Dear colleagues,
I agree with Hiroshi Yoshikura that “the objectives of monitoring and parameters to be monitored should be first identified through the process of risk assessment.”
With this I mean, that the need for and the ability of performing post release monitoring of both the spread of the LMO, its genes and/or traits as well as of its impacts on the environment, biodiversity or human health needs to be integral part of the risk assessment procedure.
The need for the ability to (1) monitor gene escape and the ability to (2) understand, anticipate and guard against long-term negative effects is evident for example in the case of genetically engineered trees.
(1) In order to be able to monitor gene escape, the extent, routes and means of gene flow must be understood. Whilst more, [though maybe not sufficient,] is known for some annual agricultural annual crop plants, the understanding of gene flow from trees is still very limited and does not allow predictions. The question thus arises of how to perform post release monitoring in cases where both time and special requirements are enormous and little detail of when and where to look is available.
In the case of trees it is evident, that propagative plant material will travel and cross national borders. Thus risk assessment and post release monitoring, risk decisions and risk management need to be carried out in a “beyond national boundaries” process, also in the understanding that long-term effects will not be limited to the release site but potentially manifest across borders.
To recall (see also Steinbrecher & Lorch 2008),
most trees and their genes will spread not only through sexual reproduction (pollen and seed) but also by asexual (vegetative) reproduction, such as roots, shoots, twigs that can set root. These propagules can be dispersed by wind, water, pollinators (insects), animals and humans. To assess possible contamination a wide range of factors need to be taken into account, ranging from normal weather conditions in which pollen and seeds already travel long distances (depending on direction, speed and uplift of the wind), to extreme conditions like storms and floodings in which broken branches are swept along and can set root somewhere else. Animals and humans also attribute to the spread of seeds when they either take fruits, nuts, cones along (such as squirrels), or even when they consume fruits, thereby passing the seeds through their body and depositing them somewhere else.
“In any event, as we deploy vast plantations of transgene-bearing forest trees, we can expect the transgenes to escape into the wild population and to persist there for a long time. In conclusion, we can probably take the view that ‘propagules will travel’.” (Smouse et al. 2007)
The issue is not only contamination, but also invasiveness, especially where pioneer species such as GE poplar or birch are modified such that they gain an advantage over wild trees of the same or of other species. An example of a transgenic trait that can confer an advantage is cold tolerance (developed in eucalyptus), allowing trees to be cultivated in colder regions and thereby potentially enabling them to get established in ecosystems where this tree species previously did not grow or maybe where trees in general did not grow. Other examples are trees producing insecticidal protein (e.g. Bt toxins) and therefore possibly (more) resistant to specific pest insects, and trees with faster growth or bigger leaves who can out-compete other tree seedlings competing for light and space in forest settings.
“Transgenes which provide a large fitness advantage, perhaps by protecting from herbivores or disease, may enhance invasiveness.” “Transgenes which enhance fitness are most likely to increase invasiveness and frequency of recipient species outside cropping system.” (James 1998, see also Andow & Zwahlen 2006).
Pollen
Forest trees are largely wind-pollinated, with pollen highly adapted to be transported by wind, often over large distances. Whilst for white spruce (Picea glauca), the vast majority of pollen was found to cross-pollinate within a range of 250-3000m (O’Connell et al. 2007), travel distances of 1000 km have been documented for spruce pollen (Gregory 1973) and 100s of kilometres for birch pollen. For risk assessment purposes, pollen dispersal rates cannot be taken into account for individual years only, but have to be looked at cumulatively over time, e.g. a long distance dispersal (LDD) rate of 1% would amount to 9.6% over the period of a decade (Smouse et al. 2007).
Seed dispersal
Seed dispersal needs to be taken into consideration when looking at gene flow. For trees we find, that they have developed a multitude of strategies to have their seeds dispersed either by abiotic means, such as wind or water, or by biotic means, mostly animals including humans.
Trees, especially forest trees, produce large quantities of seeds often well adapted to wind dispersal (abiotic seed dispersal). For examples as well as for vegetative propagules dispersal see attached paper Steinbrecher & Lorch (2008).
(2) In order to understand, anticipate and guard against long-term negative effects, it appears crucial to avoid assumption based prognosis. For this purpose it is crucial to have detailed and long term experience with the conventional parental plant of the LMO in question, thus any behavioural changes can be detected instantly and acted upon if necessary. Furthermore detailed and long-term experience is also required for the environmental and biodiversity settings and interactions in which the plant is commercially grown and/or naturally occurs. Whilst this strikes as common sense and might appear an easy task in particular cases, it is far from easy – if not currently impossible - in other cases, such as transgenic trees in the context of global forest biodiversity and global forest ecosystems.
In this context it is also important to remember, that a trait-confined risk assessment is insufficient for transgenic trees, where The ability to respond to biotic and abiotic stresses may be compromised by the performance of the transgene, its product(s) and the processes of genetic engineering. Vice versa, such stresses may also interfere with the performance of the transgene, e.g. induce gene silencing (Broer 1996, Meza 2001)
Testing for any impacts on tree performance (internally as well as externally) will (or would) require a long time and additionally necessitate exposure to all different stresses across different developmental stages.
To summarise, the ability to carry out reliable post release monitoring, including assessing gene flow, and the ability to investigate and safeguard against long-term negative effects need to be assessed in the initial risk assessment itself. If data are insufficient or results are unsatisfactory, further research is required, especially to have all necessary base line data. However, to complicate matters further, field research must only be undertaken in a way that does not pose a risk to the environment in itself.
Literature cited:
Andow DA & Zwahlen C (2006). Assessing environmental risk of transgenic plants. Ecology Letter 9(2): 196-214.
Broer I (1996). Stress inactivation of foreign genes in transgenic plants. Field Crops Research 45: 19-25
Gregory PH (1973). The microbiology of the Atmosphere. 2nd edition. Leonard Hill, Aylesbury, UK. (In OECD consensus document vol 2, p.208).
James R, DiFazio SP, Brunner AM & Strauss SH (1998). Environmental effects of genetically engineered woody biomass crops. Biomass and Bioenergy 4(4): 403-414.
Meza TJ, Kamfjord D, Hakelien AM, Evans I, Godager LH, Mandal A, Jakobsen KS, and Aalen RB (2001). The frequency of silencing in Arabidopsis thaliana varies highly between progeny of siblings and can be influenced by environmental factors. Transgenic Research 10: 53-67
O'Connell LM, Mosseler A, and Rajora OP (2007). Extensive Long-Distance Pollen Dispersal in a Fragmented Landscape Maintains Genetic Diversity in White Spruce. Journal of Heredity 98(7): 640-645 (doi:10.1093/jhered/esm089)
OECD (2006). Safety assessment of transgenic organisms: Consensus documents on the biology of trees. OECD Consensus Documents Volume 2 (1996-2006), Chapter 4.
Smouse PE, Robledo-Arnuncio JJ & Gonzáles-Martines SC (2007). Implications of natural propagule flow for containment of genetically modified forest trees. Tree Genetics & Genomics 3(2): 141-152.
Literature attached:
Steinbrecher & Lorch: Genetically Engineered Trees and Risk Assessment – An overview of risk assessment and risk management issues. Federation of German Scientists, May 2008. Available at
http://www.econexus.info/pdf/GE-Tree_FGS_2008.pdf or
http://www.ifrik.org/en/gm-trees-risk-assessment