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Asked by Robert to Nikolai on 7 Jan 2020.
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Nikolai Adamski answered on 7 Jan 2020: last edited 7 Jan 2020 5:32 pm
Hi Robert,
The wheat TILLING population(s) are not considered GM by any regulatory authorities.
TILLING populations are made by mutating a stock of seed (this could be of any plant). Most often nowadays a chemical mutagen is used. In the example of the wheat population, a substance called ethyl methanesulfonate (EMS) was used. EMS results in G->A mutations by deaminating Adenine (A) to Guanine (G). This happens randomly within the genome of a single plant, with a single individual carrying several tens of thousands mutations. Each species has different levels of mutations it can tolerate, so the exact number varies. Wheat is quite resistant due to its genetic redundancy (it is a polyploid, i.e. it contains several copies of each and every gene).
Geneticists use populations like this to study the function of genes by “knocking them out”, i.e. causing the genes to no longer function. The loss of gene activity will then possibly result in a measurable phenotype, e.g. broader leaves, deeper roots, different flower colour.
Many of the crops we grow and take for granted today have been modified in a similar fashion, using either chemical mutagens or radiation (gamma, x-rays, neutrons, etc). A good example of this are Broccoli, Cauliflower, Kale, Cabbages, and Brussels Sprouts, all of which belong to the same species (Brassica olearacea); they look (and taste) different because of different mutations that were induced to alter different parts of the plant. There is a illustration of this here:
http://microfarmgardens.com/blog/2014/8/27/brassica-oleracea-the-cabbage-family.htmlIn general, mutation breeding (that is the term for this kind of practice) is not differently regulated to “normal” breeding and it is used for crops grown under both standard and organic farm practices.
I hope this answered your question. Let me know if you need to know more about this fascinating subject.
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