|Keywords:||Apomixis, Technology transfer, Hybridization, Sterile seeds.|
|Correct citation:||Bicknell, R.A. and Bicknell, K.B. (1999), "Who Will Benefit from Apomixis?" . Biotechnology and Development Monitor, No. 37, p. 17-20.|
|Plant reproduction: Sexual versus asexual
Plants are either reproduced sexually by seed, or by some method of asexual propagation (cloning). In sexual reproduction, male and female gametes, the pollen and the egg cell, are produced separately with half the normal chromosome number. Their combination during fertilization gives rise to the development of a seed that carries a unique combination of the genes derived from both parents. It is this recombination that causes variability in a sexually propagated population, as expressed in characteristics such as plant height, vigour, seed size and nutritional composition. Seeds are physiologically robust, naturally primed for growth and adapted for field emergence. Sexual reproduction and genetic uniqueness appear to have provided most species with evolutionary advantages. In agriculture, however, it can be often regarded as undesirable, since it causes variation that can negatively effect production practices and the quality of the harvested and processed product.
Asexual reproduction, in contrast, provides the advantages of absolute crop uniformity. The genetic make-up of the parents is identical to the progeny, so a single desirable plant can become the basis of a new variety. The efforts essential for sexually propagated plants to ‘fix’ characteristics to ensure ‘true breeding’ are therefore unnecessary. Consequently, cloning makes the development of new varieties more time and cost effective. Many economically important fruiting plants, such as date palms and grapevines, have been propagated by vegetative means for hundreds, sometimes even thousands of years. Similarly, many root and bulb crops are cloned by natural means, such as cassava, potato and garlic. More recently, technologies such as tissue culture and cutting propagation have greatly expanded the number of species that can be cloned routinely. Despite these opportunities, however, cloning is currently only economic for plants that either use a convenient natural mechanism or that have a high unit value. Absent from this list are crops such as maize, rice, wheat, millet, sorghum, most pulse species, and the majority of economically important forage, fibre and timber species.
The potential benefits of apomixis
Six principle benefits of apomixis can be perceived:
Introduction of apomixis into crop plants
The potential value of apomixis for plant breeding has been recognized for many years. Attempts to introduce this trait into sexually propagated crops have taken two approaches.
|Current research on apomixis|
|wheat||Institute of Plant Genetics||Gatersleben, Germany|
|Hieracium||C&FR||Christchurch, New Zealand|
|evolution of apomicts||Utah State University||Logan, UT, USA|
|histology of apomixis||Jagellonian University||Krakóv, Poland|
|Taraxacum||NIOO||Heteren, the Netherlands|
|Pennisetum||USDA-ARS||Tifton, GA, USA|
|molecular tools for apomixis||CAMBIA||Canberra, Australia|
|Allium||Kyushu National Agricultural Experimental Station||Miyazaki, Japan|
|rice||Academia Sinica||Bejing, China|
|Pennisetum||University of Georgia||Tifton, GA, USA|
|Tripsaccum dactyloides||CIMMYT||Mexico, Mexico|
|somatic embryogenesis||Wageningen Agricultural University||Wageningen, the Netherlands|
|cassava||University of Brasilia||Brasilia, Brazil|
|Arabidopsis mutagensis||CSIRO||Canberra, Australia|
|University of California||Berkeley, CA, USA|
|Cold Spring Harbor Laboratory||Cold Spring Harbour, NY, USA|
|CPRO-DLO||Wageningen, the Netherlands|
|Harvard University||Cambridge, MA, USA|
Possible impact of apomixis on agricultural biodiversity
As apomixis results in the formation of large clonal populations, it represents a form of monoculture. It therefore poses a possible risk of widespread infestation, leading to varietal collapses and thereby losses in production. Although apomictic varieties can be vulnerable to collapse, they do have some advantages over current inbreds and F1 hybrid varieties, and could reduce the impact and frequency of such events. As resistance genes no longer need to be genetically fixed through homozygosity, many of the generations normally required to breed resistance could be skipped. Apomixis therefore permits the rapid development of new, resistant replacements for a collapsed variety.
Moreover, it facilitates the incorporation of several resistance genes in a new variety, reducing the possibility of future collapse, as multiple susceptibilities need to occur simultaneously. Currently, the main cost factor of a collapse is the use of a single variety, or a cohort of varieties with similar ancestry, over large areas of land. This is an indirect effect of the high cost of breeding. By reducing the cost and increasing the speed of varietal development, apomixis is expected to encourage the use of a broader range of varieties, each chosen either because they are uniquely suited to a particular micro-environment, farming practice or end use.
Furthermore, the simplicity of apomictic breeding may encourage the wider use of ‘synthetic’ varieties where several similar clones are deliberately mixed to provide field variation for characteristics such as disease resistance, yet still ensure sufficient uniformity for critical yield characteristics. Such synthetics may prove to be particularly suitable in developing countries, where yield security may be considered more important than absolute yield quantity.
In any crop at any one time, only a fraction of the original species diversity is utilized in production varieties. This would not change significantly with apomixis. By encouraging local breeding efforts, germplasm could be valued and become more dispersed, providing some extra security against its loss.
|Patents related to apomixis|
|Title||Abstract of claims||Applicant(s)|
|WO9743427 (13 May 1996)||production of apomictic seed||expression of a gene which renders the embryogenetic production of embryo sac tissue||Novartis|
|US5710367 (22 Sept 1995)||apomictic maize||maize/Tripsacum hybrids used to introgress apomixis into a maize background. DNA primers are listed to facilitate this process.||USDA|
|US5811636 (22 Sept 1995)
WO9710704 (23 Sept 1996)
|apomixis for producing true-breeding plant progenies||gene(s) transferred from Pennisetum squamulatum into cultivated plants resulting in apomictic progeny||USDA|
|WO8900810 (9 Feb 1989)
EP329736, AU629796, CN1040123, AU2255288
|asexual induction of heritable male sterility and apomixis in plants||induction of male sterility and apomixis through the introduction of transmissible male sterility factors present in extracts of male sterile alfalfa plants.||Maxell Hybrids Inc.|
|WO9836090 (17 Feb 1998)
|means for identifying nucleotide sequences involved in apomixis||genes in sexual species of Gramineae known to be orthologous to equences associated with apomixis in related species. Isolation and modification of those sequences.||CIMMYT-ABC|
|WO9833374 (5 Feb 1998)||methods for producing apomictic plants||construction of apomictic varieties by combining plants lines with asynchronous female developmental programmes.||Utah State University|
|CN1124564 (19 June 1996)||hybrid vigor fixing breeding process for rice apomixis||breeding and selection strategies for isolating apomixis in rice and for developing apomictic rice varieties.||Chen Jiansen|
|WO9828431 (24 dec 1997)||transcriptional regulation in plants||meiosis specific promoter that will direct gene activity to tissues associated with gamete formation in plants.||John Innes Centre Innovations Ltd|
|WO9837184 (28 Oct 1998)||leafy cotyledon1 genes and their uses||embryo specific genes and their promoters that will be valuable for targeting gene expression to embryos.||University of California|
|WO9808961 (5 March 1998)||endosperm and nucellus specific genes, promoters and uses thereof||endosperm specific and a nucellus specific promoter.||C. Linnestad, O.A. Olsen, D.N.P. Doan|
|Sources: http://patent.womplex.ibm.com/patquery; http://ep.espacenet.com/|
Distributing the benefits of apomixis
Apomixis is a technology with the potential to influence almost every farming system around the world. The distribution of rewards, however, will depend on the controlling parties and how they use this technology.
If apomixis were widely available to all parties, including breeders, seed merchants and producers throughout the world, its likely primary impacts would be to accelerate the rate of hybrid variety advance and to stimulate ‘boutique breeding’ towards specific product uses, production regions and farming practices. Apomixis technology could provide advantages to large and small producers in both the developed and developing worlds. Apomixis could also bring specific advantages to resource-poor farmers in developing nations. Currently, for many crops, the elite varieties available are bred for resource-intensive agriculture in the major production areas of the industrialized world. Furthermore, as they are controlled by international seed suppliers, the availability of seed is subject to variations in the global seed market. Apomixis would encourage local hybrid breeding programmes, which, if the agronomic characteristics are selected in a participatory manner, could ensure hybrid seed supply appropriate to farmers’ needs. Farmers could save and re-sow this seed without losing its vigour. However, the benefit for farmers would strongly depend on their ability to manage and control the use of apomixis themselves, and the possibilities for crossbreeding with locally adapted landraces. Furthermore, farmers, including peasants, producing for market or processing purposes could benefit from increased uniformity of yield.
The potential value of apomixis for the development and production of hybrids has been recognized for many years and it can be expected that seed companies will try to develop it as part of their technology portfolios. According to Michiel van Lookeren Campagne, head of the Department of Developmental Biology at the Centre for Plant Breeding and Reproduction Research (CPRO-DLO) in the Netherlands, all large ‘life science’ companies have an interest in apomixis research. At present, however, their research activity is rather limited to joint ventures, such as the contribution of Novartis (Switzerland) to the apomixis research of the European Plant Embryogenesis Network (EPEN). Novartis has already gained a patent through an earlier cooperation with CPRO-DLO (see table 2). However, Van Lookeren Campagne states that most life science companies seem mainly to be interested in keeping up to date with recent developments rather than having apomixis as a priority in their own research programmes. As apomixis undermines the proprietary protection currently provided by hybrid seed, commercial actors will only be able to reap the full benefits of apomixis if they can prevent farmers from seed saving. Therefore, recent technological developments in the control of seed germination, and the production crops that deliver non-viable seed, are of potential interest for these companies. According to Van Lookeren Campagne, however, it remains to be seen if the combination of these two approaches is technically feasible in the near future.
Apomixis technology could become a tool to cut costs in modern variety development. However, if apomixis technology were controlled by only one or a very small number of commercial entities, and protected by strict technical and/or legal means, then the wider benefits of this technology would hardly reach other actors in agriculture.
In May 1998, leading researchers in apomixis launched a declaration stating that apomixis technology needs to remain available to parties in, and/or working for developing countries. The Bellagio Apomixis Declaration expressed concern that the concentration of legal rights into a small number of hands will delay the utilization of this technology to address the needs of resource poor farmers. It was acknowledged that, realistically, the private sector will have an important role in developing apomixis technology and its commercial needs cannot be ignored. The challenge ahead will be to retain access for all parties while ensuring a reasonable return on investment for commercial agents. To this end, novel approaches to technology generation, patenting and licensing will need to be developed, because current practices promote monopolization. One possibility could be that key apomixis patents generated by public sector institutions are placed collectively under the trusteeship of a foundation. The licensing policy of this legal entity should be, while economically sound, sufficiently permissive to make the technology widely available to all interested parties.
Ross A. Bicknell1 and Katie B. Bicknell2
1. Crop & Food Research Ltd, Private Bag 4704, Christchurch,
Phone (+64) 3 325 64 00; Fax (+64) 3 325 20 74; E-mail firstname.lastname@example.org
2. Economics and Marketing Department, Lincoln University, Canterbury, New Zealand.
Jefferson, R.A. (1995), "Apomixis: A social revolution for agriculture?" Biotechnology and Development Monitor, 19, 14-16.
Koltunow, A.M., Bicknell, R.A. et al. (1995), "Apomixis: Molecular strategies for the generation of genetically identical seeds without pollination." Plant Physiology, 108, 1345-1352.
Bellagio Apomixis Declaration: http://billie.harvard.edu/apomixis/
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