Chapter 5: Assessment of Biological Effects in Agriculture in Mexico

Mexico has the most diverse maize germplasm of any country, and is characterized by many small producers and high maize consumption. The country has an intricate agrarian history and a strongly polarized society. Maize is grown in contrasting environmental, social and technological conditions in plots that range from garden size to fields of hundreds of hectares. The typical campesino subsidizes maize with revenues from offspring working in cities or abroad and uses family labor to subsist. Until the 1960s, Mexico was more than self sufficient in maize, and could quickly be so again with minimal investment in local maize improvement and sustainable maize production strategies. NAFTA accelerated US maize imports, but Mexico produces 78 percent of the maize it uses; half of this is grown by smallholders who comprise two-thirds of all producers. Social forces impel campesinos to produce maize as insurance; economic forces invite them to quit. The situation is fragile; the breaking point uncertain. Finding alternative crops or jobs and housing for more millions in cities will not be easy. Mexican campesinos depend on maize landraces, tuned to local conditions. Landraces are exchanged, mixed, re-selected and re-adapted. Varied ecology in Mexico has discouraged universal hybrid use. The proportion of maize production planted with landraces (80 percent) is high, compared to the rest of Latin America. Hybrids have existed since the 1950s, but often cannot compete with open-pollinated varieties; companies are unlikely to cater to specialized ecologies; public programs are too underfunded to develop such hybrids. Locally adapted, open-pollinated maize is often a "safer" crop under marginal farming conditions, and much maize is grown on marginal lands. Preservation of biodiversity in maize has been a service of Mexican campesinos for millennia. Germplasm banks preserve this material, but national funding has failed and continuous international funding is not available. Clearly, if widespread use of GMOs or wholesale maize imports were to become the future for Mexico, then first priority must be strengthening germplasm programs to preserve maize biodiversity. This chapter focuses on potential impacts on landrace diversity and on small-plot farmers because they are the key to Mexico's current maize biodiversity and what makes transgenic maize in Mexico unique. Impacts on agroecosystems as a whole (e.g., pest resistance and non-target populations) are not discussed in detail here, nor are they conclusive, as the topics remain controversial, but they are addressed in Chapters 2 and 4. While GMOs are the headlines, the immediate threats to Mexican maize landrace biodiversity are economic, headed by subsidies paid to US farmers. Landraces provide variability to cope with vagaries of weather patterns, pests and diseases, but they cannot overcome the 20 to 30 percent subsidies that bolster US exports. In this fragile situation of maize landraces it is necessary to analyze possible benefits and risks of transgenes and their introgression. The major detrimental effect on teosinte populations, maize’s closely related wild/weedy relative, is presently human population expansion and consumption pressures, not GMOs. Currently available transgenes (Bt, other herbicide resistances) are marginally attractive in the United States and less so in Mexico, but future advances (25+ years) in drought tolerance and resistance to pests of stored grain could be helpful to campesinos if other environmental and economic constraints can be resolved. There is consensus that transgenic traits (including current ones, reasonably-proven ones such as virus-resistance and male-sterility, and newer traits still under development) will introgress into landraces via US imports, seed introduced by migrants and the continuity of the Mexico-US border; the speed with which this happens will depend on the degree to which the sources are adapted to Mexico and the usefulness of the transgenes. Most transgenes are unlikely to pose more threat to landraces than a new, successful cultivar, but each transgene needs assessment of its long-term cost/benefit to Mexico, and costs may only become apparent long term. Opportunities lost by not using or developing useful transgenes need consideration; this is very long-term planning, as time from gene isolation to farmer-deployment is about 15 years and the cost is enormous (about US$50 million per transgene). It is conceded that widespread employment of single genes is unwise, and today's transgenes share several common traits: common background from tissue culture, usually the same promotor, similar selective agents and terminal constructs. The remedy for crop uniformity is a dynamic local seed industry developing new varieties and persistence of campesino production for local self-sufficiency, both using Mexico's diversity of maize germplasm. This appears to have been discouraged by past governmental policies. Certainly, the recent budget proposal to discontinue funding to INIFAP and Colegio de Postgraduados would discourage private investment in that arena. Private development of transgenic crops may slow as investments are directed to more lucrative medical markets. There is a limit to surcharges for transgenic seeds. One transgene is valued at about $20 per hectare, the next is unlikely to be economically viable at $20 more. Transgenes specifically useful to Mexico probably need to be developed by Mexicans. Minimal-cost, community breeding projects with few inputs have shown 20 percent on-farm yield increases while preserving local landraces. No transgene currently meets the 20 percent standard and, while a few hybrids do, they are not widely-enough adapted to spread broadly. Production of industrial/pharmaceutical chemicals in maize carries risks of pollenand seed-borne contamination; there is consensus that such endeavors are inappropriate except in extreme isolation, far removed from any place maize is now grown. Even then, risk of escape and contamination is not zero. Thus far, contamination costs, mostly from routine-, rather than industrial-transgenes, and mostly for organic growers, have been borne solely by the farmers, rather than by distributors or licensors of transgenics. If some or all transgenes are barred from Mexico, then maize imports need monitoring, and whole or cracked maize imports from any country permitting use of transgenic maize would need to be prohibited. Monitoring of all imported, unprocessed maize would be necessary as, once in commerce, tracing origins is difficult. Laboratories for quality control will need to be developed; these need unusual characteristics, if accurate monitoring of small amounts of gene flow (less than one percent) is to be done. Some US maize transgenes are expected to flow into Mexico, despite regulations. A major question is whether transgene-owners will be due fees for use of transgenes by farmers growing native, open-pollinated landraces. This is very important to Mexican agriculture and of almost no consequence to industrialized farming or to transnational seed companies. The sensible answer is that no fees should be paid by Mexican farmers for use of Mexican open-pollinated maize. A minimal requirement for transgene suppliers would be provision for inexpensive, non-ambiguous testing of each experimental transgene construct. An immediate roadblock facing the utilization of, say, Mexican-developed (and even royalty-free) transgenes aimed at characteristically Mexican campesino problems is that there are no seed distribution or agricultural extension programs in place to move such genes into local, openpollinated landraces of maize adapted to the many ecological regions of Mexico. If transgenes are envisioned as eventually helping Mexican campesinos, then this roadblock would effectively prevent that from ever happening. In the following sections, we sketch the background of maize farming in Mexico and address the following topics regarding Mexican maize: 1) The present status and future prospects of transgenic traits; 2) Their possible expansion across landrace germplasm; 3) Could they help with the most pressing problems faced by producers; 4) What risks are involved for Mexico (i.e., could these traits disrupt value, performance, diversity and integrity of landraces and their relatives, and could some impact ecological processes and have negative effects on the environment or on the economy); 5) Are the risks worthwhile or are there better alternatives; and 6) What preventive measures should be considered, what needs investigation, and what needs discussion with those at risk? 1. Current status and future prospects of conventional maize landrace production The current status and future prospects of conventional maize landrace production and conservation form a baseline for discussing the potential impact of transgene introgression in Mexican maize. Maize production and rural crisis in Mexico: A general overview Mexico has the highest diversity of maize germplasm (Ortega, 2004), a large number and high percentage of campesinos, and the highest direct, per capita, maize consumption in the world (Warman, 2001; FIRA, 1998). The country has a complex landscape, an intricate and unique agrarian history (see Appendix 1) and a strongly polarized society. Maize production occurs in myriad combinations of environmental, social and technological conditions, all of which have contrasting extremes. Production occurs in the neotropical humid lowlands, midlands and highlands, in the cool, subhumid Central Plateau, and under irrigation in the northern semiarid lowlands. Land use intensity ranges from slash-and-burn, multispecies milpa to irrigated, monocrop maize fields with two harvests per year (Aguilar et al., 2003). Land tenure is either social (ejido and comunidad indígena), private or both, and maize plots per family range in size from home gardens to the order of hundreds of hectares. Agro-industrial inputs and mechanization can be totally absent or can be used heavily (Warman, 2001; García-Barrios and García Barrios, 1992). From the data presented in the 1991 Census (INEGI, 1994) and the analysis done by different authors (e.g. García-Barrios and García Barrios, 1994, Warman, 2001; Appendini et. al, 2003; Bartra, in press), we estimate that two-thirds of maize producers fall near the following description: The most commonly found Mexican maize producing family has a 50 year old family member who coordinates maize production (most commonly a man; occasionally a woman). The family plants 1 to 3 hectares of rainfed maize fields with some significant degree of erosion, yielding 2 to 3 tons per ha in the best years and producing modest, if any, marketable excess, usually sold at or below production costs. The family uses a mixture of hand and animal (or machine) power, limited amounts of herbicides and, occasionally, insecticides. It more commonly uses natural or synthetic fertilizers as maize requires much nitrogen (Jourdain et al., 2001). It plants two or more landraces commonly tuned to different local environments (e.g. García-Barrios et al., 1988) and/or for different consumption purposes. Although associated crops and edible weeds were commonplace in the past, they are now scarce or absent in his fields because they are incompatible with atrazine-type herbicides (McKnight Foundation, 1997). The family depends on its own labor and on wage labor for field activities, spends the minute PROCAMPO governmental aid on unproductive consumption and perhaps on a little fertilizer. In classical economic terms, it subsidies maize production with external revenues from sons and daughters working in Mexican cities or abroad and uses otherwise idle family labor, already trained for agricultural activities. The family's insistence on securing as much as possible of its direct-maize consumption, seems irrational to conventional economists, given the relatively low, nominal price of purchasable maize. Yet, this persistence makes sense to poor families in the face of ever increasing maize-flour prices, uncertain employment, market failures, and local, potential pressure over idle, productive land. Values such as habits, cultural identity, landrace-tortilla quality and food security are involved in the family's decision to continue to plant maize. Under the current maize price policies, a considerable number of these campesinos with the potential for producing modest but significant maize surplus for the national market prefer to self-limit their maize production to the amount necessary for supplying high-quality tortillas for their families (Appendini, et al, 2003). The concern over ever-increasing prices for tortilla-flour with minimal prices for campesino maize, largely as a result of a shared monopoly over maize processing, may explain, in part, the widespread fear that international companies controlling seeds and transgenes are, in themselves, a threat to the independence and even to the existence of campesino farmers (Bartra, 2003). It is clear that there are many in Mexico who believe that the governmental policies favor agricultural oligarchies over the interests of campesinos. To some extent, that limits the role for science in the service of agriculture, as in the past science has been observed to simply favor business (Esteva, 2003). Until the 1960s, Mexico was self sufficient in maize production and even exported modest amounts to other countries (Barkin and Suarez, 1981a). Partly as a result, rural conditions were more inviting, emigration pressures were less, the economy (and the peso) was reasonably stable and environmental pressures were less than today. Since then, the situation has greatly changed. NAFTA has exacerbated a long-term reduction in incentives for maize production in Mexico and opened the door to increasing United States' yellow-maize imports (the latter still mainly devoted to industry and animal feed; FIRA; 1998). NAFTA, as negotiated and signed, had a 15 year phasein of liberalization of maize markets, but the Mexican government (in its goal to control inflation) allowed free importation, without invoking the tariff-rate quota. The increase of US imports has led to (or followed) an increase in domestic, industrial, livestock production utilizing these imports and an increase in meat and poultry consumption. Mexico could readily be self sufficient in maize (Esteva, 2003a, b), which would have direct positive effects on the maintenance of Mexican maize landrace biodiversity, but campesinos in remote, mountainous regions will rarely sell feed to feedlots and hog farms in other areas. The rural population has never ceased to increase, but has fallen to 25% of the total Mexican population, due to the prevalent rural crisis and exodus. National maize production has continued to increase in absolute terms, but today it represents merely 1.1% of the GNP (Warman, 2001). An increasing number of urban and semi-rural families purchase industrially-produced tortillas and maize flour, in part because there is often no alternative, despite their generally poor quality. All this suggests to some that because maize and maize producers are marginal from a macroeconomic perspective, and most are clearly uncompetitive in the global market with undifferentiated prices for Mexican maize their fate as producers should be of little national concern, given the cheap and plentiful potential maize supply produced by the heavily-subsidized US agroindustry and sold in international markets well below real costs (Bartra, in press). Yet, there is another way of looking at the situation. In spite of two decades of low incentives for maize, Mexico still produces 78% of the maize it uses. At least half of this maize is produced by campesinos who represent two-thirds of the total producers (Warman, 2001; Bartra, in press). Roughly, thirty-nine million people depend on the fate of these campesinos' production for their maize consumption (230 kgs per capita per year on average). Among the campesinos, one-third buy part of their maize, another third are self-sufficient, and the last third are maize providers for local and regional markets. In short, campesino maize production may be marginal under some standards, but still plays a significant social function in slowing down food insecurity, unemployment, migration, extreme poverty, urban criminality, and rural collapse (Bartra, in press). Nevertheless, problems keep accumulating. Pressure on land, pest problems and soil erosion continue to grow, while, at the same time, seasonal labor shortages are more common. In recent decades, opportunities for substituting land with fertilizers, and labor with herbicides and pesticides, have given campesinos a temporary break and have produced modest yield increments. But net benefits are stagnant, or continue to decrease, due to increasing input costs, loss of associated crops, development of some pest resistance, more use of marginal land and low maize prices. There is a tension between the social forces that impel campesinos to maintain maize production for food quality and as life insurance and the economic policies and ecological conditions that invite them to quit altogether. The situation is fragile, and the breaking point is uncertain. Mexican peasant organizations are becoming increasingly concerned and vocal about the matter (Bartra in press). If, in spite of increasing social unrest, nothing is done, we can expect these productive social systems to collapse in the short or medium term, one after another, depending upon their specific local conditions. It will not be easy to find alternative crops for the relatively harsh conditions of Mexican rainfed agriculture, nor to find accommodation for yet more scores of millions of people in the cities. Of direct consequence to this report, loss of campesinos and their campesino-grown maize translates directly into loss of maize landrace biodiversity in the field (Ortega, 2003b; Ortega et al., 2000). The current status of landrace and hybrid maize in Mexico Maize is both a very productive crop and a species that has responded extremely well to selection for the many local, and commonly harsh, conditions in which it is grown in Mexico. The range of environments and practices used in maize production in Mexico is extremely wide. Partly as a consequence, there is more diversity among Mexican maize than is found anywhere else in the world (Anderson, 1946; Sanchez and Goodman, 1992a, b; Sanchez et al., 2000; Wellhausen et al., 1951). Nearly all Mexican campesinos depend on one or more of the circa 60 maize races, all finely tuned to local conditions (Ortega et al., 1991). Their great-grandparents (and their greatgrandparents) would have recognized most of them, and these Mexican varieties and races of maize are one of the legacies they left to mankind. Landraces are not static and perfectly distinct resources, but are continuously being exchanged, mixed, re-selected and re-adapted by farmers, through their social networks (Perales et al., 2003b). In contrast to the situation in the United States, where hybrids were essentially introduced in the early 1930s and occupied virtually all maize farmland by 1945, the varied ecology in Mexico has greatly discouraged such universal adoption of hybrids (Frankel et al., 1995; Ortega, 2003a; Perales et al., 2003a). In Mexico, the proportion of maize land surface sown with landraces (80%) is far beyond both the average world value (48.5%) and the average for Latin America (55%; Morris, 2001), excluding Argentina, which now only plants hybrids. Excellent hybrids were developed in the public sector in Mexico in the early 1950s. Private breeding programs started in the 1960s, and their products dominate certain ecological sectors (Matchett, 2002). However, in many environments, current hybrids are not competitive with openpollinated varieties, there is little economic benefit to commercial companies to cater to small, specialized ecologies, and public programs are so underfunded and understaffed that hybrids are unlikely to be developed for such regions any time in the near future. The maize farmer growing maize for home consumption often has little reason to choose hybrid maize over locally-adapted open-pollinated maize. When maize is a main food source, texture, flavor and even appearance may be more highly valued than absolute productivity under rarely-achieved, optimal conditions (Anderson, 1952; Hernández, 1993; Ortega, 2003a). Local prices for local maize can be several times higher than for common, yellow imported maize (Barkin, 2003), but at the national level, with current governmental policies, there is pricing discrimination against native, open-pollinated maize (Ortega,2003a). Known, locally-adapted, open-pollinated maize with its more variable flowering times is often a "safer" crop under marginal farming conditions (Farr, 2001; Ortega, 2003a), and much of Mexico's maize growing is on marginal lands, especially in terms of water supplies. To date there are no comprehensive national accounts of where and to what extent hybrids are planted in different parts of the country. General estimates show that some regions have contrasting proportions of land planted to hybrids. In 1990, 38% of maize cropland surface was planted to modern varieties in Chiapas and 55% in Jalisco. That contrasts greatly with Sinaloa and Sonora, which averaged 95% hybrids, and the states of Mexico, Oaxaca, and Yucatan, which were 10% or lower (calculated by Perales, 1998, with 1992 data from SARH-FIRA-BANRURAL). Half of the very poor rural families live in the southern states of Veracruz, Puebla, Guerrero, Oaxaca and Chiapas (Warman, 2001). These are areas with high diversity of local maize landraces (Ortega, 2003a,b). Within these regions, environmental and social differences are of consequence. Some studies suggest that hybrids have been more successful in the lowlands than in the temperate and tropical highlands (Perales et al., 2003a), and that they are more common in relatively large commercial fields with irrigation or good rainfall (Perales, pers. comm.); they are not absent, however, in medium-size commercial holdings. In Jalisco, one of the three or four most important maize production regions in Mexico, two field studies (Orozco et al., 1990) report high input, commercial maize producers having only an average of 10 to 13 hectares of maize. The situation for the state of Chiapas illustrates contrasts within states. Chiapas is representative of the southern campesino-dominated mountainous region of Mexico, but also has a commercial sector of medium-size producers in the inner lowlands of the Fraylesca region. Figure 1 shows the proportion of land planted with maize; that proportion is high throughout, but is very high in higher elevation areas. Figure 2 presents the average size of a cultivated plot, which is generally very small and smaller still in the higher elevations. Figure 3 shows the average plot size for maize farmers, again very small, and smaller still at higher elevations. At high elevations only landraces are sown; in the Fraylesca valleys both hybrids and landraces are planted, the latter in higher proportion (Perales, pers. comm.) To the best of our knowledge, there are few formal studies regarding the swamping of local landraces of maize in Mexico by gene flow from hybrids or improved varieties (e.g., Ortega et al., 2000; Bellón and Risopoulos, 2001), and findings of introgression of local landraces by transgenics are still being formally confirmed. In areas where landraces are strongly preferred, the use of hybrids is usually minimal and fleeting. However, the consequences of even a small amount (less than 5%, for example) of constant gene flow can have substantial impact over time. Threats to landrace conservation in Mexico, before transgene introgression Basically, the symbiotic relationship between Mexico's maize landraces and Mexican campesinos, where each nurtures the other, is a delicate one. While GMOs may be the headline threat, the more immediate threats to both are largely economic, and, while GMOs do have potential economic risks, such risks are probably minor relative to the risks of Mexico's campesinos and their maize landraces being displaced by US imports. These economic risks include, but are certainly not limited to, subsidies paid to US and European farmers that Mexicans don't receive, large imports of U.S. maize, immigration of some of the best and brightest young people to the major metropolitan regions and to the US, lack of investment in applied agricultural research by the Mexican government, difficulties in finding loans for agricultural improvements, lack of infrastructure (roads, potable water, electricity, telephone) in many rural areas, etc. The landraces provide the variability to cope with the vagaries of changing weather patterns, pests and diseases, but they cannot overcome the huge subsidies that bolster U.S. maize exports to Mexico (US $22 to $30 per metric ton, roughly a 20% to 30% subsidy that comes to about $400 per hectare; Nadal, 1999, 2000, 2002). According to a recent report (Otte, 2004), the "average" US farm receives about $50,000 per year in governmental subsidies. If imported maize prices remain near or below cost of production in Mexico, it is likely that Mexico's own maize growing will decrease substantially and rapidly. Campesino maize farming, especially, will change status from an occupation to a luxury; maize will be grown in smaller populations (with adverse effects on vigor and diversity), mostly for household use. Maize will basically become a vegetable or horticultural crop, rather than a field crop, for many Mexican farmers. The effects are likely to be immense for those farmers, for maize is a cross-pollinated crop, and its vigor is highly dependent on population size. With small population sizes, inbreeding, drift, and loss of vigor soon occur. Loss of vigor, drift and minimal pricing are apt to jointly interact to further decrease farmers' interests in growing local-community maize varieties. The traditional, labor-intensive milpa growing system, where edible weeds were tolerated and inter-planting rather than monoculture was followed, a tradition based on millennia of farming experience (Hernández X., 1985a; García-Barrios and García Barrios, 1992; Farr, 2001; Aguilar et al., 2003), has largely been displaced because of widespread herbicide use that compensates somewhat for labor scarcity. The result is less overall biodiversity, more soil erosion on steep slopes, patchwork planting patterns and fewer companion crops grown. The milpa system probably also helped control pests that thrive best on monocultures (Altieri, 1994; Morales, 2000); it certainly served to insure that some crops reached harvest successfully (Thurston, 1990). The loss of the milpa system, followed rapidly by widespread abandonment of local maize landraces by campesinos would be a global catastrophe, given the precarious status of even the best of the world's maize germplasm banks (Goodman, 1984). Some of the political aspects of the situation have been summarized by Dyer and Dyer (2003) and Bartra (2003). Campesinos and their maize landraces are on the line, and the socioeconomic conditions described above currently constitute the most important threat to their persistence. For those who consider that the rule of comparative advantages should prevail at any cost, there is no point in continuing to support globally-non-competitive maize producers (e.g. Levy and Wijnberger, 1992; Tellez, 2004). Mexican government programs during the 1990s, such as PROCAMPO, were designed, among other things, to discourage non-competitive maize producers from continuing to grow maize (DyerLeal and Yunez-Naude, 2003). The governmental attitude, as early as 1991, was succinctly summarized by Barkin (2003, p. 171), "Es la política de este régimen remover del México rural la mitad de su población en los siguientes cinco años." Esteva (2003a, p. 205) quoted the then Secretary of Agriculture directly, "Mi obligación como Secretario de Agricultura es sacar del campo a diez milliones de campesinos." A recent Secretario de Agricultura was quoted as replying "atiendan a las señales del mercado, muchachos," dismissing requests for rural assistance (Bartra, 2003, p.227). Current Mexican landrace germplasm conservation for future maize improvement programs in Mexico or elsewhere should then be a matter of having appropriate germplasm banks and reproduction facilities, either in Mexico or abroad, if necessary. For those who value national maize sufficiency, consider it technically feasible (Turrent, 1993) and expect campesino maize production to continue to play an important social role, national support is imperative (García Barrios and García-Barrios, 1994; Appendini, et al., 2003; Bartra, in press). From an agronomic perspective, in situ landrace conservation and improvement (Brush, 1995), reduced tillage (Erenstein and Cadena Iñiguez, 1997), intercropping (García-Barrios, 2003), cover crops and green manuring (Bunch, 1994; Velázquez-Hernández et al., 1999), efficient fertilizer use (Pool-Novelo, 1999), agroforestry (García-Barrios and Ong, in press), integrated pest management (Morales, 2000) and other low input techniques are being developed further in order to meet the environmental challenges and economic constraints faced by campesinos. These efforts are not necessarily in conflict with supporting the medium and large, commercial Mexican producers who constitute the other third of Mexican producers, and who deliver the other half of the Mexican maize crop. Under this view, germplasm banks are considered as part of the effort to support in situ landrace conservation, as well as insurance policies against unknown and unpredictable future ecological threats. The preservation of the enormous biodiversity in maize in Mexico has really been the service to mankind of Mexican campesinos, who have cultivated the maize inherited from their ancestors for millennia. Basically, the world's future maize breeding depends upon access to adequate genetic diversity. Germplasm banks are useful for preserving existing diversity, they serve as essential insurance against loss of diversity, but it is the campesino that continues the development of in situ diversity. As diseases and insects continue to evolve, with several generations per season, simply locking up germplasm in freezers or housing a part of it in active breeding programs is an inadequate (although clearly a needed) response to pest evolution. Any functioning maize improvement programs for campesino regions will need to be locally-focused for the foreseeable future. Germplasm banks have tried to collect, study and preserve this material (Zavala et al., 1999), but the Mexican government has largely failed in recent decades to fund national germplasm banks (Rincón and Hernández, 2000), and international sources are not focused on such never-ending-funding missions. Even in the U.S., Duvick (1984), then vice-president for research at Pioneer, commented "I reserve my most severe condemnation for those government agencies ultimately responsible for funding of our germplasm collections. Our national stinginess in collecting, storing, renewing and describing the collections is inexcusable, not only in regard to our national obligations, but also in regard to our responsibility to the entire world." Clearly, if GMOs are any sort of threat to Mexican maize biodiversity, and that seems to be the most important question here to the world-at-large, first priority should go to strengthening the germplasm system responsible for preserving maize biodiversity. The question is not increasing its budget, but establishing a realistic one. Mexico's germplasm resources program is currently very precarious and in need of major equipment and programmatic support (Rincón and Hernández, 2000). The second need is the encouragement of in-situ germplasm improvement and conservation programs on a local level. Recognition by the government of the economic premium that local maize merits over U.S. number 2 yellow corn in Mexican markets (Appendini et al., 2003) would be a reasonable first step. This is the general context in which maize imports from the US (much of them transgenic) have grown from 396 thousand tons in 1993 to five million tons in 2001 (Meng and Ekboir, 2001), and in which the possibility of eliminating the de facto moratorium on growing transgenic maize in Mexico is being discussed. This is the complex and fragile situation of maize landraces in which it is necessary to analyze the possible biological and ecological benefits and risks of transgene introgression, and of developing purposeful, and possibly useful, transgene constructs in Mexican maize. Such constructs could add to the elimination of campesino maize farming if they contribute to US and large-scale farming dominance in Mexico. They might contribute to campesino farming and preservation of landrace biodiversity if they added traits that campesinos could use to their advantage and if adequate means of distribution existed. In the next sections, we address the following controversial topics: 1) What are the present status and future prospects of traits induced in maize varieties through transgenes; 2) How feasible would be their intended or unintended expansion across Mexican maize germplasm in the short and long run; 3) Could they solve or mitigate some of the most pressing ecological problems faced by Mexican maize producers; 4) What are the risks involved for Mexican maize production: a) under what circumstances could some of these traits further disrupt the commodity value, biological performance, diversity and integrity of landraces and their relatives; b) under what circumstances could some of these traits impact ecological processes within the maize fields that would have negative effects on the environment and on the economy of producers; 5) Are the inevitable risks worthwhile or are there more innocuous alternatives; 6) Given the uncertain responses to these questions, what preventive measures should be seriously considered, what needs to be investigated, and what needs to be discussed with the population directly at risk? 2. Maize Transgenes: Current Status Future Prospects In the US and Canada, the first generation of plant transgenes is now nearing its teenage years. The obvious candidates ("low hanging fruit" in the words of Bruce Walsh in Thro et al., in press) for transgenic deployment have largely all been tried. Four types clearly work, work reasonably well in the sense of doing what they were expected to do, have reasonably few deleterious traits on the crop itself, and have demonstrated that one more new technology works. For maize, they have thus far demonstrated little economic return to farmers or to their developers, even in the U.S. (Ferber, 1999; Duffy, 2001; Obrycki, 2001). To claim that the traits thus far harnessed are of utmost importance to mankind, or that they represent the most revolutionary achievement in plant breeding, or that they have or soon will have made a positive contribution towards relieving world hunger is patent nonsense, but some of the new traits fill gaps that breeders couldn't previously address effectively. And more useful traits, some of which may appeal to Mexican farmers and consumers, will follow, although far more slowly than the more ardent biotechnology promoters suggest (Goodman and Carson, 2000; Gepts, 2002) and at a very high cost of investment (Goodman, 2002). The new traits include several herbicide resistances (glyphosate and glufosinate types have been commercialized), Bt (Bacillus thuringiensis) toxins for certain insect resistances, a type of pseudocytoplasmic male sterility, and virus resistance. The latter two have yet to be commercialized in maize, but their general efficacy across several genera suggests that, if economic conditions become favorable, they could quickly be deployed (in plant breeding terms that means in about 15 years). Almost any single-gene trait that exists in maize can probably be altered transgenically, so a wide array of starch, protein, oil, wax and sugar variants will eventually be tested for potential use. Similarly, many single-gene traits from other organisms, with appropriate genetic modifications, should function in maize. Clearly, their potential utility depends greatly on their modes of gene action (complete dominance is usually helpful), stability across environments, interactions with other genes of consequence and pleiotropic effects on traits other than the trait the transgene itself was designed to create or modify. Pleiotropic risks are fairly minimal, but they can occur, even years after deployment, as happened in 1970 with southern leaf blight (Committee on Genetic Vulnerability of Major Crops, 1972). Risks are likely to be minor from alleles isolated directly from maize (and these will generally be incorporated by marker-assisted backcrossing rather than classical molecular engineering). Risks from modifying such alleles and using them as transgenes should also be minor, roughly equivalent to risks encountered with mutation breeding. Risks involving transgenes from other species are likely to be transgene-specific and require assessment in Mexico on an individual transgene basis (Ervin et al., in press; Wilkinson et al., in press). Before assuming that multiple transgenes will revolutionize maize breeding, it might be wise to realize that the greatest advances in plant breeding were accomplished many thousands of years ago in the fertile river valleys of Mexico and other centers of plant domestication. The next revolutionary event was the birth of hybrid maize. Both these events involved the simultaneous harnessing of multiple genes, alleles and modifiers. Today's era of modern molecular genetics can really only deal with a gene or two at a time, and we may be several generations of molecular biologists away from understanding and manipulating whole genomes (Bernardo, 2001), even within the same crop. Our current understanding of the simultaneous manipulation of numerous transgenes, their possible rewards and risks is very limited. Evaluating the direct effects of transgenes is sufficiently controversial that private companies, governmental agencies and concerned NGOs invest much effort to reach reasonable, if not always unanimous, conclusions. Efforts to monitor all of the many potential indirect effects of transgenes via pleiotropy, interactions with other genes, interactions with other organisms in the environment, or with the environment itself have generally had lower priority for transgenic developers and governmental regulatory agencies (as the list is virtually endless, funding is finite, and effort is concentrated on what are thought to be the more obvious potential problems), and some of these can only be studied in situ, once the transgene is actively deployed across a reasonably widespread area. In some ways for Mexico, the US Corn Belt is serving as a large-scale experiment for newly introduced transgenes, but the U.S./Mexican border is porous, and results in the US may not always be directly applicable to Mexico. Some results may be known only well-after widespread use of the transgene, despite widespread experimental trials (see Pline et al., 2001, and Johnson, 2003, for examples). There, of course, is the possibility of the production of industrial chemicals and pharmaceuticals in maize (Fitzgerald, 2003). "Pharming" is potentially a significant threat to Mexican maize; although, if employed, it would involve a few contract-farmers and little hectarage (hopefully very well isolated). The advantage that maize genetics has over self-pollinated crops with less detailed genetic knowledge is relatively minor relative to the risks of pollen or seed contamination of seed and food supplies (Nature Biotechnology, 2004; Thro et al., in press). Industrial-chemical production is of more general interest to farmers, because more farmers would be needed, but with a cross-pollinated crop like maize, the result is apt to turn into synthetic-rubber-infested maize flakes or solvent-contaminated maize sweeteners or some other headline-grabbing innovation that no one really wants to see. Such products would have to be restricted to 100%-male-sterile maize or its equivalent to be safe, and, as of today, no one can produce such an all-male-sterile maize (National Academy of Sciences, 2004). In the best of steriles, there are a few escapes or reversions to fertility. Whether pharma/industrial crops should use maize as a platform needs to be resolved at the US level as well. It may not be acceptable for pharmaceutical or industrial applications to use maize in the U.S., if there is any risk of gene flow into Mexico. At present, pharma/chemical production in maize is not generally prohibited, despite the risks involved. A concept that has just begun to become apparent to industry is that biotechnology is very expensive, the financial returns are distant, and the financial returns are apt to be much higher in medicine, human and veterinary, than in plant breeding or plant molecular biology. Perhaps the best example of this to date is the Pharmacia spin-off of Monsanto, freeing the pharmaceutical company from agricultural plant molecular biology (Clark, 2001). The relatively low and slow return on investment will certainly not stop the application of biotechnology to plant breeding and the deployment of transgenics, but is apt to shift some focus from private investment to public and philanthropic investment. If Mexico or Argentina were to engage in transgenic-virus resistance in maize, public financing may be required to achieve it, as the potential cost/benefit ratio to a private company is probably not as rewarding as developing a lymphoma or breast-cancer vaccine or treatment.