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Genetic Engineering

Scientific Paper - December 2006
Transformation-induced Mutations in Transgenic Plants

Analysis and Biosafety Implications

Plant transformation has become an essential tool for plant molecular biologists and, almost simultaneously, transgenic plants have become a major focus of many plant breeding programs. The first transgenic cultivar arrived on the market approximately 15 years ago, and some countries have since commercially approved or deregulated (e.g. the United States) various commodity crops with the result that certain transgenic crop plants, such as herbicide resistant canola and soya and pest resistant maize, are currently grown on millions of acres.

Scientific Paper - January 2006
The Mutational Consequences of Plant Transformation

Plant transformation is a genetic engineering tool for introducing transgenes into plant genomes. It is now being used for the breeding of commercial crops. A central feature of transformation is insertion of the transgene into plant chromosomal DNA. Transgene insertion is infrequently, if ever, a precise event. Mutations found at transgene insertion sites include deletions and rearrangements of host chromosomal DNA and introduction of superfluous DNA. Insertion sites introduced using Agrobacterium tumefaciens tend to have simpler structures but can be associated with extensive chromosomal rearrangements, while those of particle bombardment appear invariably to be associated with deletion and extensive scrambling of inserted and chromosomal DNA. Ancillary procedures associated with plant transformation, including tissue culture and infection with A. tumefaciens, can also introduce mutations. These genome-wide mutations can number from hundreds to many thousands per diploid genome. Despite the fact that confidence in the safety and dependability of crop species rests significantly on their genetic integrity, the frequency of transformation-induced mutations and their importance as potential biosafety hazards are poorly understood.

Report - October 2004
Genome Scrambling – Myth or Reality?

Transformation-Induced Mutations in Transgenic Crop Plants

Internationally, safety regulations of transgenic (genetically modified or GM) crop plants focus primarily on the potential hazards of specific transgenes and their products (e.g. allergenicity of the B. thuringiensis cry3A protein). This emphasis on the transgene and its product is a feature of the case-by-case approach to risk assessment. The case-by-case approach effectively assumes that plant transformation methods (the techniques used to introduce recombinant DNA into a plant) carry no inherent risk. Nevertheless, current crop plant transformation methods typically require tissue culture (i.e. regeneration of an intact plant from a single cell that has been treated with hormones and antibiotics and forced to undergo abnormal developmental changes) and either infection with a pathogenic organism (A. tumefaciens) or bombardment with tungsten particles. It would therefore not be surprising if plant transformation resulted in significant genetic consequences which were unrelated to the nature of the specific transgene. Indeed, both tissue culture and transgene insertion have been used as mutagenic agents (Jain 2001, Krysan et al. 1999).

Technical Report - February 2004
GM-Gene Flow (b)

Horizontal gene transfer of viral inserts from GM plants to viruses

It is our conclusion that too little is known at present about the evolution, ecology, biochemistry and pathogenicity of viruses to allay the concerns about horizontal gene transfer (HGT) from plants containing viral transgenes.

Briefing - December 2002
The CaMV 35S Promoter

Government and Corporate Scientific Incompetence: Failure to assess the safety of GM crops

The CaMV 35S promoter is being used in almost all GM crops currently grown or tested, especially GM maize. It is the promoter of choice for plant genetic engineering, as it is a strong and constitutive promoter. Failure to recognise or to take into account its capacity to be universally active in almost any organism is irresponsible and careless and shows a serious lack of scientific rigour and commitment to safety.
Any safety assessment can be expected to be flawed that does not resort to actual laboratory test of the capacity of bacteria and fungi to utilise the particular genes and their promoters.

Introduction

Techniques and effects of genetic engineering

Genetic engineering (GE) changes the genetic make up of an organism by adding, removing, inhibiting, exchanging or relocating genes or DNA sequences. The DNA sequence used to produce a genetically modified organism (GMO) may be sourced from the same species, a completely unrelated species or may be assembled from synthetic DNA.

Numerous studies have focused on the intended traits and functions associated with particular gene sequences, also covering the performance of GMOs with regards to the introduced trait, for example herbicide tolerant maize. Econexus focuses on the unintended, unpredictable or unexpected changes that take place and has examined the technologies used in GE and the unintended effects these have on the genome.

In a detailed report about Genome Scrambling, EcoNexus examined the numerous mutations in GM crop plants caused by the transformation processes themselves. The report analysed the scientific literature on the two most frequently used plant transformation methods (Agrobacterium-mediated transformation and ‘particle bombardment’ or ‘gene gun’). The results are also published in BGER, - Analysis and biosafety implications– and are also summarised in the Journal of Biomedicine and Biotechnology - The Mutational Consequences of Plant Transformation.

The transgenic inserts engineered into plants come with intrinsic risks. Just like normal genes, transgenic inserts need to be activated. For this they require a promoter sequence. In most GM plants this sequence has for many years been the same strong CaMV 35S promoter (derived from the cauliflower mosaic virus). It was introduced without an appropriate risk assessment. A number of pure assumptions were also made about how it would behave. However, the notion that the viral CaMV 35S promoter would only be active in plant cells, but not in bacteria, fungi, mammalian or human cells has by now been proven wrong, but the potential consequences are still not sufficiently assessed.

EcoNexus also studied horizontal gene transfer, such as transfer of the transgenes from the plant to other organisms, for example the horizontal gene transfer of viral inserts from GM plants to viruses.

January 2011