Smart breeding tool

August 2012

There's a new breed of DNA-altered plants looming over the horizon.

These contain no foreign DNA, no man-made DNA, and no viral DNA. In fact they're “all-natural, environmentally safe”, and they have not been subject to any radiation nor mutagenic chemicals (Beetham).

Nor, incidentally, have they been subject to any safety-testing.

The new plants have been created using the latest “smart breeding tool, the 'Rapid Trait Development System' (RTDS).

Older methods involved inflicting widespread random DNA damage in cells on the off-chance that something useful would emerge from the mess. However, the science of biochemistry has now advanced to the point where specific useful protein variations can be identified, and RTDS is used to create these to order.

RTDS uses the cell's own gene repair mechanism to induce precise site-specific single-base changes in its own DNA. By exchanging or deleting one base, or 'letter', in the DNA code, a single building block of a specific protein is changed, and a new version of the protein is created. These are mutations which can, and do, arise in any cell.

The 'gene conversion' of RTDS is achieved by sending into the cell an engineered DNA sequence which matches the gene to be converted exactly except for the single base to be changed. If the novel DNA finds its gene, it seems to naturally attach itself there, and the cell's DNA repair mechanisms are fooled into altering the cell's own gene to match the interloper. After this, it seems the engineered template is broken down just like any other spent components in the cell.

Cibus, the company which is commercialising RTDS is quick to mention that its crops “can go to market directly and will not be subject to any GMO regulation. RTDS has already won USDA (US Department of Agriculture) approval as a safe, natural technology that poses no threat to consumers or to the environment. With RTDS crops, American farmers will be able to enter the global markets that reject GMO crops and compete in those markets with a commercially viable alternative” (Beetham).

RTDS is also fast: six years compared with twelve for the closest conventional version of breeding.

That's the good news.

But, before you let out too big a sigh of relief at the news that a much less unnatural and less damaging competitor to genetic transformation is in the offing, be aware of the following:

1. The first generation of converted crops are (you probably guessed it) herbicide-tolerant. Currently being brought to market are:

• oilseed rape resistant to DuPont's 'Harmony Extra' weedkiller (associated with weight loss, liver enlargement, testicular atrophy and biochemical disturbances)
• potatoes resistant to Valent's Chateau (toxic to aquatic animals)
• potatoes resistant to Syngenta's 'Reflex' (a liver carcinogen, associated with liver and reproductive effects).

These can only herald a new wave of human and environmental distress due to the resulting overuse and accumulation of chemicals just like we are now witnessing with glyphosate-friendly GM monocultures.

2. RTDS has been patented: the control of food and feed crops from gene-converted plants is still very firmly in the hands of the biotech industry.

3. Judging from the literature cited by Cibus, the favoured method for sending the DNA template into the cell is by micro-projectile bombardemnt. In this methods, the engineered DNA is coated onto metal particles which are fired through the cells. It causes extensive co-lateral damage which has to be bred out of the crop by repeatedly crossing it with non-gene-altered plants. Micro-projectile bombardment has long been a favoured method for creating GM crops, and is a major cause for concern because of its disruption to the wider genome. Experiments on GM crops genetically transformed using a bacterial vector, which is known to cause less disruption, found that even after several generations, stress genes in the GM plants still had altered expression; microprojectile damaged plants can only be even more adversely affected (see STRESSED PLANTS, STRESSED PEOPLE - GMFS News Archive, June 2010)

4. While the occurence of a single-base mutation isn't unnatural, the artificial template sent in to achieve it certainly is. These short stretches of DNA are often linked (very unnaturally) to stretches of the related molecule, RNA, which in some way helps anchor it. The cell's ability to dispose of the template might not be as efficient as it appears: altered genetic and epigenetic activity, activation of endogenous viruses, or immune-system reactions in consumers can't be dismissed.

5. The success rate of gene-conversion described in the literature is highly variable and more-often-than-not low. This raises all the same questions as genetic transformation, such as:

• are the 'successful' converts unhealthy plants which succumb to the 'invasion'?
• will the few successful gene-converted plants become the next monocultures with a very limited gene-pool and all the same weaknesses and agri-chemical needs as GMOs?

OUR COMMENT

Note that RDTS still has all the same patent power problems and the same test-free assumptions of safety as GM crops have always had.

The products of any 'smart breeding tool', be it mutagenesis, genetic transformation, or gene conversion, are only safe if they have been tested and have proved safe. Keep saying it.

SOURCES:

• What is RTDS^TM http://cibus.com/rtds.php
• Cibus Press Releases, British Virgin Islands, 25.04.12
• John O'Connell, Firm developing non-GMO herbicide-resistant varieties, Capital Press 5.07.12
• Peter R. Beetham, et al., 1999, A tool for functional plant genomics: chimeric RNA/DNA oligonucleaotides cause in vivo gene-specific mutations, Proceedings of the National Academies of Science, USA, 96 July
• Chongmei Dong, et al., 2006, Oligonucleotide-directed gene repair in wheat using a transient plasmid gene repair assay system, Plant Cell Reproduction 25
• A. Okuzaki and K. Toriyama, 2004, Chimeric RNA/DNA oligonucleotide-directed gene targeting in rice, Plant Cell Reproduction 22
• Andrij Kochevenko and Lothar Willmitzer, 2003, Chimeric RNA/DNA Oligonucleotide-Based Site-Specific Modification of the Tobacco Acetolactate Syntase Gene, Plant Physiology 132 May
• Tong Zhu et al., 2000, Engineering herbicide-resistant maize using chimeric RNA/DNA oligonucleotides, Nature Biotechnology 18 May
• Tong Zhy et al., 1999, Targeted manipulation of maize genes in vivo using chimeric RNA/DNA oligonucleotides, Proceeding of the National Academies of Science USA 96 July
• Caitlin Smith, GMO Technology: A Research Tool Becomes An Ethical Debate, Biocompare Buyers Guide Editorial Article, 26.10.09
• Manufacturer's safety data sheet for Harmony Extra, Chateau, Reflex herbicides.