Climate change is predicted to cause losses of more than 20% in agricultural production by 2050. With a growing global population, crops adapted to the effects of climate change, such as drought and heat, are necessary for the maintenance of productivity levels to meet the demand for food.
Scientists from the International Maize and Wheat Improvement Center (CIMMYT), in collaboration with scientists from the Universidad Autónoma Agraria Antonio Narro, set out to analyze bread wheat landrace traits against seven climactic variables: mean temperature, maximum temperature, precipitation, precipitation seasonality, heat index of mean temperature, heat index of maximum temperature, and drought index. The method used genome-environment associations (GEA) and environmental genome-wide association scans (EnvGWAS), which have traditionally been poorly applied in this type of research.
Based on a sample of 990 bread wheat landraces from the CIMMYT genebank, the study discovered proteins associated with tolerance to drought and heat. With these results, new genotypes with resistant alleles can be selected for breeding programs to produce resistant varieties adapted to extreme environments and the effects of climate change.
This work was implemented by CIMMYT as part of the Seeds of Discovery (SeeD) Initiative in collaboration with Universidad Autónoma Agraria Antonio Narro (UAAAN), made possible by the generous support of the MasAgro project funded by the Government of Mexico’s Secretariat of Agriculture and Rural Development (SADER). Any opinions, findings, conclusion, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of SADER.
Cover photo: Field hand collecting wheat in Ciudad Obregon, Mexico. (Photo: Peter Lowe/CIMMYT)
Rust pathogens are the most ubiquitous fungal pathogens that continue to pose a serious threat to wheat production. The preferred strategy to combat these diseases is through breeding wheat varieties with genetic resistance.
Landraces are a treasure trove of trait diversity, offer an excellent choice for the incorporation of new traits into breeding germplasm, and serve as a reservoir of genetic variations that can be used to mitigate current and future food challenges. Improving selection efficiency can be achieved through broadening the genetic base through using germplasm pool with trait diversity derived from landraces.
In a recent study, researchers from the International Maize and Wheat Improvement Center (CIMMYT) used Afghan landrace KU3067 to unravel the genetic basis of resistance against Mexican races of leaf rust and stripe rust. The findings of this study not only showcase new genomic regions for rust resistance, but also are the first report of Lr67/Yr46 in landraces. This adult plant resistance (APR) gene confirms multi-pathogenic resistance to three rust diseases and to powdery mildew.
Using genotype sequencing and phenotyping, the authors also report an all-stage resistance gene for stripe rust on chromosome 7BL, temporarily designated as YrKU. The genetic dissection identified a total of six quantitative trait locus (QTL) conferring APR to leaf rust, and a further four QTL for stripe rust resistance.
Although use of landraces in wheat breeding has been practiced for a long time, it has been on a limited scale. This study represents a significant impact in breeding for biotic stresses, particularly in pest and disease resistance.
Sridhar Bhavani, head of rust pathology and molecular genetics and the International Maize and Wheat Improvement Center (CIMMYT), shared potential solutions for fighting back against wheat stem rusts like Ug99.
More than 200 new wheat varieties released by CIMMYT over the last ten years have contributed to reducing the spread of wheat stem rust in East Africa, where the disease originated. Scientists identify genes resistant to Ug99 and breed new varieties that are not susceptible to stem rust pathogens.
For long-term success, combining multiple resistant genes within a single variety is the way to go.
Tonahuixtla, a small town located in Mexico’s state of Puebla, had suffered extreme environmental degradation due to deforestation and erosion. Agricultural land was in poor condition and the town had stopped producing many of their heirloom maize varieties, a loss to both biodiversity in the region and local culture. Poverty had increased, forcing many to migrate to bigger cities or to the United States for work. Those who were left behind, most of them women, had few ways to generate income to support their families.
Today, the story of Tonahuixtla is different. The town actively participates in reforestation and erosion-prevention activities. Landrace maize production is increasing, preserving the town and region’s biodiversity and customs. The residents have job opportunities that allow them to stay in their town and not migrate, all while preserving local biodiversity and protecting the environment.
What caused this change?
Corn husks.
Long considered a waste product, corn husks have been given a new lease on life through the Totomoxtle project. Named for the traditional indigenous Nahuatl word for corn husk, Totomoxtle turns the husks of native maize, found in a variety of colors, into a beautiful and sustainable veneer for furniture and walls. Founded by Mexican graphic designer Fernando Laposse, Totomoxtle has given farmers an incentive to plant native maize again, preserving invaluable biodiversity for future generations.
When Denise Costich, head of the maize collection of the germplasm bank at the International Maize and Wheat Improvement Center (CIMMYT), heard about the Totomoxtle project she knew she wanted to help. Passionate about preserving native maize, she and her team identified 16 landrace varieties from the CIMMYT maize collection that would produce husks in interesting colors and could grow well in the altitude and climate conditions of Tonahuixtla. She invited Laposse and project members to come visit the genebank and learn about CIMMYT’s work, and provided them with seed of the landraces they had identified.
“This is what we normally do in our work at the germplasm bank, we give people seed,” Costich said. “But this turned into a closer collaboration.”
In the dry and mountainous terrain surrounding the village of Tonahuixtla, native maize preservation and reforestation efforts have been key in protecting the local environment and culture. (Photo: Denise Costich/CIMMYT)
Colorful collaboration
The maize germplasm bank team arranged for Totomoxtle project members to receive training in how to make controlled pollinations in the native maize varieties, at one of CIMMYT’s experimental stations.
“The technicians at CIMMYT’s Agua Fria station loved meeting the project members from Tonahuixtla, and immediately became passionate about the Totomoxtle project,” Costich said. “To this day, the technicians still save all of the colored corn husks from CIMMYT maize trials and send them to Tonahuixtla to provide them with additional material for their project.”
In the village of Tonahuixtla, project members — many of them women — work to iron the corn husks flat and glue them on to a stiff backing, then send them via courier to Laposse’s workshop in London where he uses them to create beautiful furniture and wall panels. This work allows the residents of Tonahuixtla to stay in their village and not be forced to migrate, all while preserving maize biodiversity and protecting the environment.
“Part of what this project is doing is also helping to keep families together — providing livelihoods so that people can stay in their communities, so that they don’t have to send all of their young people off to Mexico City or to the United States. To me, it’s really all connected,” Costich said.
Native maize tassels against a bright blue sky in Tonahuixtla. (Photo: Denise Costich/CIMMYT)
In the town of Tonahuixtla, Puebla, Mexico, a native maize field sits below a tree-covered hillside. The town has been active in reforestation efforts to control erosion. (Photo: Denise Costich/CIMMYT)
Denise Costich (front right, sitting) poses for a photo with Tonahuixtla residents, members of the Totomoxtle project, and CIMMYT Germplasm Bank staff. (Photo: Provided by Denise Costich/CIMMYT)
The value of sustainability
The project also shows the intersection between biodiversity conservation and protecting the local environment. The maize husks used for the project are a sustainable and biodegradable material, and any residue from the maize husks that are not used for the Totomoxtle project are either fed to animals in the dry season or used to make fertilizer, which is then returned to the maize fields, a completely circular cycle in which nothing is wasted.
“I think that many of the communities that we work in really do understand the value and the importance of biodiversity,” Costich said. “In Tonahuixtla, the people are trying to reforest the hillsides in their region. They understand the connection between having no vegetation on the hills and having the rain water just roll right off the hills and into the temporary streams, thus losing that critically important resource. Over the years, as a result of the work they have done there, they have seen with their own eyes the improvement in the environment, not only that the hills are now covered with vegetation, but also they see a lot less runoff and erosion. I think that’s a really important lesson for everyone. I come from an ecology background, so I am always very excited to get involved in projects where it’s not just about maize, it’s about everything. It’s also about people’s lives, and nutrition, and the connections between them.”
Preserving local maize biodiversity is not just important for Tonahuixtla — it is important to all of humanity. Native maize varieties have adapted for thousands of years in farmers’ fields across Mesoamerica, developing natural resistance to local plant pests and diseases, as well as climatic conditions such as heat or drought. These native maize seeds, passed down generation to generation, could hold the key to developing improved maize varieties that can resist emerging maize diseases or extreme weather events related to climate change. If this biodiversity is lost, it represents a loss to global food security as a whole.
CIMMYT works to protect many of these native maize varieties in their germplasm bank, which is home to over 28,000 different collections of maize. Kept in cold storage under optimum conditions in the CIMMYT seed vault, these seeds are preserved for future generations and are available to anyone who needs them, including farmers such as those in Tonahuixtla, who had lost much of their native maize diversity.
“The biodiversity of cultivated plants is basically the guarantee for the future,” Costich said. “This is our security backup. Seed security is food security.”
Maize cobs and veneer made out of corn husks are on display at an exhibition of the Totomoxtle project in Mexico City. (Photo: Denise Costich/CIMMYT)
Members of the CIMMYT Germplasm Bank team stand for a photo with a variety of landraces at an exhibition of the Totomoxtle project in Mexico City. (Photo: Emilio Diaz)
Cover photo: Denise Costich (center, pink hat) stands with members of the Totomoxtle project and CIMMYT Germplasm Bank staff members near Tonahuixtla. (Photo: Provided by Denise Costich/CIMMYT)
“What my project tries to do is visualize the diversity of corn that we have in my home country,” said Mexican designer Fernando Laposse. He partnered with CIMMYT, working with a village of Mixtec farmers and herders to transform waste from these plants into furniture. The corn’s kernels and husks come in hues of cream, deep red, pink, black and purple.
Corn is one of the most widely produced crops in the world, and Mexico is home to at least 60 recorded unique landraces, the traditional, locally adapted strains. Preserving these ancient varieties is key for future sustainability, explains geneticist Martha Willcox, who works with the Mexico-based International Maize and Wheat Improvement Center (CIMMYT) to conserve the genes of dwindling crops. But left in the hands of aging campesinos, ancestral maize is at risk of becoming extinct. And the consequent loss of biodiversity, the FAO warned in its 2010 report, will have a major impact on the ability of humankind—which will number nine billion by 2050—to combat food insecurity in the face of climate change.
Maize is more than a crop in Mexico. In many cases, it connects families with their past. Landraces are maize varieties that have been cultivated and subjected to selection by farmers for generations, retaining a distinct identity and lacking formal crop improvement. They provide the basis of Mexico’s maize diversity.
Back in 1966-67, researcher Ángel Kato from the International Maize and Wheat Improvement Center (CIMMYT) collected 93 maize landraces samples from 66 families in Mexico’s state of Morelos. These seeds were safeguarded in CIMMYT’s Germplasm Bank, which today stores 28,000 samples of maize and its wild relatives from 88 countries.
50 years later, doctoral candidate Denisse McLean-Rodriguez, from the Sant’Anna School of Advanced Studies in Italy, and researchers from CIMMYT started a new study to trace the conservation and abandonment of maize landraces over the years.
The study shows that landrace abandonment is common when farming passes from one generation to the next. Older farmers were attached to their landraces and continued cultivating them, even in the face of pressing reasons to change or replace them. When the younger generations take over farm management, these landraces are often abandoned. Nonetheless, young farmers still value the cultural importance of landraces.
Maize landraces can be conserved “in situ” in farmers’ fields and “ex situ” in a protected space such as a germplasm bank or community seed bank. The loss of landraces in farmers’ fields over 50 years emphasizes the importance of ex situ conservation. Traits found in landraces can be incorporated into new varieties to address some of the world’s most pressing agriculture challenges like changing climates, emerging pests and disease, and malnutrition.
This research was supported by the CGIAR Research Program on Maize (MAIZE), the Sant’Anna School of Advanced Studies, Wageningen University and the Global Crop Diversity Trust.
Mexican and international researchers have joined with farmers and specialists from Jala, a scenic valley near the Pacific Coast of Mexico’s state of Nayarit, in a critical strategy to save and study an endangered, legendary maize race whose ears once grew longer than a man’s forearm.
Specialists from the International Maize and Wheat Improvement Center (CIMMYT) are analyzing the race’s genetic diversity, in hopes of preserving its qualities and, in concert with Jala farmers, safeguarding its future and merits.
Efforts include a new maize festival that reprises a yearly contest begun in 1981 to honor the community’s largest maize ear, but the outsize Jala maize race faces myriad hurdles to survive, according to Carolina Camacho, CIMMYT socioeconomics researcher and festival collaborator.
“The Jala maize landrace is unsuited to mechanization due to its size and agronomic requirements,” said Camacho. “It must be sown by hand and, because the plant can grow to several meters or taller, the ears must be harvested on horseback.”
Jala maize is also losing out to more competitive and profitable improved varieties, Camacho added. It is prized locally for its floury texture, but many farmers favor varieties more suited to milling and which yield more husks — in high demand as tamale wraps — as well as fodder and feed. The floury texture also means the grain is less dense and so fetches a lower price on external markets, where grain is sold by weight.
Youth panel discussion at the Feria de la Mazorca del Maize Nativo with Carolina Camacho, CIMMYT (third from right). (Photo: Denise Costich/CIMMYT)
A fair fight for preservation
The most recent “Feria de la Mazorca del Maíz Nativo,” or Landrace Maize Ear Festival, was held in December 2018. Under the boughs of a giant guanacaste tree in the town square of Coapan, Jala Valley, children, elders, cooks and dancers celebrated maize and its associated traditions. The festival culminated in the contest for the largest maize ear, with the winning farmer’s submission measuring nearly 38 centimeters in length.
The competition typically takes place in August as part of Jala’s two-week “Feria del Elote,” or green ear festival, first established to foster the appreciation and preservation of the native maize.
CIMMYT scientists helped the community set up a local genebank to store Jala landrace seed, according to Denise Costich, head of the CIMMYT maize germplasm bank and festival collaborator.
“This enhances the community’s role as custodians of landrace diversity and their access to the seed,” said Costich, adding that Jala seed from as far back as the early 1980s forms part of CIMMYT’s maize collections, which comprise 28,000 unique samples.
Under CIMMYT’s Seeds of Discovery project, scientists are analyzing the remaining genetic potential in the Jala maize population, particularly to understand the extent and effects of both inbreeding and outcrossing.
On the one hand, Costich said, Jala’s unique genetic pedigree appears to be diluted from mixing with other varieties in the valley whose pollen lands on Jala silks. At the same time, she worries about possible inbreeding in some small and isolated valley pockets where Jala is grown.
Finally, the yearly contest, for which maize ears are harvested in the green stage before maturity, precludes use of the grain as seed and so may also remove inheritable potential for large ears from the local maize gene pool.
Farewell to small-scale farmers?
Setting up the contest entries in Coapan: (l-r) Cristian Zavala of the CIMMYT maize genebank recording data; Rafael Mier from Fundacion Tortillas de Maiz Mexicana; Victor Vidal, INIFAP collaborator and judge of the contest; and Alfredo Segundo of the CIMMYT maize genebank. (Photo: Denise Costich/CIMMYT)
Whatever the causes, Jala maize isn’t what it used to be. In 1924, a visiting scientist observed maize plants over 6 meters in height and with ears more than 60 centimeters long — far longer than today’s samples.
One grave challenge to the landrace’s continued existence is the steady disappearance of older farmers who grow it. As throughout rural Mexico, many youths are leaving farm communities like Jala in search of better opportunities and livelihoods in cities.
Camacho believes the festival and contest encourage farmers to continue growing Jala maize but cannot alone ensure the landrace’s preservation.
“The solutions need to encompass all aspects of Jala maize and be supported by the entire community, particularly young people,” said Camacho.
The festival in Coapan included a panel discussion with local youths, among them graduate students from the Autonomous University of Nayarit.
“The panelists highlighted the lack of opportunities in rural areas and the need for an economically secure future; things that Jala maize doesn’t offer,” Camacho said.
The festival is a collaboration among Costich, Camacho, Victor Vidal of INIFAP-Nayarit, and local partners including Gilberto González, Ricardo Cambero, Alondra Maldonado, Ismael Elías, Renato Olmedo (CIMMYT), and Miguel González Lomelí.
In the early 20th century, Aaron Aaronsohn, a prominent agronomist best known for identifying the progenitor of wheat, began looking for durum wheat landraces in Israel. He traveled to villages across the country, carefully collecting and recording details of the local varieties used in each area.
This task was not without purpose. Aaronsohn recognized that as increasing numbers of settlers like himself came to the territory, the varietal change from the introduction of new and competitive wheat varieties and the rapid intensification of agriculture would soon cause all the traditional structures he had identified to disappear.
Aaronsohn was one of the first to begin collecting germplasm in the region, but others saw the importance of collecting before large-scale change occurred. For example, Russian botanist Nikolai Vavilov gathered samples from Israel on one of his expeditions through the Middle East. By the end of the century, a number of collections had been established, but overall efforts at conservation were fragmented.
“That’s why we say the collection was on the verge of extinction,” explains Roi Ben-David, a researcher at the Volcani Center, Israel’s Agricultural Research Institute (ARO). “There were single accessions in genebanks around the world but no one really gave them special treatment or saw their value. Many were in private collections; others were simply lost.”
When Ben-David and his colleagues began looking for landraces six years ago, even the collection housed at the Israeli Genebank (IGB) was disappointing, with many samples stored in unmarked boxes in sub-optimal conditions. “When we came in nobody was really trying to study what we had and put it together to represent the area’s wheat landscape as it was 100 years ago.”
Long-term efforts to restore and conserve a collection of Israeli and Palestinian wheat landraces (IPLR) have led to the restoration of 930 lines so far, but there are many varieties that cannot be recovered. Therefore, it came as a great surprise to Ben-David when he arrived at the International Maize and Wheat Improvement Center (CIMMYT) headquarters in Mexico and stumbled upon one of the collections presumed lost. “I think it was actually my first week at CIMMYT when I spotted a demonstration plot growing one of the lost varieties — a subset of the Ephrat-Blum collection — and I couldn’t believe it.”
He had heard about this collection from the late Abraham Blum, but had never been able to locate it. “Someone might have moved the seeds, or maybe the box was not well labelled and thrown out. We don’t know, but needless to say it was a very good surprise to rediscover 64 of our missing lines.”
What prompted you and your colleagues to start looking for landraces in Israel?
We began because we recognized local landraces are good genetic resources but unfortunately, we couldn’t find any. It wasn’t so much that they didn’t exist, but the accessions were scattered across the world, mostly in private collections in countries like the USA or Australia. The Israeli Genebank, which sits only two floors above my office, had a few buckets of germplasm but nobody really knew what was inside.
The Middle East and the Fertile Crescent are centers of diversity, not only for wheat but for all crops that were part of the Neolithic revolution 10,000 years ago. They started here – the exact point of origin was probably in what is now southeast Turkey – so we have had thousands of years of evolution in which those landraces dominated the agricultural landscape and adapted to different environments.
Why do you think so much of the collection was lost?
The lines from Israel were lost because their conservation simply wasn’t prioritized. Losses happen everywhere but what was missing in this case was the urgency and understanding of just how important these collections are. Luckily, the current manager of the IGB, who is a fundamental partner in building the IPLR, understood the need to prioritize this and allocated a budget to conserve it as one collection.
What is the value of conserving landraces and why should it be prioritized?
Landraces are an extremely important genetic resource. Wild relatives are the biggest treasure, but breeders are usually reluctant to use them because they are so very different from modern varieties. So landraces form the link between these two, having already been domesticated and developed within farming systems while remaining genetically distinct from the modern. In wheat, they’re quite easy to spot because of how tall they are compared to the semi-dwarf varieties that replaced them in the 20th century.
There are two main reasons why we need to prioritize conservation. First, we believe that the evolution under domestication in this region is important to the community as a whole. Second, it is now a critical time, as we’re getting further from the time in which those traditional lines were in use. The last collection was carried out in the 1980s, when people were still able to collect authentic landraces from farmers but this is just not possible any more. We travelled all over the country but the samples we collected were not authentic – most were modern varieties that farmers thought were traditional. Not everybody knows exactly what they’re growing.
The time factor is critical. If we were to wake up 50 years from now and decide that it’s important to start looking for landraces, I don’t know how much we could actually save.
Are there any farmers still growing landraces in Israel?
When we started looking for farmers who are still growing landraces we only found one farm. It is quite small – only about ten acres shared between two brothers. They grow a variety which is typically used to make a traditional food called kube, a kind of meat ball covered in flour and then then either fried or boiled. If you boil it using regular flour it falls apart, so people prefer to use a landrace variety, which is what the brothers grow and are able to sell for up to six times as much as regular durum wheat in the market. However, they’re not really interested in getting rich; they’re just trying to keep their traditions alive.
How are you and your colleagues working to conserve the existing collection?
There are two approaches. We want to develop is ex-situ conservations to preserve the diversity. As landraces are not always easy to conserve in a genebank, we also want to support in-situ conservation in the field, like traditional farmers have done. Together with the IGB we’ve distributed seed to botanical gardens and other actors in the hope that at least some of them will propagate it in their fields.
Having established the collection, we’re also trying to utilize it for research and breeding as much as possible. So far we’ve characterized it genetically, tested for drought tolerance and other agronomic traits and we’re in talks to start testing the quality profile of the lines.
Did you continue working on this while you were based at CIMMYT?
Yes, this was an additional project I brought with me during my sabbatical. The main success was working with Carolina Sansaloni and the team at the Genetic Resources program to carry out the genotyping. If it were left to my own resources, I don’t think we could have done it as the collection contains 930 plant genotypes and we only had the budget to do 90.
Luckily, CIMMYT also has an interest in the material so we could collaborate. We brought the material, CIMMYT provided technical support and we were able to genotype it all, which is a huge boost for the project. We had already been measuring phenotypes in Israel, but now that we have all the genetic data as well we can study the collection more deeply and start looking for specific genes of interest.
What will happen to the lines you discovered at CIMMYT?
They’ve been sent back to Israel to be reintegrated into the collection. I want to continue collaborating with people in CIMMYT’s Genetic Resources program and genebank to do some comparative genomics and assess how much diversity we have in the IPLR collection compared with what CIMMYT has. Is there any additional genetic diversity? How does it compare to other landraces collections? That is what we want to find out next.
Roi Ben-David is based at Israel’s Agricultural Research Organization (ARO). He works in the Plant Institute, where his lab focuses on breeding winter cereals such as wheat. He has recently completed a one-year sabbatical placement at the International Maize and Wheat Improvement Center (CIMMYT).
CIMMYT’s germplasm banks contain the largest and most diverse collections of maize and wheat in the world. Improved and conserved seed is available to any research institution worldwide.
Expert Mexican scientists and farmer cooperatives have formed a non-profit organization to support small-scale landrace maize farmers who continue to conserve and plant seeds of their own native heirloom varieties. The civil association, known as ProMaíz Nativo, intends to work collaboratively on projects to improve the lives of native maize and milpa farm families. Group members include national and internationally recognized maize experts, ethnobotanists, socioeconomists, food and nutrition scientists, marketing experts, maize farmers and farmer groups.
The civil association has also created a collective trademark, Milpaiz, which can be used by farmers to demonstrate the authenticity of the native maize varieties they grow and sell. This trademark will certify that a farmer’s maize is native to their community and derived from their continuous selection of seed. It will also certify that it is grown by small farmers and that they are selling only the surplus of their crops after feeding their own family. The trademark will also make a transparent effort to connect these farmers to a culinary market which values the quality, rarity and history of their production.
“Mexico is the center of origin of maize, and home to much of its genetic diversity. This initiative will allow us to certify that products are truly landrace maize from smallholder farmers, so that the benefits reach the smallholder farmers that have provided us with this biodiversity,” said Flavio Aragón, a genetic resources researcher with Mexico’s National Institute for Forestry, Agriculture and Livestock Research (INIFAP).
Members of the association gather for a photo at the launch event. (Photo: ProMaíz Nativo)
Researchers like Aragon, members of farmer groups and local chefs attended the official launch of ProMaíz Nativo on June 14, 2019, at the World Trade Center in Mexico City, during restaurant trade fair ExpoRestaurantes.
Edelmira Linares, ethnobotanist at the National Autonomous University of Mexico (UNAM) and member of the association, emphasized that the collective trademark Milpaiz covers all crops grown in the traditional milpa intercrop farming system in Mexico: maize, beans, squash, edible greens, amaranth, pumpkin seeds, and certain vegetables.
“The trademark will make it easier for income to reach the farmers, will allow smallholder farmers to sell their products in supermarkets and to have a legal presence,” said Amanda Galvez, a food chemist at UNAM and president of ProMaíz Nativo.
Traditional milpa products: native maize, beans, squash, chilies and other local fruits and vegetables. (Photo: Martha Willcox/CIMMYT)
Fair and sustainable market growth
Many smallholder farmers continue to plant the same native maize varieties that their parents and grandparents planted, developed in their villages and regions and improved by farmer selection dating back to their ancestors. These varieties are prized by their local communities for their unique flavors, colors, texture and use in special dishes — and the global culinary community is catching on. Native maize, or landraces, have become extremely popular with chefs and consumers in the past few years, drawing attention and imports from across the world. However, increased demand can mean increased vulnerability for farmers.
Many maize experts in Mexico were concerned with how to best support and protect smallholder farmers navigating this increase in demand. Without guidelines and transparency, it is difficult to ensure that farmers are being fairly compensated for their traditional maize, or that they are able to save enough to feed their own families.
In a discerning culinary market, a symbol of certification such as the collective trademark could serve to differentiate the families who have long been the guardians of these native varieties from larger commercial farmers who acquire these heirloom seeds. But there was no pre-existing space for these guidelines to be determined and developed.
Martha Willcox (left) with farmers and their milpa products in Santa María Yavesía, Oaxaca state, México. (Photo: Arturo Silva/CIMMYT)
“There is a depth of expertise on maize in Mexico, but these experts all work at different institutions, making it more difficult for all of them to collaborate on a project like this,” said Martha Willcox, landrace improvement coordinator at the International Maize and Wheat Improvement Center (CIMMYT).
“The formation of this civil association is truly novel in the history of native maize in Mexico, and its strength comes from the expertise of its members, made up entirely of Mexican scientists and Mexican farmer co-ops,” Willcox explained.
She initiated and facilitated the formation of this group of scientists and continues to work closely with them as an advisor. “This association will help provide a space and network where these experts can work together and speak in one voice to support maize and maize farmers.”
CIMMYT does not have a seat in the association but has played a key role in its facilitation and has provided funding to cover logistics and fees related to the formation of the organization, through the CGIAR Research Program on Maize (MAIZE). Mexico’s National Commission for the Knowledge and Use of Biodiversity (CONABIO) has also participated in the logistics and facilitation of the formation of the organization.
Members of the association pose with CIMMYT staff that helped facilitate the creation of the group. (Photo: ProMaíz Nativo)
Maize is more than a crop in Mexico. While it provides food, feed and raw materials, it is also a bloodline running through the generations, connecting Mexico’s people with their past.
The fascinating diversity of maize in Mexico is rooted in its cultural and biological legacy as the center of origin of maize. Landraces, which are maize varieties that have been cultivated and subjected to selection by farmers for generations, retaining a distinct identity and lacking formal crop improvement, provide the basis of this diversity.
As with any cultural legacy, the cultivation of maize landraces can be lost with the passage of time as farmers adapt to changing markets and generational shifts take place.
Doctoral candidate Denisse McLean-Rodríguez, from the Sant’Anna School of Advanced Studies in Italy, and researchers from the International Maize and Wheat Improvement Center (CIMMYT) have undertaken a new study that traces the conservation and abandonment of maize landraces over the last 50 years in Morelos, Mexico’s second smallest state.
The study is based on a collection of 93 maize landrace samples, collected by Ángel Kato as a research assistant back in 1966-67 and stored in CIMMYT’s Maize Germplasm Bank. Researchers traced the 66 families in Morelos who donated the samples and explored the reasons why they abandoned or conserved their landraces.
Doctoral candidate Denisse McLean-Rodríguez (left) interviews maize farmer Roque Juarez Ramirez at his family home in Morelos to explore his opinions on landrace conservation. (Photo: E. Orchardson/CIMMYT)
Tracing landrace abandonment
In six cases, researchers were able to interview the original farmers who donated the samples to CIMMYT. In other cases, they interviewed their family members, most frequently the sons or daughters, or alternatively their grandchildren, siblings, nephews or widows.
The study reveals that maize landrace cultivation has diminished significantly within the families. Only 13 of the 66 families are still cultivating the same maize seed lots as in 1966-67 and there was consensus that the current social, economic and physical environments are unfavorable for landrace cultivation.
Among the reasons for abandonment are changes in maize cultivation technologies, shifting markets for maize and other crops, policy changes, shifting cultural preferences, urbanization and climate change.
“By finding out about landrace continuity in farmers’ fields and the factors driving change, we were able to better understand the context in which these landraces are currently cultivated,” said McLean-Rodríguez. “Our study also allowed us to evaluate the importance of ex situ conservation in facilities like CIMMYT’s Germplasm Bank.”
Juarez and Oliveros’s grandson shows the family’s heirloom maize: maíz colorado (left) and Ancho maize. (Photo: E. Orchardson/CIMMYT)
Maize biodiversity conservation
Maize landraces can be conserved “in situ” in farmers’ fields and “ex situ” in a protected space such as a germplasm bank or community seed bank.
“These conservation strategies are complementary,” explained McLean-Rodríguez. “Ex situ conservation helps to secure landraces in case of unpredictable conditions that threaten their conservation in the field, while in situ cultivation allows the processes that generated maize’s diversity to continue, allowing the emergence of mutations and the evolution of new potentially beneficial traits.”
The loss of landraces in farmers’ fields over 50 years emphasizes the importance of ex situ conservation. CIMMYT’s Maize Germplasm Bank holds 28,000 samples of maize and its wild relatives from 88 countries, spanning collections dating back to 1943. Safeguarded seed stored in the Germplasm Bank is protected from crises or natural disasters, and is available for breeding and research. Traits found in landraces can be incorporated into new varieties to address some of the world’s most pressing agriculture challenges like changing climates, emerging pests and disease, and malnutrition.
McLean-Rodríguez recalls an aspect of the study that she found particularly rewarding: “Many of the families who had lost their landrace for one reason or another were interested in receiving back samples of their maize from the CIMMYT Germplasm Bank. Some were interested due to personal value, while others were more interested in the productive value. They were very happy to retrieve their maize from the Germplasm Bank, and it would be very interesting to learn whether the repatriated seed is cultivated in the future.”
Ventura Oliveros Garcia holds a photograph of her father, Santos Oliveros, who was one of the maize farmers who donated seed to CIMMYT’s germplasm bank in 1966-67. (Photo: E. Orchardson/CIMMYT)
A family tradition
One of the families to take part in the study was farmer Roque Juarez Ramirez and his wife, Ventura Oliveros Garcia, whose father was one of the donor farmers from Morelos. “I was so happy to hear the name of my father, [Santos Oliveros],” recalls Oliveros, remembering the moment McLean-Rodríguez contacted her. “He had always been a maize farmer, as in his day they didn’t cultivate anything else. He planted on his communal village land [ejido] and he was always able to harvest a lot of maize, many ears. He planted an heirloom variety of maize that we called arribeño, or marceño, because it was always planted in March.”
Juarez senses his responsibility as a maize farmer: “I feel that the importance [of maize farming] is not small, but big. We are not talking about keeping 10 or 20 people alive; we have to feed a whole country of people who eat and drink, apart from providing for our families. We, the farmers, generate the food.”
Filling vessels of champurrado, a Mexican maize-based sweet drink, and presenting samples of the family’s staple maize — maíz colorado and the Ancho landrace — Oliveros describes what maize means to her: “Maize is very important to my family and me because it is our main source of food, for both humans and animals. We use our maize variety to make pozole, tortillas, tamales, atole, quesadillas, picadas and many other foods.”
The Juarez-Oliveros family substituted the Ancho seed lot from Olivero’s father with another seed lot from the Ancho landrace obtained from her husband’s family. The Ancho landrace is used to make pozole, and continues to be widely cultivated in some municipalities of Morelos, including Totolapan, where the family resides. However, researchers found other landraces present in the 1966-67 collection, such as Pepitilla, were harder to trace 50 years later.
Maíz colorado (left), or red maize, is an important part of the family’s diet. The family’s Ancho maize (right) has characteristically wide and flat kernels, and is a key ingredient of the pozole stew. (Photo: E. Orchardson/CIMMYT)
The study shows that landrace abandonment is common when farming passed from one generation to the next. Older farmers were attached to their landraces and continued cultivating them, even in the face of pressing reasons to change or replace them. When the younger generations take over farm management, these landraces are often abandoned.
Nonetheless, young farmers still value the cultural and culinary importance of landraces. “Maize has an important traditional and cultural significance, and is fundamental to our economy,” said Isaac Juarez Oliveros, son of Roque and Ventura. “I have been planting [maize landraces] since I was around 15 to 20 years old. I got my maize seed from my parents. I believe it is important for families to keep planting their maize, as it has become tradition passed down through many generations.”
The family’s son, Isaac Juarez Oliveros, stands outside the maize storage room where they store and dry their harvested maize for sale and consumption. (Photo: E. Orchardson/CIMMYT)
The legacy for future generations
Global food security depends on the maintenance of high genetic biodiversity in such key staple food crops as maize. Understanding the causes of landrace abandonment can help to develop effective landrace conservation strategies. The authors suggest that niches for landrace conservation and even expansion can be supported in the same manner that niches have been created for improved maize and other commercial crops. Meanwhile, management of genetic resources is vital, both in the field and in germplasm banks, especially in developing countries where broader diversity exists.
For Oliveros, it is a matter of family legacy: “It means a lot to me that [my family’s seed] was preserved because it has allowed my family’s maize and my father’s memory to stay alive.”
“Farmers who cultivate landraces are providing an invaluable global public service,” state the authors of the study. “It will be key to encourage maize landrace cultivation in younger farmers. Tapping into the conservation potential of the current generation of farmers is an opportunity we should not miss.”
A special acknowledgement to the families, focus group participants and municipal authorities from the state of Morelos who kindly devoted time to share their experiences with us, on the challenges and rewards of maize landrace conservation.
