|Rice research. Photo by IRRI images on Flickr|
Cutting-edge science is revealing layer upon layer of adaptive mechanisms within the cell which can be passed on to future generations, but which don't alter the genetic code.
Research on lower animals is showing how the expression of DNA (genes and non-gene sequences) triggers a cascade of events and feed-back loops in the cell: the cascade not only alters the RNA messenger molecules and proteins, but comes back full-circle to re-formulate the DNA's own structure (but not its base sequence) and the chromosomes which carry it.
At all these stages, permanent changes can be made resulting in permanent and heritable alterations to the whole DNA-based machinery. For example, in one experiment, the deletion of key genes in a species of worm which led to increased life-span, also led to changes which continued to impart longevity to future generations even after the missing genes had been bred back into the offspring.
Adding an even bigger layer of complexity to this picture is the influence of environmental factors: diet, early development and stress all alter DNA expression, and their effects can be permanent and heritable.
Most of the information emerging is from animal studies. However, given the ubiquitous nature of DNA and the fundamental cell structure common to all higher organisms, parallel forces are bound to be at work in plants. An artificial 'diet' of agri-chemicals and a life-long assault from toxic sprays and monoculture-banqueting pests, which is the lot of the average crop-plant, will certainly cause heritable, non-genetic changes in their cells. Add to these the inevitable permanent effects from the weed-killer accumulating in herbicide-tolerant GM plants and from the insecticidal 'Bt' protein generated in insect-resistant plants (see WHAT GLYPHOSATE DOES TO PLANTS - GMFS News Archive, December 2010, Bt IS TOXIC TO PLANTS - July 2011)
Plants developed through modern 'breeding' technologies have all been subject to DNA-damaging treatments: chemicals or radiation (mutagenesis), bombardment with DNA-coated metal particles (genetic transformation and Rapid Trait Development Systems*), infection with pathogenic bacteria (genetic transformation), and tissue culture in which the cells are grown in growth-promoting media unconnected with any whole-plant or natural environment. Changes in DNA, RNA and proteins during these procedures are well known to occur. It is accepted, for example, that unexpected physical and physiological characteristics are an inevitable outcome. One study showed clearly that genes associated with stress remained changed for several generations after radiation and Agrobacterium-mediated genetic transformation (see STRESSED PLANTS, STRESSED PEOPLE - GMFS News Archive, June 2010). The inescapable conclusion is that our food is chronically stressed, and GM food particularly so.
Modern, damaging, breeding technologies have proceeded for years on the assumption that by repeatedly 'back-crossing' the damaged individual with undamaged relatives, the unwanted changes will be diluted and will finally disappear. There's also been a reliance on the assumption that, during sexual reproduction, DNA alterations arising during the parents' lives are re-programmed back to a base-line state.
It's now clear that back-crossing might never remove all the damage from the human manipulations. It's also obvious that only certain aspects of DNA function are reset during sexual reproduction of the plants.
Whereas mutagenesis and Rapid Trait Development System* cause small changes in existing genes which might eventually repair themselves if the plants are reared in healthy conditions, the wholesale import or removal of DNA in genetic transformation imposes a permanent stress which all the scientific evidence suggests can't be healed.
There's no doubt that, if we want to be healthy we have to eat healthy food, and if we want healthy food we have to stop wrecking its DNA.
*Check out SMART BREEDING TOOL - August 2012
- Dr. Eva Sirinathsinghji, Non-genetic Inheritance of Longevity, Institute of Science in Society Report 8.05.12
- Dr. Mae-Wan Ho, Caring Mothers Reduce Response to Stress for Life, Science in Society Report, 7.09.04