Sugar beet biology

Roundup Ready sugar beets have been back in the news due to the decision by Judge White to revoke approval. As I understand it, the USDA conduced an Environmental Assessment for Roundup Ready sugar beets but did not conduct an Environmental Impact Statement. According to regulation, an EA is sufficient if potential harm is found to be minimal, but an EIS is needed for anything that is less well understood, such as a new trait (and this is hardly a new trait). After reading the EA, I agree with the USDA that the potential environmental harm is minimal, and I think the potential economic harm is minimal as well, due to some very specific characteristics of beet biology, which I’ll explain in this post, followed by a discussion of mitigation strategies that might be used to control gene flow in beets (sorry, folks, this is going to be another long one).

Beet flowers and seeds, originally from ‘Koehler’s Medicinal-Plants’ circa 1887, via Wikipedia.

Beet biology

Sugar beets are biennial, which means they need two years before they reach maturity. During the 1st year, the plants produce a large root that, when dried, is 15-20% sugar. During the 2nd year, the plant uses those stored sugars to produce flowers and then seeds. Sugar beets harvested for sugar, therefore, don’t produce flowers or pollen or seeds.

Sometimes a few plants will “bolt” or flower when they aren’t supposed to, such as when there are unusual temperatures. This happens in both GM* and non-GM beets. Modern beet varieties have been bred to not bolt. In Europe, weed beets can pollenate beets grown for seed, resulting in weed x cultivated beet hybrids that might bolt, but in the US weed beets are not a problem. There is a very low percentage of bolters in any beet field – fewer than 1 per 1000 square meters of field. Some discussion on bolter control can be found in the University of California Cooperative Extension Sugarbeet Notes, but keep in mind that some aspects of beet production in California differ from beet production in other states.

Another source of pollen could be beets or pieces of beets that are can be missed during harvest. These can flower during the following year as volunteers, but only in climates that have warm enough winters, specifically, the Imperial Valley in California, near the border with Mexico. In Oregon and the other beet producing states, cold winter weather kills any beet pieces left in the field so they can not flower the following year.

When they do flower, such as when beets are grown for seed, sugar beet pollen is fairly mobile, according to the Jan 2009 Pollen dispersal in sugar beet production fields. It is carried by the wind and possibly by insects as well. They found that pollen carried up to 1200 meters (that’s about 0.75 miles). These results are fairly consistent among papers testing dispersal of beet pollen. Even though pollen can move from field to field, most of it stays put. In the 1967 Cross-pollination between fields of sugar beet, the amount of pollen falling from one 20 acre beet field onto another that is 1000 meters away is estimated to be 0.004 compared to the amount of pollen coming from the field itself. Beet pollen can remain viable for a while when stored cold and dry in a lab refrigerator, but in the field it’s only viable for about 24 hours after it is shed by the flower.

Even though there’s all of this pollen flying around, most of it falls close to the parent plants. This is a good thing for any farmer trying to grow seed, or it would be impossible to produce seed with the genetics that they want.

Sugar beet by Mary Claire Garrison, via North Carolina State University.

Pollen potential

There are 4 situations I can imagine for combinations of GM and non-GM sugar beet fields. Only one is a problem because the seeds of sugar beets grown for sugar are irrelevant. You can not both harvest the root for sugar this year and harvest the seed next year. Even if a flower from a plant was pollinated with pollen that contains a transgene, the beet from that plant will not. So, there is no risk of contamination of non-GM beets with GM beet pollen – except in the case of seed production.

  1. Two fields growing beets next to each other, one GM and one not GM. In this case, the only pollen around will be from bolters. Even if flowers are produced and are pollinated with pollen that has a GM gene, the root is still not GM.
  2. A field growing non-GM beet seed next to a field growing GM beets. The only GM pollen around will be from bolters. It is possible that pollen from GM bolters could fertilize the non-GM beet flowers at a very low rate. Appropriate distances must be maintained by the farmer growing the seed to ensure he will produce seed with the genetics he wants.
  3. A field growing GM beet seed next to a field growing non-GM beets. As in case 1, the roots in the non-GM field will not be affected. Just like in case 2, the farmer growing seed needs to maintain appropriate distances to protect her flowers from bolters to ensure her seed will have the genetics she wants.
  4. Two fields growing beet seed next to each other, one GM and one not GM. This is where things get a little more complicated, just because there’s more pollen around. Since most beet seed is grown in Willamette Valley in Oregon, the potential for cross pollination is fairly high, if plants of different genotypes are grown close together. This problem isn’t unique to GM, though, so plants that need to be kept separate genetically are kept separate physically.
Table beets via Wikipedia.

Table beets via Wikipedia.

Sugar beets, table beets, and chard are all grown for seed in Willamette Valley, and they are all capable of cross pollination. Seed producers of any of these must keep their fields separated by distance from any other seed producers or the resulting seed could be worthless.

For example, if red table beet seeds were grown too close to sugar beet seeds, the sugar beet seed grower could end up with red sugar beet seed. Whoever bought and planted that seed would end up with a worthless crop, since all that red pigment would complicate sugar processing. Even if only a small percentage of the field had genes from table beets, the farmer would be paid less for his crop since the sugar processor would have to find a way to remove the red sugar beets. Table beets growing from the contaminated seed would likely have issues as well.

You gotta keep ‘em separated

Producing pure seed isn’t an easy job. Without GM even entering the discussion, there’s a lot to do to make sure that the seed a farmer buys is going to produce the right plants. In the case of beets, the plants are often weeded by hand to remove any plants that don’t look like the rest. The American Crystal Sugar Company has an excellent webpage that talks about sugar beet seed production, with pictures. For a non-beet centric view of how complicated it can be to produce good seed, the Seeds of Change seed company has a great article: Redefining Seed Quality. The article is about organic seed but applies equally to all seed types (there is one error in this article, see the next section of this post for details).

How do seed producers in Willamette Valley and elsewhere keep pollen from sexually compatible crops from pollinating their flowers and contaminating their seed? It all comes down to distance. The Oregon Seed Certification Service recommends different distances for stock seed and for certified seed (see the Oregon Seed Certification Service Handbook for more details on types of seed). Oregon’s sugar beet certification standards sheet (pdf) lists the following distances  for stock and certified seed production:

  1. From sugar beet pollen source of different or unknown ploidy: 5000 ft, 3200 ft
  2. From sugar beet pollen source of similar ploidy or between fields where male sterility is not used: 3200 ft, 2600 ft
  3. From other pollinator or genus Beta that is not a sugar beet (including fodder beet, red beet, swiss chard): 10,200 ft, 8000 ft

Remember, 5,280 ft is a mile, so this standards sheet is saying that seed production fields need to be 1 to 2 miles apart (the American Crystal Sugar Company site says the distance needed might be “several miles”). If this distance works well enough to keep all the different varieites of sugar beets, table beets, and chard genetically pure, then it will work to keep GM genes out of non-GM crops. Pollen from a GM plant is no different than pollen from a non-GM plant. While I could understand if someone advocated for tests with GM pollen to determine the exact distance, I don’t think that’s necessary since we already have a lot of information on how far apart fields need to be to prevent gene flow – as stated earlier, research has found that 1000 meters separating two fields results in 0.004 of all pollen coming from the distant field compared to the amount of pollen coming from the field itself.

Don’t panic, it’s organic

The Redefining Seed Quality article has one little mistake. It says “By law organic seed can not contain genetically modified organisms (GMOs).” This is a common misconception. The law actually says that GM can not be used in organic seed, not that it can’t contain GM seed. The organic standards are process-based, not content-based. As long as an organic farmer sources seed that isn’t GM and makes a reasonable effort to prevent GM materials from being in his products, organic certification will not be affected, even if the product is tested and found to have a GM gene in it. How can this be? Those reasonable efforts work the majority of the time because they are based on sound science.

The regulation isn’t completely clear on how all this works, so we can’t really blame Seeds of Change for assuming that the law says seed can’t contain GMOs. Back in 2004, USDA official Bill Hawks responded to questions about organic certification and GM by Gus Douglas of the National Association of State Departments of Agriculture. The excellent questions were met with excellent responses and really clears up what the policies are. The letter isn’t long, I recommend reading it in full.

This point of GM content is very important in the case we’re discussing here. If an organic beet or beet relative seed farmer (or any organic seed farmer) takes reasonable precautions, such as the appropriate distances as discussed above, it is still possible for cross pollination to occur at some low level. What level is acceptable? The regulation doesn’t say, because content isn’t the issue.

Of course, even though content isn’t the issue for organic certification, some people want to add extra levels of testing and certification beyond organic standards. The Non-GMO Project is a private labeling program that has established its own guidelines for what level of GM content is too high to allow use of their proprietary label. The Non-GMO Project Working Standard sets the following levels as the maximum allowable GM content: 0.1% for seed and other plant propagation materials, 0.5% for ingredients of human food, supplements, or hygiene products, and 0.9% for animal feed and supplements. These levels may or may not be met by the precautions required for organic certification, so farmers looking for a Non-GMO or similar label may need to take additional precautions.

Distance as mitigation strategy

As labels like Non-GMO become more widely used, more farmers will be testing their crops, so there is potential for economic harm due to even low levels of cross pollination. Still, none of this justifies a nationwide ban on GM sugar beet seed production. There are other options. Some would put the onus on the sugar industry and farmers who want to grow GM beet seeds, others put the onus on farmers who want more strict pollen control. Unfortunately, all options will make things difficult to varying degrees for one or the other, which I suppose is why the issue ended up in court instead of peacefully decided.

Judge White may not have known about distance as a mitigation strategy. If he had, perhaps he could have ruled that GM seed production could only take place a certain distance away from the fields of farmers who don’t want even the potential of GM pollen. I’d imagine there could be a legal argument that farmers using existing methods have certain rights when faced with a new method that could potentially affect their livelihoods. Setting such a distance may well effectively ban the growing of GM sugar beet seed in Willamette Valley.

Another option that was available to Judge White was to just prohibit GM beet seeds from being grown in Willamette Valley. There’s already a ban in all of Oregon against growing any canola (GM or not) because of concerns that the canola will pollinate other brassica crops grown for seed, like broccoli, although that concern might not be warranted, according to farmer Dean Freeborn in Farmer pushes for relaxation on canola rules. This could be used as precedent to justify a ban on GM sugar beet seed production in Willamette Valley, or even in all of Oregon.

Since Willamette Valley is apparently the best place to grow beet seed, a true ban or effective ban would likely harm the sugar industry and even farmers who don’t currently supply niche markets if the GM beet seed has to be grown elsewhere. I’m not sure what the law says about preferring one industry over another, but I think an argument can be made here.

Aside from the negative effects on the non-specialty seed market, there is another problem with distance. It requires, in any way I can think of it, that exact locations of fields be made public, at least to other seed farmers. From there I bet it wouldn’t be too hard for destructive activists to start pulling up plants or setting fields on fire. It’s an unfortunate reality that has to be dealt with.

Other mitigation strategies

If not distance, seed producers always have the option to use mobile, temporary tents over the plants while they are receptive to pollen. According to Seeds of Change, tents or field covers have a lot of advantages, including protecting the plants from insects and other pests. Here in Ames, Iowa researchers from USDA APHIS use tents made of fine mesh so the wind and sun can pass through while isolating the plants from undesired pollen. Of course, this would be a hassle for growers that don’t currently need to use them.

Another option is to use varieties that aren’t sexually compatible with your neighbor’s crops. Without going too much into detail, some varieties of beets have genes that only allow pollination with pollen that has a compatible gene. All the pollen in the world could be flying around, but only sexually compatible pollen would successfully fertilize flowers.

Another solution was suggested, briefly, by the (former?) Board President of the Organic Seed Growers and Trade Association Frank Morton in a post titled GMOs at the Door:

Some [mitigation strategies] are so obvious that it seems negligent to have not employed them, like using male-sterile maternal lines to carry the RR-genes (so no RR-pollen is created) in the hybrid seed production process (all GM-sugar beets are F1 hybrids).

This idea isn’t new, and works for many more crops than just beets. As described in The use of cytoplasmic male sterility for seed production (paraphrased from pdf, page 630):

CMS is used to produce hybrids of both table and sugar beets. Sugar beets are almost exclusively hybrids in the US and Europe, with some open-pollinated cultivars grown in regions of the world with lower inputs such as Morocco and Egypt. Approximately 50% of table-beet cultivars are hybrid; OP cultivars are still produced with the advantage of cheaper seed. CMS and its potential to be used to create hybrids was described in 1945.

Since hybrids are already used, it wouldn’t take much more effort to develop male sterile lines that carry the transgene, or to at least breed the transgene into the female side of the hybrid, which is exactly what beet seed breeders have done. According to Luther Markwart, Executive Vice President of the American Sugarbeet Growers Association, about 75% of all Roundup Ready beet seed grown in Willamette Valley has the Roundup Ready gene on the female side, so no pollen produced by these Roundup Ready beet seed production fields contains the Roundup Ready gene (personal communication).

This strategy is a win-win. Farmers of non-GM seed avoid any additional problems with cross pollination, all seed farmers keep using distances for isolation just as they always have, the sugar industry and sugar beet farmers get all the GM sugar beet seed they want… Once this economic cross pollination issue for seed production is resolved, there’s no reason to stop the deregulation of GM sugar beets. The sugar beet growers just need to edge that 75% up to 100%.

Sea spinach by Squirmelia aka Jodi via Flickr.

A history of beets

Sugar beets don’t appear in nature, nor table beets. Ancestors of beets were domesticated from a seashore living species that distributed its seeds in corky fruits that floated in the water, called sea beets or sea spinach today. By ancient times, the plants were bred into something like Swiss chard, widely grown in gardens and considered to be a very healthy addition to the diet. The plants even appeared in ancient literature, such as in this culinary quote from The Acharnians by Aristophanes circa 425BC:

Look at this charming eel, that returns to us after six long years of absence. Salute it, my children; as for myself, I will supply coal to do honour to the stranger. Take it into my house; death itself could not separate me from her, if cooked with beet leaves.

Beets and beet greens remained popular throughout the centuries. In 812, Charlemagne issued a decree that imperial estates include beets in their gardens, referring to a plant similar to table beets in that both leaves and roots can be eaten. In 1538, several varieties of beets were described by Andrea Cesalpino, an Italian botanist, in De Plantus. In 1600, the sweetness of beets was praised by Oliver De Serres, a French agronomist, in Théatre d’agriculture.

Finally, in 1747 Andreas Sigsmund Marggraf reported to the Prussian Academy of Sciences that he had extracted pure sugar from beets! However, the sugar was only about 1.6% of the total beet weight, which seemed too low to bother with. His student, Franz Carl Archard, working with white beets used for animal feed, developed the highly sweet White Silesian beet. Franz went on to open the first sugar beet extraction plant, and the rest is history.

Historical information is paraphrased from Sugar Beet by A. Philip Draycott.

.

*GM stands for genetically modified or genetic modification.

Note: Much of this post originally appeared as No risk assessment for sugar beets? but has been edited to be a broader discussion of sugar beet biology, with additional discussion of seed production. The historical part was just incidental, I found all of this cool information and just had to include it. I hope you’ll think it’s cool too!

Note: A few small changes were made on 14 October 2010 to improve accuracy. Specifically, information on freezing temperatures killing broken beet pieces and that 75% of beet seed production has the Roundup Ready gene in the female side of the hybrid.

Anastasia is a Board Member of Biology Fortified, Inc. and the Co-Executive Editor of the Biofortified Blog. She has a PhD in genetics with a minor in sustainable agriculture from Iowa State University. Her favorite produce is artichokes! Learn more about Anastasia at about.me. Disclaimer: Anastasia's words are her own and views expressed do not necessarily represent the views of her employer(s). She is not paid to blog or conduct any social media activities. Any mention of a specific company or product does not indicate endorsement of that company or product.


Science   , , , ,  


Want to write for The Biofortified Blog? Click here to find out more!

7 comments to Sugar beet biology

  • Anastasia – Nice thorough write-up on sugarbeets.

    A few points:

    In the case of Roundup Ready sugarbeets, Monsanto is the trait provider and we license the trait to the seed providers. Unlike some of our other technologies, we don’t sell or breed sugar beet seed.

    I asked our tech expert about the reason why male sterile lines aren’t used. Here is her answer:
    “Seed companies are working to put the trait in the male-sterile female parent but this takes time. Putting the trait on the female parent increases trait purity – an advantage for the grower and seed company.”

    She also provided this background on bolters:
    “Also, there are no annual weed beets known to be growing in the sugarbeet seed production areas in the US. In Europe, where annual weed beet is common, bolters may possibly arise from the cross of annual weed beet and cultivated beet as described. In the U.S. bolters are most common in California because the growing season for sugarbeets in California is May to May where beets are in the ground during the winter months and if temperatures dip low enough and long enough, the plants can be triggered to flower. In Northern sugarbeet production areas, bolting is less common but is also believed to be triggered by temperature fluctuations as you suggest.

    Side note: I am aware of at least one sugar company who will allow their growers to only plant seed grown in the U.S. U.S. growers do not want to see annual weed beet introduced into U.S. sugarbeet growing areas. The annual weed beet can be a real headache for European sugarbeet growers. There are no herbicides that European beet growers can use to control the weed beet since the herbicides that would kill with wild beet would kill the domesticated beet as well. ”

    Mica Veihman, Monsanto Company

  • Emerson White

    This is a really great writeup and I really appreciate you taking the time to do it.

  • Eric Baumholder

    Anastasia,

    Excellent writeup. Funny thing is, it’s extremely likely that all of this is known to beet growers. Obviously the GM beets can be handled using existing systems to differentiate and handle the beet varieties, conventional or organic — and it’s extremely likely that beet growers are familiar with this as well.

    That leaves us with the question of why GM beets are encountering such hostile opposition — especially when 95 percent of beet farmers want to plant them. [1]

    Popularity with farmers is the reason. Almost overnight, GM beets captured 95 percent of the conventional seed market. Which means, basically, any conventional seed producer not licensing the trait from Monsanto was essentially out of business.

    This also threatens organic beet growers. When the weed control cost differential between organic and GM becomes high enough, organic farmers will be strongly tempted to abandon organic, and many will succumb.

    ———

    1. http://www.agandfoodlaw.com/2010/08/judge-revokes-usdas-approval-of-gm.html

  • Thanks for the excellent write up — fun to read and lots of good points about mitigations that would work. To me the problem is that any working mitigation that entails extra costs for the grower and/or extra costs for inspection/enforcement is unlikely to achieve 100% compliance, and when it comes to cross-contamination you can’t be a little bit pregnant. (The argument that the number of pregnancies is de minimus is a different argument, probably happening in “genie back into the bottle” territory.)

    But really it’s Mica’s comment that got the keys clicking:

    “The annual weed beet can be a real headache for European sugarbeet growers. There are no herbicides that European beet growers can use to control the weed beet since the herbicides that would kill with wild beet would kill the domesticated beet as well. ”

    Sounds like a great chance for Monsanto to sell roundup ready sugar beets in Europe, if they can push hard enough to get in the door. Or maybe there could be a lively trade in smuggled American seed. Either way, here come some more roundup-resistant weeds to join the increasing number already documented.

    short version: Perfectly sound science is far less than perfectly reliable in an environment controlled by individual human beings. Between human nature and human error, the opportunities for perfectly avoidable catastrophe are ever-present (exploding space shuttles, deep water drilling rigs, etc.)

  • Comment sent in via email:

    I’d like to alert [readers to] the extensive literature on transgenic mitigator strategies to retard gene flow developed by Gressel:
    Al-Ahmad et al. Plant Biotech J. 4:23-33, 2006
    Al-Ahmad et al. (2004) Mol. Ecol. 13:697-710.
    (I understand this is not the focus of your post, but it would be nice to mention that gene technology has better solutions to a general problem)

    You can find some details in one of my lectures (see from slide 30 onwards). Some text is in Italian, but I guess it will be no problem to gather the essential concepts.

    Why not stress that any HT trait (be it transgenic or not, like clearfield varieties) has the same problem?

  • [...] you ever wanted to know about Sugar beet biology you can learn from Anastasia Bodnar at [...]

Leave a Reply