The salty solution: irrigation with diluted seawater

Eric Ray pulls a match from a plastic container with half-cooked rice in it. The brown round grains look like normal rice grains. Their smell is like normal rice. And when I carefully take a few of them and put them in my mouth, even their taste sensation is similar to that of ordinary rice: they are soft, chewy and somewhat bland. My hand unwittingly reaches for a bottle of soy sauce lying on the table in the kitchen of a company's offices Arcadia Biosciences In Seattle, Sharay is its CEO, to season the rice with a pinch of salt.

But in this case the desire to add salt is a little strange, since the rice grows in salt water whose salinity would have killed most plants on Earth. The rice plants whose grains I have just tasted have undergone genetic engineering that has given them salt resistance, mimicking unusual plants called salt plants (The Lophytes), which grow and confuse in marine bays, sea inlets and along marshy beaches. To my surprise, the grains in my mouth are not overly salty. In fact, when I do a blind test and compare them to regular non-GMO rice grains grown in fresh water, I don't feel any difference.

"Rice is the most valuable agricultural crop in the world," judging by the amount of crops in 2012, Ray says. But "in certain areas of China, where the salinity of the soil is steadily increasing, it is no longer possible to grow crops". Ray believes that if we decipher the mechanism by which the genes that allow saline plants to thrive in salt-rich soil work and apply advanced biotechnological methods to insert these genes into rice and other plants, we will find the way to feed the growing human population.

About a quarter of the shalein fields on earth suffer from the problem of soil salinity resulting from poor irrigation methods. The expected rise in sea level also threatens to introduce salt water into hundreds of millions of additional dunams of agricultural land. If we can grow healthy crops in such saline areas, it will be possible to provide food for tens of millions of people, an essential step in preparing to feed the two billion mouths expected to be added to the world's population by the middle of this century.

And this is not a dream in aspemia, he says Eduardo Blomwald, a scientist specializing in plant biology at the University of California at Davis, whose research work is the basis for the development of rice at the Arcadia company. "I believe that today it is possible to grow crops in salty water or recycled water of poor quality, and even in diluted seawater," he says. At a distance of about 1100 km south of Seattle, the greenhouses that Blomwald cultivates as part of his research work at the University of California at Davis abound with tall rice plants of an emerald green shade, which protrude and rise from shallow pools of salt water. Blumwald and several other scientists around the world are transferring genes from saline plants that are naturally resistant to salt and injecting them into common agricultural crops, not only rice, but also wheat, barley and tomatoes. (Cotton also participates in the study.)

But in order for these seeds, which carry the hope of salvation, to really take root, it must be proven that they can also thrive in the real world outside the greenhouses, under conditions of storm, drought and attacks by harmful insects. And if that is not enough, they will also have to withstand a barrage of queries and investigations on safety and normality issues from politicians, scientists and farmers.

And even if the taste of these plants themselves will be bitter to the palate, their genetic engineering may leave a bitter taste in the mouths of certain people who fear the transfer of genes to other creatures, a process whose consequences are unpredictable. According to the opponents of genetic engineering, projects of this type expose precisely the poorest and most vulnerable populations in the world to the uncertainties involved. Moreover, adds Janet Cotter, an environmental consultant, developing crops that can thrive in salinity conditions will encourage the continued use of poor irrigation methods. "If your irrigation methods are bad, you're already on an unsustainable path," Kotter says.

A salty story

Salt plants, or halophytes ("salt plants"), as they are called, can survive in water of any degree of salinity, even in the highest degree of salinity of sea water. Mangroves are saltwater plants. This type of plant is relatively rare. They are not pleasant to look at (nor are they appetizing) and are characterized by strange bumps and swellings, their foliage is poor and unattractive and their roots stick out of the water.

In the past, attempts were made to market mangroves as building materials, succulent and oil-rich salt plants as a source of biofuel or salt-resistant shrubs as fodder for animals. In 1998, researchers wrote an article in Scientific in which they envisioned vast farms of salt plants around the world that would provide food for humans. But in the absence of developed markets for such unique crops, the farms were doomed to failure.

When Blomwald began his research work on salting plants in the mid-90s, these plants were considered a botanical curiosity and nothing more. "Most scientists involved in agricultural research didn't think about salinity at all," says Blumwald. "What occupied them was the development of agricultural crops that would provide larger, rounder, more colorful and sweeter produce."

Blomwald, on the other hand, showed interest in a type of protein found in salt plants and called Antiporter. This protein accelerates the exchange of sodium ions (salt) and hydrogen ions through the cell membranes of the plant. When the sodium ions found in the salty water are absorbed by the plant, they disrupt the action of enzymes, the transport of water along the plant and ultimately, the process of photosynthesis. Blomwald found that genetic engineering of common plant species to make them produce large amounts of antiporter proteins allows them to grow in water whose salinity reaches up to a third of seawater salinity, with almost no negative side effects. The antiporter pushes the sodium ions into the hollowness, like sealed bubbles inside the plant cells that neutralize any harmful effect of the sodium ions. The cells of some natural salt plants have cavities that become so large that they are called salt vesicles. The quinoa plant, one of the salty plants that found its way to our dining table, is characterized by blisters that appear as tiny transparent balls that adorn its surface.

When Blomwald raised the levels of the antiporter bA special breed of tomatoes, he was able to grow the transgenic plants in water whose salinity is "four times that of chicken broth," as he puts it. These plants produced juicy, sweet, round and red fruits that each weighed about a hundred grams and even more. But while the plants Bloomwald created thrived in laboratory conditions, they struggled to survive in the real world. "Everything works in a greenhouse, where a relative humidity of 40% or more prevails," says Blumwald. But, as the humidity drops, the leaves of the plants lose water at an increasing rate, and as a defense mechanism, the pores of the plant close. Therefore, according to him, it is much more difficult to grow plants "in field conditions, with a humidity of 5% and much less water".

The problem is that the plant's ability to migrate salts is not enough to allow it to grow in soil with high salinity. Each plant has thousands of genes, involved in a variety of biological processes, which can help the plant deal with many types of stress situations, such as heat, dryness or salinity. To grow in salinity conditions, the plant needs a large number of genes that are able to change their activity according to the growing conditions to protect it in harsh environmental conditions. There is no single magic bullet, he says Simon Barak, a senior lecturer in plant sciences at Ben Gurion University of the Negev, "but we have developed a computational method to examine these genes one by one and locate those that are likely to be involved in resistance to blight."

Barak built a database of genes involved in stress conditions and in it he collected data from the scientific literature obtained from experiments conducted on a plant called white sedum, Arabidopsis thaliana, (where studies in the field of agriculture are often used to examine botanical processes). Using statistical analysis, Barak ranked the genes according to their importance to the plant's survival in harsh conditions, such as high temperatures, and thus located some promising candidates among these genes.

In the next step, Barak's research team conducted a series of laboratory experiments on plants with mutations in these genes to examine how the plants cope with harsh conditions. Mutant plants that showed resistance to drought, salinity or heat were marked as a target for further research. "In classic genetic scans to find new mutants, thousands of plants are scanned, of which only 3 to 62% may turn out to be interesting," says Barak. "We reached XNUMX% success. We have enough mutants to last our entire scientific career.”

Other scientists are also focusing on the study of survival under salinity conditions, combining research methods from the fields of biology, statistics and computer science. So, a few years ago, when he was working At the Central Institute for Salt and Marine Chemical Research In the Indian state of Gujarat, the geneticist discovered Narendra Singh Yadav Some genes involved in salt tolerance in another salt plant named dismantled. He did not know exactly how these genes worked, but the research he conducted suggested that they play an important role. To confirm his hypothesis, Yadav inserted two of these genes into tobacco plants, which are known to be vulnerable to salt. When he tried to grow these transgenic plants in water whose salinity is about one-third that of seawater, they germinated and developed wonderfully; Their roots and branches were longer than those of similar non-GM plants, and they were larger and had richer foliage. Although no salt vesicles were seen on the transgenic tobacco plants, relatively low levels of Molecules contain oxygen, whose chemical activity is harmful to plants and which accumulate in them under salt stress conditions. Yadav has since moved to Israel, as a member of Barak's research team, and his previous research group in Gujarat is currently researching a salt-tolerant cotton strain. "And I think there are many more genes that we haven't discovered yet," says Yadav.

What is important is "to act sensibly and not be foolishly optimistic," says Blumwald. His research group at the University of California, Davis conducts experiments in a dozen greenhouses, on thousands of transgenic plants, from alfalfa and pearl millet, to peanuts and rice. Most of these plants are successful industrial varieties that have undergone genetic manipulation, and in each experiment the researchers try to simulate natural stress conditions. Giant fans spinning from strong gusts of wind; The water supply to the plants is irregular, sometimes little by little and sometimes in a flood, like a rain shower in a storm; And the plants are exposed to salt and heat. "I'm tired of seeing the plants wither when I move them to the open field," says Blumwald. "Is it possible to grow crops in seawater? I believe this is not feasible. The plants may be able to grow under these conditions, but their nutritional value will be extremely low. But with diluted sea water or recycled water? Definitely yes."

Natural concerns

However, genetic engineering is still a controversial topic in many circles in the world. According to Cotter, "We'll never know for sure in what other ways this might affect the plant and whether it would have any implications for food safety and the environment." It prefers a system of praise known as Select with markers, which uses genomic tools to identify genes that confer salt resistance in wild varieties of edible plants. In the next step, a natural hybridization of the wild strains with domesticated strains is carried out with the aim of transferring these genes to the plants growing on agricultural farms.

also toTimothy Russell, an agronomist working in Bangladesh on behalf of The International Rice Research Institute, there are doubts about it. "In my opinion, the main problem is not genetic engineering when it is for itself. Simply, it is much easier to market a strain that has undergone natural improvement," he says. "We believe that we can achieve fairly good resistance to salinity with conventional methods. What is the point of choosing a more complicated path if it is not necessary?"

According to advocates of genetic engineering, a distinct advantage of the method is the speed with which results can be achieved. The processes of hybridization, selection and repeated hybridization take a long time. Salt-resistant crops through genetic engineering are expected to reach the markets long before crops that have been improved by conventional methods, probably during the next four years. The salt-resistant rice that I tasted at the offices of Arcadia Biosciences is already halfway through the final field trials being conducted in India and is expected to be submitted soon for regulatory approval by the country's authorities. The grain yield of the transgenic plant is 40% greater than that of the rice currently grown in water whose salinity is only one-tenth the salinity of seawater, and Ray predicts that a more advanced strain under development will be twice as salt resistant as the current strain. "Better crops mean a higher income for farmers, a financial gain for all of us, and a reduction in the load on fresh water sources," he says.

Admittedly, for the time being this is a small step forward, but Blomwald feels that "it is a step in the right direction." Bringing in many more billions in the future will require success on a much larger scale, and dozens if not hundreds of successful projects like our one successful project.”