Background: This series contains brief reports on each of the "600 studies" held on the GENERA database, published at Bifortified.org, in the order in which they were listed on 18 Sept 2013. The general purpose is to counter the extraordinary claims that the entries on this list demonstrate the human food safety of GM crops. See the Introduction to this series [link].
Great Big List of Studies: Entry 17 – Asanuma 2011 [abstract link]
The full text pdf is behind a paywall. When it is received this article will be updated if necessary. See UPDATE below.
This is not a study answering any human health and food safety questions about GM crops. However it is a study in an interesting field that I haven't explored before - allelopathy. According to Wikipedia [link]
- "Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms."
Although recognised over millennia it is apparently a relatively new scientific discipline. It seems to offer promise in the development of new organic herbicides, provides explanation for the anecdotal and heritage of companion planting and offers potential for development of new positive symbiotic relationships in food production – some weeds may greatly benefit food plants. [link]
From the two pages of the study that were made available by the journal, the authors noted that Japan, as a result of its obligations to the Cartegena Protocol on Biosafety [link], consequent legislation, and alone amongst all other countries, "requires assessment of the potential production of harmful substances or allelochemicals that directly affect other plants or soil microflora" of GM organisms. They have a requirement to investigate
(1) Secretions from transgenic plant roots that affect other plants
(2) Substances in the plant body that affect other plants after the transgenic plant dies, and
(3) Secretions from roots that affect soil microorganisms
In this paper the authors stated an objective of establishing an evaluation method to be used for environmental safety assessment. Thus this may have been the first attempt. The authors researched the allelochemical characteristics of two Bayer GM commercial canola (oilseed rape) crop lines ("T45" and Topas19/2"), two GM hybrid lines and their three GM parent lines (MS1 and RF1 and RF2), and non-GM isolines. I feel uneasy about this hybrid breeding system used by Bayer (Aventis), using the barstar/barnase male sterility and restoration system, explained at this link by Dr Mae-Wan Ho and Dr Joe Cummins of the Institute of Science In Society [link].
The authors reported a finding of "no potential production of allelochemicals [..] compared with the conventional canola lines". Without access to the full text I can't say what their investigation involved and whether they searched beyond the known allelochemicals of canola, such as glucosinolates, to novel unintended products.
May be updated.
The full text doesn’t note any chemical identification. Three tests were applied:
Succeeding crop test: The test and control canola plants were grown in potted sterile soil. After harvest the plants were carefully
removed from the soil and other seed was trialled in the soil.
Plough-in test: Ground, dried residues of the harvested test and control plants were combined with fresh soil and other seed was trialled in this combination.
Soil microflora test: Microflora in soils from the test and control plants was quantified.
The study reported some significant differences between the GM hybrid lines and their non-GM parent on the soil microflora variables.
I think there are some issues to consider. The GM test and control plants were canola, going under the botanical species name “Brassica napus”. Although allelopathic effects can be very plant-specific they only used one type of seed to test the potential for allelopathy, being radish, or “Raphanus sativus”. Their reason for using radish was “because seeds are easy to obtain and are often used in assays for allelopathy”. Both radish and canola are brassicas, they produce glucosinolates with established allelochemical effects. The wild radish “Raphanus raphanistrum” and canola are so similar that they can hybridise in natural conditions.
This is a new field to me and I didn’t want to explore all avenues for the sake of this brief report, but there is a report of canola having allelopathic effects on wild radish (Mondani 2009). There is also a review on the use of canola in weed management that addressed its allelopathic features in some detail (Haramoto 2004). Information provided by the review highlights many interactions that would have the potential to influence the findings in this study yet weren’t controlled for, including the breakdown half-lives of biologically active products of glucosinolates, and their effect on soil bacteria.
When Monsanto applied for approval of its Roundup Ready Canola GT73 it reported that the line produced a higher level of glucosinolates than its parent ‘Westar’. Monsanto provided an expert report on the heterozygosity of Westar. I understood the references to mean that perhaps Monsanto had the misfortune of transforming a high glucosinolate individual in the line rather than it being a consequence of the plant transformation and generation process. There is a possibility that not only the unknown consequences of the GM transformation process but the particular individual plants used in the trials could produce differing allelopathic outcomes and should be given consideration in this particular case.
I think the questions asked by this study merited an examination of the glucosinolate levels in the test and control plants. If there had been differences protocols could have been put in place to investigate any interactions and/or control for them if possible, lest they mask the potential to identify novel allelochemical affects.
It would have been interesting to compare the germination and growth attributes of the radish seeds in new soil as a control for these
known allelopathic effects.
It would have been good to see an analysis of the classes of bacteria that had established in the (previously sterile?) soil, rather than
simply a count.
Canola is often used in cropping rotations with wheat - studies report little allelopathic effects on wheat. If wheat seed had been used in
the test instead of or in addition to radish it could have produced a finding with more agricultural significance.
(Mondani et al 2009): The Allelopathic Potential of Canola (Brassica napus L.) for Wild Radish (Raphanus raphanistrum L.) Management; Mondani F,Golzardi F, Ahmadvand G, Sarabi V, Sarvar Amini SH ; Weed Research Journal; Summer 2009; 1(2);13-24.
Unusual link but it works (full stop included):
(Haramoto et al 2004): Brassica cover cropping for weed management: A review; Erin R. Haramoto and Eric R. Gallandt; Renewable
Agriculture and Food Systems Volume 19, Issue 04, December 2004, pp 187-198; http://journals.cambridge.org/action/displayAbstract;jsessionid=5AE79F750F4C5A074FA85D67DD92E8CC.journals?fromPage=online&aid=686848 fulltext pdf is available through google scholar