In this week’s edition of PNAS, crop scientists at Texas A&M University report the engineering of cotton strains with edible seeds. Now, when I think of cotton, I generally think of clothes, especially the kind that really seem to like getting wrinkled in the drier. Not counting the unrelated–but still delicious–exception of cotton candy, food generally doesn’t come to mind. However, the new PNAS paper from the lab of Keerti Rathore may mean that it’s time to think outside of the (clothes) box when it comes to cotton, especially in addressing world hunger.
According to the paper, for every 1 kg of fiber produced by cotton, the same plants grow about 1.65 kg in seeds. These seeds offer a potentially useful source of protein that could (theoretically) “provide the total protein requirements of half a billion people for 1 year.” So, what’s the catch? The seeds are toxic–containing (as with the rest of the plant) large amounts of the toxin gossypol–making them completely inedible. Previous attempts to make edible cotton have failed because gossypol-free cotton turns out to be particularly susceptible to insects and disease. Rathore and colleagues, though, were able to use RNA interference (RNAi) to specifically knock out gossypol production in just the seeds, creating still robust cotton strains that produce seeds without unsafe levels of gossypol.
Coming from a molecular/cell biology background, I tend to think of RNAi (a technique, by the way, which served as the basis for this year’s Nobel Prize in Physiology or Medicine) as something used to transiently knock down a gene product to study its function. However, the authors of this study inserted a piece of DNA that would code for the interfering RNA into the cotton genome–making the trait heritable–and placed it under the control of a promoter that would only express this gene in the seeds of the plant.
Granted, people in the developing world or elsewhere probably won’t be making cotton seeds a part of their daily diet anytime soon. Still, this is a nice example of the largely unrealized potential of crop biotechnology to address the world’s nutritional problems in novel ways. Interestingly, though, as Rathore pointed out when I interviewed him for an article in Texas A&M University’s Battalion newspaper back in 2005 and as the numbers in a recent report from the International Service for the Acquisition of Agri-Biotech Applications (ISAAA) bears out, the vast majority of transgenic crops currently grown feature herbicide resistance (71%), the ability to produce their own insecticides (18%), or both (11%). More creative uses of crop biotechnology have yet to make a dent.
I also mentioned my interview with Rathore previously on my old blog when discussing my one big hangup with transgenic crops: their role in further consolidating agricultural production and profits into the hands of just a few major corporations:
[Rathore] noted that within the next few decades the patents on the first round of transgenic crops will expire. When that happens, a major barrier to wider ownership and development of transgenic crops will be removed. This would allow university scientists who had developed their own crops to provide them directly to small farmers, without strings attached.
This answered the burning question on my mind: why should universities fund (using taxpayer dollars) scientists working in a field that at this point only benefits major agricultural corporations? Apparently it is a long-term strategy. Academics may also be more likely to develop more innovative, humanitarian, or medically or environmentally-driven strains of transgenic crops, since they are not as concerned with sticking to what is currently profitable.
Although it may seem counterintuitive, the solution, it seems, is to invest even more funding in plant biotechnology research at universities, not less. Instead of assisting the large corporations, this could even undermine them in a sense, and in this case that is probably in the best interest of the general population. Universities, not so motivated by profits, are much more likely to put these crops “in the hands of” small farmers and give them a respectable degree of independence and control as well.
Based on Rathore’s previous comments, then, I’d say that this new technology and its potential to benefit society are in good hands. It should certainly be interesting to see what he and his colleagues do with it.
Ganesan Sunilkumar, LeAnne M. Campbell, Lorraine Puckhaber, Robert D. Stipanovic, and Keerti S. Rathore, Engineering cottonseed for use in human nutrition by tissue-specific reduction of toxic gossypol, PNAS 103 (2006), 18054-9.