A GMO pineapple with a blush

A couple of months ago, I saw an article about a new "pink pineapple" that was being approved by the FDA and was a GMO. I've wanted to learn more about the variety, so in this blog post I'll be exploring the topic.

The pineapple was developed by Del Monte Fresh Produce (not to be confused with Del Monte Foods). The company plans to label it as "extra sweet pink flesh pineapple" and it will be grown in Costa Rica. In addition to pink flesh, it has a few other traits and we'll go through these one-by-one. Much of the information below came from the FDA submission documents.

Pink Flesh

To understand how the pineapple's flesh was made pink, we have to review how beta-carotene is made in plants. Beta-carotene is a pigment that has an orange color and is essential to us for vitamin A synthesis. We usually associate it with carrots. Its synthesized in plants in a multi-step process involving several enzymes. One of the intermediates in this pathway is lycopene, which is also a pigment but is bright red. Watermelon, tomatoes, and grapefruit are all fruits that are rich in lycopene. It is due to the accumulation of this pigment that the pineapple turns pink.

How was this accomplished? To make a pink pineapple, two things need to happen: a lot more lycopene needs to be made and its conversion to beta-carotene needs to be halted. To make more lycopene, the gene for phytoene synthase from a tangerine was added and was over-expressed (meaning that it was regulated in a such a way that the gene produced a lot of the phytoene synthase protein). This means that the crop can produce a lot more lycopene and beta-carotene.

However, the developers of the crop wanted lycopene accumulation without its conversion to beta-carotene. To achieve this, they silenced the lycopene β-cyclase (b-Lyc) and lycopene ε-cyclase (e-Lyc) genes in the pineapple using RNA interference. This is a naturally occurring defense mechanism that scientists have harnessed to silence genes by using the sequence of the gene itself. It triggers a pathway within the cell that chews up the RNA for the targeted gene. In this case, scientists added snippets of the b-Lyc and e-Lyc genes from the pineapple in a specific configuration. Once these snippets were turned on or expressed, it triggered the degradation of the lycopene-cyclase enzymes which are needed to convert lycopene into carotenes. Without this conversion, lycopene accumulates and the pineapple gets its beautiful pink colour.

Pineapple farm in Ghana
Image from Wikimedia Commons

By now you're probably wondering "Ok, pink pineapples are cool. But why?" Good question. The patent on the pineapple, which was published in 2013, claims "Carotenoids may contribute fundamentally to human health and in recent years there has been considerable interest in dietary carotenoids with respect to their potential in alleviating age-related diseases in humans." With a quick google search you can find tons of websites claiming that lycopene can do everything from preventing cancer to preserving bone health. Since lycopene is an antioxidant, there are a lot of websites that sell antioxidant supplements with information about the compound. However, there's little evidence supporting this.  The CDC states,"research studies have shown inconsistencies in the relation between carotenoid intake and protection from cancer." Regarding antioxidants, multiple studies have been conducted using dietary supplements and the NIH summarizes these findings by stating that "antioxidant supplements did not help to prevent disease."

Consequently, regarding this particular trait, I think that we should consider it as part of our diet rich in fruits and vegetables. As part of such a diet, it may help prevent disease. However, it's not a panacea that will cure you of your ailments. It's also a very stunning fruit from a visual perspective. Pineapple is a favorite in our house, so having a pink pineapple would be very nice to have on a fruit platter. And if that helps us eat more fruits, then why not have it as an option in our food supply? But if I'd had my choice in traits, I would have picked a pineapple that's easier to cut and handle :)

Alrighty, moving on to the next trait...

Controlled flowering

The second trait in the pineapple is controlled flowering. According to this paper: "A major limitation that afflicts pineapple growers is the phenomenon of natural flowering, which results in unscheduled fruiting. The percentage of natural induction is highly unpredictable and the incidence may vary from 0% to 100% in any given year (Kuan et al., 2005), which causes serious scheduling problems for growers and, in particular, fresh market growers".

Ethylene is a plant hormone that controls pineapple flowering, among many other things. According, to the same paper cited above, farmers currently use ethylene to "force" flowering which has been practiced for decades. This paper, which compared natural vs forced flowering, highlights that forced flowering "(a) advances flowering, (b) improves uniformity of flowering, (c) makes the harvest moment predictable, and (d) makes harvesting more uniform". The paper found that natural flowering was much more costly, but fruits produced by forced flowering were not as high quality as pineapples produced through natural flowering.

In 2006, a paper was published outlining that by silencing an enzyme involved in the synthesis of ethylene, they could delay natural pineapple flowering. The same idea was carried out in the making of the pink pineapple: an enzyme involved in the biosynthesis of ethylene (1-aminocyclopropane-1-carboxylic acid synthase) was silenced. This allows farmers to use ethylene to force flowering whenever they'd like so that all the pineapples can produce fruit at the same time.

I was left with a lot of questions about this trait, and I can only speculate on the answers. I imagine that the trait could reduce food waste on the farm. I do not know whether the need to apply ethylene increases the carbon footprint, if this is done mechanically. Ethylene ripens some fruits, however, the pineapple does not produce much ethylene to begin with, so I don't know what the silencing of ethylene synthesis does in this regards. 

Regulation

The regulatory documents state that the GM pineapple is substantially equivalent to its control, with the exception of increased lycopene (which is expected) and decreased beta-carotene (which is also expected). The amount of lycopene present matched those of other fruits, such as watermelon. There were a couple of other metrics that were significantly different between the GM and the control, however, these were within the range of natural variation for the crop.

The crop will be labeled as "“Extra Sweet Pink Flesh Pineapple”. According to this article, the regular Del Monte pineapple is labeled as "extra sweet", so the pink one isn't any sweeter than "normal".

Conclusions

So, will I buy this pineapple? If I were to guess, I'd say that the company started working on this pineapple about 10 years ago when the antioxidant craze was at its peak. But 10 years later, that craze has fizzled away. I think the company has a pink pineapple that's visually beautiful, but has no real health benefit. I'd buy this pineapple if it doesn't cost more than usual. I'd like to know whether the controlled flowering trait reduces food waste, because if that's the case it would be worth paying a small premium. Otherwise... meh?

Man, I learned a crap ton about pineapples by writing this post... Let me know if you have any questions below.

Review of "Compositional differences in soybeans on the market: Glyphosate accumulates in Roundup Ready GM soybeans"

Soy bean field with irrigation system.
Wikimedia Commons. Image by Dwight Burdette.

A friend asked me to review the paper entitled "Compositional differences in soybeans on the market" (free available here), so I thought I'd make my comments publicly available. I'm going to read the paper first, provide comments as I go along, and then find reviews online (if any exist).

The paper starts by outlining the principle of substantial equivalence, meaning that GMOs have the same nutritional content than their unmodified counterparts. The authors outline that studies examining substantial equivalence for Round-Up Ready soybean were performed early on, but not when treated with Round-Up. A follow-up study found substantial equivalence when the soy was sprayed with Round-Up, but didn't examine how much glyphosate accumulated in the plant. It is the authors' hypothesis that this is a flaw and their study is designed to examine this question (i.e. is GMO Round-Up Ready soy substantially equivalent to its non-GMO counterpart when sprayed with Round-Up, and how much Round-Up accumulates). They hypothesize that high levels of glyphosate may affect plant metabolism. The authors point out that USDA data highlights that glyphosate use is increasing, so this question is all the more important.

I pause here to note that the authors do not clarify if this is glyphosate use per acre, or total glyphosate use. If I owned a house with 0.5 acre backyard ten years ago and now owned a house with 10 acre yard, and I used weed killers on both properties, then of course the total amount of weed killer I used would show an increase, simply because I have more land. But that may not mean that I've been using more weed killer per acre.

In their study, they examine 31 samples of soybeans grown in the state of Iowa to examine their two questions. They examined 3 different types of soy:
1) Round-Up Ready Soy
2) Conventional Soy possibly sprayed with other pesticides
3) Organic Soy bean which would have no glyphosate residues

The authors then list the variety of soy bean and how they were grown. They collected 3 kilos of soy from 31 different farmers, and it seems very odd to me that they'd select different varieties of soy and different methods of treatment for each category. Why wouldn't they try to find 31 farmers that used the same type of seed? The authors don't specify if the conventional soy is the isogenic variety to the Round-Up Ready soy. This is a key issue given the question they're trying to answer: for example, if I did a study on apples and collected apples from 31 different farmers, you'd want them all to be of the same variety rather then having some Red Delicious, some Fuji, etc.  Otherwise, it's not really an apples to apples comparison. Ha!! Get it???

So, they did a bunch of analyses on the soy beans. They found residues of glyphosate and one of the compounds it breaks down into in all the GM-soy, but not the conventional or organic (oddly enough, their graph doesn't have error bars...). Then, they did statistics on nutritional content and the authors highlight some of the differences (it's also worth nothing that they highlight measurements where the organic category had higher measurements, but not where GM/conventional had higher measurements). The authors then cluster the soy samples based on the results and find that the three different categories tend to group together.

Then the authors go on to reject the null-hypothesis of substantial equivalence. They highlight that their paper identified glyphosate residues in the crops at higher levels than had been hypothesized. They highlight the "toxicity" of Round-Up by citing Seralini (minus 200 points for citing Seralini).

My main comment, as I've mentioned in the past, is that substantial equivalence does not mean identical: "Substantial equivalence is often confused for identicality, however, the Food and Agricultural Organization of the United Nations states that substantial equivalence “is established by a demonstration that the characteristics assessed for the genetically modified organism, or the specific food product derived therefrom, are equivalent to the same characteristics of the conventional comparator. The levels and variation for characteristics in the genetically modified organism must be within the natural range of variation for those characteristics considered in the comparator and be based upon an appropriate analysis of data”" (emphasis has been added)

Also, the levels of glyphosate are provided and the authors point out that these are below the maximum permissible levels. So I'm not sure what their problemo is.

So, I searched for reviews of the paper and found one on GMOanswers, written by someone at Monsanto. They too, made the same criticism as me about the seeds: "When the authors collected the soybean varieties for this study, they separated them into the three groups — organic, conventional and GM. Unfortunately, each group contained different soybean varieties, with no overlap (with one exception) of varieties between the three groups, so each group was already inherently different from the others. Even the authors acknowledge that different varieties can have widely different seed composition. Therefore, concluding that any differences between the groups in this study were due to the way the soybeans were grown (organically or not), or the presence/absence of a glyphosate-tolerance gene in the GM varieties, is simply not possible. The three groups are expected to produce different results because they started out with different genetics."

GMOanswers also notes the fact that they were grown in different farms: "Since the plants in this study were not grown together but rather taken from separate fields across a region spanning a 200 km radius, any real differences between the three groups can’t be separated from the variation caused by location, and no reliable conclusion about their nutritional quality can be made. To put this in context, we are looking at satellite imagery to help farmers make more-informed decisions by increments of meters, not miles." I agree with this point, but having a bunch of crops that were grown in the same area could have provided some information if they were the same type of seed. But since they weren't, the different farms makes matters only worse.

GMOanswers puts the findings within the context of natural variation, which I appreciated: "Finally, when we take into account the effects of genetics and location, we see that the compositional differences the authors observed in this design are not unexpected. Protein levels in soybeans generally average ~40 percent dry weight (dwt) but have been shown to range naturally from 34.1 to 56.8 percent dwt (Wilson, 2004). This natural variability can be due to variety, location or environment, and it means that people are already consuming soybeans with larger variability than the differences in soybeans reported here."

The reviewer also notes that glyphosate residues were within permissible levels and then there's a blurb about the safety assessment of pesticides, yada, yada, yada... He also noted the slant that the authors have in not really discussing what pesticide residues in organic food means.

Amelia Jordan, whom I've interviewed in my series "Better Know a Scientist", did a review on Skepti-forum, and highlighted several other issues: the fact that there's no information on how the organic crops were treated, how the soil was treated in any of the farms, and very importantly, the
fact that 31 samples for a study with this much variability in a number of factors is very, very low.

All in all, I don't think the study is conducted well enough to draw any meaningful conclusion, especially not the one that they're trying to draw which is that organic food is "better" than GM. Their finding about glyphosate is interesting and I think that future studies that examine compositional differences between pesticide/herbicide tolerant crops and controls should do similar analyses, but the measurements in this study have been deemed to be safe.