Kumara are transgenic

By Grant Jacobs 21/04/2015 8

Like some genetically-engineered plants are.

Kumara have a long history in New Zealand, being brought here by early Polynesian settlers and are well-known to Kiwis.[1]

They’re a crop that has been cultivated in South America for about 8,000 years that have been spread to other parts of the world.[1]

Research just published show that they are transgenic plants, plants with genes from other species in them.

While doing other research, the scientists found clues that there might be genes from bacteria that are able to transfer genes to plants in the sweet potatoes (locally, kumara) they were working on.

In the research published they checked this closely and found indeed there were, and that these genes were a feature of cultivated sweet potato. They’re not found in wild species, suggesting that ancient sweet potato growers selected them because the transgenic potatoes made a better crop.

As noted in the ‘significance’ statement for the research paper,

One of the T-DNAs is apparently present in all cultivated sweet potato clones, but not in the crop’s closely related wild relatives, suggesting the T-DNA provided a trait or traits that were selected for during domestication.

This research is a useful reminder that ‘natural’ foods can be transgenic, just as some non-crop species are. (Crop foods aren’t really ‘natural’ in the way wild plants are as we human have cultivated them for so long.)

It’s also a useful reminder that what makes a crop safe is not how it got the genes it has, but the effect of the genes they have however they got them. (Same too for any environmental effects.)

It’s also a reminder that transgenic plants can be a better crop, just as the ancient potato growers must have seen these to be to select them and grow them.

A particular concern of those opposing (some) crop GMOs is that they contain genes from other species, that they’re transgenic.

Humans have been eating sweet potato for a long time. Turns out that they’re transgenic. It’s not that they’re transgenic that might make a plant ‘unsafe’.

It’s important not to focus to tightly how a plant got it’s genes, but look at what that plant is. This is a key recommendation for further discussion of genetically-engineered crops.[2]

Species are not tidy idealised things. Genetic change includes alteration of our genes (mutations)[3] and, occasionally, a bit of mixing with other species (so-called horizontal gene transfer).

Horizontal transfer of genes is found in many species. It’s more often found in bacteria because they have a mechanism that lets them swop genes amongst themselves, but as researchers study the genomes of other species examples are found there too.

Treating a species as genetically sacrosanct makes species out to be ‘whiter than white’.[4] In reality genomes are usually pretty messy when you look closer. Peter Dearden gives a nice example in later parts of How to Avoid DNA: Bdelloid rotifers are genetically very messy, their genomes have all sorts of stuff in them. That might seem an unfair extreme example, but even we have stuff in us—our genomes have copies of ancient viruses imbedded in them and they’re not just ‘junk’ either. We’ve co-opted some those viral genes and those genes are vital to us. (A topic I must get back to, endogenous retroviruses or ERVs are fascinating things, an important part of us primates and a great story. But some other time, sorry.)


The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop

Tina Kyndta, Dora Quispea, Hong Zhaic, Robert Jarretd, Marc Ghislainb, Qingchang Liuc, Godelieve Gheysena, and Jan F. Kreuzeb.

Direct link

DOI link (broken at the time of writing – any complaints about that to PNAS, not me!)


If anyone is interested in me breaking down the paper, telling you more about what they did, let me know. These bacteria have a ‘natural’ gene transfer system, one that has been used to transfer some genes into plants. It’s a story with long roots (no pun intended!), but an interesting story.

This story is one of many examples of where access to embargoes would be good, something I hope to write about some other time.

1. I’m writing including those overseas in mind. Several NZ studies are amongst those exploring the origins of kumara. I hope readers can forgive me for not digging out the latest on this work for this post – my focus is on the transgenic aspect, after all, not the origins of the plant.

2. One I’ll have more to say on, as I’ve yet to complete my coverage of this report.

3. I’m keeping that very simple. There are many ways our genes can change – not just so-called point mutagenesis but also ways new genes can be made  from existing ones. As one example, new genes can form by patching together bits of two (or more) genes in the same genome. (Recombination forming recombinant genes – some of these are classically associated with genetic diseases, including some types of cancer.) Another is duplicating gene, so that a second copy if present, with one copy slowly differing and taking on a new function. (Duplication and divergence.)

4. I’m tempted to suggest that is almost like a creationist argument, but we can leave the popular philosophy aside here.

Other articles in Code for life:

The House of Commons Science and Technology Committee on GMO legislation

Better discussion of GMOs in NZ needed and the Food Matters Aotearoa lineup

Gene editing and GMOs in NZ, part one

GMOs and the plants we eat: neither are “natural”

Food and genetic modification: better informed policy and legislation wanted

Doggie ERVs

8 Responses to “Kumara are transgenic”

  • As an expat Kiwi living in Australia I really miss the NZ kumara. Even though the sweet potatoes sold here that are red on the outside and white on the inside are supposed to be Kumara, they cook, taste and behave nothing like them. They are the same species though. Could this be explained by the transgenic feature you mention? Or is there some other explanation?

    • Sorry I haven’t got back to you sooner. I really wouldn’t know the answer to your question, I’m afraid.

      One thought might be that they are a slightly different variety to the ones in NZ. (The authors of research tested 291 different examples of cultivated sweet potato, for example.)

  • You have some nerve printing this kind of stuff, Grant. Jack Heinemann and his friends call this “worthy of Goebbels”. Sure, you think you are just discussing scientific work. But no–this is you and your ilk: “One thing quickly became clear: Hitler’s propaganda chief Joseph Goebbels would have been proud of the spin put on this paper.”


    How twisted is that? But I have a clearer understanding of what those scientists who support that type of claim are. They are revealing themselves to be purely ideologues. They are misusing the concepts of evolution and plant breeding in really sad ways.

    In fact, humans have been breeding toxic plants because they work for us. http://www.ncbi.nlm.nih.gov/pubmed/9431670. They are cherry-picking around these facts to suit their agendas.

    They are essentially creationists in lab coat drag.

    • “You have some nerve printing this kind of stuff, Grant.” – I do? (Just kidding.)

      I’ll have more coming, in time. Wonder what I’m supposed to make of that, then? More seriously, I need to find time to come back to the UK S&T report; I also would have liked to cover that paper again, looking at the science this time. And a huge long list of other topics…

      re “worthy of Goebbels”: Eh, Godwinning is “supposed” to happened eventually somewhere way down the comments, not in the title before anyone else can!

      I have to admit I’m startled (not in a good way) at JH in being quoted in that piece as writing “Agrobacterium DNA in sweet potatoes isn’t ‘natural transgenics’ […]” I could elaborate, but it’s late at night (almost 1am). More later, maybe, then. Enough for now to say I’d have thought it’s a good example of a transgenic effect occurring in a ‘natural’ setting.

      (‘Transgene’ is defined as including from natural processes; ‘transgenic’ simply means having gene(s) from another species, it’s not limited by how the transgene was transferred.)

      There’s a lot you could unpick in that article, a lot of unhelpful stuff.

    • “Heh. Yeah, sorry, I figured you’d see it in the morning after some coffee. I didn’t mean to put you off before bedtime.”

      No problem. After all, I could have just left it for the morning…

      “Actually, I think the most disturbing thing is them equating journalists and science writers with Nazis.”

      You could hope that for most people it would backfire, with them seeing it as silly and raising a question mark over the rest of what the author has written (or, in the case of someone endorsing, the rest of what they support).

      (That should be ‘happen’, not ‘happened’, in my previous comment. What I get for writing in the wee hours! My excuse anyway… *wink*)

  • Heh. Yeah, sorry, I figured you’d see it in the morning after some coffee. I didn’t mean to put you off before bedtime.

    Actually, I think the most disturbing thing is them equating journalists and science writers with Nazis. This is the second time in a few months this kind of unhinged rhetoric has come along. And I think it’s appalling that scientists like Heinemann support that.