funder_partner: CGIAR

CIMMYT E-News, vol 3 no. 1, January 2006

CIMMYT’s biometrics team receives special recognition for advancing the science behind crop genetic resource conservation.

The nightmare of a gene bank curator: You have a collection of 25,000 precious, unique samples of maize seed; one of the world’s most extensive. You store it carefully, keep it cold and dry, but—little by little over the years—the seed dies! Eventually you’re left with so many packets of useless kernels, and the precious genetic diversity they once embodied is lost to humanity forever.

To keep this very bad dream from becoming a reality, Suketoshi Taba, head of maize genetic resources at CIMMYT, and his team constantly monitor the germination capacity of collections. When it drops below 80-85%, they take viable seed from the endangered accession (the term for individual, registered samples in the bank), sow it under controlled conditions, and harvest enough from progeny to replenish the accession. Known as “regeneration,” the process sounds simple, but in fact must be done painstakingly to capture a faithful snapshot—rather than a faded copy—of the genetic diversity from the original accession.

The Crop Science Society of America recently bestowed the honor of “2004 Outstanding Paper on Plant Genetic Resources” on an article by CIMMYT biometricians that provides models for proper handling of repeated cycles of regeneration. Their work, which was funded by the Australian Grains Research and Development Corporation (GRDC), is particularly relevant for outcrossing, genetically diverse crops like maize, legumes, or sorghum, to name just a few.

“For maize regeneration, we use artificial pollination, to avoid out-crossing with pollen from other maize fields,” says Taba. “But even the individuals in a maize population or accession are genetically diverse. How can we decide on the best way to pollinate the plants, or how many ears we need to harvest, or how many and which seeds to choose from each ear?” According to Taba, the danger is ending up with a sample that differs from the genetic make-up of the original. And with each successive cycle of regeneration, you can drift further and further.

Building on a strong body of work in this area by CIMMYT biometricians since the 1980s, the award-winning paper refines and expands the statistical model and provides reliable computer simulations. “Among other things, the simulation model shows exactly how many alleles are likely to be lost through various sampling and regeneration strategies,” says Jiankang Wang, CIMMYT biometrician who is first author of the study. “It describes how different strategies can affect the conservation of alleles and gives gene bank curators options that can be tailored for specific types of accessions.”

Jiankang Wang says he and his co-author, CIMMYT biometrician José Crossa, are now working with Taba to apply the paper’s model in managing CIMMYT’s maize gene bank collection. “Many other gene banks will find this approach useful,” says Crossa, explaining why their study received the award. “For example, we collaborate closely with the National Center for Genetic Resources Preservation in Fort Collins, Colorado, in the USA. They can apply the same principles in their regeneration work.”

Jiankang Wang was excited by the recognition and the fact that peers might find his work useful. “In middle school, teachers saw I had talent and told me to specialize in mathematics, but at the university I discovered that I was most interested in the practical applications of mathematics,” says Jiankang Wang. “Using science to help preserve the world’s crop genetic resources is a great satisfaction.”

For more information contact Jiankang Wang ( j.k.wang@cgiar.org)

CIMMYT E-News, vol 2 no. 11, November 2005

Young Indonesian researchers are reaping the benefits of collaboration with CIMMYT and at the same time helping farmers in their country.

It could be a biotech laboratory almost anywhere in the world, but this one is the Indonesian Center for Agriculture Biotechnology and Genetic Resources Research and Development in Bogor, Indonesia. What makes it remarkable is that just ten years ago Indonesia had virtually no agricultural biotechnology capacity at all. At the lab benches, in standard issue white lab coats, two of Indonesia’s brightest students, each with a strong commitment to helping their country, are doing the painstaking work that molecular biology requires and their PhD supervisors demand.

Marcia Pabendon is doing a maize diversity study, using DNA fingerprinting to identify maize germplasm from diverse sources to use as parents in a breeding program to find resistance for downy mildew and drought tolerance. These are the two most serious production constraints for maize in Indonesia, where half of all maize is grown in dry land areas. By analyzing the DNA she can be sure male and female parents in the breeding program are not closely related, which is detrimental to the hybrids.

Mohamed Azrai wants to convert local maize varieties into quality protein maize, maize with higher levels of the amino acids lysine and tryptophan, which occur at low levels in most maize and could result in protein deficiencies for anyone who relies heavily on maize in their diet. “I want my research to result in quality protein maize varieties that farmers will use,” he says. “Maybe quality protein maize can help solve the problem of protein malnutrition on my country.”

“This is the untold story of the quiet biotech revolution going on in maize breeding in Asia,” says CIMMYT’s Luz George. “It is a successful transfer of technology from CIMMYT to developing countries which has now found direct application in the work of national program maize breeders.”

It began with the Asian Maize Biotechnology Network, AMBIONET, which was funded by the Asian Development Bank and which George coordinated. K.R. Surtrisno, the Director of the biotech center in Bogor, says the capacity enhancement the network provided was vitally important. “The network has given us, through CIMMYT, genotype data and training in mapping. Now the government of Indonesia has made a commitment to support and improve our facility, just in time to do useful work for farmers.”

His thoughts are echoed by Marsum Dahlan, the head of the Breeding and Germplasm section of the Indonesian Cereals Research institute. “When AMBIONET came we thought not only to help farmers but also to create capacity,” he says. “This technology will help us, though we must still combine it with tests in the field.”

AMBIONET and the work with CIMMYT have proven very valuable to agricultural biotechnology in Indonesia. “Even though the AMBIONET program is over, we still maintain collaboration with CIMMYT,” says Surtrisno. That is good news for Indonesia and good news for promising young researchers like Mohamed and Marcia.

For further information, contact Luz George (m.george@cgiar.org).

June, 2005

What role do farmers play in the evolution of maize diversity? How extensive are the farming networks and other social systems that influence gene flow? These and other questions are helping researchers to combine knowledge of the genetic behavior of plants with information on human behavior to understand the many factors that affect maize diversity.

Outside a straw and mud-walled house in rural Hidalgo, Mexico, with chickens walking around and the smell of the cooking fire wafting through the air, CIMMYT researcher Dagoberto Flores drew lines with a stick in the red earth as he explained to a farmer’s wife how maize seed should be planted for an experiment. Along with CIMMYT researcher Alejandro Ramírez, Flores was distributing improved seed in communities where they had conducted surveys for a study on gene flow.

The movement of genes between populations, or gene flow, happens when individuals from different populations cross with each other. CIMMYT social scientist Mauricio Bellon is leading a study that aims to find out the impact of farmers’ practices on gene flow and on the genetic structure of landraces. It will document how practices differ across farming systems, analyze their determinants, figure out how much farmers control gene flow, and explore gene flow’s impacts on maize fitness and diversity and on farmers’ livelihoods.

The farmers visited by Flores and Ramírez in early June near Huatzalingo and Tlaxcoapan, Hidalgo are from just 2 of 20 study communities spanning ecologies from Mexico’s highlands down to the lowlands. Six months earlier, when farmers in these communities responded to researchers’ survey question, they asked some questions of their own: What does CIMMYT do? How can we get seed?

The team made it a priority to give the farmers what they requested for free. They drove around in a pick-up truck with seed they had acquired from CIMMYT scientists. They brought black, white, and yellow varieties that were native to the area and had been improved with weevil and drought resistance, and they also brought three CIMMYT varieties that were well adapted to a similar environment in Morelos, Mexico. They explained to the farmers how each variety should be planted in separate squares to facilitate pure seed selection.

“It’s a way to thank them, to bring something back to the communities,” says Bellon. Bringing improved germplasm for experimentation to interested small-scale farmers also allows researchers to get feedback in a more systematic way. The farmers will produce the maize independently, and they can save or discard seed from whichever varieties they choose. The team also distributed seed to farmers in Veracruz, and they plan to return after flowering and at harvest time to see how the improved seed fares compared with native varieties. That component of the project could be the beginning of further research in collaboration with farmers.

Farmers in the survey area of rural Hidalgo grow maize on the poorest, most steeply sloping land and struggle with soil diseases, low soil fertility, leaf diseases, low grain prices, and limited information about the use of chemical herbicides. Strong wind, rain, and hurricanes damage crops. Landslides cause erosion. Some farmers have access to roads and can transport their harvest by vehicle, but some farms located far from the communities have no highway access. The paths to farmers’ fields can be so narrow that not even cargo animals can maneuver on them with loads, so farmers must carry the harvest on their backs. Some walk 10 kilometers up and down slopes with heavy bags on their backs.

Many people grew coffee around Huatzalingo until about 10 years ago when the price plummeted. A kilogram of coffee used to fetch a price of about 20 pesos, or US$ 2. Now it fetches about five pesos, or 50 cents, per kilo, and even less during harvest time when the crop is abundant. Coffee producers in the area receive average government subsidies of between 125 and 300 pesos, or between US$ 10-30. One effect of the price drop has been increased immigration to Mexico City, to the city of Reynosa near the US border, and to lowland areas where orange cultivation is booming.

Partly in response to the crisis, farmers have started diversifying into alternative crops such as vanilla, citrus fruits, bananas, sugar cane, sesame, beans, chayote, chili peppers, and lentils, but the poor soils do not favor more lucrative crops. Maize is still the most important agricultural product in people’s diets in this area, and farmers grow it primarily for family consumption. They exchange seed with friends, neighbors, and producers in nearby communities, and they have conserved diverse native varieties.

In Mexico, maize has such great genetic diversity because farmers’ practices encourage the further evolution of maize landraces. Maize was domesticated about 6,000 years ago within the current borders of Mexico. Farmers created a variety of races to fit different needs by mixing different maize types, and they still experiment like that to this day. They save seed between seasons and trade seed with each other, and the wind carries pollen between different cultivars to create new mixtures.

“They are not artifacts in a museum,” Bellon says about landraces. “They are changing, they are moving.” Seed selection has a great impact on gene flow. Poor farmers typically exchange seed with each other, but little has been documented about the social relations that drive seed systems. With growing concerns about a loss of crop genetic diversity and a need to conserve genetic resources in recent years, it is important to understand the social principles of seed flow (and ultimately gene flow) in Mexico. The study findings will assist in exploration of the potential impact of transgenes. The researchers will develop models to try to predict how a transgene would diffuse and behave after it has been in a population for 10 or 20 years.

By learning about the relationships between farmers’ practices and gene flow, researchers hope to promote more effective policies regarding the conservation of diversity in farmers’ fields, the distribution of improved germplasm, and transgene management. Funded by the Rockefeller Foundation, the study combines social science with genetics to connect social and biological factors in maize varieties. Molecular markers will help show how much gene flow has occurred over time between the Mexican highlands and lowlands.

Researchers used geographic information systems to choose varied environments for the survey. Starting in October 2003, they sampled maize populations and interviewed the male and female heads of 20 households in each community for a total of 800 intensive interviews in 400 households. They asked about topics such as principal crops, planting cycles and methods, maize varieties, machinery and tools, infrastructure, language, seed selection, fertilizer, pest and weed control, plant height, harvest, transportation, production problems, maize uses, the sale and demand of different varieties, knowledge about maize reproduction, husk commercialization, and level of migration.

Preliminary findings have already surprised Bellon. A growing market for maize husks, which are used to wrap traditional foods such as tamales, is changing the economics of maize production. Owing to increasing demand from the US, husks have become more commercially important and profitable than grain in some communities. Facing abysmally low grain prices, the success of husk production has caused some producers to seek maize varieties with high quality husks, almost regardless of grain quality.

Bellon was also surprised at the lack of improved varieties in the areas they studied. Farmers tended to seek out and plant native varieties instead of hybrids. Some farmers thought hybrids were expensive, produced poor quality husks, and required good land, chemicals, and fertilizer, but they thought native varieties adapted easily to marginal local conditions.

The study grew out of a six-year project in Oaxaca that examined the relationship between farmers’ practices and the genetic structure of maize landraces and seed flow among farmers. It also explored the implications of transgenic technologies. However, while the Oaxaca project examined a few communities located in one environment, the idea with this follow-up study was to examine many locations in the same and different environments. In that way researchers can find out if gene flow is localized or if it crosses between regional environments. “It’s the same research model on a broader scale,” says Bellon.

For information: Mauricio Bellon