- Email: [email protected]
Future importance of biotechnology in arable farming
T I B T E C H - F E B R U A R Y 1 9 8 9 [Vol. 7]
in Sugar and Sweetener Situation and Outlook Yearbook, pp. 13-19, US Department of Agriculture, Economic Research Service, Washington DC 20005-4788, USA 3 Commodity Yearbook (1988) Commodity Research Bureau Inc., 82 Beaver Street, New York, NY 10005, USA 4 National Advisory Panel on CostEffectiveness of Fuel Ethanol Production (1987) Final Report on the Fuel Ethanol Cost Effectiveness Study, US Government Printing Office (Publication 1987-201-036:60252) 5 Chambers, R.S., Herendeen, R.A., []
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Joyce, J.J. and Penner, P.S. (1979) Science 206, 789-795 6 Venkatasnbramanian, K. and Keim, C. (1985) in Starch Conversion Technology (van Beynum, G. M. A. and Roels, J. A., eds), pp. 143-173, Marcel Dekker 7 Issues Facing Illinois Corn Growers
(1988) Kelly Harrison Associates Inc., Annandale, VA 22003, USA 8 Cooley, M. L. (1976) Feed Manufacturing Technology (Pfost, H. B., ed.), p. 285, American Feed Manufacturers Association 9 Corn Oil (1986) Corn Refiners Association Inc., 1001 Connecticut Avenue NW, Washington DC 20032, USA []
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Future importance of biotechnology in arable farming Nikolaus Gotsch and Peter Rieder In agriculture, biotechnology and genetic engineering are expected to change production methods, the products themselves and the structure of the whole agricultural sector. We have conducted an international survey of plant and microbial biologists, plant breeders and experts in product development and management to gauge the likely directions and time-scales for such developments. The survey aims to provide useful data for realistic discussion on the extent, purpose and effects of future developments in arable agriculture. Making any prognosis in plant b i o t e c h n o l o g y is c o m p l i c a t e d b y the time-scale in w h i c h technical dev e l o p m e n t s will b e c o m e relevant for practical agriculture - t y p i c a l l y 20 to 30 years. In addition, the lack of past experience h i n d e r s projections into the future. Of course, any forecast based on specialized literature could be misleading, because basic research success does not necessarily translate into applications u n d e r the ecological, e c o n o m i c and political circumstances of practical agriculture. Forecasting is also h i n d e r e d by the 'privatization' of information. N u m e r o u s studies carried out by commercial organizations for private Nikolaus Gotsch and Peter Rieder are at the Institute of Agricultural Economics, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zurich, Switzerland.
i n d u s t r y are not available to the public. In addition, they f r e q u e n t l y cover o n l y parts of the field or do not address the practicalities of farming.
Survey method Long-range forecasting must allow for discontinuities w h i c h can be caused by innovations. This excludes m e t h o d s based on statistics but 'intuitive' methods, such as the Delphi m e t h o d used in our s t u d y a, are suitable. In the Delphi p r o c e d u r e stage 1, a n o n y m o u s personal answers to questions from a formal questionnaire are analysed statistically to p r o v i d e a set of group answers. These are t h e n circulated to the participants, w h o m a y t h e n revise their answers in the light of the group response. The s u r v e y results comprise the analyses of these re-
10 Corn Wet-Millers Feed Products (1975) Corn Refiners Association Inc., 1001 Connecticut Avenue NW, Washington DC 20032, USA 11 Information Resources (1988) Octane Week October 10, p. 13 12 Gasoline - Monthly Energy Review (August) (1988) US Department of Energy 13 Weaver, J. B. and Beuman, H. C. (1973) Chemical Engineers' Handbook Sect. 25 (Perry, R. H. and Chilton, C. H., eds) (Vol. 8), pp. 31-32, McGraw-Hill 14 Flannery, R. J. and Steinschneider, A. (1983) Bio/Technology 1, 773-776 []
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vised opinions. For our study, we contacted experts in genetics and m o l e c u l a r biology, plant breeding, plant physiology, agricultural product research and d e v e l o p m e n t and c o m m e r c i a l aspects of agriculture (Table 1). To assist analysis, m a n y of the questions were phrased to yield a n u m e r i c a l answer. For instance, participants were asked to consider the following suggestion: Genes responsible for important agronomic traits (disease, pest and stress resistance, economically interesting secondary metabolites) can be identified by a routine procedure T h e y t h e n estimated h o w likely this was to be realized by 1997 or by 2007 (expressed as percentage likelihood). Other questions required an estim a t i o n of the m a g n i t u d e of particular future d e v e l o p m e n t s (e.g. the n u m b e r of herbicidal substances for w h i c h resistant crops will be available in 1997 or in 2007). The r e s p o n d e n t s could s u p p l e m e n t their n u m e r i c a l answers with explanations. We n a r r o w e d the scope of t h e s u r v e y b y concentrating particularly on crops c o m m o n in central Europe. Tropical crops were investigated o n l y if t h e y had been p r o p o s e d by the participants during the first stage of the investigation. Generally, we also tried to obtain forecasts of practical progress at the farm" level. The experts were r e q u e s t e d to answer o n l y the questions on w h i c h they c o n s i d e r e d themselves to be authorities. F r o m these answers we have
@ 1989, Elsevier Science Publishers Ltd (UK) 0167- 9430/89/$02.00
TIBTECH - FEBRUARY 1989 [Vol. 7]
--Table I
Participation in the study (a) Response to questionnaires First stage
made forecasts regarding both general and specific questions in plant agriculture.
Will the tools for genetic engineering in plant production be in place? Within the next ten to 20 years, agronomically important traits in crop plants will be manipulated by genetic engineering. But there will be no 'box of bricks' system enabling plant breeders to select traits using genes from a gene bank. Table 2 shows the summarized expectations of various steps in plant genetic engineering by 2007. Will the methods progress beyond basic research to the stage when they can be applied by specialized public or private institutions? Essentially, the survey suggests that the individual steps of genetic manipulation will be known and it will be possible to work on practically any trait - but only with considerable input of highly qualified staff and very expensive equipment. Research in plant genetic engineering will be done largely by private industry. Thus, all projects will be scrutinized for economic competitiveness. It follows that the crops most important for the world seed market will be pursued: corn (78% 'expectation' that the different steps of genetic engineering will be solved for single-gone traits by 2007), rice (76%), wheat and barley (both 67%). Of the dicotyledonous plants, potato (85%), rape seed (82%) and soybean (78%) will be of greatest interest, but so too will be the field pea (79%) and sugar beet (78%). Genetic manipulation of less important crops, such as common rye, common oats (both 62%) and triticale (60%), is likely to be less advanced. Many of the expert participants repeatedly warned against an overoptimism with respect to genetic engineering. Sixteen of them pointed out independently that there is practically no experience of the influence of new gone products on plant metabolism and very little is known about gone interactions. Thus, the isolation of genes, their transfer to cells of a target organism and the regeneration of plants from cells will only be addressed in the most economically interesting cases. Within the next ten to 20 years,
sent
S e c o n d stage
returned
returned
Total
157
69
62
Europe
115 42
59 10
56 6
81 76
38 31
35 27
Elsewhere Public Private
(b) Expertise of respondents Field
No. in field
Plant genetics and molecular biology Plant physiology Microbial genetics and molecular biology Plant breeding (private and public) Chemical and biological plant protection (except resistance
13 7
5 20
breeding) Research and development Product registration and management
there will be a number of varieties of genetically engineered, economically important crops available, containing single genes from microorganisms and plants. The following contributions can be mentioned: herbicide-resistant crops, virus-resistant potatoes and sugar beet, nematode resistance in potatoes and sugar beet, resistance of corn to the European corn borer Ostrinia nubilalis, resistance of wheat and barley to fungal diseases, protein quality improvement in cereals and legumes, and adapting the triglycerides of oil plants.
Biotechnology: its role in plant breeding There are several reasons why, in the next ten to 20 years, biotechno-
10 7
logical methods will not replace conventional plant breeding in the field, but complement it, suggests the survey. Despite biotechnology, field tests will still be necessary (mentioned by 17 participants). High labour and laboratory investments will increase its cost (eight participants). Some of these will be required to close the gaps between molecular geneticists working on model plants and conventional breeders' crops (17 participants). In any case, improvements in conventional plant breeding will compete with biotechnological methods (eight participants). The experts responding to our study expected a variety of biotechnological methods to improve plant breeding (Table 3). Overall, a reduction in the breeding time of
- - Table 2
Success anticipated in plant genetic engineering by 2007 Monocotyledonous plants Technical problem Gene mapping Gene isolation Gene transfer Targeted integration Gene activation and regulation Protoplast regeneration
single genes
several genes
++
-
Dicotyledonous plants
single genes
several genes
++
-
++ ++ -
++ -
++
+ ++
++
++, Probable (average median >60%); +, possible (average median 40-60%); - , improbable (average median <40%)
TIBTECH - FEBRUARY 1989 [Vol. 7]
Table 3
The expected use of different biotechnological methods in plant breeding Crop
Method Haploid breeding E m b r y o culture In-vitro selection S o m a c l o n a l variability Protoplast fusion In-vitro m u l t i p l i c a t i o n
cereals
corn
potato
++ + + . -
+ -
++ + + . + ++
.
. -
sugar beet
rape seed
grain legumes
+ + +
++ + +
+ + +
-
-
.
. + +
++, Probable (average median >60%); +, possible (average median 40-60%); - , improbable (average median <40%)
about 10-20% by 1997 and of about 20-30% by 2007 was expected. Biotechnological methods, especially for economically important crops, will thus make it possible to offer new marketable qualities more rapidly. Biotechnology will not primarily reduce the costs of plant breeding, but will increase the competition between breeders since speed to the market will become more critical (an important argument for six experts). However, an equal number of participants thought that this increased competition, combined with more stringent legal regulations, could demand more detailed and time-consuming tests, negating any time saved through biotechnology. Half the experts did not expect any cost reduction in the breeding of new varieties for the next 20 years. Nearly 20% felt that biotechnology will result in high labour and laboratory costs. A similar number thought that the gain of shortening the breeding time would be won only by higher technology costs. Furthermore, as nine participants pointed out, more breeding material would have to be tested to realize improvements on the already high level of performance. New breeding aims and breeding for resistance against new pathogens (e.g. Rhizomania of sugar beet) will increase costs.
Herbicide-resistant crops Of the specific projects considered in this study, the area of herbicideresistant crops seems to have the best chance of success by 2007. (The other projects were nutrient assimilation/ availability, nitrogen fixation, crop quality and photosynthesis.) Resistance is based on single genes and there are already resistant varieties of corn, rape. seed, potato, tobacco and
tomatoes. More are expected soon, e.g. soybean. Some of the experts (seven) forecast the development of crops resistant to herbicides that are themselves not yet on the market. The main criterion for success in the production of herbicide-resistant varieties of a crop is its economic importance on the seed market. Thus resistant corn seems the most likely (90% 'expectation' of resistant varieties by 2007), followed by soybean (85%), common rye (35%), common oats (30%), triticale (30%), field pea (60%) and faba bean (50%). Some (seven) experts felt the development of monocotyledonous herbicide-resistant crops (except corn) could be impaired by technical problems but more (13) thought
environmental, economic and legal aspects w o u l d be an impediment. In view of the effect of public opposition on regulatory measures for genetically engineered plants, 12 experts felt that only the environmentally safest herbicides would have a chance of success. Others (six) thought safety, price and the weed spectrum of the herbicides would be further aspects limiting the number of herbicides to which each crop could be made resistant. Half the experts believed that crops would be made resistant to between one and four herbicides by 1997 and between two and six herbicides (corn, four to ten) by 2007. High development costs and the appearance of resistant weeds could hinder progress.
Nutrient assimilation capacity and availability Most of the participants (-75%) felt that the application of nitrogen and phosphate per hectare would not increase within the next 20 years as plant varieties with improved nutrient assimilation capacity, or microorganisms that improve the plants' nutrient uptake are produced
-- Table 4
Possibilities for saving mineral nitrogen and phosphorus Nutrient
Possibilities f o r saving
nitrogen
phosphorus
By breeding
L o w - i n p u t varieties of corn and wheat, otl~erwise controversial
Little activity
By m a n i p u l a t i n g soil microorganisms
Possibly rice and sugar
cane Legumes: i m p r o v e m e n t of the f i x a t i o n capacity of rhizobia
Possibility of inoculation with mycorrhiza controversial
M o r e f r e q u e n t cultivation of legumes in the crop rotation By better use of organic manures
Existing
Existing
Saving in 1997 c o m p a r e d w i t h 1987
0-10%
0-10%
Saving in 2007 c o m p a r e d w i t h 1987
0-20%
0-20%
TIBTECH - FEBRUARY 1989 [Vol. 7]
Table 5
Practical nitrogen fixation in 2007: approaches and probabilities Use in Approach
non-legumes
legumes
Improvement of the N2-fixation efficiency of non-symbiotic and symbiotic N2-fixing microorganisms
General:
Probable (average median 40%) especially soybean (upper quartile 90%)
Transfer of nifgenes to non-legumes Transfer of genes for complete rootnodule symbiosis to non-legumes
(see Tables 4 and 5). Lowered nitrogen requirements are forecast for wheat, corn, rice and sugar cane. There were some voices of dissent. Several participants (five) had doubts about improving the nitrogen assimilation by breeding, especially over already high yields. Two respondents saw improved grain yield in cereals coming mainly via improvements in leaf area duration (LAD) - a function of leaf area and growing season. Improving it might impair the transfer of proteins from vegetative parts of the plant to the grain. It would then be necessary to supply extra mineral nitrogen. There could be nutrient saving from low-input varieties which have better nutrient assimilation capacities but do not attain top yields. Inoculation of plants with bacteria and a better knowledge of rhizobium genetics are also cited (five times) as likely to lead to nutrient savings by 2007. Of the minority who considered that there would not be a reduction in the mineral phosphorus requirement per hectare, four thought there were no short-term possibilities (until prices shifted significantly). Three others considered that mycorrhizal inocula would be ineffective because of competition with natqrally existing strains.
Unlikely (average median 0-20%) Exceptions: Rice: possibly use of N2-fixing symbiosis (S. rostrata, AnabenaAzolla symbiosis) Wheat, corn for extensive production: transfer of nifgenes to rhizosphere microorganisms which do not fix N2 naturally Sugar cane: possibly improvements of the fixation capacity of symbiotic N2-fixing microorganisms Unlikely (average median 0%) Very unlikely (average median 0%)
Nitrogen fixation Improving the nitrogen fixation capacity of symbiotic bacteria of legumes is considered to be the only way of improving biological N2 fixation within the next 20 years at the farm level (see Table 5). Even that could fail because of competition with microorganisms in the rhizosphere. A minority (two) foresaw the possibility that in wheat and corn (especially in varieties for extensive production systems) the transfer of nitrogen fixation capacity to microorganisms naturally associated with the crops in the rhizosphere could occur. The transfer of n i l genes to non-legumes, however, was considered impractical, at least within the 20-year time-flame, as was the transfer of genetic traits for complete root nodule symbiosis to non-legumes. Saving mineral nitrogen by improving nitrogen fixation was considered unlikely, although some savings may be made in low-yielding systems and where low levels of nitrogenous fertilizer are used. A few participants (three) foresaw good prospects for nitrogen-saving rice (e.g. by a simultaneous cropping and inoculation with stem-nodulating species like S e s b a n i u rostratu). Even if it became possible to make
nitrogen fixation available to nonlegumes, 56% of the respondents believed that there would be reductions in yield: nitrogen fixation requires energy (mentioned eight times) - the reduction in the net assimilation rate of legumes due to biological N2 assimilation is estimated to be 12-17%. A similar yield reduction could be expected for nonlegumes (but it could be even higher, especially in species with carbohydrate-rich seeds).
Composition of plant products Can the energy:protein ratio of crop plants, and especially the content of essential amino acids, be improved by genetic engineering? Several respondents (seven) felt that improvements in the amino acid pattern (particularly of wheat and barley) would be economically competitive), but a similar number argue that it would be more economic to satisfy protein needs using proteinrich crops, and to balance the energy:protein ratio by combined cropping of energy-rich and proteinrich plants or by mixing of their components after harvesting. Whether today's food crops will be used industrially or pharmaceutically is primarily a question of continued on p. 33
TIBTECH - FEBRUARY 1989 [Vol. 7]
continued from p. 32
future agricultural policies. Breeding and genetic engineering could produce varieties of different crops with special qualities if these were of economic interest in the face of competition from cell or microbial culture methods. The respondents believed that substances such as monoclonal antibodies, hormones, dyes or plastics would be synthesized more economically microbially (although petunia or tobacco, or cell and tissue cultures might be preferred if the substances were chemically complex). It was felt that, at least until 2007, plants would be used primarily as food, feed and industrial bulk raw material, and very little for the production of refined products such as pharmaceutical or fine chemicals.
Photosynthesis Will it be possible to reduce photorespiration with the aid of genetic engineering? Manipulating single aspects of carbon assimilation (e.g. reducing photorespiration by altering the carbon-fixing enzyme Rubisco) can only improve yield if other metabolic factors do not limit the transformation of these improvements to the final harvested crop, several respondents (nine) stated. In trying to increase yield by improving plant photosynthesis, one always needs to consider the implications for the physiology and architecture of the whole plant. The complexity of the readjustment that the plant might have to perform makes it impossible to foresee exactly the consequences of altered photo-
Table 6
The future contribution of biotechnology and genetic engineering to plant production under different scenarios Scenario more technology
as present
technology
1 1
1 2
2 3
1 1
1 1
2 2
1 1
1 1
1 2
less
Disease resistance
in-vitro methods (breeding) genetic engineering Pest resistance in-vitro methods (breeding) genetic engineering Virus resistance in-vitro methods (breeding) genetic engineering T o l e r a n c e to drought and cold in-vitro methods (breeding) genetic engineering Herbicide tolerance in-vitro methods (breeding) genetic engineering Amino acid pattern adaptation in-vitro methods (breeding) genetic engineering Improvement of nutrient assimilation capacity . in-vitro methods (breeding) genetic engineering Improvement of biological N2fixation capacity legumes
non-legumes Photosynthetic efficiency in-vitro methods (breeding) genetic engineering
1
1
2
3
3
4
1 1
1 1
1 2
1
1
1
1
1
2
1 2
2 3
2 4
1
2
3
3
4
4
1
2
2
3
4
4
1, certain; 2, probable; 3, improbable; 4, impossible
synthesis. However, there is consistency amongst the predictions of our experts for yield improvements due to photosynthetic efficiency. No one expected more than 10% yield increase for any crops listed by 1997; 50% of the experts forecast that ten years later in 2007 an increase of 1020% in yield could be clue to improvements in photosynthesis.
Conclusion We agree with other studies 2'3 that biotechnology in plant production will only refine conventional methods of research and development: [Biotechnology] is another tool [in] the arsenal of the conventional plant breeder. Biotechnology will provide for more rapid and precise introduction of improved plant traits and will provide the starting material that will be fed into conventional breeding programs. 2 This supports our finding that biotechnology helps to shorten the breeding" period for new varieties. The practical use of genetic engineering in plant production is a longterm matter. Products will be available after 1990, the earliest being plants improved in qualities influenced by single genes. Improvements through genetic engineering of traits controlled by several genes, such as tolerance to cold and drought or nitrogen fixation by non-legumes can be expected only after 2000. Biotechnology will be only one element of progress in plarrt production and can not be considered in isolation from other technologies. Furthermore,- the future importance of biotechnotogy depends on eco= nomic, legal and social developments. Table 6 summarizes the likely states of certain biotechnologies and genetic engineering in plant production in different scenarios in the year 2007 based on the responses of the participating experts in our study. In the 'more technology' scenario, research and development expenditures grow faster than today and the social, political and legal environment allows a better adoption of technological progress. In the 'less technology' scenario, the increase of expenditure in research and development is stopped, and the adoption of
TIBTECH
new technologies is delayed. The 'as present' scenario represents an extrapolation of today's situation. In all scenarios, biotechnology and genetic engineering will contribute to progress in plant production. R&D inputs and anti-technology measures will only influence the quantitative
and qualitative extent of its contribution.
References 1 Gotsch, N. (1988) Future BiologicalTechnological Progress in Plant Production, Institute of Agricultural Economics, Zurich 2 Farrell, C., Funk, T. and Brinkman, G.
Improved Trichoderma spp. for promoting crop productivity Ralph Baker Bacteria have potential advantages over fungi in biocontrol of plant diseases. Among these is the ability of some bacteria to colonize the rhizospheres of roots from inoculation onto seed. This property is k n o w n as rhizosphere competence. Fungal mutants have been produced, however, that are rhizosphere competent. These can not only protect developing roots from microbial attack in soil but also produce a plant growth-stimulating factor. Bacteria and fungi are frequently employed in research to promote crop productivity. They can be used for biological control of insects and microbial diseases; others may be used to parasitize and destroy weeds. Fungi have a number of advantages in some of these applications. They can induce resistance responses in plants ordinarily susceptible to pathogens 1. Avirulent strains of the devastating pathogen of chestnuts (Endothia parasitica) contain a factor - double-stranded RNA - that can be transmitted within the trees to debilitate virulent strains 2. Fungi may be antagonistic to pathogens: they can produce antibiotics; they may compete for nutrients essential for activities of pathogens; or they may become parasitic on other plantparasitic fungi 3. As well as this Ralph Baker is at the Department of Plant Pathology and Weed Science, Colorado State University, Fort Collfns, CO 80524, USA.
battery of mechanisms, fungi can use their hyphal morphology to glean resources from a wide catchment volume. Bacteria cannot do this. Fungi use such mechanisms for activity and survival in their ecological niche. While fungi certainly have no teleological objective of promoting crop production, scientists have wondered for over half a century whether it would be possible to exploit such attributes in biological control and for promotion of crop yields 4. But antagonists have their own agenda which does not necessarily conform to that of the crop scientist. Therefore, the challenge is to turn the performance of such creatures to human ends: to enhance their beneficial aspects by numerous strategies 5 including genetic improvement.
Strategies for genetic improvement Improvement by screening fungal agents for their potential use in biological control has limitations.
© 1989, Elsevier Science Publishers Ltd (UK) 0167- 9430/89/$02,00
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FEBRUARY 1989 [Vol. 7]
(1984) An Evaluation of the Economic Potential of Biotechnology in the Process of Crop Improvement, University of Guelph 3 Office of Technology Assessment (OTA) (1986) Technology, Public Policy, and the Changing Structure of American Agriculture, OTA-F-285, US Congress, Washington DC
In-vitro tests seldom mimic the conditions under which crops are produced so that extensive, timeconsuming studies of interactions between host, pathogen and environment, and the effects of potential biological control agents are necessary. Even the 'best' strains seldom meet all the requirements for efficient exploitation 5. Fungi could be genetically manipulated to acquire desirable traits through sexual recombination. Unfortunately, most of the potentially promising agents have no capacity for sex; they reproduce only asexually. Even in those fungi with sexual stages, genetic manipulation is often cumbersome and unpredictable. Fungi without functioning sexual stages may be altered genetically by three methods: conventional mutation techniques, protoplast fusion 6, or transformation systems 7. All of these presently have limitations. The greatest impediment to improving fungi, however, may be the limited fundamental knowledge of how, where and w h y fungi function in beneficial ways. For example, is the production of an antibiotic by an agent responsible for biological control of certain plant diseases3? If so, then efficiency of a fungus in biological control might be enhanced by modification of genes promoting antibiotic production and/or by inserting genes coding for the capacity to metabolize antibiotics. Similarly, the physiology of the competitive saprophytic ability of fungal agents is not well studied s. Enzymatic processes involved in mycoparasitism have been elucidated 9, but it is not known whether such antagonists can be induced to become more virulent. In some cases the processes involved in these mechanisms may be complex. When the targets are so undefined and the traits of interest are
in Sugar and Sweetener Situation and Outlook Yearbook, pp. 13-19, US Department of Agriculture, Economic Research Service, Washington DC 20005-4788, USA 3 Commodity Yearbook (1988) Commodity Research Bureau Inc., 82 Beaver Street, New York, NY 10005, USA 4 National Advisory Panel on CostEffectiveness of Fuel Ethanol Production (1987) Final Report on the Fuel Ethanol Cost Effectiveness Study, US Government Printing Office (Publication 1987-201-036:60252) 5 Chambers, R.S., Herendeen, R.A., []
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Joyce, J.J. and Penner, P.S. (1979) Science 206, 789-795 6 Venkatasnbramanian, K. and Keim, C. (1985) in Starch Conversion Technology (van Beynum, G. M. A. and Roels, J. A., eds), pp. 143-173, Marcel Dekker 7 Issues Facing Illinois Corn Growers
(1988) Kelly Harrison Associates Inc., Annandale, VA 22003, USA 8 Cooley, M. L. (1976) Feed Manufacturing Technology (Pfost, H. B., ed.), p. 285, American Feed Manufacturers Association 9 Corn Oil (1986) Corn Refiners Association Inc., 1001 Connecticut Avenue NW, Washington DC 20032, USA []
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Future importance of biotechnology in arable farming Nikolaus Gotsch and Peter Rieder In agriculture, biotechnology and genetic engineering are expected to change production methods, the products themselves and the structure of the whole agricultural sector. We have conducted an international survey of plant and microbial biologists, plant breeders and experts in product development and management to gauge the likely directions and time-scales for such developments. The survey aims to provide useful data for realistic discussion on the extent, purpose and effects of future developments in arable agriculture. Making any prognosis in plant b i o t e c h n o l o g y is c o m p l i c a t e d b y the time-scale in w h i c h technical dev e l o p m e n t s will b e c o m e relevant for practical agriculture - t y p i c a l l y 20 to 30 years. In addition, the lack of past experience h i n d e r s projections into the future. Of course, any forecast based on specialized literature could be misleading, because basic research success does not necessarily translate into applications u n d e r the ecological, e c o n o m i c and political circumstances of practical agriculture. Forecasting is also h i n d e r e d by the 'privatization' of information. N u m e r o u s studies carried out by commercial organizations for private Nikolaus Gotsch and Peter Rieder are at the Institute of Agricultural Economics, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zurich, Switzerland.
i n d u s t r y are not available to the public. In addition, they f r e q u e n t l y cover o n l y parts of the field or do not address the practicalities of farming.
Survey method Long-range forecasting must allow for discontinuities w h i c h can be caused by innovations. This excludes m e t h o d s based on statistics but 'intuitive' methods, such as the Delphi m e t h o d used in our s t u d y a, are suitable. In the Delphi p r o c e d u r e stage 1, a n o n y m o u s personal answers to questions from a formal questionnaire are analysed statistically to p r o v i d e a set of group answers. These are t h e n circulated to the participants, w h o m a y t h e n revise their answers in the light of the group response. The s u r v e y results comprise the analyses of these re-
10 Corn Wet-Millers Feed Products (1975) Corn Refiners Association Inc., 1001 Connecticut Avenue NW, Washington DC 20032, USA 11 Information Resources (1988) Octane Week October 10, p. 13 12 Gasoline - Monthly Energy Review (August) (1988) US Department of Energy 13 Weaver, J. B. and Beuman, H. C. (1973) Chemical Engineers' Handbook Sect. 25 (Perry, R. H. and Chilton, C. H., eds) (Vol. 8), pp. 31-32, McGraw-Hill 14 Flannery, R. J. and Steinschneider, A. (1983) Bio/Technology 1, 773-776 []
[]
[]
vised opinions. For our study, we contacted experts in genetics and m o l e c u l a r biology, plant breeding, plant physiology, agricultural product research and d e v e l o p m e n t and c o m m e r c i a l aspects of agriculture (Table 1). To assist analysis, m a n y of the questions were phrased to yield a n u m e r i c a l answer. For instance, participants were asked to consider the following suggestion: Genes responsible for important agronomic traits (disease, pest and stress resistance, economically interesting secondary metabolites) can be identified by a routine procedure T h e y t h e n estimated h o w likely this was to be realized by 1997 or by 2007 (expressed as percentage likelihood). Other questions required an estim a t i o n of the m a g n i t u d e of particular future d e v e l o p m e n t s (e.g. the n u m b e r of herbicidal substances for w h i c h resistant crops will be available in 1997 or in 2007). The r e s p o n d e n t s could s u p p l e m e n t their n u m e r i c a l answers with explanations. We n a r r o w e d the scope of t h e s u r v e y b y concentrating particularly on crops c o m m o n in central Europe. Tropical crops were investigated o n l y if t h e y had been p r o p o s e d by the participants during the first stage of the investigation. Generally, we also tried to obtain forecasts of practical progress at the farm" level. The experts were r e q u e s t e d to answer o n l y the questions on w h i c h they c o n s i d e r e d themselves to be authorities. F r o m these answers we have
@ 1989, Elsevier Science Publishers Ltd (UK) 0167- 9430/89/$02.00
TIBTECH - FEBRUARY 1989 [Vol. 7]
--Table I
Participation in the study (a) Response to questionnaires First stage
made forecasts regarding both general and specific questions in plant agriculture.
Will the tools for genetic engineering in plant production be in place? Within the next ten to 20 years, agronomically important traits in crop plants will be manipulated by genetic engineering. But there will be no 'box of bricks' system enabling plant breeders to select traits using genes from a gene bank. Table 2 shows the summarized expectations of various steps in plant genetic engineering by 2007. Will the methods progress beyond basic research to the stage when they can be applied by specialized public or private institutions? Essentially, the survey suggests that the individual steps of genetic manipulation will be known and it will be possible to work on practically any trait - but only with considerable input of highly qualified staff and very expensive equipment. Research in plant genetic engineering will be done largely by private industry. Thus, all projects will be scrutinized for economic competitiveness. It follows that the crops most important for the world seed market will be pursued: corn (78% 'expectation' that the different steps of genetic engineering will be solved for single-gone traits by 2007), rice (76%), wheat and barley (both 67%). Of the dicotyledonous plants, potato (85%), rape seed (82%) and soybean (78%) will be of greatest interest, but so too will be the field pea (79%) and sugar beet (78%). Genetic manipulation of less important crops, such as common rye, common oats (both 62%) and triticale (60%), is likely to be less advanced. Many of the expert participants repeatedly warned against an overoptimism with respect to genetic engineering. Sixteen of them pointed out independently that there is practically no experience of the influence of new gone products on plant metabolism and very little is known about gone interactions. Thus, the isolation of genes, their transfer to cells of a target organism and the regeneration of plants from cells will only be addressed in the most economically interesting cases. Within the next ten to 20 years,
sent
S e c o n d stage
returned
returned
Total
157
69
62
Europe
115 42
59 10
56 6
81 76
38 31
35 27
Elsewhere Public Private
(b) Expertise of respondents Field
No. in field
Plant genetics and molecular biology Plant physiology Microbial genetics and molecular biology Plant breeding (private and public) Chemical and biological plant protection (except resistance
13 7
5 20
breeding) Research and development Product registration and management
there will be a number of varieties of genetically engineered, economically important crops available, containing single genes from microorganisms and plants. The following contributions can be mentioned: herbicide-resistant crops, virus-resistant potatoes and sugar beet, nematode resistance in potatoes and sugar beet, resistance of corn to the European corn borer Ostrinia nubilalis, resistance of wheat and barley to fungal diseases, protein quality improvement in cereals and legumes, and adapting the triglycerides of oil plants.
Biotechnology: its role in plant breeding There are several reasons why, in the next ten to 20 years, biotechno-
10 7
logical methods will not replace conventional plant breeding in the field, but complement it, suggests the survey. Despite biotechnology, field tests will still be necessary (mentioned by 17 participants). High labour and laboratory investments will increase its cost (eight participants). Some of these will be required to close the gaps between molecular geneticists working on model plants and conventional breeders' crops (17 participants). In any case, improvements in conventional plant breeding will compete with biotechnological methods (eight participants). The experts responding to our study expected a variety of biotechnological methods to improve plant breeding (Table 3). Overall, a reduction in the breeding time of
- - Table 2
Success anticipated in plant genetic engineering by 2007 Monocotyledonous plants Technical problem Gene mapping Gene isolation Gene transfer Targeted integration Gene activation and regulation Protoplast regeneration
single genes
several genes
++
-
Dicotyledonous plants
single genes
several genes
++
-
++ ++ -
++ -
++
+ ++
++
++, Probable (average median >60%); +, possible (average median 40-60%); - , improbable (average median <40%)
TIBTECH - FEBRUARY 1989 [Vol. 7]
Table 3
The expected use of different biotechnological methods in plant breeding Crop
Method Haploid breeding E m b r y o culture In-vitro selection S o m a c l o n a l variability Protoplast fusion In-vitro m u l t i p l i c a t i o n
cereals
corn
potato
++ + + . -
+ -
++ + + . + ++
.
. -
sugar beet
rape seed
grain legumes
+ + +
++ + +
+ + +
-
-
.
. + +
++, Probable (average median >60%); +, possible (average median 40-60%); - , improbable (average median <40%)
about 10-20% by 1997 and of about 20-30% by 2007 was expected. Biotechnological methods, especially for economically important crops, will thus make it possible to offer new marketable qualities more rapidly. Biotechnology will not primarily reduce the costs of plant breeding, but will increase the competition between breeders since speed to the market will become more critical (an important argument for six experts). However, an equal number of participants thought that this increased competition, combined with more stringent legal regulations, could demand more detailed and time-consuming tests, negating any time saved through biotechnology. Half the experts did not expect any cost reduction in the breeding of new varieties for the next 20 years. Nearly 20% felt that biotechnology will result in high labour and laboratory costs. A similar number thought that the gain of shortening the breeding time would be won only by higher technology costs. Furthermore, as nine participants pointed out, more breeding material would have to be tested to realize improvements on the already high level of performance. New breeding aims and breeding for resistance against new pathogens (e.g. Rhizomania of sugar beet) will increase costs.
Herbicide-resistant crops Of the specific projects considered in this study, the area of herbicideresistant crops seems to have the best chance of success by 2007. (The other projects were nutrient assimilation/ availability, nitrogen fixation, crop quality and photosynthesis.) Resistance is based on single genes and there are already resistant varieties of corn, rape. seed, potato, tobacco and
tomatoes. More are expected soon, e.g. soybean. Some of the experts (seven) forecast the development of crops resistant to herbicides that are themselves not yet on the market. The main criterion for success in the production of herbicide-resistant varieties of a crop is its economic importance on the seed market. Thus resistant corn seems the most likely (90% 'expectation' of resistant varieties by 2007), followed by soybean (85%), common rye (35%), common oats (30%), triticale (30%), field pea (60%) and faba bean (50%). Some (seven) experts felt the development of monocotyledonous herbicide-resistant crops (except corn) could be impaired by technical problems but more (13) thought
environmental, economic and legal aspects w o u l d be an impediment. In view of the effect of public opposition on regulatory measures for genetically engineered plants, 12 experts felt that only the environmentally safest herbicides would have a chance of success. Others (six) thought safety, price and the weed spectrum of the herbicides would be further aspects limiting the number of herbicides to which each crop could be made resistant. Half the experts believed that crops would be made resistant to between one and four herbicides by 1997 and between two and six herbicides (corn, four to ten) by 2007. High development costs and the appearance of resistant weeds could hinder progress.
Nutrient assimilation capacity and availability Most of the participants (-75%) felt that the application of nitrogen and phosphate per hectare would not increase within the next 20 years as plant varieties with improved nutrient assimilation capacity, or microorganisms that improve the plants' nutrient uptake are produced
-- Table 4
Possibilities for saving mineral nitrogen and phosphorus Nutrient
Possibilities f o r saving
nitrogen
phosphorus
By breeding
L o w - i n p u t varieties of corn and wheat, otl~erwise controversial
Little activity
By m a n i p u l a t i n g soil microorganisms
Possibly rice and sugar
cane Legumes: i m p r o v e m e n t of the f i x a t i o n capacity of rhizobia
Possibility of inoculation with mycorrhiza controversial
M o r e f r e q u e n t cultivation of legumes in the crop rotation By better use of organic manures
Existing
Existing
Saving in 1997 c o m p a r e d w i t h 1987
0-10%
0-10%
Saving in 2007 c o m p a r e d w i t h 1987
0-20%
0-20%
TIBTECH - FEBRUARY 1989 [Vol. 7]
Table 5
Practical nitrogen fixation in 2007: approaches and probabilities Use in Approach
non-legumes
legumes
Improvement of the N2-fixation efficiency of non-symbiotic and symbiotic N2-fixing microorganisms
General:
Probable (average median 40%) especially soybean (upper quartile 90%)
Transfer of nifgenes to non-legumes Transfer of genes for complete rootnodule symbiosis to non-legumes
(see Tables 4 and 5). Lowered nitrogen requirements are forecast for wheat, corn, rice and sugar cane. There were some voices of dissent. Several participants (five) had doubts about improving the nitrogen assimilation by breeding, especially over already high yields. Two respondents saw improved grain yield in cereals coming mainly via improvements in leaf area duration (LAD) - a function of leaf area and growing season. Improving it might impair the transfer of proteins from vegetative parts of the plant to the grain. It would then be necessary to supply extra mineral nitrogen. There could be nutrient saving from low-input varieties which have better nutrient assimilation capacities but do not attain top yields. Inoculation of plants with bacteria and a better knowledge of rhizobium genetics are also cited (five times) as likely to lead to nutrient savings by 2007. Of the minority who considered that there would not be a reduction in the mineral phosphorus requirement per hectare, four thought there were no short-term possibilities (until prices shifted significantly). Three others considered that mycorrhizal inocula would be ineffective because of competition with natqrally existing strains.
Unlikely (average median 0-20%) Exceptions: Rice: possibly use of N2-fixing symbiosis (S. rostrata, AnabenaAzolla symbiosis) Wheat, corn for extensive production: transfer of nifgenes to rhizosphere microorganisms which do not fix N2 naturally Sugar cane: possibly improvements of the fixation capacity of symbiotic N2-fixing microorganisms Unlikely (average median 0%) Very unlikely (average median 0%)
Nitrogen fixation Improving the nitrogen fixation capacity of symbiotic bacteria of legumes is considered to be the only way of improving biological N2 fixation within the next 20 years at the farm level (see Table 5). Even that could fail because of competition with microorganisms in the rhizosphere. A minority (two) foresaw the possibility that in wheat and corn (especially in varieties for extensive production systems) the transfer of nitrogen fixation capacity to microorganisms naturally associated with the crops in the rhizosphere could occur. The transfer of n i l genes to non-legumes, however, was considered impractical, at least within the 20-year time-flame, as was the transfer of genetic traits for complete root nodule symbiosis to non-legumes. Saving mineral nitrogen by improving nitrogen fixation was considered unlikely, although some savings may be made in low-yielding systems and where low levels of nitrogenous fertilizer are used. A few participants (three) foresaw good prospects for nitrogen-saving rice (e.g. by a simultaneous cropping and inoculation with stem-nodulating species like S e s b a n i u rostratu). Even if it became possible to make
nitrogen fixation available to nonlegumes, 56% of the respondents believed that there would be reductions in yield: nitrogen fixation requires energy (mentioned eight times) - the reduction in the net assimilation rate of legumes due to biological N2 assimilation is estimated to be 12-17%. A similar yield reduction could be expected for nonlegumes (but it could be even higher, especially in species with carbohydrate-rich seeds).
Composition of plant products Can the energy:protein ratio of crop plants, and especially the content of essential amino acids, be improved by genetic engineering? Several respondents (seven) felt that improvements in the amino acid pattern (particularly of wheat and barley) would be economically competitive), but a similar number argue that it would be more economic to satisfy protein needs using proteinrich crops, and to balance the energy:protein ratio by combined cropping of energy-rich and proteinrich plants or by mixing of their components after harvesting. Whether today's food crops will be used industrially or pharmaceutically is primarily a question of continued on p. 33
TIBTECH - FEBRUARY 1989 [Vol. 7]
continued from p. 32
future agricultural policies. Breeding and genetic engineering could produce varieties of different crops with special qualities if these were of economic interest in the face of competition from cell or microbial culture methods. The respondents believed that substances such as monoclonal antibodies, hormones, dyes or plastics would be synthesized more economically microbially (although petunia or tobacco, or cell and tissue cultures might be preferred if the substances were chemically complex). It was felt that, at least until 2007, plants would be used primarily as food, feed and industrial bulk raw material, and very little for the production of refined products such as pharmaceutical or fine chemicals.
Photosynthesis Will it be possible to reduce photorespiration with the aid of genetic engineering? Manipulating single aspects of carbon assimilation (e.g. reducing photorespiration by altering the carbon-fixing enzyme Rubisco) can only improve yield if other metabolic factors do not limit the transformation of these improvements to the final harvested crop, several respondents (nine) stated. In trying to increase yield by improving plant photosynthesis, one always needs to consider the implications for the physiology and architecture of the whole plant. The complexity of the readjustment that the plant might have to perform makes it impossible to foresee exactly the consequences of altered photo-
Table 6
The future contribution of biotechnology and genetic engineering to plant production under different scenarios Scenario more technology
as present
technology
1 1
1 2
2 3
1 1
1 1
2 2
1 1
1 1
1 2
less
Disease resistance
in-vitro methods (breeding) genetic engineering Pest resistance in-vitro methods (breeding) genetic engineering Virus resistance in-vitro methods (breeding) genetic engineering T o l e r a n c e to drought and cold in-vitro methods (breeding) genetic engineering Herbicide tolerance in-vitro methods (breeding) genetic engineering Amino acid pattern adaptation in-vitro methods (breeding) genetic engineering Improvement of nutrient assimilation capacity . in-vitro methods (breeding) genetic engineering Improvement of biological N2fixation capacity legumes
non-legumes Photosynthetic efficiency in-vitro methods (breeding) genetic engineering
1
1
2
3
3
4
1 1
1 1
1 2
1
1
1
1
1
2
1 2
2 3
2 4
1
2
3
3
4
4
1
2
2
3
4
4
1, certain; 2, probable; 3, improbable; 4, impossible
synthesis. However, there is consistency amongst the predictions of our experts for yield improvements due to photosynthetic efficiency. No one expected more than 10% yield increase for any crops listed by 1997; 50% of the experts forecast that ten years later in 2007 an increase of 1020% in yield could be clue to improvements in photosynthesis.
Conclusion We agree with other studies 2'3 that biotechnology in plant production will only refine conventional methods of research and development: [Biotechnology] is another tool [in] the arsenal of the conventional plant breeder. Biotechnology will provide for more rapid and precise introduction of improved plant traits and will provide the starting material that will be fed into conventional breeding programs. 2 This supports our finding that biotechnology helps to shorten the breeding" period for new varieties. The practical use of genetic engineering in plant production is a longterm matter. Products will be available after 1990, the earliest being plants improved in qualities influenced by single genes. Improvements through genetic engineering of traits controlled by several genes, such as tolerance to cold and drought or nitrogen fixation by non-legumes can be expected only after 2000. Biotechnology will be only one element of progress in plarrt production and can not be considered in isolation from other technologies. Furthermore,- the future importance of biotechnotogy depends on eco= nomic, legal and social developments. Table 6 summarizes the likely states of certain biotechnologies and genetic engineering in plant production in different scenarios in the year 2007 based on the responses of the participating experts in our study. In the 'more technology' scenario, research and development expenditures grow faster than today and the social, political and legal environment allows a better adoption of technological progress. In the 'less technology' scenario, the increase of expenditure in research and development is stopped, and the adoption of
TIBTECH
new technologies is delayed. The 'as present' scenario represents an extrapolation of today's situation. In all scenarios, biotechnology and genetic engineering will contribute to progress in plant production. R&D inputs and anti-technology measures will only influence the quantitative
and qualitative extent of its contribution.
References 1 Gotsch, N. (1988) Future BiologicalTechnological Progress in Plant Production, Institute of Agricultural Economics, Zurich 2 Farrell, C., Funk, T. and Brinkman, G.
Improved Trichoderma spp. for promoting crop productivity Ralph Baker Bacteria have potential advantages over fungi in biocontrol of plant diseases. Among these is the ability of some bacteria to colonize the rhizospheres of roots from inoculation onto seed. This property is k n o w n as rhizosphere competence. Fungal mutants have been produced, however, that are rhizosphere competent. These can not only protect developing roots from microbial attack in soil but also produce a plant growth-stimulating factor. Bacteria and fungi are frequently employed in research to promote crop productivity. They can be used for biological control of insects and microbial diseases; others may be used to parasitize and destroy weeds. Fungi have a number of advantages in some of these applications. They can induce resistance responses in plants ordinarily susceptible to pathogens 1. Avirulent strains of the devastating pathogen of chestnuts (Endothia parasitica) contain a factor - double-stranded RNA - that can be transmitted within the trees to debilitate virulent strains 2. Fungi may be antagonistic to pathogens: they can produce antibiotics; they may compete for nutrients essential for activities of pathogens; or they may become parasitic on other plantparasitic fungi 3. As well as this Ralph Baker is at the Department of Plant Pathology and Weed Science, Colorado State University, Fort Collfns, CO 80524, USA.
battery of mechanisms, fungi can use their hyphal morphology to glean resources from a wide catchment volume. Bacteria cannot do this. Fungi use such mechanisms for activity and survival in their ecological niche. While fungi certainly have no teleological objective of promoting crop production, scientists have wondered for over half a century whether it would be possible to exploit such attributes in biological control and for promotion of crop yields 4. But antagonists have their own agenda which does not necessarily conform to that of the crop scientist. Therefore, the challenge is to turn the performance of such creatures to human ends: to enhance their beneficial aspects by numerous strategies 5 including genetic improvement.
Strategies for genetic improvement Improvement by screening fungal agents for their potential use in biological control has limitations.
© 1989, Elsevier Science Publishers Ltd (UK) 0167- 9430/89/$02,00
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FEBRUARY 1989 [Vol. 7]
(1984) An Evaluation of the Economic Potential of Biotechnology in the Process of Crop Improvement, University of Guelph 3 Office of Technology Assessment (OTA) (1986) Technology, Public Policy, and the Changing Structure of American Agriculture, OTA-F-285, US Congress, Washington DC
In-vitro tests seldom mimic the conditions under which crops are produced so that extensive, timeconsuming studies of interactions between host, pathogen and environment, and the effects of potential biological control agents are necessary. Even the 'best' strains seldom meet all the requirements for efficient exploitation 5. Fungi could be genetically manipulated to acquire desirable traits through sexual recombination. Unfortunately, most of the potentially promising agents have no capacity for sex; they reproduce only asexually. Even in those fungi with sexual stages, genetic manipulation is often cumbersome and unpredictable. Fungi without functioning sexual stages may be altered genetically by three methods: conventional mutation techniques, protoplast fusion 6, or transformation systems 7. All of these presently have limitations. The greatest impediment to improving fungi, however, may be the limited fundamental knowledge of how, where and w h y fungi function in beneficial ways. For example, is the production of an antibiotic by an agent responsible for biological control of certain plant diseases3? If so, then efficiency of a fungus in biological control might be enhanced by modification of genes promoting antibiotic production and/or by inserting genes coding for the capacity to metabolize antibiotics. Similarly, the physiology of the competitive saprophytic ability of fungal agents is not well studied s. Enzymatic processes involved in mycoparasitism have been elucidated 9, but it is not known whether such antagonists can be induced to become more virulent. In some cases the processes involved in these mechanisms may be complex. When the targets are so undefined and the traits of interest are