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2-Plants: The role of non-GM biotechnology in developing world agriculture



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TITLE:  The role of non-GM biotechnology in developing world agriculture
SOURCE: SciDev.Net, UK, Dossier by Zephaniah Dhlamini
        http://www.scidev.net/dossiers/index.cfm?
fuseaction=printarticle&dossier=6&policy=114
DATE:   Feb 2006

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The role of non-GM biotechnology in developing world agriculture


Summary

Discussions about the role of agricultural science in boosting food
production tend to be dominated by controversy over the characteristics
of genetically modified (GM) crops and the implications of their use. But
this has tended to overshadow consideration of the many other
contributions that cutting-edge research can make to increasing crop
productivity. This briefing summarises the main ways in which these non-
GM techniques are helping plant breeders to develop and propagate new
crop varieties.

Zephaniah Dhlamini is a former consultant to the plant breeding and
genetics section of the International Atomic Energy Agency.


Introduction

In the intense debates around the applications of modern biological
research to agriculture and food production, genetic modification (GM
techniques) -- and the novel crops that result from their application --
tend to attract the lion's share of public attention.

This is despite the fact that such research offers a range of other tools
and techniques that do not involve genetic modification, and yet can
still make major contributions to agriculture.

One result of the disproportionate focus on GM crops is that policymakers
in the developing world often lack adequate information on the nature and
potential use of non-GM biotechnologies.

This briefing seeks to help fill this information gap by summarising the
characteristics of the most common non-GM biotechnologies that are being
developed and applied to crop improvement in the developing world.

Drawing on the Food and Agriculture Organization's (FAO) database on
Biotechnologies in Developing Countries (BioDeC), it focuses on four
types of non-GM biotechnology: tissue culture, molecular markers,
diagnostic techniques and microbial products. [1]


Tissue culture technologies

One technology that deserves greater attention from both the public and
policymakers is the use of tissue culture, the most widely used
application of which involves creating copies of plants through a process
known as micropropagation.

In essence, micropropagation involves taking tissue (known as an
'explant') from a plant and growing it on sterile media containing
substances essential for growth. Once it is growing well, samples of this
culture can be taken and used to grow entire plants under laboratory
conditions.

The technique is currently used mainly with perennial crops that can
reproduce vegetatively, producing new stems directly from the existing
ones rather than needing to be pollinated and produce seeds.

It can be used to create millions of new 'clones' from a single plant,
each genetically-identical to the parent plant.

The method can be used to produce large quantities of high-quality plant
lines, to eliminate pathogens from infected planting materials, or to
produce 'true-to-type' material from desirable plant lines.

Micropropagation has been developed over many decades, and can now be
considered a 'mature' plant biotechnology. It is already widely used in
developing countries, especially Asia - in particular as a result of the
immense market in China for plants generated in this way.

It is relatively cheap, and has been shown in general to increase
productivity (especially of root and tuber crops, such as sweet potatoes
and potatoes).

Its most common application in developing countries involves producing
virus-free plantlets by heat-treating the explant to kill any viruses
present and then culturing cells from its 'meristem', the plant's
actively growing tissue.

Because micropropagation cannot, however, guarantee that plants will be
virus-free access to a virus diagnostic facility is essential.


*****     *****     *****     *****     *****     *****     *****
Micropropagation in developing countries: some examples

In China's Shandong Province, a micropropagation project that created and
distributed virus-free sweet potatoes led to an increase in yields of up
to 30 per cent. By 1998, productivity increases were valued at US$145
million annually, raising the agricultural income of the province's seven
million sweet potato growers by three to four per cent in one season.
Government subsidies helped to encourage adoption of the technology and
keep the cost of the planting material low. [2]

In Kenya, the commercial micropropagation of disease-free bananas is
currently being carried out. The initiative has been shown to offer
significantly higher financial returns than traditional growing practices. [3]

In Vietnam, introducing improved, high-yielding potato cultivars able to
resist the late-blight disease has seen yields double, from 10 to 20
tonnes per hectare. The farmers are themselves multiplying their
plantlets through micropropagation, making the seed more affordable. [4]
*****     *****     *****     *****     *****     *****     *****


Anther culture and embryo rescue

Another widely used tissue culture technique, 'anther culture', uses the
immature pollen-producing organs of a plant to generate fertile 'haploid'
plants, which have half the full set of genetic material.

These plants can later be crossed to produce pure homozygous 'diploid'
plants, with identical copies of each gene, thus eliminating undesirable
variation in key traits.

The technique is popular among breeders as an alternative to the numerous
cycles of inbreeding or 'backcrossing' usually needed to obtain pure lines.

In vitro anther culture is now used routinely for improving vegetables,
such as asparagus, sweet pepper, eggplant, watermelon and Brassica
vegetables. It is also used, though to a lesser extent, for cereal crops
such as rice, barley and wheat.

A further refinement of the technique is the so-called 'microspore
culture'. This involved isolating and culturing the cells from which
pollen grains develop, and can yield up to ten times as many haploid
embryos as anther rescue.

A further tissue culture technique, known as 'embryo rescue' (or
sometimes 'embryo culture') involves crossing species that are not
normally sexually compatible. In nature embryos that result from such
'wide crosses' usually fail to develop. But in the laboratory, wide
crosses can be used to transfer genetic traits from wild relatives of
crops (i.e. secondary and tertiary gene pools) into cultivated crop
plants (primary gene pools).

An example is triticale, a relatively new hybrid variety that is the
result of a cross between rye and wheat.


*****     *****     *****     *****     *****     *****     *****
New Rice for Africa: a tale of two techniques

Both embryo rescue and anther culture have recently been used extensively
in the successful development of the so-called New Rice for Africa (NERICA).

Breeders at the Africa Rice Center (WARDA) in Benin, for example, have
used both techniques to cross Oryza sativa (Asian rice) with Oryza
glaberrina (African cultivated rice). Farmers have selected new rice
varieties from the resulting germplasm, with qualities such as higher
yields, shorter growing seasons, resistance to local stresses, and higher
protein content than traditional African varieties.

The new varieties have been released in Cote d'Ivoire, Nigeria and
Uganda, and are being evaluated in Benin, Burkina Faso, Ethiopia, The
Gambia, Malawi, Mali, Mozambique, Sierra Leone, Tanzania and Togo.

WARDA researchers suggest that some 200,000 hectares will soon be under
NERICA cultivation, producing about 750,000 tonnes of rice per year, and
leading to an annual saving on rice imports of nearly US$90 million. [5]
*****     *****     *****     *****     *****     *****     *****


Molecular marker techniques

A second set of non-GM biotechnologies that are having a growing impact
in crop development are a range of techniques that use 'molecular
markers'. These are relatively short and easily-identifiable strips of
DNA whose location can indicate the presence in a plant's genome of a
gene with desired characteristics.

The physical proximity on the genome between the marker and the gene
responsible for a particular trait means that scientists can select for
the marker, rather than the gene itself. The value of 'molecular markers'
to plant breeders is therefore that they allow plant species to be
investigated at the level of their DNA, and for the knowledge generated
in this way to be used to manage genetic variation and diversity in plants.

The first generation of molecular markers, known as restriction fragment
length polymorphisms (RFLP), required slow and expensive ways of
reproducing lengths of DNA through a process known as DNA-DNA hybridisation.

However the invention of the technique known as polymerase chain reaction
(PCR), which amplifies short segments of DNA and thus makes them easier
to identify, gave rise to a second generation of faster and less
expensive molecular markers. The most common of these are randomly
amplified polymorphic DNA (RAPD), amplified restriction fragment length
polymorphisms (AFLP), and simple sequence repeat (SSR).

Cost-effective techniques based on molecular markers have many
applications in plant breeding, and the ability to detect the presence of
a gene (or genes) controlling a particular desired trait has given rise
to what is called 'marker-assisted selection' (MAS).

This approach makes it possible to speed up the selection process. For
example, a desired trait may only be observable in the mature plant, but
MAS allows scientists to screen for the trait at the much earlier
plantlet stage.

Other advantages of techniques based on molecular markers as that they
make it possible to select simultaneously for more than one
characteristic in a plant. They can also be used to identify individual
plants with a particular resistance gene without exposing the plant to
the pest or pathogen in question.

However, the current cost of applying these techniques is high, which
means that for many breeding programmes -- particularly in the developing
world -- they may be unaffordable.

Furthermore, there are relatively few useful molecular markers for traits
that are important to plant breeders, such as those leading to increase
yield. As a result, only a handful of crop varieties in farmers' fields
have so far been developed through MAS.

However the relative cost-effectiveness of conventional breeding methods
compared to using MAS depends on the circumstances. Where the
characteristics of new, experimental crops can be examined in the field,
conventional breeding methods can be very cost-effective.

But where this is not possible, or is particularly costly or difficult,
the use of molecular markers can be significantly cheaper. [6] This is
the case, for example, with breeding projects that involve multiple
genes, recessive genes, the late expression of the trait of interest, or
seasonal and geographical constraints.

Molecular markers can also be used to characterise germplasm in
situations in which a detailed database of the genetic material of
different varieties of a particular plant species has been built up.
Indeed DNA-based genetic markers are often more useful for studies of
genetic diversity than morphological and protein markers because their
expression is not affected by environmental factors.

As the BioDeC database reveals, molecular markers are already being
widely used for characterising and managing germplasm in many developing
countries.


DNA and immuno-diagnostic techniques

In addition to seeking ways of breeding better, stronger or higher-
yielding crops, much agriculture research and development focuses on ways
of fighting plant diseases. This is a key area of research as many crop
diseases are difficult to diagnose, especially at the earliest stages of
infection. Successful diagnosis can also be made harder by the fact that
a number of different viral diseases exhibit similar symptoms.

In such circumstances, diagnostic efforts can be assisted by molecular
assays -- such as enzyme-linked immunosorbent assay (ELISA) - that can
precisely identify viruses, bacteria and other disease-causing agents.

ELISA has become an established tool in disease management in many
farming systems. Indeed it is now the most widely used commercial
diagnostic technique in all regions of the developing world.

In addition, diagnostic assays have been developed that identify a wide
range of other organisms, chemicals - including undesirable by-products
such as aflatoxin - and impurities that affect food quality. [7]

A relatively new but increasingly powerful technique for identifying
pathogens and other organisms in agriculture is known as DNA diagnostics.
This works by identifying a suspected pathogen from details of its DNA.

Most DNA diagnostics are now based on the PCR. Until recently, this was
problematic because the effectiveness of PCR was based on the heat-
resisting properties of the enzyme Taq polymerase, which is heavily
protected by patents.

More recently, however, Taq polymerase has come to be treated as a
'generic' biochemical reagent, substantially reducing the cost of PCR
applications in research and commerce.


Microbial products for agriculture

Pest control and soil enrichment are as important to agriculture as
accurate disease diagnosis. Products based on microorganisms play an
increasing role in both processes, and include biocontrol agents (or
'biopesticides'), 'biofertilizers' and products that aid fermentation and
food processing.

In Africa and much of Asia, research in biocontrol and biofertilisation
is still at the early stages. But countries such as China, India and the
Philippines, as well as several in Latin America, are already routinely
using advanced techniques. Some of their results are already being tested.


Bio-pesticides

Although conventional chemical pesticides are still widely used across
the developing world, some countries are shifting to the use of newer
types of pesticide that are more selective and less toxic to humans and
the environment, as well as remaining effective at lower rates of application.

A small but growing proportion of these are biopesticides, based on
naturally occurring organisms or substances. These include microbial
pesticides such as Bacillus thuringiensis (Bt), Trichoderma,
Verticillium, Bauveria and Bacillus subtilis; plant extracts; and
nematode worms or viruses such as the nucleopolyhedrosis virus (NPV) that
are 'entomopathogenic' i.e. they attack insects.

Other biocontrol agents include pheromones, growth regulators and
hormones. Many of these agents are increasingly used in integrated pest
management (IPM), which uses a variety of methods -- from monitoring pests
to planting pest-resistant crops -- to minimise the use of pesticides .


Bio-fertilisers

Recent progress on biofertilisers has been equally impressive. For
example, there has been much research on biological nitrogen fixation
(BNF), the process by which microorganisms in the soil 'fix' atmospheric
nitrogen, mostly within subsoil plant nodules, and make it available for
assimilation by plants.
The most studied and important nitrogen-fixing bacteria are Rhizobia. But
a number of endophytic (growing within a plant) bacteria are now also
known to do the job. Using such bacteria to fix atmospheric nitrogen is
an environmentally-friendly alternative to applying chemically generated
fertilizers.

Other microorganisms, such as Mycorrhiza, can establish a symbiotic
relationship with both cultivated plants and forest trees, facilitating
the uptake of phosphorus and water uptake. Inoculating plants with these
fungi is an efficient substitute (or complement) to phosphorus-based
chemical fertilization.

Research on biofertilizers -- mainly Rhizobium - is currently being
carried out in many developing countries. For example, the UNESCO
Microbiological Resources Centre (MIRCEN) project at the University of
Nairobi in Kenya has developed a Rhizobium inoculant, known as BIOFIX,
that is currently the main inoculant available on the local market.

100 grams of BIOFIX will treat a hectare of crops, costs about US$1.25,
and has a comparable effect to 90 kilograms of chemical nitrogen costing
about 10 times as much. [8]


Conclusion

Policy makers and research managers need to focus more attention on the
full range of promising tools and techniques offered by modern biological
research -- not only those that involve genetic modification.

As this brief review shows, there are already many promising non-GM
biotechnologies in the public domain that could make significant
contributions to crop improvement and agricultural management. Each has
both advantages and disadvantages, each of which needs to be carefully
assessed.

For most developing countries, however, the main challenge is not to
develop new agricultural technologies (such as plant breeding techniques
or disease diagnostics) but to design and implement the capacity building
programmes and regulatory systems needed to facilitate the sustainable
transfer of these technologies to the relevant farming systems.

Furthermore if the full potential of these non-GM biotechnologies is to
be realised, they must not be adopted as stand-alone interventions.
Rather they should be treated as tools that need to be fully integrated
with other proven agricultural research and farming practices.


References

[1]	Food and Agriculture Organization of the United Nations database on
Biotechnologies in Developing Countries (BioDeC). www.fao.org/biotech/
inventory_admin/dep/default.asp
[2]	Fuglie K.O, Zhang L., Salazar L.F., et al. Economic Impact of Virus-
Free Sweet Potato Planting Material in Shandong Province. International
Potato Center. www.eseap.cipotato.org/MF-ESEAP/Fl-Library/Eco-Imp-SP.pdf
(1999)
[3]	Mbogoh S., Wambugu F.,. Wakhusama, S. Socio-economic impact of
biotechnology applications: some lessons from the pilot tissue-culture
(TC) banana production project in Kenya, 1997-2002. A contributed paper
submission for the XXV IAAE Conference, Durban, South Africa. www.iaae-
agecon.org/conf/durban_papers/papers/037.pdf (2003)
[4]	Van Uyen N., Truong V. H., Pham X. T., et al. Economic impact of the
rapid multiplication of high-yielding, late-blight-resistant varieties in
Dalat, Vietnam. In:Walker T., Crissman, C., eds. Case studies of the
economic impact of CIP-related technology. pp 127-138. International
Potato Center, Lima, Peri. www.cipotato.org/Market/ImpactCS/seedviet.htm
(1996)
[5]	Africa Rice Center (WARDA). www.warda.cgiar.org
[6]	Dreher K. Khairallah M., Ribant J., et al. Money matters (I): costs
of field and laboratory procedures associated with conventional and
marker-assisted maize breeding at CIMMYT. Molecular Breeding, 11, 221-234
(2003)
[7]	Dhlamini Z., Spillance C., Moss J.P., et al. Status of Research and
Application of Crop Biotechnologies in Developing Countries - A
Preliminary Assessment. Food and Agriculture Organization of the United
Nations, Rome. ftp://ftp.fao.org/docrep/fao/008/y5800e/y5800e00.pdf (2005)
[8]	Zechendorf, B. Sustainable development: how can biotechnology
contribute? Trends in Biotechnology 17,219-225 (1999)

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