Messing With Gene Expression in Corn
A study is about to be published by scientists at the independent RIKILT – Institute for Food Safety in Wageningen, Netherlands. It will appear in the next edition of Plant Biotechnology Journal – a prestigious, peer reviewed publication. The study followed gene expression, protein levels and other metabolites associated with 60,000 genes in corn. They compared different corn hybrids, GMO and non-GMO lines, and different growing locations. Guess what they found?
“The researchers concluded that the environmental influences led to a far greater variety in gene expression, proteins and metabolites than did the different genotypes.”
So it seems like “Mother Nature” is messing with gene expression more than any corn breeder or biotechnologist.
This work represents “independent testing” by a group that is skeptical about GMOs. One of the “precautionary principle – driven” arguments against GMOs in Europe has been the possiblity that GMO crops will have unanticipated changes in gene expression. This study suggests that if Europeans want to prevent any unexpected changes in genetic expression in corn, what they really need to do is to ban weather and soil differences. It looks like there is more variation than they can ever sort through for a “complete safety assessment.”
This result is actually not surprising. There are many well known ways that the environment changes the way a plant grows, and many of those changes have to involve changes in gene expression. The quality of bread wheat is highly related to weather – so much so that bakers have to shift where they buy their wheat year to year to get the quality then need. Corn growing under heat and drought stress becomes much less able to protect itself from infection by Aspergillus flavus which can lead to contamination with the deadly mycotoxin, aflatoxin. Corn seedlings “see” whether there are weeds growing near them very early in the season (based on near infrared reflectivity – they don’t respond to the wavelengths reflected from other corn plants) and they shift gene expression to grow taller, faster and even orient their leaves differently. Unfortunately they short change root growth in that case and it can lead to more drought susceptibility later.
You Want to Talk About Changes in Gene Expression!
Plants are pretty remarkable. They started out complex, and we have modified them a great deal by selection and breeding over millennia. What we now know as maize or corn was a wild plant called teosinte in the mountains of Mexico 12,000 or so years ago (see the little heads of teosinte next to the knife in the picture above). People selected it and progressively modified it with no real knowledge of what they were doing and turned it into what we would call “Indian Corn.” More intentional breeding took that and turned it into something vastly more productive and adapted to different environments all over the globe. We are just now beginning to breed corn with the tools to know how the changes happen (genomics, proteomics, marker assisted breeding). Lately, we’ve made a few very small changes in genes with transgenics. Any potential “changes in gene expression” from that look pretty insignificant against the background of the massive changes we’ve already made and the influence of the environment.
Cornfield Image from Lars Plougmann’s Photostream
Maize and teosinte image photo by Hugh Iltis (Creative Commons)