, because otherwise we can not modify, modify or disable them using gene editing.

The domestication of agricultural products, including tomatoes, has led to a sharp decline in genetic diversity. Modern commercial cultivars may grow rapidly and are easy to harvest, but they are genetically quite uniform.

Only four highly homogeneous crops (soybean, rice, wheat and corn) dominate global agriculture and account for more than half of all agricultural land. In contrast, their wild relatives, as well as native and environmentally friendly plants (traditional varieties adapted to specific locations), are a treasure trove of genetic diversity. That’s why scientists are searching this genetic repository to identify traits that could be reintroduced into commercial plants. This process is made possible by the rapid reduction in the cost of DNA sequencing technologies.

The destructive effect of climate change on the tomato plant / climate change

Because climate change is changing rainfall patterns, new varieties of drought-resistant crops will be needed in water-scarce areas.

In a 2021 study of the Solanum Citins genome (Solanum sitiens) Checked out. Solanum citines is a species of wild tomato that grows in the extremely unfavorable conditions of the Atacama Desert in Chile and is also found at altitudes of 3,300 meters. In this study, several genes associated with drought resistance were identified in Solanum citins, including a gene called YUCCA7.

Of course, there are other genes that can be used to strengthen tomatoes. In 2020, Chinese and American scientists conducted genome-level correlation studies and analyzed the genomes of 369 tomato cultivars, breeding lines, and native species adapted to a gene called SlHAK20, which was important for salinity tolerance.

Once the genetically intelligent genes have been identified, such as those identified, they can be targeted with Crisper to remove other unwanted genes, deactivate some genes, or insert new genes. This has recently been done on salt tolerance, resistance to various tomato pathogens, and even the creation of short plants that can tolerate strong winds (another adverse effect of climate change).

However, scientists like Sarmak go so far as to start over. They are using crisper to tame wild plant species from the beginning. Not only can they achieve something that has been going on for thousands of years in a generation, but they can also do so with much greater precision.

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Cormack and colleagues at the University of Minnesota taming Solanum pimpinellifolium, Reached their plant in 2018. They targeted five genes in this species to reach tomatoes that can withstand a variety of stresses while adapting to modern agriculture (for example, being denser for mechanical harvesting). The new plant also had larger fruits than the wild plant. “It was almost double in size and weight,” says Sarmak.

However, this was not the ideal tomato he was trying to achieve. More needs to be done to achieve this goal. He says:

By adding extra genes, we can make the fruit bigger and more abundant, increase the amount of sugar to improve the taste, and increase the concentration of antioxidants, vitamin C, and other nutrients.

Of course, resistance to various forms of stress, from heat to pests and drought and salinity can also be strengthened with the help of this method.

Domestication from the beginning can also make agricultural products without a place and support more attractive. These are plants that are grown on a small scale but have great potential to contribute to food security.

Lantern tomato is one of the wild relatives of tomatoes that produces delicate sweet fruits, one of the products that has recently been domesticated with Crisper technology. In the near future, domestication will be able to make crops such as cowpea, sorghum and tef (all native African grains) available to more people around the world. Crisper is also used to improve other crops, from bananas and grapes to rice and cucumbers.

Some scientists believe that the Crisper gene modification initiates the second green revolution to help nourish the growing human population. Of course, while this technology promises to improve products, according to Weiser, it is not a magical solution, and there are technical barriers that need to be overcome. “Editing efficiency can be difficult in some crops,” says Van Eck. Unlike diploid plants such as tomatoes (which have two sets of similar chromosomes), it is much more difficult to work on plants that have more than two pairs of chromosomes (such as wheat, which is called polyploid). “In polyploid plants, you have more copies of a gene that should be affected by Crisper,” adds Van Eck.

Nobel laureate Emmanuel Sherpentier and Jennifer Davoudna / Charpentier and Doudna

Emmanuel Sherpentier and Jennifer Davodena win Nobel Prize in Chemistry for discovering Crispr-Cas9 genetic scissors

Regulation and social acceptance is another problem. Crisper-modified plants can be transgenic. That is, unlike GM (genetically engineered organisms) products, plants produced with Crisper technology do not contain DNA of another species (ie, transgenic), because this technology either involves the removal of genes or may involve the insertion of genes from different varieties of the same species. (As is being done on tomatoes).

However, few existing studies on the acceptance of food products edited with Crisper show a contradictory picture. In a nationwide poll conducted in the United States, Canada, Belgium, France and Australia, people identified crisper-edited products and GM foods as similar. However, in a study published in 2020, Canadian consumers were more likely to accept crisper-edited foods.

There is also a law. Although Crisper-assisted fungi were able to evade regulation in 2016, the European Supreme Court ruled in 2018 that genetically modified products should be subject to the same regulations as conventional GM organisms.

For the ideal cold tomato, which is supposed to be climatically intelligent, such legal barriers, along with consumer skepticism, can be a significant barrier.

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