4. Analysis of the FAO-BioDeC data on genetically modified (GM) crop varieties

This section contains an analysis of the data gathered to date on transgenic plant varieties which are resistant to pathogens, pests, herbicides, tolerant to abiotic stresses, and with modified quality traits.

4.1 TRANSGENIC CROP VARIETIES RESISTANT TO PATHOGENS0

The data contained in the FAO-BioDeC related to transgenic varieties resistant to pathogens are summarized in Table 6. These data suggest that most pathogen-resistance development programmes oriented towards the development of genetically modified (GM) plant varieties, are concentrated on generating resistance to viruses and fungi, particularly in Asia and Latin America, with very little activity devoted to developing transgenic crop varieties resistant to bacteria.

The current emphasis on viruses most likely reflects the relative simplicity of viral genomes, and the generic `proof of concept' of virus-derived strategies such as coat protein and replicase-mediated resistance in generating virus-resistant transgenic varieties.

Transgene-mediated resistance strategies against fungi are still in their infancy. Overall, it is unclear from the available data in the inventory why transgenic approaches are more predominant for fungal compared to bacterial pathogens, or why some regions report more research initiatives than others.

Although planting disease-resistant varieties is one of the better ways of combating viruses, bacterial and fungal plant pathogens, as with all biotic stresses with the capacity to mutate and evolve, it would be prudent to develop resistance management strategies to limit the incidence of selection for resistance-breaking pathogen isolates.

4.1.1 Development of transgenic crop varieties resistant to viral diseases

In the case of virus resistance, conventional strategies to control viral diseases are limited to the production of virus-free propagation material and to the control of insects transmitting virus pests. While some crop gene pools harbour resistance to viruses, there are crop gene pools which are completely lacking in resistance against key virus pathogens. The figures in Table 6 suggest a rapid adoption in some regions of pathogen-derived transgene-mediated virus resistance strategies, which were first demonstrated in greenhouses in 1986 for tobacco mosaic virus (TMV) (Beachy, 1999). The few examples of large-scale plantings of virus resistant GM varieties should be monitored to determine if resistance breaking variants of the virus pathogens are being selected over a number of growing seasons for large scale crop populations.

In Africa, only three crops, sweet potato, potato and maize, have so far been targeted for transgene-mediated virus resistance. The FAO-BioDeC indicates only two transgenic varieties that to date have been tested in a field trial, namely, a sweet potato variety for resistance to sweet potato feathery mottle virus (SPFMV) in Kenya and a potato variety for resistance to potato leaf roll virus (PLRV) in South Africa. The FAO-BioDeC currently reports only three other research initiatives in an experimental phase in South Africa, namely, the development of potato for resistance to potato virus Y (PVY) and potato virus X (PVX), and development of maize resistant to the maize streak virus (MSV). The inventory indicates that no virus resistant GM varieties have been commercially released in Africa.

In the Eastern and Central Africa region, maize is a major staple of the rural and urban poor. In the same region, potato has become a major highland cash crop and a food staple in some urban areas. Sweet potato is an important crop in the countries surrounding Lake Victoria (Burundi, the Democratic Republic of the Congo, Kenya, Rwanda, United Republic of Tanzania and Uganda). The FAOSTAT database indicates that the 2003 production in Africa for sweet potato was 10 787 127 tonnes, potatoes 12 530 119 tonnes and maize 43 522 313 tonnes. Indigenous to Africa and its offshore islands, MSV causes yield losses of up to 100 percent even in high potential agricultural zones. MSV is considered the most serious virus threat to maize production in Africa, while SPFMV is a serious constraint to sweet potato production.

TABLE 6
Number of initiatives to develop GMOs with resistance to pathogens

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of countries involved (for the total column of N, if more than one activity is being carried out by a given country, the country is only counted once).

In the Near East region, Egypt is conducting field trials on virus-resistant GM varieties of potato, tomato, cucumber, melon, muskmelon, cantaloupe, squash and sugar cane. Tunisia has initiated virus-resistant GM research work on potato and Vitis, and The Islamic Republic of Iran has initiated this research work on sugar beet. Most virus-resistant GM varieties under field testing are of imported origin. However, one country in this region, Egypt, is carrying out field testing of locally developed virus resistant varieties, mainly cucurbits with resistance to ZYMV, and potato resistant to PVY and PLRV.

At least two virus-resistant transgenic crop varieties have been commercially released in the Asia region. These include virus-resistant tomato and green pepper varieties in China. In general, current research efforts to develop transgenic virus-resistant crop varieties in this region are mostly focused on Solanaceae, Cucurbitaceae and tropical fruit trees. Special attention is being given to development of virus-resistant papaya, as transgenic papaya varieties resistant to papaya ringspot virus (PRSV) now provide an additional strategy to restore papaya cultivation in areas where the virus has been most destructive (e.g. in Hawaii where major successes have been reported). Research has been reported in Malaysia, the Philippines and Thailand on the development of different ring spotvirus resistant transgenic varieties of papaya, some being combined with delayed fruit ripening.

Field trials are being conducted in China for transgenic varieties exhibiting resistance to: CMV in sweet pepper, CMV and TMV in chilli pepper, TMV in tobacco, PRSV in papaya, stripe virus in groundnut, PVY in potato, BYDV in wheat and turnip mosaic virus in Chinese cabbage. Laboratory stage research work on RDV in rice and WYMV in wheat is in progress in China. Thailand has field trials in progress for transgenic virus resistant varieties of tomato (TYLCV), papaya (PRSV) and pepper (CVbMV), and laboratory stage work on pepper (PepLCV), yard long bean (aphid-borne mosaic virus) and rice (ragged stunt virus). The Philippines has field trials underway for virus-resistant transgenic varieties of banana (BTV), and laboratory stage experimental work on transgenic papaya (PRSV). Indonesia has laboratory research underway on the development of virus-resistant peanut (peanut stripe virus), tobacco (TMV), sweet potato (SPFMV), chilli pepper, papaya and potato (PVX and PVY) varieties. Malaysia is conducting transgenic experiments on the development of virus-resistant rice (tungro virus), papaya (PRSV), pepper (CMV) and chilli pepper, while Bangladesh is undertaking research on papaya to develop transgenic cultivars resistant to papaya mosaic virus. India and Pakistan are currently working on the development of virus-resistant rice, cotton, as well as tomato (Pakistan only).

Of all the regions covered by the FAO-BioDeC, Latin America has the highest number of reported research activities regarding the development of transgenic virus-resistant crop varieties. The FAO-BioDeC indicates that nine countries in Latin America are conducting research and/or development on transgenic virus-resistant crop varieties: Mexico (14 reported activities), Brazil (13), Cuba (four), Argentina (two), Colombia (two), Peru, Chile and Costa Rica (two each), and Venezuela (one). No virus-resistant transgenic crop variety has been reported to be commercially released in this region. In Brazil, field trials are underway for virus-resistant transgenic varieties of sugar cane (SCMV, yellow virus), potato (PVY, PLRV), papaya (PRSV), tobacco (TSWV, PVY), bean (bean golden mosaic virus), Solanaceae (isolation of virus resistance genes), and tomato (Gemini and Tospovirus), and laboratory stage experiments are underway on virus-resistant sugar cane. Mexico has virus-resistance trials underway on varieties of papaya (PRSV), potato (PVY and PVX), squash (PAMV, SMV2 and ZaMV), tobacco (TMV), zucchini (PMV, PAMV, SMV2 and ZaMV), melon (CMV), and tomato (CMV). In Cuba, field trials of virus-resistant varieties of papaya (PRSV), and experiments on potato (PLRV), citrus (tristeza virus), and tomato (Gemini virus) are underway. Laboratory stage experiments to develop virus-resistant transgenic varieties are ongoing in Chile for potato and melon, in Costa Rica for rice and maize, in Venezuela for coffee and in Peru for potato and sweet potato.

The large number of research activities reported in the FAO-BioDeC, regarding genetic engineering approaches to generate virus-resistant crop varieties indicates that the basic molecular techniques are well established to develop transgene­cassette based approaches for control of most crop viruses. This basic molecular biology capacity is seemingly available in many of the countries covered by the database and the transgene cassettes can often be developed or obtained through collaboration with partner laboratories in other countries with more advanced research capacity. The rapid adoption of this technology within the context of broader agricultural R&D reflects the widespread occurrence of viruses across the regions and crop species, and the difficulty of controlling crop viruses by conventional (non-transgenic) means.

4.1.2 Development of transgenic crop varieties resistant to bacterial diseases

The FAO-BioDeC provides details on the use of genetic engineering for the development of bacterial-resistant transgenic crop varieties. The results suggest a low level of R&D activity in this area in the five regions. Just one transgenic variety with enhanced bacterial resistance is reported as being under field trial - a potato variety with wilt resistance in China. However, laboratory stage research initiatives to develop bacterial resistant crop varieties are reported in six countries: in China (potato and wheat wilt resistance); in Thailand (bacterial wilt and other resistances in tomato); blight resistance in Basmati rice in Pakistan; leaf blight in rice, potato and cabbage in the Republic of Korea ; and also bacterial-resistance work on jute in Bangladesh and banana in Venezuela.

The lower level of activity on resistance to bacterial diseases compared to other diseases may be due to both a lower perception of the importance of bacterial diseases and the number of crops infected by them compared to the incidence of viral diseases, and to more readily available alternative technologies to combat bacterial diseases.

4.1.3 Development of transgenic crop varieties resistant to fungal diseases

Some of the most devastating and universal crop diseases are caused by fungal pathogens (Box 2). For instance, the rust fungi are the most widespread and generally cause the largest crop losses per season. Crop losses can be considerable due to fungal pathogens. For example, the fungal agent of rice blast disease (Magnaporthe grisea) destroys 157 million tonnes of cultivated rice each year, enough rice to feed 60 million people worldwide (Pennisi, 2001).

The negative effects of some fungal pathogens can be limited by the use of chemical fungicides. Demand for fungicides amongst farmers is high, indicating that for many farmers there are few available alternatives. The world market for agricultural and non-crop fungicides amounted to an estimated US$6 billion at the end-user level in 1999. The United States, Western Europe and Japan together accounted for 75 percent of the total world market. Small grains constitute the largest market for fungicides worldwide. This sector accounted for an estimated 27 percent of the total world market in 1999, followed closely by tree and vine crops (24 percent), rice (16 percent), and vegetables and potatoes (10 percent). Other crop markets accounted for 17 percent of the world fungicide market, and non-crop markets accounted for 6 percent.

In many countries, fungicides as crop protection products are subject to strict legislative regulation and undergo a rigorous and expensive process of registration for public sale. While fungicides can provide a level of control, this chemical option is often limited for many farmers, particularly in developing countries, by high costs and lack of knowledge about application. In addition, the negative effects of fungicide applications on human health, with special reference to the labourers and the environment can be considerable. There is a need to find more environmentally benign alternatives to fungicides to control fungal diseases of crops.

Genes can be identified that confer resistance to fungal pathogens. For instance, many genes have been found that provide resistance to specific races of each rust pathogen. In many cases, resistance genes are available in the gene pool of cultivated plants and can be transferred to them by cross-breeding programmes. The incorporation of plant-derived resistance genes against fungal pathogens into susceptible varieties could allow development of resistant varieties which can deliver high yields in the absence of fungicide applications.

Actual and potential access by farmers to traditional fungal control measures such as fungicides, and the absence of durable transgenic genetic resistance strategies, may explain why there are few reported efforts to develop transgenic varieties which are resistant to fungal pathogens. In relation to fungi, the current stage of successful research worldwide on identification/isolation of genes conferring durable resistance to fungal diseases of crops, is probably not encouraging developing countries with scarce research resources to embark on transgenic approaches to fungal resistance.

In the African region, only two initiatives for fungal resistant transgenic varieties are reported, a field trial of transgenic strawberry with phytoalexin synthesis genes (e.g. Vst1, Vst2) and laboratory work on transgenic maize for resistance to cob rot (Stenocarpella maydis), both in South Africa.. The three initiatives for development of fungal resistant transgenic varieties reported in Eastern Europe were all in Bosnia and Herzegovina where laboratory testing of transgenic potato for resistance to Fusarium, Verticilium and Rhizoctonia has been initiated. In the Asian region, there is a field trial underway in China for transgenic cotton with resistance to Verticilium and Fusarium. Other R&D initiatives reported include the involvement of India, Malaysia and Pakistan in research on sheath blight of rice, and of Indonesia on rice blast and leaf rust of coffee.

A few countries in Latin America, mainly Argentina, Brazil and Cuba, are carrying out a number of activities on transgenic resistance to fungi, particularly on tropical fruit trees, with some results already being tested in the field. In this region, most of the activities for transgenic fungal resistance are reported in Cuba, in particular involving field trials of transgenic potato for late blight resistance, and fungal-resistant sugar cane. Other field trials in the Latin America region for transgenic fungal resistance are reported for maize, sunflower and wheat in Argentina, and tobacco in Mexico. Other crops subject to transgenic R&D for fungal resistance in Cuba are banana, plantain, pineapple, tomato, papaya, citrus and rice. Other countries involved in transgenic fungal resistance research are Argentina on alfalfa, Brazil on rice, barley and cocoa, Chile on grape and apple, Colombia on tree tomato, Peru on potato for late blight resistance and Venezuela on sugar cane.

TABLE 7
Number of initiatives to develop GMOs with resistance to pests

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of involved countries. (Totals of this column have been calculated taking into account that sometimes more than one activity is being carried out by the same country, although that country will only be counted once.)

4.2 DEVELOPMENT OF TRANSGENIC CROP VARIETIES WITH ENHANCED RESISTANCE TO PESTS AND HERBICIDES

4.2.1 Resistance to insect pests

Insects consume a large share of food and fibre destined for humans (pre- and post-harvest). The worldwide economic damage caused by insect pests to agricultural and horticultural crops and to orchards stands at a hundred billion dollars annually (Ulenburg, 2000). The strategies to limit the damage from insect pests fall into three categories:

1. Treatment of crops and their pests with chemical insecticides. Drawbacks of the use of chemicals are the development of resistance by the insects to the insecticides and secondly, the toxicity of many pesticides for the environment and human health.
2. Development of insect-resistant crops by hybridization or by transgenic modification. While transgenic approaches to the development of insect resistance are likely to be the fastest route, or the only means when pest resistance is not available in the genetic pool of the crop plant considered, they are more controversial, as with all genetic modifications of crop plants.
3. Introduction of natural enemies (usually alien species introductions) to further biological balance with limited damage. This approach is limited by the availability of natural enemies of the target pest and often risky as it is difficult to predict the outcome of the changes in the agro-ecological niche.

For all these strategies, it is important to gain good knowledge of the pest species that may cause damage at a certain place and time. Quick and reliable identification of the species and monitoring of their geographical distribution and life history is the basis of all effective policies to control insect pests. Worldwide, there are several thousands of insect pest species known to affect a range of crop species, each with their own characteristic damage, distribution and natural enemies. The knowledge and expertise in this scientific field is still limited and often insufficient to develop effective control strategies, especially in tropical or subtropical environments which characterize most developing countries.

Development of transgenic crop varieties resistant to Lepidopteran pests

Among the insect pests, Lepidoptera represent a diverse and important group. The FAO-BioDeC indicates that most insect-resistant transgenic crop varieties under R&D are obtained for the control of Lepidoptera (Table 7), predominantly using transgene cassettes including a toxin-producing gene from the soil bacterium Bacillus thuringiensis (Bt) see Box 3.

In Asia, Lepidoptera-resistant cotton varieties developed using Bt transgenes have been commercially released in China, India and Indonesia and field trials are underway in Thailand. Other field trials underway in China involve local varieties of rice containing Bt transgenes, transgenic cotton expressing Cowpea Trypsin Inhibitor (CPTI), rice transformed for resistance to stem borer and yellow borer, maize for corn borer, cotton for bollworm, and poplar for gypsy moth. Bt tobacco is also in field trials in India and Bt maize in Indonesia. Laboratory stage research work is ongoing in Asia on potato to generate resistance to tuber moth in India and Indonesia, diamond back moth (cabbage) in India, in addition to generation of resistance to Lepidopteran pests of cotton, rice and chickpea in Pakistan. Bt maize has been commercially released in the Philippines, research is underway in Indonesia on transgenic maize for corn borer, soybean for pod borer, rice for stem borer, Cacao for fruit borer, sugar cane for stemborer and oil palm for Setothosea asigna. Research is also ongoing on transgenic cotton for bollworm resistance in China and Thailand, jute for hairy caterpillar in Bangladesh, soybean in China and Chinese cabbage in the Republic of Korea .

In Latin America, transgenic maize resistant to Lepidopteran pests has been released in Argentina, and is in field trials in Brazil and Mexico, and undergoing laboratory testing in Cuba. Other field trials are underway on transgenic soybean in Argentina and Brazil, and cotton in Bolivia, Brazil and Mexico, potato in Mexico and Peru, sugar cane in Brazil and Cuba, tomato in Mexico, sweet potato in Cuba and sunflower in Argentina. Laboratory stage work on transgenic resistance to Lepidiopteran pests of rice, coffee and pineapple is ongoing in Cuba and on sugar cane in Brazil.

In the Near East there are field trials of Lepidoptera-resistant transgenic varieties of maize and potato in Egypt and rice in the Islamic Republic of Iran , and laboratory work on cotton and maize in Egypt and the Islamic Republic of Iran, respectively. Only four activities to generate Lepidoptera-resistant transgenic varieties are reported for Africa. Both Lepidoptera-resistant transgenic maize and cotton are under commercial cultivation in South Africa, and laboratory work is underway in Kenya. Transgenic Bt cotton is reported to be under field trial in Zimbabwe.

The rapid adoption of the use of Bt derived transgenes for development of pest-resistant crop varieties, suggests that this approach has generated a new and valuable option for control of some crop pests, which can be applied across a range of agro-environments, crop species and pests.

Development of transgenic crop varieties resistant to Coleopteran pests

Beetles and weevils are also important insect pests of crops. A wide range of beetles are of economic importance since they interfere with agricultural and forestry crops, timber products and stored products, etc. However, beetles do not transmit any diseases of humans or livestock. Due to the fact that there are many predators, herbivores and scavengers amongst the beetles, they play an important role in maintaining the ecological balance in natural systems. Furthermore, many host-specific species are used as biocontrol agents of insect pests and noxious weeds.

As an example of Coleopteran pests, the African sweet potato weevils (Cylas puncticollis and Cylas brunneus) are major pests of sweet potato production in sub-Saharan Africa. Sweet potato crop losses due to weevils range from 20­100 percent with more severe losses reported in the dry season or during droughts. No genes conferring durable resistance to such weevils have yet been identified within the sweet potato gene pool. The case of sweet potato weevils in Africa is an interesting one regarding decisions on the most effective options for control of the weevils. There are options for the control of other weevils (e.g. Cylas formicarius) used in other regions of the world, which are based on the use of pheromones and bio-insecticides. However, control of African sweet potato weevils has not been successful in Africa and bio-insecticides are generally not available or affordable to African sweet potato farmers. In such a context, the generation of weevil resistant crop varieties using transgenic technology presents a new and potentially valuable option for weevil control.

In spite of their agronomic and economic relevance, the FAO-BioDeC (Table 7) suggests that there is no R&D activity to develop transgenic crop varieties which are resistant to Coleoptera pests in any of the regions.

4.2.2 Development of transgenic crop varieties resistant to nematode pests

Nematodes are distributed worldwide and live saprotrophically or as parasites of plants, animals and humans. While most nematodes in soil are actually beneficial, farmers are most concerned with nematodes that are pathogens of the roots, stems, leaves or seeds of plants. Plant parasitic nematodes are of great economic importance, they are responsible for over US$100 billion in annual crop losses worldwide (Sasser and Freckman, 1987). They attack a wide variety of plant species, among them many staple crops, vegetables and ornamentals. The root-parasitizing nematodes of the genera Meloidogyne (root-knot nematodes), Heterodera and Globodera (cyst nematodes) are the most important pathogens.

While substantial yield increases have been realized with the discovery and use of nematocides, considerable work remains to be carried out in many aspects of nematode biology and management. On average, only 0.2 percent of the value of crop loss due to nematode damage is invested into nematode research. Furthermore, nematology is a relatively young science and although many crops suffer losses due to nematodes, the number of nematologists working in agriculture is still largely insufficient to properly address this problem. Therefore, much remains to be learned to manage these serious pests.

Due to high crop losses, there is generally a need for the treatment of infested soil with chemical nematocides. Many synthetic chemical nematocides are very unspecific and possess a high general toxicity so that they have been, or will soon be, banned by many governments. Alternative efficient methods to control nematode infestations are rare. Therefore, the search for new nematode control methods is of great economic interest for developing countries.

Strategies deploying crop genetic resistance to nematodes could generate new options for nematode control. The FAO-BioDeC contains no reports in all regions on the use of transgenic technology to develop nematode resistant crop varieties. This was surprising given the high frequency and ubiquity of nematode pest species and the wide range of potential hosting species, across all the regions surveyed. The lack of reports of R&D to develop nematode resistant transgenic crop varieties might be influenced by three factors:

1. the remaining existence on the market of some nematocides that maintain their effectiveness for a  considerable number of growing seasons. Many of these nematocides are no longer patent-protected and are available at reasonable cost to some farmers;
2. the limited geographic mobility of the nematode species, which spreads from one field to another very slowly. In many cases, therefore, farmers tend to solve the nematode problem inexpensively by transferring cultivation to other nearby fields; and
3. the slow progress to date in identification of monogenes conferring efficacious resistance to nematodes.

4.2.3 Development of transgenic crop varieties resistant to herbicides for weed control

Adequate systems for weed control are an essential component of all farming systems. Depending on the crop and weeds present, uncontrolled weeds can reduce yields by over 50 percent, impair crop quality, contaminate the harvest with undesirable weed material, and increase the likelihood that the crop will be attacked by insects or diseases. Weeds compete for nutrients and light, especially during the early stages of crop growth, and for moisture in drought stressed areas, often causing severe yield losses. For example, in labour intensive, small farm operations on the Nigerian savannah, weed-related yield losses from 65 to 92 percent have been recorded (IAC, 2004). The parasitic flowering plant known as “witchweed” (Striga spp.) remains a major pest of staple crops in sub-Saharan Africa, despite a number of unsuccessful initiatives and considerable research input to find a means of control. The areas infested with parasitic broomrapes (Orobanche spp.) and witchweeds are vast and expanding. Striga is considered as the greatest single biotic constraint to food production in Africa, where the livelihood of 300 million people is adversely affected. In infested areas, yield losses associated with Striga damage are often significant, ranging from 40-100 percent (Bebawi and Farah, 1981; Lagoke et al., 1991; Ejeta et al., 1992). Crop yields could potentially be doubled if such weeds could be controlled. However, labour intensive weeding is largely ineffective against weeds like Striga.

Weeds can be controlled mechanically (by cultivation or hoeing), chemically (with herbicides) or agronomically (e.g. crop rotation). In addition to the undesirable effects of weeds on agricultural production, many weeds can also damage natural areas, alter ecosystem processes and facilitate displacement of native species.

Herbicide tolerant varieties provide new options for the control of major weeds which are constraining agricultural production in the regions surveyed. The FAO-BioDeC shows (Table 8) that in relation to herbicide resistant transgenic varieties, the situation is rather different among regions and most of the R&D activity in this area seems to be concentrated in a small number of countries per region. To date, the database suggests that research attention has been focused largely on the development of transgenic crop varieties resistant to glyphosate (Roundup) and glufosinate ammonium (or phosphinothricin, commercialized under the name Basta). There are also reports of some instances of development of crops resistant to herbicides such as bromoxynil, imidazolinone, bialaphos and isoxazoles.

Glyphosate resistance has been most widely used in Latin America, where Roundup-Ready^TM (RR) transgenic soybean has been cultivated in Argentina and Uruguay. According to other reports, the same two countries have released two more herbicide-resistant soybean varieties, however, without specification of the kind of herbicide resistance. A glufosinate-resistant transgenic maize variety has also been released in Argentina. Brazil has recently accepted the RR soybean and is now cultivating it on a large scale. Thirty-four herbicide tolerant transgenic varieties are being field tested in Latin American countries, particularly in Argentina, Brazil and Mexico. In this regard, field trials have been performed for transgenic cotton, alfalfa, maize, sunflower, sugar beet and wheat in Argentina, maize, cotton, sugar cane and eucalyptus in Brazil, and cotton, maize and soybean in Mexico.

TABLE 8
Number of initiatives to develop GMOs with resistance to herbicides

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of involved countries. (Totals of this column have been calculated taking into account that sometimes more than one activity is being carried out by the same country, although that country will only be counted once.)

In addition to glyphosate, glufosinate resistant varieties are important in Latin America, where 14 field trials have been carried out in the region on transgenic soybean in Argentina, Brazil and Mexico, sugar cane in Brazil and Cuba, maize in Brazil and Mexico, wheat in Argentina and Mexico, sugarbeet in Argentina, rice in Brazil and potato in Cuba, which also has extensive laboratory input into rice, banana, plantain, coffee and pineapple. However, it must be noted that the number of laboratory research activities in the area of glufosinate resistance is much lower (5), and all such research activities are concentrated in Argentina (barley and sugar cane), Cuba, (rice, banana and plantain, coffee and pineapple) and Venezuela (sugar cane and mango).

In Eastern Europe, field trials on glyphosate and glufosinate tolerant maize are ongoing in Serbia and Montenegro, whereas Bulgaria is commercially cultivating unspecified herbicide tolerant maize. In the Near East, the only research reported is on transgenic canola in the Islamic Republic of Iran. In Asia, Indonesia is conducting herbicide tolerance field tests on imported GM maize, cotton and soybean, and China on soybean. China is conducting research on herbicide tolerant rice, Pakistan on wheat and the Republic of Korea on cabbage, chinese cabbage and potato, though no details are given.

In Africa, the only GM herbicide tolerance research reported in the FAO-BioDeC is taking place in South Africa, with field trials of 11 transgenic varieties resistant to different herbicides. The crops involved included canola, cotton, Eucalyptus, lucerne, maize, soybean, sugar cane and strawberry.

In all regions, the higher number of field trials when compared to laboratory stage research in this area, suggests that most of the varieties undergoing field trials are likely to have been generated outside of the regions or result from crosses with local varieties. In addition, the relatively high number of laboratory research in this area compared to e.g bacteria resistance may also reflect the comparative technical simplicity for many species of generating herbicide tolerant crops using transgene cassettes obtained from research institutions or companies with more advanced research capacity.

The limiting factors to R&D to generate herbicide tolerant transgenic crops are the number and type of herbicides and transgene resistance cassettes available, the ease with which the crop species or variety can be transformed, the registration requirements both for the herbicide and the transgenic crop variety, and the level of access of farmers and researchers to proprietary herbicides and transgene resistance cassettes. Yet, the early experiences with herbicide resistant maize to control Striga infestations in Africa suggest that novel models to disseminate herbicide tolerant transgenic crops could benefit even resource-poor farmers.

TABLE 9
Number of initiatives to develop GMOs with resistance to abiotic stresses

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of involved countries. (Totals of this column have been calculated taking into account that sometimes more than one activity is being carried out by the same country, although that country will only be counted once.)

4.3 TRANSGENIC VARIETIES RESISTANT OR TOLERANT TO ABIOTIC STRESSES

Abiotic stresses continue to limit crop productivity in every season and in every agro-ecosystem worldwide. Among the abiotic stresses affecting crop production in developing countries, drought and low soil fertility are the most significant. Plants vary tremendously in their ability to withstand abiotic stresses, both between species and within populations of a single species, but the nature of abiotic stress tolerance is not well characterized. Understanding the mechanisms of abiotic stress tolerance will have a significant impact on crop productivity. For instance, crop loss to drought in the tropics alone is thought to exceed 20 million tonnes of grain equivalent per year, or around 17 percent of well-watered production, reaching up to 60 percent in severely affected regions such as southern Africa in 1991-92 (Ribant et al., 2002). The development of crop varieties (transgenic or non-transgenic) which can tolerate abiotic stresses would be of major benefit to agriculture in cropping regions where abiotic stresses are a chronic problem.

As shown in Table 9, no transgenic crop variety tolerant to abiotic stress has so far been reported to be released for cultivation in any of the regions covered by the database. However, 7 transgenic varieties exhibiting tolerance to a range of abiotic stresses underwent field testing in Bolivia (a frost tolerant potato variety), China (a cold tolerant tomato), Egypt (a salt tolerant wheat variety), India (moisture stress tolerant Brassica variety) and Thailand (salt tolerant and drought tolerant rice varieties). The number of research initiatives at the laboratory stage in this area totals 27.

Most of the R&D activities on development of abiotic stress tolerant crops are being carried out in six countries of the Asian region, namely Bangladesh, China, India, Indonesia, Pakistan and Thailand. China is relatively active in this area, and has reported preliminary successes with rice, maize and sorghum tolerant to high salt concentrations. Transgenic studies on salt resistant crop development are also being undertaken on rice in Bangladesh, Brazil, India and Pakistan, and on tobacco in Argentina. Transgenic research approaches to obtaining aluminium-resistant varieties are underway for wheat in Mexico and sugarbeet in China.

Despite the effects of drought on crop production, very little transgenic research on drought resistance is reportedly being carried out in the five regions. Drought-tolerant rice is currently being field tested in Thailand. The rest of the activities in this area are mainly at the laboratory stage, with work on sugar cane (Indonesia), rice (China and Indonesia), and groundnut (South Africa).

Overall, the extent of R&D reportedly devoted to abiotic stress tolerance is insufficient when compared to the well known needs for abiotic stress tolerant varieties in the regions surveyed. For instance, vast areas of soils containing an excess of heavy metals are present in Brazil and Africa. Also, a steadily increasing acreage of agricultural land in Asia and elsewhere is becoming agriculturally sterile because of salinity brought about by poorly managed irrigation practices. The major limitation is the complexity of tolerance to abiotic stresses that is normally dependent on a number of physiological traits, each under multigenic control. The increased wealth of knowledge that is being acquired by means of genomics, mainly functional genomics, and other molecular biology studies, will certainly contribute to the development of tolerant genotypes.

TABLE 10
Number of initiatives to develop GMOs with improved quality traits

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of involved countries. (Totals of this column have been calculated taking into account that sometimes more than one activity is being carried out by the same country, although that country will only be counted once.) AA: amino acid

4.4 TRANSGENIC VARIETIES WITH MODIFIED QUALITY TRAITS

The nutritional and economic value of many grain crops depends on the quantity and types of compounds (e.g. protein, starch and oil) that accumulate during seed development. Plant breeders have long strived to develop new crop varieties with enhanced quality trait profiles.

The results shown in Table 10 describe the different situations, regarding the development of transgenic crops with enhanced quality traits in each region. No research or field testing activity is reportedly taking place in the African or Near Eastern regions, despite well-known dietary deficiencies prevailing in both regions. However, this situation is not paralleled in Asia, where a total of 34 activities on this topic are reported in eight countries or in Latin America where 31 reported initiatives in eight countries. In Latin American countries, there are 12 research activities reported and 19 transgenics under field testing, mostly in Argentina and Mexico.

A wide range of characteristics can fall under the topic of `quality trait' and the use of this loose term in a survey can result in different categorizations by different respondents. For instance, the reports from Latin America indicate that there are field trials of varieties with enhanced quality traits underway on rice (Sucrose-phosphate synthase) and other trials for unspecified characteristics are underway on soybean in Argentina, and canola and flax in Mexico. Laboratory studies cover alfalfa (veterinary edible vaccines), Paspalum dilatum (foddering quality), Triticale (biomass production) in Argentina, eucalyptus (reduction of lignin content) and Psychotria spp. (improved alkaloid production) in Brazil, sugar cane (altered lignin content and high quality sugar) in Cuba, Echinaceae, Psychotria and Tagetes (alkaloid production) in Costa Rica, and improvement of flour quality and reduction of natural toxicants in potato in Peru.

Quality traits also exist in the floriculture industry. In this regard, a petunia variety with altered flower colour is now in commercial production in China.

Micronutrient malnutrition, especially lack of iron, zinc and vitamin A, currently afflicts more than half the world's population. Called “micronutrients” because they are needed in only miniscule amounts, these substances enable the body to produce enzymes, hormones and other substances essential for proper growth and development. Tiny though the amounts are, the consequences of their absence are severe. Iodine, vitamin A and iron are most important in global public health terms. Their lack represents a major threat to the health and development of populations the world over, particularly to pre-school children and pregnant women in low-income countries. Enhancing the micronutrient (vitamin and mineral content) status of staple crops is considered to be one approach where crop biotechnology could generate crop varieties that could be used to strengthen food security and prevent malnutrition.

4.4.1 Protein content and amino-acid profiles

Protein-energy malnutrition (PEM) is a most lethal form of malnutrition. Children are its most visible victims. Malnutrition contributes to at least half of the 10.9 million child deaths each year (El-Nawany et al., 2002; World Hunger Facts, 2004). PEM disorders result from a lack of protein and carbohydrates (energy). Cereals and root crops such as cassava form a substantial portion of developing country staple diets, thus improving their protein content and quality will go a long way to curbing the devastating effects of PEM. Seed proteins of many major crops often do not contain sufficient quantities of amino acids essential in the diet of humans and other monogastric animals. As cereals are usually deficient in lysine and tryptophan, and legumes are deficient in the sulphur amino acids methionine and cystine, a mixture of cereals and legumes is used to provide a balance of amino acids in the diet. Breeders at CIMMYT (Mexico) have managed with conventional breeding (over three decades) to develop quality protein maize (QPM) varieties which have enhanced levels of the two `essential' amino acids, lysine and tryptophan, in the endosperm protein. These new varieties look and taste like normal maize but the nutritive value of their protein is nearly equivalent to cow's milk. Modifying the genes that encode seed proteins by genetic engineering is one additional option to address the problem of nutritional quality in some staple crop varieties.

The FAO-BioDeC does not reveal any significant level of research on metabolic engineering of protein content nor quality in crop varieties in the vast majority of countries surveyed. The only research reported is on field trials for high lysine maize in China. Argentina is also reported to have conducted field trials for unspecified traits in maize and soybeans as well as wheat with high molecular weight glutein.

4.4.2 Vitamin profiles

Vitamins are essential components of the human diet and dietary deficiencies in some vitamins can have tragic effects. For instance, vitamin A deficiency (VAD) is the leading cause of preventable blindness in children and raises the risk of disease and death from severe infections. In pregnant women, VAD causes night blindness and may increase the risk of maternal mortality. It is a public health problem in 118 countries, especially in Africa and South-East Asia, once again hitting hardest young children and pregnant women in low-income countries. Crucial for maternal and child survival, supplying adequate vitamin A in high-risk areas can significantly reduce mortality.

The arsenal of nutritional approaches to combat VAD includes a combination of breastfeeding and vitamin A supplementation, coupled with enduring solutions, such as the promotion of vitamin A-rich diets and food fortification. Among these approaches, biotechnology research has contributed the additional option of increasing the vitamin A content of staple foods which are typically low in vitamin A content. The proof of concept of this approach has been the highly publicized high-beta carotene (pro-vitamin A) rice transgenics recently developed, and currently under dissemination to many NARS, under the name of `golden rice' and `golden mustard' in India. Yet, the FAO-BioDeC indicates that there is little R&D underway on enhancement of vitamin content in crop varieties in the regions surveyed.

4.4.3 Mineral profiles

Most staple crops are not considered an important source of minerals in the human or domestic animal diet. Yet, because of the high level of consumption of staples, small increases in the mineral concentration of staples could have a significant effect on human nutrition and health. Iron deficiency anaemia afflicts an estimated 1.5 billion people in developing countries, most of them women, reducing mental ability, creating severe complications at childbirth, and lowering physical capacity. Zinc deficiency, though less well understood, is also known to be widespread in the tropics and is a major threat to children's growth and health. The nutritional quality of staple crops (rice, cassava, wheat, maize and beans) in terms of mineral content can be improved by both conventional breeding and/or biotechnology. Currently the FAO-BioDeC does not report any biotechnology activity targeted towards the improvement of crop mineral profiles in developing countries.

4.4.4 Oil composition

It seems from the countries covered by the FAO-BioDeC that the modification of plant oil and wax composition has received little attention. Among the instances of R&D in this area are ongoing field trials in Argentina on maize and soybean, and in Mexico on canola expressing high levels of lauric acid. In addition, there is ongoing laboratory work on oil palm with low saturated fatty acids in Indonesia and Malaysia and high lauric acid content in coconut in the Philippines. Furthermore, in Malaysia there is development of oil palm with special oils for the production of biodegradable plastics.

4.4.5 Plant growth traits

The genetic manipulation of the metabolic routes leading to plant hormone (e.g. ethylene) synthesis and degradation can induce modifications of plant organ maturation. Such control of maturation can allow the production of fruits showing resistance to postmaturation deterioration, resulting in the ability to be transported without refrigeration, extended shelf life and improved quality. For many developing countries with limited refrigeration capacity and transport infrastructures, this research avenue is extremely promising, insofar as it improves flexibility of transport of otherwise perishable products to distant markets and on poor routes. Most of the research reported on alterations in plant growth has concentrated on delayed fruit ripening. In Latin America, Mexico reports a large number of field trials for altered growth in varieties of crops such as tomato (two approaches), chilli pepper, banana, melon, papaya and pineapple. In this area, Chile has a laboratory research initiative on stone fruits. In Asia, papaya varieties with altered growth traits are under laboratory study in China, Indonesia and the Philippines. In the latter, mango is also being researched, as is tobacco for delayed leaf senescence. Other growth phase changes receiving attention are short-stature and profuse tillering in basmati rice in Pakistan. In Eastern Europe, laboratory work in this area is ongoing in Bosnia and Herzegovina in potato for higher cytokinin levels.

TABLE 11
Number of initiatives to develop GMOs with multiple resistances

C: number of GM varieties released as commercial varieties; F: number of GM varieties in field trials; E: number of activities at experimental level (including laboratory or glasshouse activities); U: number of GM varieties at unknown status; N: number of involved countries. (Totals of this column have been calculated taking into account that sometimes more than one activity is being carried out by the same country, although that country will only be counted once.)

4.5 `STACKING' TRANSGENES – GENERATING CROP VARIETIES WITH MULTIPLE TRANSGENIC TRAITS

The first generation of commercially available transgenic crop varieties has typically included cases where one transgene has been used to add an enhanced characteristic to a particular crop variety. Yet, there are a multitude of characteristics which are assessed by farmers to determine whether a variety is suitable or unsuitable. The production of crops with multiple genetically engineered traits may seem a logical step to follow and, as more locally adapted transgenic varieties become available and accepted on the market, these will become the source material into which novel genes will be incorporated. However, some problems (e.g. trait silencing due to similarities between transgene cassettes or epistatic interactions between transgenes) can arise if too many transgenes are incorporated into a single variety, and such effects may be cumulative over successive generations. To overcome such problems, novel approaches to simplify and improve the process of introducing multiple transgenes into crop varieties are under development.

Where data on the use of multiple transgenes to develop single crop varieties are present in the FAO-BioDeC, the most commonly used dual-transgene combination is herbicide resistance combined with insect resistance (see Table 11).

In Latin America, Argentina has released transgenic maize with Lepidoptera resistance and glufosinate tolerance and there are 11 field trials reported in the region on GM crops. The absence of laboratory work suggests that this material is a technology import. Transgenic traits of Lepidoptera resistance with glyphosate tolerance are undergoing field trials in alfalfa, maize, soybean and sunflower in Argentina, and in cotton in Argentina, Brazil and Mexico, where maize with Coloeptera, Lepidoptera resistance and glyphosate tolerance is also being field tested. Lepidoptera resistance combined with glufosinate tolerance is undergoing field testing in maize in Argentina. In South Africa, two field trials tested insect resistance combined with bromoxynil or glyphosate tolerance, and maize with potential insect resistance and glyphosate tolerance was field tested. Other traits that are combined with herbicide tolerance are fungal resistance with glufosinate tolerance in wheat in Argentina, and unspecified pathogen resistance with glyphosate tolerance in Mexico. In Argentina, Coleoptera and PVY resistant potato is undergoing field trials.

In Asia, two field trials are ongoing in China to test transgenic rice for combined blight and RDV resistance and combined bacterial wilt and PVY resistance in potato, as well as salt and herbicide tolerance in potato. In the Philippines, experiments to combine fungal, insect and bacterial resistance with salt tolerance in rice are underway. Papaya is receiving attention for combined ringspot virus resistance and delayed ripening in the Philippines, and similar work to combine virus resistance with extended shelf life is reported in Malaysia.

Golden rice is a multi-trait transgenic plant since it was made by the transfer of three different transgenes for the synthesis of β-carotene taken from daffodil (Narcissus pseudonarcissus) and bacterium Erwinia uredovora (Ye et al., 2000; Beyer et al., 2002). Metabolic pathway engineering is technically complex and challenging, and according to the FAO-BioDeC it has not yet been carried out in any crop within a developing country setting.