Apomixis: the plant breeder's dream

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Date: 26 September 2001
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GRAIN | 26 September 2001 | Seedling - September 2001

 

APOMIXIS: THE PLANT BREEDER'S DREAM

by GRAIN

Seedling September 2001

www.grain.org/publications/seed-01-9-2-en.cfm

In discussions of the benefits genetic engineering can bring to small farmers, proponents love to point to apomixis - the production of cloned seed. This article examines apomixis research, and the main implications that transferring apomixis into crops may have for industry, farmers and the environment. It also looks at how the apomixis research agenda is being up led by the private sector through patent applications, licensing agreements and confidential research projects.
Apomixis is the asexual production of seeds, so that apomictic seeds are clones of the mother plant. Uncommon in wild plants and rare in crops, apomixis is one of the most cherished dreams of plant breeders. They argue that everyone would gain from apomixis: plant breeders would be able to produce new varieties of seeds more quickly and more cheaply; seed companies would gain from the accelerated breeding capabilities and their ability to produce new, cheaper varieties faster than their com-petitors. Farmers would be able to save hybrid seed for the following crop, saving themselves money and keeping their yields high. But in spite of earlier claims that its transfer into crops was around the corner, apomixis is proving elusive. Some experts predict that apomictic crops may still be 20 years away from reaching the market.

The apomixis accelerator

In nature, apomixis is widespread but infr-equent: it occurs in around 10% of the 400 families of flowering plants, but only in 1% of the 40,000 species that make up those families. Apomixis is most frequent in Gramineae (the cereal family), Compositae (which includes sunflowers), Rosaceae (which includes many fruit trees) and Asterceae (the dandelion family). Only a handful of crops are apomictic: citrus, mango, some tropical forages and a few others.
Apomixis can come about in two ways. Apomictic seeds can arise from a plant's sexual cells, which fail to go through the cellular mechanism underlying sexual reproduction (meiosis). Alternatively, seeds can be generated from non-sexual (somatic) cells. Sometimes, both sexual and asexual seeds develop from the same flower. Apomictic plants produce cloned seed, enabling them to reproduce asexually. But their pollen is often viable, so that apomixis can also be transmitted through the more common mechanism of sexual reproduction.

The most obvious benefit of introducing apomixis into crops would be to allow selecting an individual plant and propagate it as clones through its seeds. A second benefit would be to expand the range of wild relatives that could be integrated into breeding programmes. This is because asexual seeds can contain two sets of chromosomes of different sizes and still be viable, while equivalent sexual seeds would probably not develop.

Like genetic engineering, apomixis would demolish some of the species barriers that have contained the evolution of our crops. The combination of apomixis' capacity to create and stabilise new genetic combinations and to break the species barriers could lead to the "asexual revolution", which some think could even dwarf the Green Revolution.
As shown in the box on p 13, commercially viable apomictic seeds are still a far-off dream. The question is: would apomixis be worth the effort? What is to be gained from it?

GLOSSARY OF TERMS RELATING TO APOMIXIS

Backcrossing: A procedure for introducing characteristics from one donor variety or species into a second recipient variety or species. Backcrossing consists of crossing hybrids with the recipient variety, selecting the offspring expressing the targeted character, and crossing them with the recipient species again and again until a new line is obtained that resembles the donor species or variety in terms of the selected character.

Ectopic expression: Expression of a gene out of its expected time or place.

Functional Genomics: The science of how the genes in organisms interact to express complex traits.

Hybrid: This article refers to two kinds of hybrids. Interspecific hybrids result from crossing two related, but different, plant species. One example is crossing maize with its wild relative, Tripsacum sp. Intraspecific hybrids are the result of crossing two different varieties of the same species. The term "hybrid" is also used to signify intraspecific hybrids obtained from crossing two inbred lines of the same crop. These hybrids are commercially valuable because they express hybrid vigour.

Hybrid vigour: High performance (usually in terms of yield) expressed by interspecific hybrids, resulting from their genetic heterogeneity. This high performance is lost in hybrid offspring, forcing farmers to obtain new hybrid seed for every planting.

Inbred lines: Crop lines resulting from repetitive inbreeding. These lines are used to develop commercial hybrids.

Polyploid: Plant that receives more than one set of chromosomes from each of its parents. In turn, it transmits more than one set of chromosomes to its offspring. In contrast, diploid plants receive only one set of chromosomes from each parent, and transmit only one set of chromosomes to their offspring.

Supergene: a group of genes that are always transmitted together as a package.

 

Apomixis and formal plant breeders

To begin with, apomixis would dramatically decrease the costs of hybrid production. Just as farmers cannot save the seeds from hybrids because they do not breed true, neither can industry. Companies need land and labour to maintain the parental inbred lines that are crossed every year. With apomixis, hybrid seed could be developed from hybrid seed (see figure opposite), leading to impressive time and cost savings. An Australian study estimated that the introduction of apomixis in rice alone would have a value of US$2.5 billion (but note that the figure also includes the earnings from increased yields arising from the use of hybrids).

The implications of the apomixis-led accel-eration of plant breeding could be dramatic. Lower costs and much shortened time frames could change the focus of plant breeding. As AgBioTech Net says, breeders would be able to "genetically adapt plants to specific micro-environments, rather than the current practice of adapting the overall cultivation environment to the crop plants' requirements". Such breeding à la carte would further benefit from research on plant genomics, which aims to identify the groups of genes that are responsible for complex plant traits. Apomixis and plant genomics would also combine to quickly deliver uniform crops better tailored to end-product uses, be it as food, fibre, pharmaceuticals, plastic or any raw material.

The question of who controls or owns apomixis will determine the impact apomixis has on farmers, breeders and the seed industry. If made available in the public domain, apomixis would likely result in a general decrease of seed prices, and in a steep increase in the varieties available to farmers. If one or a few companies control apomixis, the effects would be radically different. Apomixis-led savings in variety development could allow the companies in control of the technology to push competitors out or impose abusive licensing conditions.

Apomixis and farmers

Farmers, and particularly poor farmers in developing countries, are expected to benefit from apomixis in two ways: saving hybrid seeds and stabilising their best plants. Commercial farmers are to benefit as clients of a more responsive seed industry.

First and most publicised, apomixis would allow farmers to save the seeds from hybrid plants but still conserve the superior yields. Farmers would no longer need to access or purchase new hybrid seed for every planting season in order to ensure a marketable surplus. In particular, apomixis would serve farmers living in remote areas where neither the seed industry nor governments can guarantee a yearly supply of hybrid seed. But apomictic seeds would still be hybrids, which means they would demand dependency on fertilisers and pesticides. Like other hybrids, apomictic hybrids would still be designed to perform their best under certain environmental conditions, which small farmers are unlikely to achieve and maintain. Apomixis might increase farmers' access to hybrids, but not their control of them.

Second and perhaps more important in the long run, apomixis would allow farmers to fix the genetic characteristics of any of their individual crop plants, by crossing them with an apomictic line (see figure on p 11). Apomixis would allow farmers to become faster breeders, just as it would for formal breeders. It would give farmers more control of their local agro-environment. It would theoretically guarantee yield and uniformity (and therefore, marke-tability) of their own selected varieties. For the pro-poor proponents of apomixis research, here lies its main potential.

Others are unconvinced. Many people working directly with farmers think that existing approaches to participatory plant breeding would be much more helpful. From her work on participatory breeding with Brazilian family farmers, Angela Cordeiro has learnt that skilled farmers breed for variability rather than yield, to afford security in the face of unpredictable environmental conditions. The stability and fixation entailed by apomixis is alien to small farmers' traditional strategies. In addition, Cordeiro's work has demonstrated that yields in traditional, open-pollinated maize varieties are limited by bottlenecks in soil management and seed storage, rather than genetic potential.

Farmers, and especially commercial farmers, are expected to benefit from the acceleration in formal plant breeding that apomixis would create: cheaper seed, more varieties adapted to their particular growing conditions and more potential end-product markets to choose from. This would depend on whether apomixis is accessible to all seed companies or only to a small group of them. In the latter case, companies might lower seed prices to wipe competitors out, and then raise them to whatever price they choose.

One of the significant threats to farmers getting any benefits from apomixis is the potential use of Traitor/Terminator Technologies, also known as Genetic Use Restriction Technologies (GURTs). Because in principle apomixis would allow farmers to save hybrid seed, it has been touted as the antidote to Terminator, which renders seeds sterile. However, seed companies will only capitalise on apomixis if they prevent farmers and competitors from obtaining clones from apomictic varieties. It seems likely that companies will use GURTs in conjunction with their apomictic varieties, just as they plan to do with other seeds. As a result, apomixis would not be an antidote to the Terminator: it would simply complement it.

SEARCHING FOR CLUES TO APOMIXIS

There are at least four different scientific approaches to the study of apomixis:

1) Generation of hybrids between crops and apomictic wild varieties. This strategy has been applied on maize, pearl millet, cassava, beets, apples, wheat grasses and wild rye. However, so far the lines obtained are agronomically unsuitable, only partially apomictic and even infertile.

2) Identifying and mapping the genes regulating apomixis, with the view of transferring them to crops through genetic engineering. Gene mapping efforts have found that apomixis is closely related to a supergene: a group of genes that are always transmitted together as a package.

3) Mutagenesis in model plants through the use of mutation inducers. This approach has been applied to wild mustard and rice.

4) Crossing plant varieties with different periods of egg development. John Carman of Utah State University is trying to obtain apomictic plants by crossing two plant varieties of the same species but with different periods for egg maturation. The idea is that the offspring of these matings might produce confusing signals about when to develop the egg, causing the plant to skip egg formation and produce an apomictic embryo. The University has created a new company, F1 Technologies, to commercially exploit its findings.

Recent research suggests that biology is at least as important as genes for apomixis to occur.
According to Dr. Yves Savidan, a leading authority on apomixis, apomictic plants seem to be caused by the ectopic expression of the genes regulating embryo development, which all plants with flowers share. In other words, the genes that regulate embryo development are "turned on" earlier than in sexual reproduction, and they are turned on in cells that would otherwise not be turned on at all. But this ectopic expression only results in apomixis where there is also a favourable genetic background.

Savidan is hopeful that the tools of functional genomics will elucidate the genetic switches triggering the ectopic expression of regulatory genes. These mechanisms could be introduced in crops through genetic engineering. The favourable genetic background is likely to be much harder to pin down. The supergene may play a role. Yet the fact that apomixis only happens in polyploid plants suggests that polyploidy might be a prerequisite for apomixis expression. Although some crops such as potatoes are polyploid, many others, including maize, rice and pearl millet, are not.

If apomixis is linked to polyploidy, then developing apomictic maize or pearl millet would only be possible after radically transforming the genetic structure of these crops. Thus it is not surprising that scientists forecast that developing apomictic maize may take up to 20 years.

 

Apomixis and the environment

The introduction of apomixis into crops would alter the genetic diversity of both crops and their wild, non-apomictic relatives. What the result would be nobody knows, because apomixis is so poorly understood. This makes predictions on apomixis' impact on biodiversity highly speculative, and even contradictory. The first image apomixis conjours up is uniform fields of clonic plants. More uniform than current monocultures, these crops will be more fragile, and more susceptible to pest and disease pressures. This will lead to an accelerated genetic treadmill to keep pest and diseases at bay. Some authors think that the low rate of apomixis in nature might be the result of extinction brought about by its long-term disadvantages.

There is also a danger that apomixis could harm the process of natural selection and reduce biodiversity. This may come about because of the way apomixis "fixes" genetic combinations, promotes asexual reproduction, and sometimes creates genetic combinations that are not even viable for sexual reproduction. These would place constraints on crop evolution that cannot compensate for clever genetic juggling in the long run. Sudden environmental changes and new pests or diseases would be harder to respond to, because there would be fewer viable varieties and a smaller genetic pool available.

There are a whole host of issues around the dangers of the apomixis mechanism spreading to wild populations and the impact that could have on genetic diversity and plant evolution. Since the genetic and biological basis of apomixis is still little understood, it makes speculation difficult, but there are some serious concerns. For example, it seems that in nature apomixis is limited to polyploid species, which are relatively few in number. But if it becomes feasible to transfer an apomixis supergene into diploid plants, the supergene could spread to wild diploid species. The competitive adv-antage this might afford these plants could lead to the genetic erosion of many of wild, non-apomictic relatives.

Corporations in pursuit

Commercially viable apomictic crops are still a dream, but the 15 patents and patent app-lications covering apomixis are real. Apomixis research accelerated in the late nineties, when most of these patent applications were filed. Five of the 15 patent applications belong to the public sector; five to multinational corporations; and four to academic research centres (see table opposite). But corporations have already managed to entangle themselves in the publicly-owned patents.

The first public institution to file apomixis-related patent applications was the US Dep-artment of Agriculture (USDA). The USDA initiated its work on apomixis in the 1960s. It has two main research lines on maize and pearl millet. The project on maize has been carried on in collaboration with the Institute of Cytology and Genetics at Novosibirsk in Siberia, Russia. This team obtained comm-ercially unviable apomictic lines through backcrossing with its wild relative Tripsacum. The team working on pearl millet undertook a parallel strategy, with equally limited results. However, in September 1995, the USDA filed patent applications on both teams' hybrid lines and some associated genetic markers.
The USDA has developed its apomixis patenting policy through consultations with the US seed industry. As a result, it decided to map, clone and sequence the genes in its patented lines in-house in order to ensure broad availability of the technology. Prior to this decision, though, the USDA had already agreed confidentiality agreements with more than 20 companies, including Pioneer Hi-Bred International. Whether these previous agreements will impact the availability of apomixis is unknown

In February 1997, the French development agency IRD (Institut de Recherche pour le Développement) and CIMMYT (the Inter-national Maize and Wheat Improvement Centre based in Mexico) filed a patent application on a method to identify genes involved in apomixis in Tripsacum. In 1989 the IRD/CIMMYT Apomixis Project was launched. Its aim was to transfer apomixis into crops so that small farmers in developing countries might even-tually be able to save hybrid seed.

The apomixis patent application was the first one ever filed by CIMMYT, which was heavily criticised by civil society organisations opposing the privatisation of agricultural research. CIMMYT claimed that it was pursuing a "defensive patent", that would: (1) ensure that the technology will be available to small farmers, by preventing others from appropriating the results of its joint project with IRD, and (2) provide a bargaining chip to access the genomics tools necessary to map the apomixis genes, by then mainly in private hands.

In 1997, IRD and CIMMYT started cons-ultations with large seed companies to further their research work. They refused Monsanto's inflexible request for an exclusive licensing agreement. After two years of negotiations, IRD and CIMMYT entered into five-year research collaboration with a consortium of three multinational seed companies - Pioneer Hi-Bred International (since bought by DuPont), Limagrain (closely linked to Aventis) and Novartis Seeds (now part of Syngenta). Under the terms of the (confidential) agreement, the companies received a global non-exclusive license to the research from the partnership. CIMMYT and IRD also received a global license, which is confined to research products for subsistence farmers (defined as those with farms where more than 50% of the harvest is used on the farm).

By virtue of this agreement, a successful IRD/CIMMYT Apomixis Project could ensure subsistence farmers' access to the technology, but it would also have very significant imp-lications for the seed industry. Support to the IRD/CIMMYT initiative might help Pioneer, Limagrain and Syngenta push out smaller seed companies because of their lower costs of seed production. The stakes are very high, and Pioneer, Limagrain and Syngenta seem bent on controlling apomixis technology if and when it materialises. The three companies have developed - and patented - their own apomixis technology and also have entered into partner-ships with several research initiatives from the public and academic sectors (see table). The three of them seem to have created a consortium on apomixis and even outlined their agenda in a paper on the socio-economic impact of apomixis at the 2nd International Apomixis Conference. The key points of their agenda are:

· First and foremost, respect for intellectual property rights on apomixis and enabling technologies;
· The need to ensure that technology "donated" for humanitarian use does not interfere the patent owners' profits, and
· Introducing technologies that "might need to be brought into an overall apomixis utilisation plan"; ie preventing commercial farmers from saving apomictic seed.

Patent applications on apomixis

Institution Status No.

USDA

Public

3

Cold Spring Harbour Lab

Public

3

ORSTOM/CIMMYT

Public

1

University Utah State

Public

1

Novartis

Private

2

Pioneer Hi-Bred; DuPont

Private

1

Advanta

Private

1

Sudwestdeutsche Saatzucht

Private

1

Mary Wiles Eubank

Private

1

Rohm & Hass

Private

1

Source: compiled by GRAIN


Private money, private information

Although no figures on the investments on apomixis have been published, it can be safely assumed that currently the public sector accounts for half of current investment. Much of the private money has been channelled into public research projects. As a rule, such collaboration agreements include clauses preventing the early dissemination of research results, which turn into proprietary information. As a consequence, information flows among the scientific community have collapsed to the point that, in 1999, the CIMMYT-based "Apomixis Newsletter" was discontinued, as it was not relevant any more.

The same secrecy permeated the 2nd Inter-national Apomixis Conference. Many groups could not share their most relevant results because of their legal obligations. Ironically, many of them worked with the same companies. As a result, the public research programmes are left in the dark, working on their particular piece of the puzzle. Only the gene giants can see the whole picture.

Apomixis and the gene giants: research partnerships and collaborative agreements

Company Partner Relationship

Syngenta

EPEN (European Palnt Embroyogenesis Network)

Novartis involved in the project "Apomixis in agriculture: a molecular approach"

Syngenta

ECAA (European Concerted Action on Apomixis)

Syngenta to participate in the creation of European Apomixis network

Limagrain

ECAA

Limagrain has followed up Biogema's work in the ECAA

Limagrain

Australian National University

Common research to find genes regulating meiosis

Pioneer, Syngenta, Limagrain

IRD/CIMMYT

Non-exclusive use of IRD/CIMMYT patent

Pioneer Hi-Bred

USDA

Pioneer providing money and technology for USDA work on pearl millet

Pioneer Hi-Bred

Agricultural University of Norway

The university uses Pioneer's gene collections in its research

Source: compiled by GRAIN


Should we worry about apomixis?

Apomixis is likely to remain one of the most cherished dreams of plant breeders for many years to come. The hurdles are significant, but key actors seem motivated because the rewards could be immense. Companies are likely to continue investing in apomixis research because of the technology's potential to transform agriculture completely. Apomixis could put an end to variability within plant varieties and hence make them more predictable. This would open the way to the use of plants as bioreactors to extract uniform, high-quality substances for any kind of industrial use. Agriculture could then compete with industry in producing organic polymers, for example. Servicing a whole new range of markets promises spectacular profit gains to the seed industry.

For gaining public support for apomixis, industry is likely to emphasise its positive impact on small farmers. But the likelihood is that if the gene giants are controlling apomixis, none of these benefits will materialise. Small farmers working with traditional varieties might have more to fear from apomixis than to gain from it. Apomixis' ability to genetically freeze particular plants would compromise attempts to maximise variability, which is an important farmer strategy. Moreover, if polyploidy turns out to be a prerequisite for apomixis and the seed industry turns exclusively to polyploid seeds, farmer's diploid varieties will be further marginalised. In fact, apomixis might be marginalising farmers' varieties already. By promising to solve farmers' loss of hybrid vigour, it indirectly helps to promote hybrids at the expense of other technological options which are more appropriate to farmers' objectives of minimising risk and promoting diversity in their crops.

Apomixis caters to industrial agriculture's corporate agenda, rather than food security or farmers' needs. It should not be up to corp-orations to decide on whether or not to introduce it into agriculture. No one knows what the mid- and long-term impact of apomixis would be on crop diversity, biodiversity and the environment more generally. After all, transferring apomixis to crops equates with removing the reproductive barriers that have shaped domestication. This is too serious an issue to mess about with, no matter how cherished the dream of apomixis might be.

Main Sources:

· Vieille Calzada et al (1996), "Apomixis - The Asexual Revolution", Science 274 (5291): 1322.
· Ramulu KS et al. (1999) "Apomixis for crop improvement", Protoplasma, No 208, p 196-205.
· Spillane C (2000) "Could agricultural bio-technology contribute to poverty alleviation?", AgBiotechNet 200, Vol 2 March, ABN 042. www.agbiotechnet.com/reviews/march00/html/spillane.htm.
· Savidan, Y (2000), "L'apomixie, ou le clonage par les graines", Biofutur No. 198, March 2000.,
· Bicknell, RA, Bicknesll, KB (1999), "Who will benefit from apomixis?, Biotechnology and Devel-opment Monitor .No.37, pp 17-20, and
· RAFI (1999), "Traitor Technology: The Term-inator's wider implications", RAFI Comunique, 30/01/1999
· Van Dijk P and Van Damme J (2001) "Apomixis technology and the paradox of sex", Trends in Plant Science, Vol 5, No 2, pp 81-84.
· Kuyek D (2001), Intellectual Property Rights: Ultimate Control of Agricultural R&D in Asia, Biothai, GRAIN, KMP, Masipag, PAN Indonesia, Philippine Greens and UBINIG.
· Albertsen MC et al, "ABC's that Impact The Future Of Apomixis", Programme and Abstract Book of the 2nd International Apomixis Conference, p. 67



Reference for this article: GRAIN, 2001, Apomixis: the plant breeder's dream, Seedling, Volume 18, Issue 3, September 2001, GRAIN Publications

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