78
Implementing the Biodiversity
Treaty: how to make international
co-operative agreements work
Maurice M. Iwu
The Convention on Biological Diversity provides an international legal framework
and multilateral mechanism for the exchange of genetic materials and conservation
of biodiversity. The Convention recognizes the sovereign rights of states over
their natural resources, and the authority to determine access. The research
agreements and legal contracts must address the needs of indigenous people,
community rights, sustainable methods of sample collection, compensation and
intellectual property issues. Implementation of the articles of the treaty requires
not only the formulation of legal agreements and contracts, but also the
establishment of meaningful and just collaborations, and functional partnerships
between industrialized nations and source countries.
The Convention on Biological Diversity (CBD) is an
international treaty- that has been signed by more than
160 member states of the United Nations (Box l) since
the Earth Summit in Rio de Janeiro, Brazil, in June
1992. It provides an international legal framework for
the exchange of genetic materials and for biodiversity
prospecting 1.
Article 1 of the Convention seeks to accomplish
three related objectives: the conservation of biological diversity, the sustainable development of genetic
resources, and 'fair and equitable' sharing of the resulting benefits. (The main features o f the Convention are
shown in Box 2.) The architects of the treaty envisage an integration o f free trade in genetic resources
(Article 15), the exchange of relevant technologies
(Article 16), and equitable compensation for access to
the biological resources of others (Article 19). Periodic
meetings of the signing parties have been held
(November 1994 and 1995) to establish the rules of
procedure, and to consider issues related to 'bio-safety'
protocol. A major problem that has not been resolved
at these meetings is the establishment of a mechanism
for improving access to the genetic resources of tropical countries, while guaranteeing fair and equitable
compensation to developing countries for the exchange. This is due to the inherent differences in
the interpretation o f the CBD. Furthermore, the
Convention does not provide a blueprint that should
be followed by collaborating groups; there is no ideal
agreement or model contract available to address
satisfactorily all the expectations of the contracting parties, and to satisfy, the various interpretations of the
treaty. Perhaps what is needed is not just a legal agreement or contract, but a covenant, or a c o n u n i t m e n t to
begin a new type of relationship between nations and
cultures that will involve a reordering of priorities
and values2.
W h o should reap the rewards?
Negotiating contracts has never been an easy task,
but designing an international co-operative agreement
is especially difficult given the enormous gulf that
exists between the key players. The stakes are also very
high. To a large extent, the biotechnology industry
depends on germplasm that originates in developing
countries for the production of biomolecules and
improved crop varieties through recombinant D N A
technology and plant breeding. Pharmaceutical companies that are based in developed countries often
sponsor expeditions to tropical countries to collect
unusual plants, microorganisms and soil samples that
might yield compounds with therapeutic activity. Such
economic and scientific activities, which generate over
US$200 billion annually for developed countries, may
M. M. Iwu is at the Bioresources Development and Conservalion Probe threatened if the present rate of conversion of forests
gramme, Box 3138, University of Nigeria, P O Nsukka, Nigeria; a,d
tke 1Valter Reed A~rny Institute qflResearch, Washington, D C 20307, to agriculture and other anthropogenic activities is not
halted or even reversed.
U&4 .
TIBTECH MARCH 1996 (VOL 14)
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0167 - 7799/96/$15.00
79
feature
Box 1. Countries ratifying the Convention on Biological Diversity by 25 August 1995 a
1. Mauritus(4.9.92)
2. Seychelles (22.9.92)
3. Marshall Islands (8.10.92)
4. Maldives (9.11.92)
5. Monaco (20.11.92)
6. Canada (4.12.92)
8. St Kitts & Nevis (7.1.93)
9. Ecuador (23.2.93)
10. Fiji (25.2.93)
11. Antigua & Barbuda (9.3.93)
12. Mexico (11.3.93)
13. Papua New Guinea (16.3.93)
14. Vanuatu (25.3.93)
15. Cook Islands (20.4.93)
16. Guinea (7.5.93)
17. Armenia (14.5.93)
18, Japan (28.5.93)
19. Zambia (28.5.93)
20. Peru (7.6.93)
21. Australia (18.6.93)
22. Norway (9.7.93)
23. Tunisia (15.7.93)
24. St Lucia (28.7.93)
25. Bahamas (2.9.93)
26. Burkina Faso (2.9.93)
27. Belarus (8.9.93)
28. Uganda (8.9.93)
29. New Zealand (16.9.93)
30. Mongolia (30.9.93)
31. Philippines(8.10.93)
32. Uruguay (5.11.93)
33. Nauru (11.11.93)
34. Jordan (12.11.93)
35. Nepal (23.11.93)
36. Czech Republic (3.12.93)
37. Barbados (10.12.93)
38. Sweden (16.12.93)
39. European Community
(21.12.93)
40. Denmark (21.12.93)
41. Germany (21.12.93)
42. Portugal (21.12.93)
43. Spain (21.12.93)
44. Belize (30.12.93)
45. Albania (5.1.94)
46. Malawi (2.2.94)
47. Western Samoa (9.2.94)
48. India (18.2.94)
49. Hungary (24.2.94)
50. Paraguay (24.2.94)
51. Brazil (28.2.94)
52. Cuba (8.3.94)
53. Sri Lanka (23.3.94)
54. Ethiopia(5.4.94)
55. Commonwealth of Dominica
(6.4.94)
56. Italy (15.4.94)
57. Bangladesh (3.5.94)
58. Luxembourg (9.5.94)
59. Egypt (2.6.94)
60. Georgia (2.6.94)
61. United Kingdom (3.6.94)
62, Chad (7.6.94)
63. Gambia (10.6.94)
64. Micronesia (20.6.94)
65. Malaysia(24.6.94)
66. Benin (30.6.94)
67. France (1.7.94)
68. The Netherlands (12.7.94)
69. Kenya (26.7.94)
70. Pakistan (26.7.94)
71. Estonia (27.7.94)
72. Finland (27.7.94)
73. Greece (4.8.94)
74. Grenada (11.8.94)
75. Kiribati (16.8.94)
76. Romania (17.8.94)
77. Austria (18.8.94)
78. Indonesia (23.8.94)
79. Slovakia (25.8.94)
80. Costa Rica (26.8.94)
81. Ghana (29.8.94)
82. Nigeria (29.8.94)
83. Guyana (29.8.94)
84, Djibouti (1.9.94)
85. Kazakhstan (6.9.94)
86. El Salvador (8.9.94)
87. Chile (9.9.94)
88. Iceland (12.9.94)
89. Venezuela (13.9.94)
90. Comoros (29.9.94)
91. Bolivia (3.10.94)
92. South Korea (3.10.94)
93. Senegal (17.10.94)
94. Cameroon (19.10.94)
95. North Korea (26.10.94)
96. San Marino (28.10.94)
97. Swaziland (9,11.94)
98. Zimbabwe (11.11.94)
99. Vietnam (16.11.94)
100. Switzerland (21.11.94)
101. Argentina (22.11.94)
102. Myanmar (Burma)
(25.11.94)
103. Colombia (28.11.94)
104. Ivory Coast (29.11.94)
105. Zaire (3.12,94)
106. Equatorial Guinea (6.12.94)
107. Sierra Leone (12.12.94)
108. Lebanon (15.12.94)
109. Jamaica (6.1.95)
110. Lesotho (10.1.95)
111. Panama (17.1,95)
112. Ukraine (7.2.94)
113. Oman (8.2.94)
114. Cambodia (9.2.95)
115. Central African Republic
(15.3.95)
116. Mali (29.3.97)
117. Cape Verde (29.3.95)
118. Russian Federation (5.4.95)
119. Guatemala (10.7.95)
120. Uzbekistan (19.7.95)
121. Niger (25.7.95)
122. Honduras (31.7.95)
123. Israel (7.8.95)
124. Algeria (14,8.95)
125. Morocco (21.8.95)
126. Bhutan (25.8.95)
128. Rwandab
129. Republic of South Africab
aDataderivedfrom a meetingof the UnitedNationsEnvironmentProgram(UNEP).
bRwandaand the Republicof SouthAfrica haveratifiedthe convention,but ratificationdates are not available.
In the past, genetic resources, especially those in
developing countries, were considered the common
heritage of humankind and, therefore, not regulated
by any trade treaty. During this period of 'open access',
neither the developing countries nor their indigenous
peoples benefitted significantly from the products
developed from the genetic materials collected in their
country. Questions are now being raised in developed
countries concerning national rights to profits stemming from the commercial use of biological resources
from public land. A good example is the development
of the polymerase chain reaction (PClK) by Cetus
(Emeryville, CA, USA) from a microorganism collected from Yellowstone National Park (VgY, USA)
and deposited at the American Type Culture Collection (1Lockville, MD, USA) by academic researchers
from the University of Indiana (Bloomington, IN,
USA). Cetus sold the PCtL technolog3, to Roche
Diagnostics (Branchburg, NJ, USA) in 1991 for
US$300 million, and the new owner is estimated to
earn over US$100 million annually from the sales of
PClK equipment and supplies 3. The unanswered question is: should the US Park Service benefit from profits made from a microbe collected from its grounds?
Another controversial issue concerns the ethics of
using materials deposited in research institutions for
commercial purposes without compensating the
person who made the discovery. While it can be
TIBTECHMARCH1996(VOL14]
8O
feature
Box 2. Main features of the Convention on Biological Diversity
The Convention comprises 42 Articles and Annexes. The first 18 Articles deal with recommendations for interactions
between national governments and their agencies, and prescribe certain codes of conduct among those utilizing genetic
resources for research or commercial purposes. Article 19 provides recommendations for the handling of biotechnology and the distribution of its benefits. Articles 20-42 specifically address the administrative, financial and legal
issues that may arise from the Convention. The Convention required ratification by 30 signatories before it could be
enforced as an international agreement. On 30 September 1993, Mongolia became the 30th country to ratify the Convention, and the Treaty became legally binding on 29 December 1993. Although it was specifically stated that 'No
reservations may be made to this Convention' (Article 37), several interpretative statements and reservations have
been included in the ratifying legislations by many countries.
The details of the first 18 Articles are as follows:
• Article 1 sets out the three main objectives of the Convention: the conservation of biological diversity, the sustainable use of biological resources, and the fair and equitable sharing of resulting benefits. It also recognizes the interdependency of nations.
• Article 2 defines the key terms used in the Convention.
• Article 3 gives recognition to the sovereign right of source countries over their genetic resources, their right to exploit
such resources in accordance with the nation's own environmental policies, and the responsibility to ensure that activities within their area of jurisdiction and control do not cause damage to the environment of other nations.
• Article 4 further defines the scope of jurisdiction.
• Article 5 encourages cooperation between the Parties to the Convention directly or through competent international
organizations to help in the conservation and sustainable use of biological diversity, especially as it relates to areas
outside individual national jurisdictions.
• Article 6 outlines measures and strategies expected of nation states to promote conservation.
• Article 7 deals with issues of species identification, classification and monitoring.
• Articles 8 and 9 give guidance on measures to be used both for in situ and ex situ conservation.
• Article 10 provides recommendations for the sustainable use of components of biological diversity. It specifically
encourages the integration of conservation and sustainability into national policy frameworks. National governments
are also requested to encourage the participation of the private sector in developing methods for the sustainable
use of biological resources.
• Article 11 calls for economic and social incentives that promote the objectives of the Convention.
• Article 12 deals with research and training. It requires the contracting parties to recognize the special needs of developing nations in scientific and technical education. The provisions under this Article can provide more-beneficial
methods of compensation to source countries than the over-rated royalty sharing arrangements.
• Article 13 stresses the need for public education and awareness of biodiversity conservation.
• Article 14 relates to impact assessment and the need to minimize adverse impacts on the environment from development projects.
• Article 15 reaffirms the sovereign rights of states over their natural resources and recognizes the authority of national
governments to grant access to their genetic resources. It also encourages the Contracting Parties to endeavour
to create conditions that would facilitate access to genetic resources for environmentally sound uses by others.
• Article 16 provides for access to, and transfer of, technology. It calls on each Contracting Party to provide and/or
facilitate access for, and transfer to, other Contracting Parties' technologies that are relevant to the conservation
and sustainable use of biological diversity. Such transfers should be under 'fair and most favorable terms'.
• Article 17 encourages the exchange of information relevant to the conservation and sustainable use of biological
diversity, 'taking into account the special needs of developing countries'.
• Article 18 promotes technical and scientific cooperation among nations. Like Article 12, it emphasizes the need for
training and education in the source country. It requires that '...special attention should be given to the development
and strengthening of national capabilities by means of human resources'. The Article states that the Conference of
the Parties should determine, at its first meeting, how to establish a clearing-house to promote and facilitate
technical and scientific cooperation.
argued that the US tax payer has benefitted indirectly
both from the tax paid by the commercial users and
from the transmission of the new technology to their
society, one cannot make the same argument for genetic materials that have been collected from other
countries and deposited in developed countries in the
name of academic exchange.
Contra W to the widely held view, the Convention
focuses neither on the issue of property rights, nor on
the question ofbiodiversity prospecting or the extraction o f plant substances for medicinal and related purposes. The CBD is explicit in its prescription for access
to the genetic materials of others and in its benefitsharing rules; but, as has been pointed out by David
IBTECHMARCH1996 (VOL 14)
Downes 4, it does not create a patent-like propertyrights situation over genetic resources. Therefore, the
Convention is more relevant and specific to biotechnology firms than is generally recognized. It facilitates
the exchange of genetic materials by requesting the
signatory nations to '... endeavour to create conditions
to facilitate access to genetic resources for environmentally sound uses by other Contracting Parties, and
not to impose restrictions that run counter to the
objectives of this Convention' [Article 15(2)]. H o w ever, no legislative structure is imposed on unwilling
nations. The present situation, in which the majority
of the genebanks are under the control of the industrialized nations, while virtually all the genetic diversity
81
feature
originates in poor, developing countries s, is clearly
against the tenets of Articles 17 and 18. Article 15 of
the Convention specifically addresses access to genetic
materials, and is complemented by Article 16, which
calls for access to technology. These two articles are
the core tenets of the Convention dealing with the
issue of equity. Any agreement on genetic materials
must treat the two issues of 'access' as inseparable. To
reduce the clauses in Article 16 to mere payment o f
royalties, betrays a lack of understanding of the spirit
of the Convention.
While it is easier to design intellectual property
rights and royalty-sharing agreements around the use
of plant extracts exported to pharmaceutical companies, it is far more difficult to allocate specific
royalty percentages to genetic materials that are used
to create a new plant variety., as each plant may be just
one building block in a long lineage of the modern
crop variety. For example, at least 13 species o f
potato have been used in developing the most
common variety cultivated in the USA. So, how does
one then determine how to compensate individual
countries for the ownership of the cascade of genetic
materials that contributed to this crop? Agreements on
the exchange of genetic materials that have clauses for
substantial cash payments may, therefore, not be feasible in the agricultural sector. It has also been argued
that, while there is substantial commercial interest in
searching rainforests for plants with novel biological
activity for development into pharmaceuticals,
prospects of commercial gains in the agricultural
sector are less alluring 6. However, seed compames
make sufficient profit for a significant fraction of the
proceeds to be channeled back to source countries. In
order to achieve this linkage between 'access' and
'equity', various legal frameworks can be used, as long
as the issue of fair compensation is agreed by all
parties. The points to be negotiated include: methods
of sample collection; payment for the samples and
other forms of compensation; assurance o f future
supply of materials; reciprocity and equity considerations; and intellectual property issues (Box 3). Regardless of the type and content of the agreement, the issue
of'informed consent' nmst be ascertained prior to any
biological prospecting across national boundaries.
Indigenous peoples' rights
A consensus is now emerging that important values
and benefits lie in the conservation of the world's biodiversity - especially rainforests - and that the fate of
the earth's 'ark' of wild species cannot be separated
from material poverty in tropical countries. The Convention accords recognition to the contribution o f
indigenous peoples and their knowledge to the preservation of fragile ecological systems and the sustainable
utilization of genetic materials. The declaration by the
United Nations that 1993 should be the 'International
Year o f Indigenous Peoples', and the decade of
1995-2004 should be the 'International Decade for
the World's Indigenous Peoples' added a further
dimension to the issue of equity in trade on genetic
Box 3. Key issues that should be addressed
in a model contract for biodiversity prospecting
• Supply of samples (determination of the ownership of samples).
• Up-front payments and royalties.
• Non-monetary compensation: training and sponsorship of research
in the source country; availability of test results to source country
scientists; authorship of publications.
• Future supplies of raw materials: sustainable collection; collaborating institution and country as first source; fair price.
• Provisions for conservation.
• Technology transfer.
• Rights of indigenous people: reciprocity and equity considerations.
materials, and recognition o f the vital role that the
knowledge o f indigenous peoples plays in the use of
plants for medicinal purposes. While there is an apparent relationship between the two, there is a contradiction that is not immediately obvious. Recognition
of indigenous rights poses a serious dilemma for those
who wish to respect the sovereign rights of nations to
regulate access to their genetic materials and, at the
same time, accept the rights of indigenous connnunities.
These considerations have made the question of just
compensation one of the most intractable issues arising from the Convention. The Convention places the
ownership of genetic resources on national governments, yet the knowledge of the use of biogenetic
resources belongs to individuals and communities.
However, the interests of indigenous communities are
not necessarily in harmo W with those of the ruling
elites that control the national governments. A rigid
enforcement of the Convention to mean that all
genetic resources should be considered a legacy that
belongs to the nation may, in fact, be interpreted to
deny indigenous communities the ownership of rights
to their land, and to remove from them completely
the fundamental right of self determination. This is
clearly not the intention o f the Convention.
In designing co-operative agreements, the ownership
of genetic materials has to be separated from the ownership o f knowledge about plants. The much reported
INBio-Merck agreement provides an example in
which non-exclusive access to genetic materials has
been granted to a foreign private company through a
local facilitator7. While this type of agreement may be
appropriate for Costa Rica (a country without a large
population of indigenous people), it would be unsuitable for multi-ethnic societies, or in countries that lack
governments with responsive leadership. By relying on
ethnomedical knowledge as the main criterion in its
drug-development program, the US-based Shaman
Pharmaceuticals (South San Francisco, CA, USA)justifiably addresses the needs o f indigenous communities
as the core element of its reciprocity arrangements 8.
It would have been inappropriate for the company
to adopt the INBio-Merck model, or to treat the
issue o f compensation as a nation-to-nation affair.
Traditional healers and their communities deserve to
participate in decisions concerning the use of their
TIBTECHMARCH1996 (VOL 14)
82
feature
Box 4. Essential features of international
research collaborations
The relationship
• must yield tangible benefits for the partners - or realistic hope of
such benefits;
• should offer collaborative advantage;
• generate new shared values and not just an exchange of skills;
• should offer organizational flexibility, not be rigidly directed by
formal systems and contracts, and should involve interpersonal
contacts;
• should involve integration, whether it be strategic, tactical, cultural,
or interpersonal.
resources and knowledge, and to share in the benefits
that arise from commercialization of their resources.
The intra-national issues have to be separated from
international concerns, However, it has not yet been
resolved whether indigenous communities can enter
into international agreements without the endorsement or concurrence of their national governments.
Implementation of the CBD will not, by itself, prevent the erosion o f biodiversity; many factors contribute to the degradation of the environment and the
loss of the world's biological diversity. These include
unrestrained depletion o f resources by humans,
poverty, population growth, and inequalities in land
and resource tenure. Extraction from tropical forests
has not been proved to be a contributory factor in the
erosion ofbiodiversity, in fact, 'extractive reserves' are
a viable conservation strategy9.
Establishing a relationship - n o t just a deal
A co-operative agreement should not be perceived
as a mere business deal, because what is being traded
is not just a commodity but a priceless resource that
embodies the cultural views, life style and even religious icons of a community. The aim is to establish
a relationship that can be nurtured over time. Cultures
that have been governed by a philosophy based on
co-operation rather than on competition may be
viewed as foolish in the eyes of get-rich-quick
entrepreneurs. The value of the commodity to be
traded must also take into account the real or hidden
cost of the genetic resource. Therefore, the formal
document should be a covenant between two friendly
groups or partners with all the responsibilities, and
'caring and sharing' that characterize long-lasting
relationships; it should not be a dry legal agreement
between adversaries (Box 4). Nonetheless, the contract should cover all the key points that are considered
necessary in biodiversity-prospecting agreements 1°.
Fear o f being engulfed
Many scientists and industrialists from developed
countries, apparently with good intentions, try to
negotiate contracts with rural indigenous communities in order to ensure that benefits reach the true
owners of genetic materials. While this approach
guarantees direct compensation to the indigenous
TIBTECH MARCH1996 (VOL 14)
populations, the approach is flawed by the one-sided
nature of negotiations between unequal partners,
There is still the question about the extent of equity
that is possible from such an arrangement. It is imperative that a knowledgeable local institution should be
involved as a facilitator in negotiations between indigenous communities and foreign research institutions.
Even in negotiations involving two institutions, it is
helpful to choose partners that are relatively matched
in size and capability,
'Participation in the process' is the key - not
'share o f the product'
The discussion about intellectual property rights and
compensation has been reduced to determining the
share of royalties. The cost of developing a single
pharmaceutical agent is estimated to range from
US$200 million to US$380 million, depending on
the amount of work required to convert the active
molecule to a therapeutic agent. This expenditure
aggregates to an annual expenditure of over US$600
billion by the major pharmaceutical houses. A commitment to involve developing countries in research
and development activities, by channeling a small percentage of the 1K & D budget to the source countries,
is far more valuable to these countries than a promise
of large royalties that may never materialize.
Unrealistic expectations may harm biodiversity
conservation
Article 11 of the CBD calls on signatory parties to
formulate economically and socially sound measures
that act as incentives for the conservation and sustainable use of components of biological diversity. The
provisions of this section were not intended to replace
the financial arrangements envisaged under Articles 21
and 39. There is an increasing impression that biodiversity prospecting could serve as the main source
of funding for programmes to conserve biodiversity11.
Developing countries are being told that all their economic problems would be solved overnight from the
royalties generated by, supplying genetic materials to
pharmaceutical companies. The real benefit of establishing a biodiversity-prospecting partnership is that it
may provide the necessary stimulus and 'seed money'
to establish or improve the capacity of source countries to conduct research on genetic resources, and to
support indigenous biotechnology and pharmaceutical industries. The market potential o f crude drugs
from genetic materials is not as high as is often envisaged. If the expectation of a nmlti-million-dollar
windfall is not realized, there may be a backlash against
conservation.
In conclusion, it would be wise to remember the
words of caution credited to Sherblom: 'No negotiation, no matter how artful, can result in a preagreed
solution to every possible eventuality. N o contract, no
matter how carefully drafted, is entirely clear on everything that was intended by the principals, when they
are no longer around to interpret its clauses. Thus,
negotiations and contracts are, at best, agreements at a
83
Aueements f v &e hTtemational Agticuhural Research Centers?, p. 53,
point in time, and good relationships predictably
outgrow their original contracts. For the relationship
to grow and mature well over the years requires careful management of expectations' (Ref. 12, and cited
in Ref. 10).
International Plant Genetic Resources Institute
7 Reid, W. V. et al. (1993) in Biodiversity Pwspectiny: L#ing Genetic
ResourcesfJr Sustainable Development (Reid, W. V. et al., eds), pp. 1-52,
World Resources Institute
8 King, S. and Tempesta, M. S. (1994) in Ethnobotany and the Seanh
for ,N~'wEh'ugs (Ciba Found. Syrup.) (Vol. 185) (Chadwick, D. and
Marsh, J., eds), pp. 197-206, Wiley
9 Ryan, J. C. (1991) World lVatch,July/August, pp. 19-26
10 Laird, S. A. (1993) in Biodiversity Prospectin¢: Using Generic Resources
for Sustainable Development (Reid, W. V. et al., eds), pp. 99-130,
World Resources Institute
11 Escobar, G. The Washington Post 30July 1995 'IKainforest May- Hold
Prescription for Economic Survival' (Feature Article)
12 Sherblom, J. (1991) in The Business of Biotechnology: From the ldendl to
the Street (Ono, D., ed.), p. 223, Butterworth Heinemann
References
1 UN (1992) Convention on BiologicalDiversity, United Nations
2 Posey, D. (1990) Anthropol. Today 6, 13-16
3 Wolf, R. Business Monday, San lose Mercury N1,u,s 25 July 1994,
pp. 1F & 8F
4 Downes, D. (1994) BioScience 44, 381-383
5 Hobbelink, H. (1991) Biote~}mologyand the Future of World Agriadture,
p. 5, Zed Books
6 Barton, J. H. and Siebeck, W. E. (1994) in Materials Transfer
Engineering the rhizosphere:
expressing a bias
Kevin P. O'Connell, Robert M. Goodman and Jo Handelsmar
The rhizosphere is a largely unexplored frontier for genetic engineering. Processes
in the rhizosphere influence plant disease, plant nutrition and root architecture by
affecting the dynamics of microbial populations and communities. There is interest
in engineering plants to manipulate the rhizosphere for numerous reasons. Such
plants might resist soilborne pathogens more effectively, be better hosts to
beneficial microorganisms, remediate toxic waste, or attract communities of soil
microorganisms that enhance plant health. Central among the strategies to
engineer the rhizosphere is the effort to create a 'biased rhizosphere', which
involves engineering plants to secrete nutrients that specifically enhance the
growth of desirable microorganisms.
The exchange of nutrients and signals between parts
of the plant that are above and below ground is the
result of a remarkable genetic and developmental integration of roots and shoots. Roots supply inorganic
nutrients, including water, to the rest of the plant, and
play a crucial role in the hormone gradients that govern shoot ontogeny. Shoots fLx carbon through photosynthesis, and transport organic carbon to the roots,
which excrete a significant proportion of the plant's
carbon into the surrounding environment. This
surrounding environment, or the volume of soil that
is influenced biologically and biochemically by the
living root, is known as the rhizosphere 1,2. R o o t
K. P. O'Connell is at the N S F Centerfor Microbial Ecology, ,~lichigan
State University, East Lansing, MI 48824, USA. R. M. Goodman
and J. Handelsman ([email protected]) are at the Department
of Plant Pathology, 1630 Linden Drive, University of VViseonsin,
~9ladison, IYI 53706, USA.
exudates and secretions create a 'rhizosphere effect'
(Re£ 2), which manifests itself in the intense microbial
activity that is associated with the immediate vicinity
of the root.
Some of the microorganisms in the rhizosphere
contribute to plant health by mobilizing nutrients,
some are detrimental to plant health because they
compete with the plant for nutrients or cause disease,
and some stimulate plant growth by producing hormones or suppressing pathogens. Alteration of the
biological and chemical composition of the rhizosphere can, therefore, be expected to modify plant
health. Historically, various methods have been used
to modify the rhizosphere, including the application
of organic amendments and nficrobial inoculants, and
the manipulation of plant genotypes3 ~.
In this review, we focus on plant genetic engineering
to influence the rhizosphere; this involves manipulating
Copyright © 1996, Elsevier Science Ltd. All rights reserved. 0167 - 7799/96/$15.00
TIBTECH MARCH 1996 (VOL 14)