I shouldn’t have to say this, but there are currently no genetically engineered tomatoes on the market. For a short time in the 1990s Calgene sold the Flavr Savr tomato in California grocery stores, but they weren’t able make a profit doing so, so they stopped. The poor taste of most tomatoes for sale in the grocery store today is purely the result of conventional breeding (my post on the subject and Mat_kinase’s).

I shouldn’t have to say this, but there are currently no genetically engineered tomatoes on the market. For a short time in the 1990s Calgene sold the Flavr Savr tomato in California grocery stores, but they weren’t able make a profit doing so, so they stopped. The poor taste of most tomatoes for sale in the grocery store today is purely the result of conventional breeding (my post on the subject and Mat_kinase’s).

Before getting into the how, let’s talk about why this research is important. According to Enhancement of fruit shelf life by suppressing N-glycan processing enzymes in this week’s PNAS, post-harvest fruit and vegetable softening is a big problem, with losses accounting for almost 50% of all produce in developing countries. India, the country that funded the research, and the world’s 2nd largest fruit and vegetable producer, loses 35-40% of produce to softening.

Squished tomato by limaoscarjuliet via Flickr.

We all know that post-consumer food waste is a big problem, and we can alleviate this somewhat in our homes and by choosing restaurants that try to reduce waste. But there isn’t much we can do about pre-consumer waste – from grain that rots in the silo due to fungus to tomatoes that rot in transit due to ripening. By reducing pre-consumer food waste, we can reduce the number of acres needed to produce the same amount of food. In India, preventing all fruit and vegetable softening would be like reducing the amount of land needed to grow fruits and vegetables by 35-40%!

So, how could that softening be prevented?

Researchers have been working for a long time on different parts of the ripening and spoiling process, trying to find ways to slow it down. Nothing has been really effective in getting produce to last longer, and we’ve ended up with produce that is more bland than it used to be, especially when it comes to tomatoes. In short, neither breeding nor genetic engineering has been successful… until now.

In Enhancement of fruit shelf life by suppressing N-glycan processing enzymes, Meli* and fellow researchers found two enzymes that contribute to fruit softening. The enzymes are α-mannosidase and β-D-N-acetylhexosaminidase, α-Man and β-Hex for short. Both of these enzymes break the glycosidic bonds between carbohydrates, as well as between carbohydrate and noncarbohydrate. The role of these enzymes in ripening and softening is to help break down the cell walls that keep the fruit firm. If the enzymes are stopped from breaking down the cell walls, the tomato stays fresh!

Meli and fellow researchers turned off the genes that code for these two enzymes α-Man and β-Hex with biotechnology, but they didn’t use any whole genes from tomatoes or any other species. Instead, they used some pieces of the tomato α-Man and β-Hex genes. These gene fragments are transcribed into RNA under control of the constitutive (always on) CaMV 35S promoter. They then twist and bind with themselves, resulting in double stranded RNA, which activate the RNA interference mechanism that plants and other organisms naturally use to combat double stranded RNA viruses.

The results are pretty striking, as you can see from these pictures. The control tomatoes were unappealingly wrinkly by 20 days, and rotten by 45 days. The tomatoes with α-Man or β-Hex turned off were still firm even at 45 days.

Control and experimental tomatoes over time, from the PNAS article "Enhancement of fruit shelf life by suppressing N-glycan processing enzymes" by Meli, et. al.

RNAi can be used just about any time you want to turn off a gene – it’s even being tested for human use to help combat genetic diseases. For an overview of RNAi that’s a little more detailed than the picture below, check out the RNA Interference interactive video by Nature Reviews (via ERV. Note: the video wouldn’t play on my Mac in Firefox but worked great in Safari).

Overview of RNAi from Huntington's Outreach Project for Education, at Stanford.

The researchers used Agrobacterium to carry the DNA sequences into very young tomato plants, along with a marker gene for kanamycin resistance. Biotech plants can be made without markers but it’s much easier to use them, and there is no risk (for more on antibiotic resistance markers, see GMO Compass).

This work, as far as I can tell, is funded purely by the Indian government – not by private corporations. Specifically, it is funded by the Department of Biotechnology which is part of the Ministry of Science and Technology. They have some pretty impressive goals, as listed in the Plant Biotechnology section, including:

• Genetic engineering and molecular biology tools for forest tree improvement including reduction of generation time, production of horticultural and plantation crops with desired characteristics.
• Transgenics for improved yield, stress tolerance, balanced nutrition, keeping quality of flowers, fruits and vegetables, better nutrient and water utilization capacity should be produced.
• Cataloguing of accessions of wild and land races to study genetic diversity for resolving taxonomic problems.

Tomatoes at Union Square by Lindsay Beyerstein via Flickr.

One of the biggest arguments against biotechnology is that it has been under corporate control. Unfortunately, that’s been true in the United States, where publicly funded research in agriculture has been all but ended. Happily, that’s not the case in India and China. These governments are researching biotech traits for the benefit of their farmers, not for the benefit of shareholders.

If this biotech trait is available royalty-free, then it will presumably be available for breeding by small seed companies and by farmers. I’m imagining beautiful genetically-diverse heirloom tomatoes that have this amazing ability to stay firm on your counter well past the tomato growing season. This means that fewer tomatoes will need to be shipped around the world, and that more can be grown locally. I hope to see some long-lasting tomatoes in my CSA share soon!

* You may have noticed that I usually use the name of the first author rather than the name of the last author when I’m referring to a peer-reviewed paper. In biology-related papers, the first author is the graduate student, or sometimes post-doctoral researcher, who did most if not all of the labwork and writes most if not all of the paper.The last author is the PI (Primary Investigator), who generally provides guidance, helps with experimental design, and edits the paper. The authors in the middle are usually other grad students and their PIs who helped with the project. While all of the authors usually have put in a lot of time and effort, it’s that first author who worked the hardest, and I like to recognize that.

Meli V, Ghosh S, Prabha T, Chakraborty N, Chakraborty S, & Datta A. (2010). Enhancement of fruit shelf life by suppressing N-glycan processing enzymes Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0909329107

Having a CSA share is such a good experience in so many ways, but the most important one for me is that I know the farmers who grow the food I put on my table are getting honest pay for their labor, that they can afford to take care of their land and to take care of their employees. I also like the idea of keeping my food dollars in the local economy and of giving the money straight to the producer instead of through a string of middlemen and packagers. Another benefit that small vegetable farms provide is high biodiversity due to the many species of plants (and often animals too!) on the farms. They are often certified organic, but due to the high cost of certification,some farms forgo the label and just list their practices on signs or websites. Customers can actually meet the people who grow the food, ask questions, and make friends.

CSA’s are just one of many ways that farmers can receive fair pay for their produce; others include farmers markets and direct sales to restaurants. The one common factor across these is that they need to convince their customers that an increased cost is worth it. While there are certainly times when a certain fruit or vegetable is so locally abundant that it can be cheaper than the same fruit or vegetable from a large farm, there is no doubt that the economy of scale is lost on smaller farms. In order to break even, small farms have to charge a realistic amount for their produce. I’m ok with that. Are you?

You can look for CSAs (and farmers markets, etc) near you at Local Harvest.

Have any commonly held beliefs about corn that you’d like to know more about? Let us know in the comments.

Myth: Huge amounts of the sizable US corn crop go to HFCS production. Here’s a condescending example that sums up this idea from Grist: “The Big Corn People began to grow so much royally-subsidized GMO corn that they turned it into millions of gallons of high fructose corn syrup.”

It’s true, a portion of the US corn crop is used for HFCS production. It’s also true that corn syrup is cheap because the corn industry receives subsidies. But there’s a lot more to this story.

How is corn used?

Most of the US corn crop is used for animal feed. In 2006-2007, 5.6 billion bushels of corn were used for animal feed, 2.1 billion for exports, 2.1 billion for ethanol, 753 million for corn sweeteners, 272 million for corn starch, 190 million for corn foods (tortillas, cereal, etc), and 137 for alcoholic beverages, according to Iowa State University’s High Fructose Corn Syrup – How sweet it is (pdf).

It’s more than a little dishonest to blame the monocultures on HFCS, when so much of the crop is used for feed. Again, that’s 5.6 billion bushels of corn for animal feed versus 753 million bushels for sweeteners in 2007. We might also take a second look at ethanol.

Corn is used for so many things because it can be separated into fractions fairly easily. According to that same ISU Factsheet, a single bushel of corn (about 60 lbs) produces three primary products after wet milling:

• 1.6 lbs corn oil
• 13.5 lbs corn protein gluten animal feed
• 2.6 lbs corn gluten meal used for poultry feed, pre-emergent herbicide, and fur cleaner.

The remaining starch can then be used to produce one of three alternatives:

• 33 pounds of corn sweetener
• 32 pounds of cornstarch
• 2.5 to 2.7 gallons of ethanol or beverage alcohol

In other words, a bushel of corn can be used to make animal feed and either corn syrup or ethanol – not both. Over the years, the percentage of the crop that’s gone for sweetener or ethanol has changed a great deal. According to Table 27  – US use of field corn, by crop year (.xls), in 1991 7% of the corn crop was used to make sweetener, and 6.10% was used to make alcohol. In 2009, 5.78% of the corn crop was used for sweetener, while 35.82% was used for ethanol. Over the same years, the amount of corn harvested increased, so total corn syrup production did increase, but not much compared to ethanol.

If you’re looking to blame something for corn monocultures, it makes sense to turn first to animal products and then to ethanol… not to corn syrup.

How much does it cost?

Corn syrup is cheaper than sugar because of the climate in the US, tariffs on imported sugar, and because of corn subsidies. Sugar can be refined from two crops: sugar cane and sugar beets. Sugar cane is a tropical crop, and there aren’t many places in the US where it can be grown (see this map of US sugar cane acres in 2007 from the USDA to see just how few places). Sugar beets aren’t grown in many places in the US either (see this map of US sugar beet acres in 2007). Sugar cane and sugar beets both produce about 50% of US sugar, according to University of Florida Extension’s Overview of Florida Sugarcane.

Since there isn’t much sugar produced in the US, and due to the climate in the US we couldn’t produce much more even if we wanted to, we would need to import it from Brazil, India, or Europe. That could be a problem for locavores looking for sugar, but it’s definitely a problem for US sugar producers who want to stay competitive with producers overseas. Sugar producers have been successful in lobbying for high tariffs, so we don’t import much sugar. I don’t understand all the tariffs and other programs, but you can learn more at the USDA Foreign Agricultural Service’s US Sugar Import Program.

Since we can’t and don’t produce much sugar in the US, and there are trade barriers to importing sugars, it makes sense for food producers to look for an alternative sweetener. We have excellent climate and soils for corn (see this map of US corn acres in 2007), and it’s not that difficult to make sugar from corn starch.

More questions

I have to wonder if, in the absence of trade barriers, we would still have more corn syrup than corn sugar. Similarly, how much would the balance of sweeteners actually change if corn subsidies were removed? Since such a small amount of the crop is used to produce all the sweetener we need, I wonder if things would change much at all. Finally, even if we had enough sugar to meet consumer demand for sweet processed foods, would Americans actually consume any less total sugar than we do now? I’m thinking it wouldn’t change at all. As for what might change consumption of total sugars, we might consider subsidies on healthy (or at least healthier) foods and/or a tax on unhealthy foods and sodas. Here’s hoping.

Modern Flourishes at Obamas’ State Dinner in the New York Times leaves me hungry. How wonderful: “the meatless menu included a mix of Indian and American favorites, including some African-American standards. Collard greens and curried prawns, chickpeas and okra, nan and cornbread”. Sounds like a lot of agricultural biodiversity to me! Cheers to Mrs. Obama for continuing to encourage Americans to consider healthy food options by setting such an exquisite example.

For the full menu, see this official press release from the White House (pdf). For pictures, you must see the slide show at the Times – there are very few pictures of the event online.

Karl, you’ll be happy to hear that the pears served for dessert were poached in honey from the White House’s own beehive!

Why am I bringing this up at Biofortified?

Sunshine quinoa salad by sonicwalker. Click the photo for the recipe. Via flickr.

The prepared food from Full Yield is not your typical prepared food. “The choices may include turkey chili, quinoa salads, salmon cakes, chicken tagine, mixed bean wraps and whole-grain peanut butter cookies,” according to the Times article. Employees in the program are encouraged to eat only Full Yield items or similar whole food meals prepared at home. In these few menu items I see a swath of biodiversity, things never seen in the typical American’s diet. If the people on the program can lean about (and enjoy!) food options that are more healthy and more varied, maybe they will continue to choose these healthy varied items when they are done with the program. Maybe, just maybe, this will lead to an increase in demand for small grains and legumes and a decrease in demand for foods like feedlot beef and white bread. Maybe, just maybe, this could lead to big changes in farming.

Michael Pollan, not surprisingly, is way ahead of me on this idea. His editorial Big Food vs. Big Insurance appeared in the Times in September. Pollan argues that the proposed changes in health insurance regulation, particularly requiring companies to take everyone (no more pre-existing conditions), will cause the health insurance lobby to start fighting for changes in things like the Farm Bill. Pollan suggests: “Insurers will quickly figure out that every case of Type 2 diabetes they can prevent adds $400,000 to their bottom line. Suddenly, every can of soda or Happy Meal or chicken nugget on a school lunch menu will look like a threat to future profits.”

I agree with Pollan that national food policies have an effect on what people eat, particularly when it comes to affecting how much food costs. When we subsidize commodity crops but don’t subsidize fruits and vegetables, we’re effectively reducing the cost to the consumer of processed foods and grain-fed meat. However, I don’t think a potential battle between “Big Food” and “Big Insurance” will lead to as much change as many of us would like to see.

Kid Cuisine photo by Matt, via the very odd but quite funny review of the product on the X-Entertainment blog.

Even if food subsides and policies are balanced to make healthy foods more affordable, people will still make the choices they’ve always made. Even if healthy foods become cheaper than unhealthy food, I’m not convinced that people will choose the cheaper option. People who grew up on box mac n’ cheese and “fun-shaped” chicken nuggets will not suddenly make and eat quinoa salad (maybe quinoa needs a snowboarding penguin?). But, if their workplace encourages them to try new foods, then maybe they’ll want to try them again.

We can’t just leave it up to a few scattered employers, though. We all have a responsibility, if we want farms to grow a larger variety of crops, to eat those crops, and to encourage our friends to eat them. Yum! Quinoa salad, anyone?

Eating locally is great, but since apples only ripen once per year, and they spoil relatively fast, that means we only have fresh apples for a short time each year. That’s too bad, since apples are a wonderful crunchy snack loved by kids and adults that provide health benefits from their fiber and antioxidants.

Shipping the apples from another place (like New Zealand) extends the time that apples are available, but shipping in refrigerated containers is expensive and results in greenhouse gas emissions, and we all know that those apples from far away just don’t taste as good as local ones.

Scab Resistant Selection RS103-130. Image from "Organic Production of a New Australian-bred Scab Resistant Apple in Queensland, Australia" by Middleton, et. al

There might be a way to have local apples available for a much longer time, as well as to have apples shipped in that use less energy and less pesticides!

After more than 20 years of work, researchers in Australia have developed apples that are resistant to black spot aka apple scab, a fungus that destroys fruit and leaves. The scab resistant line, called RS103-130, also stays fresh and crunchy much longer than typical apple lines. They achieved this through some initial crosses with a crabapple species followed by years of selective breeding. The crabapple provided RS103-130 with the Vf gene complex, which has been previously used to produce transgenic scab-resistant apples, which I’ll describe in more detail shortly. You can find the Australian patent for RS103-130 at FreePatentsOnline.

In 2005 and 2006, comparison experiments showed RS103-130 to have many benefits over Galaxy, a typical non-resistant cultivar (see chart below). According to Middleton, et. al, RS103-130 has off white flesh and medium texture, is crisp, sweet, low-acid, and juicy, with a mild flavor.

Chart from "Organic Production of a New Australian-bred Scab Resistant Apple in Queensland, Australia" by Middleton, et. al.

Because of all of these benefits and the reduced pesticides needed, organic apple growers in Australia are very interested in RS103-130. I wasn’t able to find any information on whether RS103-130 has been commercialized yet, or on how long it might be before I can try them. Apparently something happened with RS103-130 lately, because stories appeared in The Independent and in the New York Daily News last week. Neither of the stories say what prompted the coverage, nor does Treehugger, which picked up on the 1st two. If you know what’s new with these apples, please comment!

My first question upon reading these articles was: why has it taken twenty years?! Selective breeding can be painstaking, especially when you’re talking trees. There is a faster way…

The HcrVf2 gene from a wild apple confers scab resistance to a transgenic cultivated variety showed that the Vf gene can be inserted with biotechnology into apple varieties (in this case, the gene was inserted by Agrobacterium tumefaciens into the Gala apple cultivar). In the introduction of this paper from 2003, Belfanti et. al point out that:

the transfer of these genes by classical breeding to cultivated apples is difficult because of the long juvenile phase, self-incompatibility, and the impossibility of exactly reproducing the heterozygous state of cultivated varieties. Starting from the wild species Malus floribunda 821 carrying the Vf gene, breeders have developed several scab-resistant apple cvs. (2), but not one has met with commercial success. Indeed, when compared with such commercially popular cvs. as Golden Delicious and Gala, the main horticultural and fruit-quality traits of these scab-resistant cvs. are notably different and undoubtedly less acceptable.

Using biotechnology, the researchers were able to confer scab resistance in one generation. In this paper, the authors don’t mention any increase in lifespan for the fresh apples – I’ll look on Web of Science for more info tomorrow. I do appreciate that the authors are hopeful for the future of apple biotech.

The cloning of an apple scab resistance gene represents the basis for further investigation of the resistance mechanism. It also represents a step toward a gene therapy (restoring resistance where lost) of the scab-susceptible cvs. that currently dominate the apple industry. This strategy will allow the transfer of resistance from a wild apple species to any commercial apple genotype while maintaining the horticultural and fruit-quality traits growers and consumers prize most. It may also be possible to achieve greater resistance durability by the simultaneous transfer of several resistance genes from wild apple species. Going one step further, it may be possible to use apple promoters and novel techniques that, by eliminating selective marker genes (38, 39), generate transgenic varieties without any foreign genes and, hence, may make genetically modified plants more acceptable to growers and consumers alike.

I’m particularly interested that Balfanti et. al mentioned cisgenics, although they didn’t use the term. There is potential to insert genes like Vf into many varieties of apples, meaning that cultivars developed for specific microclimates may be quickly made resistant to scab (and potentially given a longer shelf life) without any loss of their other traits. This is a good example of how biotechnology and breeding can have the same results – get a gene into a cultivar – although one takes much longer than the other.

Anthocyanin-rich berries are delicious but expensive and only available during certain times of year. Most people do not seek out red cabbage or brightly colored heirloom varieties of veggies like carrots and cauliflower. In the US, the most frequently eaten vegetables are potatoes, lettuce, and tomatoes. Purple tomatoes exist, but heirloom tomatoes have issues like splitting and little time till spoilage. This is fine if you buy them at the farmer’s market and eat them the next day, but is not suitable for things like pasta sauce production (cans and bottles are where most people get their RDA of tomatoes, but it turns out they are healthier that way!). Varieties like Cherokee purple, while awesome, don’t produce anthocyanins throughout the fruit.

One option would be to develop tomatoes with high concentrations of anthocyanins. The trait could be bred into varieties that have more of the characteristics needed for processing into pastes and such (although I’m personally looking forward to purple cherry tomatoes, as in the photo). A collaboration of researchers in Europe has done it.

Could this GMO be accepted by people looking for healthier foods? It’s possible, but likely depends on marketing. Some people are simply afraid of anything new, from purple cauliflower (a heirloom variety) to Grapples (infused with grape juice in a dissapointingly boring way). Ah well. For the rest of us, though, purple tomatoes could be an interesting addition to our diets.

As Cathie Martin, the lead researcher, said: this is “certainly the first example of a GMO with a trait that really offers a potential benefit for all consumers.” The health benefits need to be verified in humans, but results look good so far. “In a pilot test, the lifespan of cancer-susceptible mice was significantly extended when their diet was supplemented with the purple tomatoes compared to supplementation with normal red tomatoes (SD).”

Will people be more willing to look into what GM really means when it has potential to benefit them directly? Will they even care how the tomatoes were made if benefits can be shown? This particular GMO transcends a lot of the issues associated with ones currently on the market.

Labeling isn’t as much of an issue when the trait is obvious, and these tomatoes will likely be proudly labeled due to their health benefits. Gene flow isn’t an issue because pollen spread in tomatoes doesn’t seem to be a problem, the trait can be eliminated from fields by sight, and will be of no advantage to wild relatives. The trait could be used with equal benefit in any farming strategy, organic or conventional, large or small, and will have no effect on natural ecosystems (except maybe preventing cancer in herbivores). The only issue left (please remind me if I’ve left any out!) is seed cost due to licensing. However, we must consider that all seed has a cost (simply Google purple tomato seeds to find prices – up to $4 for 20 seeds!), especially for hybrids.

I have to admit to surprise that this research was done in Europe – a collaboration of scientists from the UK, Italy, Germany, and the Netherlands. I’m happy that the research was able to bear fruit before anyone burnt down their lab.

Ok, back to the science.

First, the paper was really easy to read. I think a layperson wouldn’t have too hard of a time reading most it, given a glossary of genetics jargon. Of course, I could be totally wrong on that. Let me know what you think!

The results were achieved by expressing two interacting transcription factors from snapdragons (one of my favorite flowers) that in turn affect expression levels of genes in the anthocyanin pathway. I have to wonder why they ended up using snapdragon genes. You’d think there would be similar transcription factors in tomatoes.

The authors did thoroughly document an entire list of unsuccessful attempts at improving anthocyanins in tomatoes, both by themselves and other labs, including altering expression levels of transcription factors in related pathways and traditional breeding with wild tomatoes, so it seems unlikely that they would overlook a traditional breeding or cisgenic approach in favor of genetic engineering, if the other methods would accomplish their goals.

Although, they did use a cauliflower mosaic virus terminator (stop signal – has nothing to do with the so-called “terminator gene”).  They used a fruit specific promoter, so why not just use the terminator from that gene?

I am very glad that they chose a fruit specific promoter, though. There is no reason to tax the plant’s resources by producing anthocyanins in the leaves and other non-edible parts, unless there is some advantage to expressing them in these parts, such as pest deterrence.

I’m not convinced that they couldn’t do achieve this result with an entirely cisgenic gene construct, but I’m  a particularly big fan of cisgenics. All in all, this seems like a beautiful use of genetic engineering to achieve a result that is important to consumers that could theoretically be achieved by decades of breeding (although it hasn’t yet!). I hope people are able to look past the scary GMO label.

Eugenio Butelli, Lucilla Titta, Marco Giorgio, Hans-Peter Mock, Andrea Matros, Silke Peterek, Elio G W M Schijlen, Robert D Hall, Arnaud G Bovy, Jie Luo, Cathie Martin (2008). Enrichment of tomato fruit with health-promoting anthocyanins by expression of select transcription factors Nature Biotechnology DOI: 10.1038/nbt.1506