[SANET-MG] gm rice in china

[jcummins <jcummins@UWO.CA>]

http://www.i-sis.org.uk/GMRIC.phpRice War Continues
Editor’s note

The productivity of rice has been falling along with that of other food
grains. Chief among the causes of the fall in productivity are severe
water shortages due to over-irrigation and depletion of aquifers, eroded
soils from over-application of chemical fertilizers and pesticides, and
rising temperatures from global warming.

While innovative farmers have been addressing these problems with a
range of effective measures to increase yields through regenerating
degraded soils, conserving water and minimizing inputs (see many
articles in SiS23), pro-GM scientists in the three major rice-growing
countries, China, India and Japan, have all been researching and
promoting GM rice with scant regard for safety or sustainability.

We are circulating Professor Joe Cummins’ review on GM rice in China,
and making available two others, on GM rice in India and Japan
respectively on ISIS’ website:

GM Rice in Japan
GM Rice in India

ISIS Press Release 30/11/04
GM Rice Release in China?
Reduced production and transportation bottlenecks have persuaded China
to think of growing GM rice, but Prof. Joe Cummins says it is unwise for
serious safety reasons.

The references for this article are posted on ISIS members’ website.
Details here.

GM rice a solution to rice shortfall?
Remote sensing data reveal that China has about 1.27 million square
miles of cropland. Annual rice production, as a single or double crop,
or cropped with wheat or oilseed rape, accounts for about 19% of the
cropland in China [1]. Rice is far and away the most important food crop
in China.

At the same time, agricultural biotechnology is growing faster in China
than in any country apart from the United States. In 2002, China
announced regulations for biosafety management of genetically modified
(GM) crops and rules for labeling GM products [2].

This year, rice prices rose about 27% in China because of reduced
production and transportation bottlenecks; and it was thought that
commercializing GM rice could solve the problem.

The government reportedly set aside one billion dollars to hasten the
commercial release of GM rice to farmers [3]. Even though there has been
extensive research on GM rice in China, it is not yet clear which GM
rice varieties will be selected for first release to farmers. Likely
candidates may be among those featured in recent scientific publications
in international journals.

Insect resistant rice
Insect resistant rice tops the list of likely candidates for commercial
release; the most widely used transgenes being the Cry toxins isolated
from the soil bacterium Bacillus thuringiensis (Bt). There are a number
of Cry toxin proteins, each specific for a range of insect pests.
Individual cry genes and their proteins are identified by a number 1, 2,
3 etc., followed by a letter A, B, C etc. That letter is followed by a
lower case letter a, b, c, etc. The numbers signify a cry gene on the
bacterial chromosome, while the letters signify the alleles (different
forms) of the gene; the upper and lower case letters indicate
respectively greater and lesser DNA code letters differences between the
alleles, which in turn determine their toxicities to different insect pests.

A gene fusion protein toxin made up of two different synthetic Cry
toxins - Cry1Ab fused with Cry1Ac - has been inserted into Indica rice
[4]. The fusion protein was under the control of the rice actin promoter
with its first intron and the nos gene terminator, tnos, from the soil
bacterium, Agrobacterium. The fusion toxin was active against two insect
pests of rice, leaf folder and yellow stem borer. However, the fusion
toxin does not appear to have been tested for mammalian toxicity and it
has not yet been used in any GM crop that has been released commercially.

About a third of rice lines transformed with Bt toxin Cry1Ab or Cry1Ac
suffer genetic aberrations, such as chlorophyll deficiency or stunted
plants. The variability was ascribed to ‘somaclonal’ variation [5], the
consequence of genetic instability common to the plant tissue culture
technique used in creating the GE lines. It is thought to result from
the activation of mobile genetic elements or transposons that frequently
insert into and disrupt the rice genes. Such insertion mutations are
capable of creating unexpected toxins and for that reason cannot be
ignored.

Research has shown that rice leafhoppers are controlled by GM rice with
Cry1Ab toxin. The synthetic cry1Ab gene was placed under the control of
the maize ubiquitin promoter, linked in tandem with gus (encoding the
b-glucuronidase, a positive selection marker), and the negative
selection antibiotic resistance markers hpt (encoding hygromycin
resistance), and npt (encoding neomycin resistance) [6]. The GM rice
reduced leafhopper damage, but there has not been much study on the
environmental and human-health impacts.

Straw from GM rice containing Cry1Ab was found to alter important
biological properties in water-soaked soil, indicating a shift in the
metabolic activities of the soil [7]. In China, rice straw is usually
incorporated along with the plant residues into soil to enhance
fertility, so the implications of these changes are important.

There are both scientific and anecdotal evidence, reviewed in earlier
reports, suggesting that the natural Cry toxins pose serious health
hazards to human beings and animals. Bt spores containing a mixture of
different Cry toxins caused allergic reactions in farm workers [8].
Cry1Ac, in particular, has been shown to be a potent immunogen [9, 10].
The synthetic Cry toxins incorporated into GE crops differ from the
natural toxins in many respects and are often hybrids of two or more Cry
proteins. These synthetic proteins are completely unknown and untested
for their toxicities and allergenicities [11].

A screening of transgenic proteins expressed in market-approved
transgenic food crops against known allergens in the public databases
raised further concerns [12]. Twenty-two out of 33 proteins screened
were found to have stretches of identities with known allergens, and
therefore "warrant further clinical testing for potential
allergenicity". These include all the Cry toxins, the CP4-EPSPS and GOX
(responsible for glyphosate tolerance), many viral coat proteins (viral
resistance) and even proteins encoded by marker genes such as GUS.

The Galanthus nivalis (snowdrop) plant lectin gene (gna) was used to
protect rice from the small brown planthopper [13]. The genetically
engineered rice contained the gna gene, driven by the phloem-specific
Rss1 promoter, accompanied by the markers hpt gusA, both driven by the
cauliflower mosaic virus (CaMV) 35S promoter. While the GM rice
controlled the sap-sucking insect [8], further studies on the safety of
GNA rice should be undertaken because GNA potatoes containing the
snowdrop lectin and the CaMV 35S promoter were found to increase
proliferation of the gastric mucosa, and the hyperplasia was attributed
to the transgenic construct or process [14].

Disease resistant rice
One of the most devastating diseases of rice in Africa and Asia is
bacterial leaf blight (BB), which is caused by the Gram-negative
bacterium Xanthomonas oryzae pv. oryzae (Xoo). The rice gene Xa21
provides resistance against some races of Xoo, although the endogenous
gene is expressed at a low level.

A ferredoxin-like protein from sweet pepper was found to confer
resistance to Xoo. Ferredoxins are iron-sulphur proteins that mediate
electron transfer in a range of metabolic reactions, and plant type
ferredoxin is located in the chloroplast membrane.

The sweet pepper ferrodoxin gene (ap1) was inserted in the rice genome
to confer resistance against BB [15]. Ap1with the chloroplast transit
peptide was driven by the CaMV promoter and transcription terminated by
tnos. The transgenic rice also contained the marker genes gusA and hpt,
both driven by the CaMV 35S promoter and terminated by tnos.

Enhanced resistance to BB was conferred using the rice Xa21 gene.
However, the transformation included the bacterial hygromycin antibiotic
resistance marker and the gus marker along with the bacterial
beta-galactosidase (z) gene [16], not to mention the CaMV 35S promoter
and Agrobacterium nos terminator. Transferring genes from rice to rice
using genetic engineering, rather than crossing and selection, was
justified by the researchers, as they considered the conventional
crosses needed to separate Xa21 from flanking genes that were
undesirable too time-consuming. Yet, molecular marker-assisted selection
has actually been used to introduce the Xa21 gene into rice cultivars
using conventional breeding and selection [17]. The marker-assisted
variant of conventional breeding and selection provides the advantage of
conferring BB resistance, while avoiding the insertion of antibiotic
markers and other potentially problematic genes into rice.

Rice blast is one of the most important diseases of rice worldwide; and
is caused by a fungus, Pyricularia oryzae (Pyricularia grisea), which
can attack the aerial parts of the rice plant at any stage of growth.
Trichosanthin, a protein isolated from the medicinal Chinese cucumber,
Trichosanthes kirilowii, was found to control the rice blast fungus. The
gene for trichosanthin was introduced into rice, driven by the CaMV
promoter and terminated by tnos. Rice with the trichosanthin gene
resisted the blast disease [18]. However, trichosanthin has long been
used to produce abortion in humans and is immunosuppressive and can
induce renal toxicity [19]. The immunosuppressive ability of
trichosanthin has been used to treat HIV/AIDS and cancer. It is clear
that exposure of the general public to GM trichosanthin rice is unwise.

A conventionally-selected rice resistant to blast disease has been
pyramided (pyramiding is conventional crossing and selection) with
transgenic rice carrying the Xa23 gene, to induce tolerance to both the
fungal and the bacterial diseases [20]. Xa23 comes from rice, but it has
regulatory genes from other organisms associated with it, so it is a
transgene. The full health and environmental implications of pyramiding
genes have yet to be considered. At the very least, the toxicity of each
transgenic toxin, and the combinations of toxins brought about by
crossing must be considered and assessed for risks.

Safety concerns still to be addressed
Scientific research on transgenic crops in China has focused on the
control of important pests and diseases. However, the remedies appear to
have had little scrutiny regarding human health and environmental
(including the implications of gene flow to wild and weedy relatives of
rice) impacts.

In the case of Bt rice straw on wet soil there is evidence of a clear
impact that bears fuller study. Concerns about the impacts of insect
resistant rice on non-target organisms and of the development of insect
resistance have been raised for other Bt crops, and these must be
considered in relation to GM rice as well.

The Bt cry genes used in insect resistant rice are synthetic
approximations of the real bacterial gene, altered for high-level
production in rice plants. It is thus crucial that the real toxin from
Bt rice, not the bacterial surrogate, is tested for health and
environmental impacts.

The use of antibiotic resistance marker genes in GM crops is an
acknowledged risk factor, with European legislation mandating a phasing
out of such marker genes. This is because of the serious concern of
potential gene transfer to pathogenic bacteria, which could compromise
the treatment of diseases. Most of the GM rice lines reviewed here have
used antibiotic resistance marker genes, and this factor must be
adequately considered in the risk assessment.

In addition, the potential of the CaMV 35S promoter to cause genetic
instability, genome rearrangements, and secondary gene transfer into
genomes of animals including humans [21], should also be given
sufficient consideration.



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