Biotechnology is affecting plant breeding in a number of different ways. 1. Advances in tissue culture and embryo rescue make it possible to use wild and weedy rice to develop new varieties that are resistant to diseases and pests for which genetic resistance had not been available.
2. Molecular markers have greatly increased the speed of screening germplasm of cultivated and wild rice by allowing the identification of a characteristic in the tissue of seedlings rather than waiting a season for the characteristic to express itself in the mature plant.
3. Recent advances in cloning genes and transforming plants greatly reduce the cost of using characteristics from landraces and wild relatives. Instead of requiring many years of backcrossing first to incorporate useful traits into high-yield varieties and then to eliminate harmful traits, the process can be reduced to a few years through biotechnology.
4. Genetic markers and maps will allow the identification of alleles for traits that are present in rice but which would never show up through conventional breeding.
5. Characteristics from other crops, from bacteria, and from animals can now be incorporated into rice, and the characteristics from rice can be incorporated into other crops.
In addition to its impact on the technology of plant breeding, biotechnology can reduce the cost of evaluating rice germplasm and wild relatives as they are collected or evaluating collections that are already in germplasm banks. The tools of biotechnology may make it easier to protect breeders' IPR by making hybrids easier to produce. In addition, in countries where new plant varieties can be protected with patents or plant variety protection laws, biotechnology may make it easier to prove that someone is copying your variety.
Like plant breeding, almost all of the rice biotechnology research in Asia is conducted by public sector research. By the autumn of 1992, India's total investment in rice biotechnology research was about $9 million at 19 institutions, which spent about $800,000 a year on current expenses. Seventy scientists, of whom 68 had PhDs, were working on rice biotechnology (Parthasarathy, 1993). Based on the number of Rockefeller Foundation projects in India and China, it appears that China was allocating perhaps twice as much annually to rice biotechnology as India. Unfortunately, we have not found any other sources of data on this. Comparing the number of conventional rice scientists in India with the number of biotech scientists shows that only a small share of total public research on rice is on biotechnology. Biotechnology is more expensive and better funded per scientist than conventional rice research.
IRRI's biotechnology research started with its wide crossing and anther culture programme in the 1980s. In the 1990s, IRRI worked with Cornell University and others to develop molecular markers for useful traits and a rice genome map. A molecular biology programme was initiated to increase basic understanding of rice and to develop and transfer the tools of biotechnology to national programmes. In the plant protection area, entomologists used biotechnology to study insect-plant interactions. IRRI purchased Bt genes for resistance to yellow stem borer from Ciba-Geigy for free use in developing countries. Plant pathologists are using biotechnology to study important rice diseases.
Two programmes have been established to encourage collaboration on rice biotechnology research among national programmes - the Rockefeller Foundation Rice Biotechnology Network and the IRRI Asian Rice Biotechnology Network. The Rockefeller Foundation has made a concerted effort to promote collaboration among developed and developing country scientists through financing the Rice Biotechnology Network, which brings scientists together, financing pre- and post-doctorates in the US and Europe, and financing collaborative research. Between 1984 and 1994, $62.7 million was committed to rice biotechnology research. In 1994, the budget for the Rice Biotechnology Network was $7.7 million.
The second programme to promote international collaboration is the Asian Rice Biotechnology Network (ARBN). It is led by IRRI and financed by the Asian Development Bank and the German aid agency. It was started in 1993. ARBN attempts to build or strengthen biotechnology research within research institutes and agricultural universities that have strong programmes of breeding, pathology, etc., for rice improvement and strong linkages with IRRI.
Relative to the size of public sector rice biotechnology research, private companies are carrying out only a limited amount of research. The number of private companies that are working on rice biotechnology is slightly larger than the number doing conventional rice breeding. In 1991, only a few companies were working on rice. Since then, Proagro/PGS and MAHYCO have established biotechnology laboratories working on rice in India. Agracetus and a number of other firms are working on rice biotechnology in the US.
Biotechnology in rice has made rapid progress in the last decade. In 1995, several breakthroughs in biotechnology occurred that should greatly enhance the productivity of rice breeding. First, transformation of indica rices using the ballistic gun and Agrobacterium has become relatively routine (G. Toenniessen, personal communication, 1996). Second, the first gene for disease resistance was cloned from an African wild rice, engineered into susceptible lines, and the transgenic plants showed resistance to the disease (bacterial leaf blight) (Song et al., 1995).
The techniques used in wide crossing (embryo rescue and tissue culture) were the first biotechnology techniques that encouraged breeders to use more than the elite lines and landraces that they usually use in their crossing programmes. It took 8-10 years of backcrossing and good luck to incorporate traits from a wild species, but it could be done. Thus, the only people who did this were international or government breeders who had long-term funding and a lot of patience.
Now, with the help of biotechnology, more breeders are exploiting traits from wild species because the time required has been cut to 2-3 years rather than 8-10 years. The head of IRG reports (M. Jackson, personal communication, 1996):
There seems to have been an increase in interest in the wild species and in recent years we have received more requests for these materials. We assume this is related to developments in biotechnology which are permitting researchers to use germplasm more effectively.
Most of the other work on rice biotechnology has so far primarily made use of the genetic material that conventional breeders are already using. For example, in the search for resistance to bacterial leaf blight, mentioned above, biotechnology scientists started their search using segregated materials from crosses that already included wild species that were thought to have some resistance. Biotechnology essentially greatly speeded up the process of identifying and engineering the gene into commercial varieties.
Some of the most recent work is less dependent on the collections of conventional breeders and thus is making use of a much wider range of genetic material. A group at Cornell and IRRI is using genetic markers to identify alleles that would never be identified by conventional breeding because they are 'hidden' by dominant characteristics. Dr Susan McCouch from Cornell and IRRI reports (personal communication, 1996):
I am able to say that our work with maps and markers is, in fact, providing evidence that wild or weedy ancestors can be productive sources of new genes for improvement of cultivated rice. We are demonstrating that marker-assisted breeding allows us to discover previously unidentified alleles hidden in low yielding wild ancestors that can boost yields of cultivated rice. The use of maps and markers not only provides an opportunity to identify these new alleles, but these tools also make it possible to speed up the process of moving them into locally adapted, highly productive cultivars. The concepts we are working with here at Cornell are aimed at broadening the pool of genetic diversity that breeders work with. ...
Today and in the near future it appears that, among the grasses, rice is more likely to be a source of genes and of probes for other species rather than other grasses being a major source of genes for rice. A few breeders of other grasses are starting to search rice genetic libraries for rice genes that control certain traits in rice and that they would like to have in other crops such as sorghum. The rice gene can be used to construct a probe. This probe can be used to screen germplasm of sorghum for the desired trait. If the trait is found, then it can be used in a conventional breeding programme or isolated and inserted into elite lines of sorghum. If the trait is not found, then the scientists might try to transform the sorghum by inserting the rice gene.
Another example of using the rice map for other crops is the CIMMYT/ORSTOM project studying apomixis in maize. They have not found apomixis in cultivated maize, but they recently identified the apomixis gene in a wild relative of maize, Tripsacum. Instead of going directly to maize to look for this gene and to study why it does not cause apomixis in the maize plant, they are first looking at the rice genetic maps. Using the markers from Tripsacum, they identify the region on the genetic map of rice where the apomixis gene is located. They then make probes from rice which can be used in Tripsacum and maize to study what turns apomixis on and off (D. Hoisington, personal communication, 1996).
These research projects are useful to rice scientists because they will identify and clone traits of rice which had not been done so far. Rice is chosen for a number of reasons: (i) the rice genome is smaller than that of most other grasses; (ii) more complete molecular maps of rice have been constructed; and (iii) bacterial artificial chromosome and yeast artificial chromosome libraries have been constructed and are more readily available because the Rockefeller Foundation has funded their construction, while libraries for corn, cotton and others are proprietary or more difficult to get access to.
Before the development of biotechnology, it was impossible to breed traits of crops other than rice or traits from bacteria or animals. Now that is possible. Are breeders now searching other crops for traits that they need in rice? The answer seems to be not yet. So far there have been no applications to the Rockefeller Foundation to do this type of research (G. Toenniessen, personal communication, 1996). The head of plant breeding at IRRI reports: 'I do not know of any project underway which aims at cloning genes from other cereals for transformation of rice. One project which is being discussed aims at cloning gene(s) for apomixis from pennisetum or brachiaria (range grass from Brazil) and their introduction into rice' (G. Khush, personal communication, 1996).
The most common use of non-crop genes that are being introduced into rice is Bacillus thuringiensis (Bt). The genes that produce poison to some insects are inserted into rice to protect against yellow stem borer and some other insect pests. Transgenic plants containing Bt are now being tested in a number of countries.
The use of genes from other crops, from bacteria or animals will become more important in the future. But in the near future it appears that the demand for rice germplasm is likely to be greater than the demand for non-rice genes by rice breeders.
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