|
Health
Scientific Committees
Scientific Committee on Plants
Outcome of discussions
Genetically modified organisms
Opinion of the
Scientific Committee on Plants on the genetically modified
cotton line, insect-tolerant notified by the Monsanto
company (notification C/ES/96/02) (Opinion expressed by SCP
on 14 July 1998)
1. Title
Application for consent to place on the
market insect-protected cotton expressing a gene for
B.t.k. endotoxin (notification C/ES/96/02)
2. Terms of reference
The Scientific Committee on Plants (SCP
The Working Group Plant GMOs comprises members from the
following Scientific Committees: Plants, Animal Nutrition,
Food, and Toxicity, Ecotoxicity and the Environment) is
asked to consider whether there is any reason to believe
that the production and marketing of varieties of seed from
IPC 531 cotton line, tolerant to feeding by certain
lepidopteran insects and any progeny derived from crosses
between Cotton line IPC 531 and other cotton varieties and
the import of commodity cotton grain that contains Cotton
line IPC 531 grain mixed with other genetically modified
and non-modified cotton grain, is likely to cause any
adverse effects on human health and on the
environment.
3. Background
Directive 90/220/EEC (Council Directive
90/220/EEC of 23 April 1990 on the deliberate release into
the environment of genetically modified organisms, O.J. no.
L 117, 08/05/1990, p. 15-27) requires that an assessment
has to be carried out before a product containing or
consisting of genetically modified organisms (GMOs) can be
placed on the market. The aim of the assessment is to
evaluate any risks to human health and the environment
connected with the release of the GMOs. For genetically
modified plants, the assessment must be based on
information outlined in Annex II B of Directive 90/220/EEC
and take into account the proposed uses of this
product.
Following the entry into force of the
regulation on Novel Foods and Novel Food Ingredients (EC N°
258/97) (Regulation (EC) No 258/97 of the European
Parliament and of the Council of 27 January 1997 concerning
novel foods and novel food ingredients, O.J. no. L 043,
14/02/1997, p. 1-7). on 15 May 1997, in order for this
cotton and its derived products to be placed on the market
for food purposes, the requirements of the regulation will
have to be satisfied. Such regulation does not exist on
Novel Feeds and Novel Feed ingredients.
4. Proposed Uses
Seeds shall be imported, planted, grown,
harvested, and processed to non-viable products. Cottonseed
from insect-protected cotton will be utilised in the same
manner as other cottonseed products from cotton varieties
produced or imported into the European Union (EU).
5. Description of the product
The product consists of cotton (
Gossypium hirsutum) cultivar Coker 312, which has
been transformed using plasmid PV-GHBK04. The transgenic
line produced is called IPC 531, and expresses the
cry1A(c) gene (origin:
Bacillus thuringiensis subsp.
kurstaki) which encodes a modified
CRY1A(c) B.t.k. protein.
6. Opinions of the committee
6.1. Molecular/Genetic Aspects
6.1.1. Transformation technique: According to
information provided, the construct was introduced into
cells of cotton hypocotyl sections by
Agrobacterium tumefaciens-mediated transformation.
Plantlets were regenerated after selection on kanamycin,
and were assayed for insect resistance.
6.1.2. Vector construct: Line IPC 531 was produced
with vector PV-GHBKO4 containing the following
elements.
The 0.4 kb
oriV fragment from the RK2 plasmid fused to the 3.4
kb segment of pBR322 allowing maintenance in
E. coli and in
Agrobacterium tumefaciens. This was fused to the
0.36 kb DNA fragment from pTiT37 plasmid which contains the
nopaline right border. The remaining portion consists of
two chimeric genes that encode the
B.t.k. HD 73 and NPTII protein and a bacterial
selectable marker (
aad). The chimeric gene consists of the 35S
promoter, the modified
cry1A(c) gene [part of the 5 ' end of the
cry1A(b) gene with a portion of the
cry1A(c) gene] which encodes the
B.t.k. protein and the mRNA polyadenylation signals
(7S 3 terminator sequence) of the soybean alpha subunit of
the beta-conglycin gene. This is fused to the
aad gene isolated from Tn7 transposon (allowing
bacterial selection on spectinomycin or streptomycin). The
chimeric gene for selection on kanamycin which consists of
the cauliflower mosaic virus 35S promoter, the neomycin
phosphotransferase (
nptII) gene and the non-translated region of the 3
region of the nopaline synthase gene (
nos) is located downstream of the
aad gene.
6.1.3. Transgenic construct in the GM plant: The
ori322 region, present in PV-GHBK04, was not
transferred in the genome of IPC 531 line as shown by
Southern analyses. The
aad gene, under the control of a bacterial promoter
is present in the genome of IPC 531 line, but for the AAD
protein, an ELISA confirmed the lack of detectable
expression of the protein. Southern and genetic analyses
demonstrate that two copies are inserted in a head-to-tail
arrangement into the genome of IPC 531 line. One T-DNA
insert contains a full-length
cry1A(c) gene and a
nptII gene and the second insert contains an
inactive 3 portion of the
cry1A(c) gene. The two inserts are linked and behave
genetically as a single locus. The stability of the insert
has been demonstrated over four generations of backcrossed
derivatives of IPC 531 lines in several elite
cultivars.
6.2. Safety aspects
6.2.1. Potential for gene transfer: Although the
final construct contains two antibiotic resistance markers,
nptII conferring resistance to neomycin/kanamycin
and
aad conferring resistance to
streptomycin/spectinomycin, it is unlikely that either gene
survives processing in a functioning form. The defatted
seed meal remaining after oil extraction is used as animal
feed, the bulk of which is fed to ruminants able to
tolerate the presence of the terpinoid gossypol and the
cycloprenoid fatty acids which are toxic to other livestock
species. Removal of these components allows a limited
amount of cottonseed meal to be used in the diets of pigs,
poultry and fish. The physical and heat treatment used to
obtain maximum oil recovery is adequate to coagulate
protein and to damage substantially the DNA present.
It is theoretically possible that DNA
containing a resistance marker gene could survive
processing, that this DNA could transform an intestinal
bacterium and, in the case of
nptII
, recombination could bring the gene under the
control of a bacterial promoter. Even if this extremely
unlikely chain of events occurred, the potential to
compromise chemotherapy in humans is non-existent. Both
kanamycin and streptomycin resistant bacteria are
relatively common in nature and the introduction of either
resistance gene would not increase the existing risks to
any significant extent.
6.2.2. Safety of the gene products/metabolites: The
B.t.k. toxin is present at a concentration of less
than 1
m
g/g fresh weight in whole seeds and the
nptII gene product, neomycin phosphotransferase II, at
approximately 2.5
m
g/g fresh weight. The
aad gene product could not be detected using ELISA.
These values would be proportionally higher in the extracted
seed meal but without biological activity. No toxic effects
have been observed in acute and short-term toxicity studies
made with
B.t.k. protein produced in
E. coli. Widespread use of
B.t.k. as an insecticide spray has not produced
evidence of any allergenic response. Similarly no homologies
have been found between the
B.t.k. toxin or NPTII and any known
allergens.
The weight of evidence provided by the
Company and available elsewhere leads the Committee to
conclude that there is no significant risk to humans or
livestock following ingestion of these gene
products.
6.2.3.
Substantial equivalence:
Compositional analyses of the intact
seeds and extracted seed oil samples of the transformed
line 531 were compared with those of its parent line Coker
312, taken from six sites during one growing season and a
further four sites the following season. The yield and
fraction of the seed dry matter represented by the major
components did not differ significantly and fell within the
published range for other cotton varieties. Small
significant differences were observed in the composition of
the extracted oil for three of the eleven measured fatty
acids. All values however, fell within the normal published
range and were not a consequence of the introduced traits.
The concentration of potential toxicants (gossypol and the
cyclopropenoid fatty acids) did not differ significantly.
On the basis of this evidence, the Committee is of the
opinion that the transgenic cotton line 531 is
substantially equivalent to non-transgenic cotton except
for the transferred traits.
6.3. Environmental Aspects
6.3.1. Potential for gene
transfer/escape: Cotton (
Gossypium
hirsutum), a member of the
Malvacea family, is a perennial plant which is
planted and harvested annually. It is mainly
self-pollinating, but pollen is also transferred by insects
(in particular various species of bees and
bumblebees).
Outcrossing rates of up to 28% to other
cotton cultivars have been observed under field conditions
in adjacent plots, declining rapidly with distance. Given
proximity and the availability of insects as pollen
vectors, Insect Protected Cotton line 531 is likely to
hybridise with other cotton varieties.
Other species of the Gossypiaea tribe
are not native to the EU but are cultivated as ornamental
plants or vegetables (e.g. Hibiscus, Okra or Ladys
fingers) in Member States which also grow cotton.
Hybridisation experiments with several species either
failed or resulted in cottonseeds. Taking into account also
the need of close proximity, synchronous flowering and the
availability of insect pollinators, the probability of
fertile hybrids can be considered to be very unlikely. The
potential transfer of genetic material to micro-organisms
in the soil is considered to be very low against a
background of the natural occurrence of kanamycin and
streptomycin resistance in soil microbes.
6.3.2.
Treatment of volunteers: There are no specific
problems with cotton as a weed. Cottonseed may remain in
the field after harvesting and germinate under favourable
conditions. Seeds may also survive mild and dry winters.
However, no wild populations of cotton are known.
Germination, vegetative vigour and reproduction of IPC line
531 are equivalent to non-modified varieties.
Suitable treatments for any volunteers
in the next crop include cultivation and the use of
chemical herbicides.
6.3.3.
Safety to non-target organisms: The target pests in
Europe are the cotton bollworm (
Helicoverpa armigera) and the pink bollworm (
Pectinophora gossypiella). The
cryIa(c) protein is specifically toxic to certain
Lepidopteran larval pests on ingestion and appears
non-toxic to other arthropod species. Exposure of
non-target species to seeds can be considered as especially
low, due to the morphology of the boll. Feeding studies
with birds and mammals indicate very low toxicity of the
cryIa(c) protein. Field studies on agronomic
performance showed equivalent susceptibility of IPC line
531 and non-modified varieties to diseases and arthropod
pests other than Lepidoptera (to which
cryIa(c) is toxic). The toxicity of the
cryIa(c) protein was further tested in laboratory
and field experiments in a wide range of arthropod species
from different orders, including honey bees, lacewing
larvae, ladybird beetles and parasitic Hymenoptera.
Laboratory studies showed very low toxicity for all species
except Lepidopteran larvae. In the field, populations of
non-target arthropods were frequently higher in IPC line
531 plots than in those of non-modified cotton, attributed
to less use of insecticides in the IPC line 531
fields.
6.3.4.
Resistance and tolerance issues: The development of
resistance in target pests will be delayed by the rigorous
adoption of a comprehensive resistance management strategy.
To be effective, this should require the active involvement
of the notifier to monitor for control failure, to provide
technical support and to educate growers to implement the
strategy.
The speed with which resistance to
cryIa(c) protein develops will depend on the rigour
and efficiency of any insect resistance management
strategy. Such a programme designed to delay resistance
development requires:
- knowledge of pest biology and
ecology
- gene deployment strategy (full-season,
constitutive, optimal dose
cryIa(c) expression to control insects heterozygous
for resistance alleles)
- refuges to support the development of
B.t.k. - susceptible insects
- monitoring and reporting of incidents
of resistance development
- employment of integrated pest
management practices to encourage ecosystem diversity and
provide multiple tactics for insect control
- communication and education
plan
- development and deployment of products
with alternative modes of action.
The notifier intends to recommend
resistance monitoring and management strategies, addressing
the elements listed above. The success of such resistance
management strategy will depend on the ability of any
monitoring programmes to detect resistance as soon as
possible, and the extent and quality of advice given to
farmers. The proposed plan if rigorously carried out with
the active involvement of the company should provide an
adequate framework to delay the onset of resistance in the
target pests.
The Scientific Committee on Plants
should be kept informed of the results of the proposed
surveillance of resistance in the target pests in Member
States.
7. Overall assessment and conclusion
The Commission requested the Scientific
Committee on Plants to consider whether the placing on the
market of insect-resistant cotton line IPC 531 (expressing
the modified
cry1A(c) gene) is likely to cause any adverse
effects on human health or on the environment.
1. The Committee, after examining and
considering the existing information and data provided in
the dossier, against the background of available knowledge
in the areas concerned, considers that there is no evidence
to indicate that the placing on the market of line IPC 531
(expressing a
B.t.k. toxin) with the purpose to be used as any
other cotton is likely to cause adverse effects on human
health and on the environment.
2. The Committee was also of the opinion
that the proposed plan for risk management with regard to
B.t.k. endotoxin resistance provides an adequate
framework to delay the onset of such resistance in the
target pests. The Scientific Committee on Plants should be
kept informed of monitored progress in the field.
The present opinion relates to the
assessment provided for under Directive 90/220/EEC, all
applications relating to the placing on the market of this
cotton and its derived products intended for food use
purposes must also comply with the provisions and
procedures of EC Regulation No 258/97 on Novel Foods and
Food Ingredients of 15 May 1997 including, as appropriate,
consultation of the Scientific Committee on Food.
[
©]
- [
HEALTH] - [
SCIENTIFIC COMMITTEES] -
[SCIENTIFIC COMMITTEE ON PLANTS]
- [
OUTCOME OF DISCUSSIONS]
-
[
GENETICALLY MODIFIED
ORGANISMS]
|