Producing tastier fruits and vegetables without genetic engineering / Ferris Jaber

The produce sold in modern supermarkets has become more beautiful and durable, but also almost tasteless and odorless. Scientists can now bring them back - without the use of genetic engineering.

The agricultural products on the shelves of modern supermarkets are full of visual illusions.

The strawberries are full and bright, the tomatoes are smooth and shiny and the melons are firm and bright, but most of them are tasteless and odorless. We have no one to blame for this bland beauty but ourselves. Picky hybrids of crops made them spectacular and resistant to the hardships of transport and storage in the dark and cold. But along the way we lost the taste, the aroma and the nutritional value of our food.

Take for example the dilemma posed to growers of the orange melon, cantaloupe. To enjoy the wonderful taste of the cantaloupe, it must be picked and eaten at the peak of its ripeness, before it becomes too soft. Towards the last stages of cantaloupe development, a burst of the plant hormone ethylene causes the fruit to ripen and soften quickly. This rapid ripening made it difficult to transport the fruit across the country or to other countries. Even when packed with ice, the melons ended the journey as sticky mush. Plant breeders therefore reduced the ethylene in cantaloupes intended for export to distant destinations. They did this by cross-pollinating melons that naturally had the lowest hormone levels. Without a strong burst of ethylene, the melons remain firm during the journey from the field to the grocery store shelves, but the biochemical reactions that create the characteristic taste and smell of ripe melons do not occur.

Breeders have had some success in trying to overcome this obstacle. In the 90s of the 20th century, Dominique Chambiron, who was then working at the "Dutch Seed Group De Reuter", managed to create a variety of small, striped cantaloupes that retain their firmness and flavor for several weeks after picking. This variety, known as Melorange, is grown in Central America and marketed to elite marketing chains in the US every year from December to April, a season when it is too cold to grow local cantaloupe. Last March I tasted a slice. Its texture was dense and its taste and smell were very strong, on the verge of being spicy. Unfortunately, the method of hybridization to obtain the malorange relied heavily on chance discovery. Sometimes it takes more than ten years to consistently improve an impressive cultivar. The breeders have to pollinate plants again and again in the hope that one of the offspring will inherit the desired traits, and then you usually have to wait until the plant grows and its fruits ripen. Most of the strains they create are very far from what is desired and completely unusable.

Geneticists have recently proposed another way. Jeff Mills and his colleagues at Monsanto, which acquired de Reuter in 2008, can predict the quality of the fruit even before a single cantaloupe seed is planted in the ground. First, Mills and his team identified the genes responsible for the unique combination of firmness and flavor in oranges. Now they can search for these genetic "markers" in cantaloupe seeds using autonomous robots.

I saw many such machines when I visited the molecular breeding labs at Monsanto's plant research and development headquarters in Woodland, California, in November 2013. A machine shaves a chip from each seed, which is used for DNA analysis. The seed is not damaged, and it can be sown later in the field or in the greenhouse. Another robot extracts the DNA from the piece of sperm and adds the molecules and enzymes necessary to attach glowing molecular tags to the relevant genes, if they are indeed present in the DNA. Another machine replicates the DNA and multiplies the number of glowing tags to measure the light they emit and determine if the gene is indeed present in the sperm.

Such methods, known as "marker breeding", are not new, but they have enabled unprecedented progress in the last decade on the way to the perfect fruits because determining the DNA sequence has become very fast and cheap. Monsanto's robots can operate 24 hours a day, and the entire system can deliver results to growers within two weeks. In the last decade, growers, both in private companies and universities, have succeeded in creating a variety of vegetables and fruits that are tastier, more colorful, more beautiful and more nutritious, and some of them are already available in greengrocers and farmers' markets. And it's not just about the mouth-watering types of melons, the number of which is increasing; The broccoli, healthy in itself, was filled with more nutrients, the strawberries are particularly juicy, and the tomatoes please both the eye and the tongue.

"The impact of genomic research on plant breeding is beyond imagination," says Shelly Janesky, a potato breeding researcher at the US Department of Agriculture and the University of Wisconsin-Madison. "Five years ago I had a PhD student who spent three years trying to identify DNA sequences associated with disease resistance. After hundreds of hours of work in the laboratory he found 18 genetic markers. Now I have students who can get 8,000 markers per plant out of 200 different plants in just a few weeks.”

All this discussion about DNA analysis raises the suspicion that this is genetic engineering, the method that makes it possible to edit genes to create new organisms (GMOs). But it is not so. This is a method that has nothing to do with genetic engineering and GMO technology. In fact, this is one of the main reasons why it is so attractive to scientists and seed companies like Monsanto.

sowing change

Humans have been modifying plants to suit their needs for 9,000 years. Almost every fruit and vegetable we eat is a cultivated variety that has been modified by decades of artificial selection and hybridization: humans have saved seeds only from plants with the most desirable characteristics and deliberately mated certain plants to create a new combination of traits. In this way, our ancestors improved the skinny grass called teosinte and created from it the plump and tall corn, and from a single variety of wild cabbage they created broccoli, Brussels sprouts, cauliflower and leafy cabbage (kale).

In the 80s, scientists invented a much more precise method for changing the DNA of plants: genetic engineering. Using laboratory tools they can add, remove or change the genes in the plant. Yields of genetically modified plants appeared on the American market in the 90s. Although more than 70% of processed food in the US contains ingredients from corn, soybeans or canola that have undergone genetic modifications, only very few of the fresh vegetables and fruits sold in supermarkets have undergone such treatment. Exceptions are papaya, plums, and squash that are resistant to viruses and sweet corn that is resistant to insect pests.

One of the reasons for the paucity of vegetables and fruits that are products of genetic engineering is that they are less profitable and are therefore grown less than more common crops: corn, soybeans, fodder, wheat, cotton, sorghum and rice. When it comes to vegetables, fruits and other limited crops, the seed companies have no incentive to go through all the burdensome and expensive safety tests and the governmental regulatory procedures required to approve the sale of products.

The other high hurdle hindering the development of genetically modified fruits and vegetables is public opinion. Universities and seed companies know that the introduction of a new product that has been genetically improved could incite outrage among certain segments of the US population who oppose what they consider to be "Frankenfoods". Most shoppers are unaware of the few GM fruits and vegetables already in stores because they are usually not labeled as GM.

In the last decade, the improvement with the help of markers has become more and more accepted as a practical way to improve fruits and vegetables that bypasses this controversy. The method also received a boost from the improvement of genetic methods and the continued work of scientists to determine the gene sequence of more and more crop plants. The combination between traditional hybridization and DNA analysis helps direct the attention of breeders to the food qualities that are important to consumers. "It sounds obvious to ask what consumers want, but it's not," says Harry Kelly, a tomato breeder at the University of Florida. Instead, he says, strain developers always put the needs of farmers and food distributors first.

An excellent example is the classic supermarket tomato. For decades, the experts believed that the balance between the level of acids and the level of sugars in a tomato is the main factor that determines whether we enjoy it. In general, people like sweet tomatoes, but most praisers did not attach much importance to the taste. Instead, they thought mainly of the large commercial growers and therefore preferred tomato plants that yield lots of smooth, hard fruit that remain full even after long journeys on the way to the stores. But the more tomatoes the plant produces, the less sugar it can provide per tomato. The typical supermarket tomatoes can therefore look pretty, but they don't have enough sugar to please the taste buds.

Kelly is determined to save the tomato industry from the fattening of the taste. Through a series of taste tests, Kelly evaluated about 200 non-industrial tomato varieties that were preserved by small groups of farmers and gardeners and sold in local grocery stores and farmers' markets. The tomatoes from these local varieties are known for their bright colors and wonderful taste, but their skins crack and damage easily, they soften quickly and grow on plants that do not produce enough fruit to satisfy the needs of large commercial farmers.

In his research, Kelly learned that many of these local varieties taste better than regular commercial tomatoes not because their tomatoes have more sugar but because they are packed with more complex flavor components: pungent-smelling volatile organic compounds that are carried in the air from the plant to our nostrils (think freshly cut grass or the seductive scent of the citrus fruits). In a study done by Kelly and his colleagues in 2012, they found that people enjoy a tomato even if it has moderate levels of sugar, provided that it has a large enough amount of a fragrant organic compound called geranial. Kelly speculates that greniel and other volatiles not only give the tomato its aroma, but also increase the underlying sweetness of the fruit. In his further research, he created tomatoes without geraniel and without other scent molecules. People didn't like their taste. The volunteer tasters did not feel sweetness in tomatoes without volatile substances, even if they had an average to high amount of sugar.

Recently, Kelly has been trying to produce hybrid plants that will give growers and consumers the best of both tomato worlds, the old local and the new commercial tomato. Over the past three years, Kelly and his team have mated the tastiest varieties with the most common modern varieties to create varieties that yield large yields of firm, smooth, and incredibly delicious tomatoes. Kelly keeps a stock of cheap electric toothbrushes with which his team members gently but thoroughly stroke the tomato flowers and collect the pollen into test tubes so they can make matches. At the same time, the researchers collected tiny pieces of leaves to analyze the DNA of the plants and look for the genetic patterns responsible for high concentrations of volatile substances, for example, or for a perfect peel. "There is no doubt that the genetic analysis made it possible to achieve intelligent crosses," says Kelly. "Our work got a real boost in the last two years, with the publication of the tomato genome sequence."

The University of Florida recently released two of these hybrid varieties, which received the nicknames "Garden Jewel" and "Garden Treasure", in an effort to grant a seed company a license for their wide distribution. Although the hybrid varieties did not produce a commercial crop of tomatoes, they provided three times as many tomatoes as the parental varieties. Tomatoes have a wonderful taste and are able to withstand to a considerable extent the hardships of marketing. Kelly's colleague, Ness Whittaker, is making good progress on a similar project in which he is trying to restore the intense flavor to strawberries in supermarkets, which have been grown to gain a long shelf life but have lost their flavor.

Another victim of the transportation and distribution difficulties worth noting, in addition to the melons and tomatoes, is the broccoli. Almost 75% of the broccoli in the US is grown in California. Broccoli prefers cool weather, and thrives on the fogs that sometimes blanket the Salinas Valley. When forced to withstand the hot and humid summers of the Northeastern US, it develops gnarled heads with uneven buds. Each little bud in the dome-shaped inflorescence of the broccoli is a flower that has not yet bloomed. Thomas Bjorkman and his colleagues from Cornell University found that during a critical period in its development, broccoli tracks the number of hours it enjoys cool temperatures and produces a uniform inflorescence head only if it has accumulated enough hours. This is why broccoli grown on the East Coast can ripen with an unappealing mix of buds, some beautiful and full and some tiny and almost invisible.

Three and a half years ago, Bjorkman, Mark Farnham from the US Department of Agriculture and their many colleagues decided to develop a new variety of broccoli that would also thrive in the eastern United States. In the greenhouse in their laboratory, Bjorkman exposed the broccoli to the temperature and humidity characteristic of the East Coast and kept only the seeds of the plants that grew magnificently even under these conditions. Although they still have a lot of work to do, they have already improved broccoli that can withstand the summer heat a few weeks longer than the varieties grown in the east. In the meantime, the researchers are scanning the genomes of the various plants they have grown to discover the genes that will explain why some cope better than others. Finding them will make it possible to significantly shorten the journey towards the ideal plant.

Improving broccoli so that it remains beautiful even in the heat is not only an exercise in aesthetics but is also related to obtaining more delicious and nutritious broccoli for sale at farmers' markets and greengrocers. Fresh broccoli picked the day it is eaten is different from the usual food we find in supermarkets, says Bjorkman. Its taste is mild, its sweet herbal aroma is reminiscent of a honey forest, and it does not leave a spicy aftertaste. Transporting broccoli from California to the rest of the US requires storage in ice and darkness for days. Without light photosynthesis stops and the cells stop producing sugars. A rapid lowering of the temperature breaks the cell walls, irreversibly weakens the structure of the plant and softens it. When the broccoli thaws, various molecules and enzymes that leaked out of the cells when they were broken trigger a series of chemical reactions, some of which cause the breakdown of flavor compounds and nutrients. If farmers in the East had a local broccoli variety that they could grow and sell locally, all these problems would be solved.

In another attempt to increase the nutritional value of broccoli, Richard Mitten of the Food Research Institute in England and his colleagues used marker enhancement to increase the concentration of the compound glucocorphanin, which has some evidence that it helps fight bacteria and cancer. The researchers received a license to market the broccoli variety they developed, called Beporte, to the Monsanto company. You can find this variety in several chains that market natural and organic food in the USA.

Sow initiatives

In order to obtain the grant that allowed Bjorkman and Farnham to begin research, they had to prove to the US Department of Agriculture that the seed companies were indeed genuinely interested in developing the new regional market for broccoli by securing funding from the private sector. The seed companies Monsanto, Syngenta and Bezos are contributing money to the project even though they compete with each other. In theory, both the seed companies and university researchers can benefit from such cooperation. During the research and development phase, everyone shares information and exchanges seeds. But eventually comes the time of negotiation. As in the case of Kelly and his delicious tomatoes, Bjorkman also hopes that when the day comes when he and his colleagues get close to the beautiful broccoli, one of the private companies will obtain a license for the widespread production of the seeds and their commercial distribution. Björkman and his team do not have the financial resources to do this themselves. Although searching for genetic markers in individual plants is becoming increasingly cheaper, the process of producing and marketing huge quantities of seeds is still expensive.

However, because the giant seed companies have far greater financial and technological resources than the smaller companies and universities, some plant advocates worry that this will stifle real innovation. "Since the technology moved to the private sector, there has been a sharp decline in public sector plant breeding programs," says Erwin Goldman of the University of Wisconsin-Madison, who recently introduced a bright orange beet with circular golden stripes. "Some people claim that this transition [to the private sector] is a success for the US, but public sector researchers will do things that the private sector will not do, those that take too long to develop or the risk involved is too high.

Jack Jubik, director of the Plant Breeding Center at the University of Illinois at Urbana-Champaign, who started breeding in the 70s, remembers that the big companies didn't dominate the field the way they do today. "When I started, there were many companies that sold many seeds, but they were bought or removed from the market by the giant companies. It changed the structure of the entire industry," says Jobik. "Instead of the researchers in the public institutions completing the development of the plants, most of us are currently planning the genomes of plants that the big companies are developing. While these companies have resources that allow them to conduct efficient testing and produce superior selections, they control most of the genetic information and technology used to produce the seeds."

Goldman and his colleague Jack Klopfenburg of the University of Wisconsin-Madison belong to a group of 20 breeders and farmers from all over the US who are interested in creating a system that will operate in a similar way to open source software and provide a selection of patent-free seeds for general use. There is no precedent for such an arrangement in the 21st century seed market. One of the expensive alternatives facing the group is to hire lawyers and register a standard patent or copyright on their seeds to allow almost anyone who wants to use them (except for private giant companies, of course). Alternatively, they could try to create a cooperative license that would allow people to use the seeds provided they also agree to share the seeds they develop and everything related to them. Goldman also proposed a compromise whereby the breeding researchers would license some of the seed types to private sector companies to allow them to make a profit, and share the rest of the seeds freely.

Kelly wonders if a certain compromise is the best way forward. "The reality is that we in academia cannot compete with Monsanto and other seed companies," he says. "University professors find research on major crops and are relegated to niche crops. In my department there is a peach picker, a blueberry picker and a strawberry picker. I know many people at Monsanto who have abandoned such crops because they think they are marginal.” He hopes that such a separation will allow the private and public sectors to complement each other.

In the end, Kelly is interested in promoting the possibility that will attract more and more plant breeders: bridging the chasm between the growers' need to make a living and what consumers want to see on their plates. "Improving with markers allows you to go back and correct things like taste and texture," says Kelly. "It's actually very simple: you have to give people what they want."

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About the author

Paris Jaber is a reporter for Scientific American and a freelance journalist. He writes for the New York Times, Wired, Popular Mechanics, New Scientist, NOVA and The Awl.

in brief

Creating fruits and vegetables large and beautiful enough to satisfy the demands of industrial agriculture is responsible for the loss of the taste and nutritional value that characterized the varieties of the past.

Instead of improving these crops through genetic engineering and adding to the prevailing controversy on the subject, scientists turned to improvement using genetic markers, which combines traditional hybrids and DNA analysis, which is becoming faster than ever.

In the past, the breeding researchers at the public universities donated the crops they developed to the farmers. Today they must issue a license to use seeds for a handful of private giant companies, which many believe have gained too much power.

Basic ideas

Breeding with the help of genetic markers

In order to improve a particular variety, traditional plant breeders had to engage in botanical matching for long years. Through labor they had to eliminate the undesirable qualities without losing the desirable ones. The identification of the genes underlying these traits allowed for a much more efficient and accurate process, known as "breeding with the help of genetic markers".

More on the subject

Improving the Flavor of Fresh Fruits: Genomic, Biochemistry and Biotechnology. Harry J. Klee in New Phytologist, Vol. 187, no. 1, pages 44-56; July 2010.

Breeding Better Crops. Richard Hamilton, Scientific American Earth 3.0 JUNE 2009.

Are genetically engineered foods a bad thing? by David H. Friedman, Scientific American Israel, December 2013-January 2014, page 36,

This article was published with the permission of Scientific American Israel