Maize and wheat fields at CIMMYT’s El Batán experimental station. (Photo: Alfonso Cortés/CIMMYT)
The International Maize and Wheat Improvement Center (CIMMYT) is pleased to announce the release of a new category of maize inbred lines called CIMMYT Maize Genetic Resource Lines (CMGRL). The CMGRLs are derived from crosses between elite CIMMYT lines and landrace accessions, populations or synthetics from the CIMMYT Germplasm Bank.
Although high standards of yield and agronomic performance are applied in their selection, CMGRLs are not intended to be used directly in commercial hybrids but rather by breeders as sources of novel alleles for traits of economic importance. These lines should also be of interest to maize researchers who are not breeders but are studying the underlying genetic mechanisms of abiotic and biotic traits.
A tar spot disease resistant line next to a non-resistant line. (Photo: Terry Molnar/CIMMYT)
Currently the maize genetic resources breeding team has projects in drought tolerance, heat tolerance, tar spot complex (TSC) disease resistance and in the development of lines and hybrids with blue kernel color. For all of these projects, the best lines identified for a given trait objective will be recombined to produce open-pollinated varieties that will be made available to the public.
The inaugural class of CMGRLs includes five subtropical adapted lines for tolerance to drought during flowering and grain-fill and four tropical adapted lines for TSC resistance. Both phenotypic and genotypic data will be published online for all CMGRL releases. CIMMYT will periodically release CMGRLs as superior lines are identified for economically important abiotic and biotic stresses as well as end-use traits.
Release Summary:
CMGRL Name
Trait Target
Type
Level
Landrace Donor Parent
Landrace Country of Origin
Recurrent Parent
Heterotic Group
Adaptation
CMGRLB001
TSC resistance
BC1
S5
OAXA280
Mexico
CML576
B
Tropical
CMGRLB002
TSC resistance
BC1
S5
OAXA280
Mexico
CML576
B
Tropical
CMGRLB003
TSC resistance
BC1
S5
GUAT153
Guatemala
CML576
B
Tropical
CMGRLB004
TSC resistance
BC1
S5
GUAT153
Guatemala
CML576
B
Tropical
CMGRLB005
Drought tolerance
BC1
S5
ARZM12193
Argentina
CML376
B
Subtropical
CMGRLB006
Drought tolerance
BC1
S5
ARZM12237
Argentina
CML376
B
Subtropical
CMGRLB007
Drought tolerance
BC1
S5
SNLP169
Mexico
CML376
B
Subtropical
CMGRLB008
Drought tolerance
BC1
S5
SNLP17
Mexico
CML376
B
Subtropical
CMGRLB009
Drought tolerance
BC1
S5
SNLP17
Mexico
CML376
B
Subtropical
Full details including phenotypic and genotypic data on the nine lines are available here. To order a 50-kernel seed sample of the CMGRLs, please contact Terry Molnar.
Francelino Rodrigues prepares an UAV for radiometric calibration for multispectral flight over a maize tar spot complex screening trial at CIMMYT’s Agua Fría experimental station, Mexico. (Photo: Alexander Loladze/CIMMYT)
A new study from researchers at the International Maize and Wheat Improvement Center (CIMMYT) shows that remote sensing can speed up and improve the effectiveness of disease assessment in experimental maize plots, a process known as phenotyping.
The study constitutes the first time that unmanned aerial vehicles (UAVs, commonly known as drones) with cameras that capture non-visible electromagnetic radiation were used to assess tar spot complex on maize.
The interdisciplinary team found among other things that potential yield losses under heavy tar spot complex infections could reach 58% — more than 10% greater than reported in previous studies.
Caused by the interaction of two fungal pathogens that thrive in warm, humid conditions, tar spot complex is diagnosed by the telltale black spots that cover infected plants. (Photo: Alexander Loladze/CIMMYT)
“Plant disease resistance assessment in the field is becoming difficult because breeders’ trials are larger, are conducted at multiple locations, and there is a lack of personnel trained to evaluate diseases,” said Francelino Rodrigues, CIMMYT precision agriculture specialist and co-lead author of the study. “In addition, disease scoring based on visual assessments can vary from person to person.”
A major foliar disease that affects maize throughout Latin America, tar spot complex results from the interaction of two species of fungus that thrive in warm, humid conditions. The disease causes telltale black spots on infected plants, killing leaves, weakening the plant, and impairing ear development.
Phenotyping has traditionally involved breeders walking through crop plots and visually assessing each plant, a labor-intensive and time-consuming process. As remote sensing technologies become more accessible and affordable, scientists are applying them more often to assess experimental plants for desired agronomic or physical traits, according to Rodrigues, who said they can facilitate accurate, high-throughput phenotyping for resistance to foliar diseases in maize and help reduce the cost and time of developing improved maize germplasm.
“To phenotype maize for resistance to foliar diseases, highly trained personnel must spend hours in the field to complete visual crop evaluations, which requires substantial time and resources and may result in biased or inaccurate results between surveyors,” said Rodrigues. “The use of UAVs to gather multispectral and thermal images allows researchers to cut down the time and expenses of evaluations, and perhaps in the future it could also improve accuracy.”
Color-infrared image of maize hybrids in the experimental trials under fungicide treatment (A1) and non-fungicide treatment (A2) of tar spot complex of maize. Image data were extracted from two polygons from the two central rows in each plot (B).
Technology sheds new light on phenotyping
Receptors in the human eye detect a limited range of wavelengths in the electromagnetic spectrum — the area we call visible light — consisting of three bands that our eyes perceive as red, green and blue. The colors we see are the combination of the three bands of visible light that an object reflects.
Remote sensing takes advantage of how the surface of a leaf differentially absorbs, transmits and reflects light or other electromagnetic radiation, depending on its composition and condition. The reflectance of diseased plant tissue is different from that of healthy ones, provided the plants are not stressed by other factors, such as heat, drought or nutrient deficiencies.
In this study, researchers planted 25 tropical and subtropical maize hybrids of known agronomic performance and resistance to tar spot complex at CIMMYT’s experimental station in Agua Fría, central Mexico. They then carried out disease assessments by eye and gathered multispectral and thermal imagery of the plots.
This allowed them to compare remote sensing with traditional phenotyping methods. Calculations revealed a strong relationship between grain yield, canopy temperature, vegetation indices and the visual assessment.
Future applications
“The results of the study suggest that remote sensing could be used as an alternative method for assessment of disease resistance in large-scale maize trials,” said Rodrigues. “It could also be used to calculate potential losses due to tar spot complex.”
Accelerated breeding for agriculturally relevant crop traits is fundamental to the development of improved varieties that can face mounting global agricultural threats. It is likely that remote sensing technologies will have a critical role to play in overcoming these challenges.
“An important future area of research encompasses pre-symptomatic detection of diseases in maize,” explained Rodrigues. “If successful, such early detection would allow appropriate disease management interventions before the development of severe epidemics. Nevertheless, we still have a lot of work to do to fully integrate remote sensing into the breeding process and to transfer the technology into farmers’ fields.”
Funding for this research was provided by the CGIAR Research Program on Maize (MAIZE).
As the world heats up and water grows scarce, threatening the productivity of humankind’s preferred crops, breeder Marcela Carvalho Andrade and her colleagues at the International Maize and Wheat Improvement Center (CIMMYT) are working to toughen maize, drawing resilience traits from landraces, the forerunners of modern maize.
For decades, scientists have sought to utilize the hardiness of maize landraces, which evolved over millennia of farmer selection for adaptation to diverse and sometimes harsh local settings in Mexico, Central and South America.
But crossing elite varieties with landraces brings along wild traits that are difficult and costly to purge, including lower grain yields, excessive tallness or a tendency to fall over in strong winds. For this and for their genetic complexity, landraces are seldom used directly in breeding programs, according to Andrade.
Crosses that home in on genetically complex traits
“Our strategy is to cross selected landraces with elite maize lines, thus developing improved lines that can be directly incorporated and recycled in breeding programs,” explained Andrade, who joined CIMMYT in 2016.
The traits sought include better resilience under high temperatures, drought conditions or the attacks of rapidly-evolving crop diseases. “All these features will be critical for the future productivity of maize,” said Andrade.
One of the world’s three most important crops, maize contributes over 20% of the calories in human diets in 21 low-income countries, as well as being used in industry, biofuels, and feed for livestock and poultry.
Andrade and the maize breeding team develop new lines that carry a 75 percent genetic contribution from the elite source and 25 percent from a landrace. The aim she said is to get the good components from both sides, while broadening maize’s genetic diversity for use by breeders and ultimately farmers.
The resulting lines and hybrids are tested for yield, resilience and overall agronomic performance, under both normal growing conditions and “stressed” environments; for example, in plots grown at sites with high temperatures or reduced water availability.
“We can thus identify landraces that offer traits of interest, as well as generating improved breeding lines to strengthen the resilience of elite maize without reducing its yield,” said Andrade, noting that the research employs conventional cross-pollination and selection.
According to Andrade, CIMMYT has carried out large-scale molecular analysis of its maize seed collections, which number around 28,000 and comprise landraces from 70 countries.
“Over the past years, CIMMYT has used genetic diversity analyses of its maize collections to select landraces for use in drought tolerance breeding or for finding lines that are resistant to newly important diseases such as Maize Lethal Necrosis or Tar Spot,” she explained. “Genetic diversity analysis allows us to narrow the number of candidate landrace sources that we need to cross and assess in the field.”
The viral disease Maize Lethal Necrosis (MLN) has devastated crops in eastern Africa since its appearance there in 2011.
The researchers have also found landrace sources of resilience against Tar Spot Complex, a maize disease of the Americas that can cause 50 percent or greater yield losses in infected crops.
Benefiting breeding and farmers
Andrade said the breeding team expects to release a first wave of landrace-derived, improved maize lines in 2019, some featuring enhanced drought tolerance and others that provide better resistance to Tar Spot.
“The lines we offer will be freely available to breeders worldwide and must yield well and show superior resilience,” Andrade explained. “They will have reasonable agronomics—ear and plant height and standability, for example. The lines will not be perfect, but breeders won’t hesitate to use them because we’ve ensured that they are superior for at least one crucial trait and reasonably competitive for most other traits.”
From Brazil to the world
Growing up in a small town and having direct contact with her father’s dairy farm in Minas Gerais, a mainly rural state in Brazil, Andrade finds her CIMMYT work enormously satisfying. “My dad and a few uncles were farmers and complained some years that their crops didn’t yield well,” she says. “I knew I wanted to help them somehow.”
Andrade obtained Bachelor and Master’s degrees in agronomy/plant science from the Universidade Federal de Lavras (UFLA), one of Brazil’s premier institutions of higher education. She later completed a Doctorate in Genetics and Plant Breeding at UFLA, in partnership with Ohio State University.
She credits CIMMYT maize scientist Terry Molnar, her supervisor and mentor, with teaching her the complex ins and outs of maize breeding. “I am a plant breeder and worked previously with vegetables, but I learned the practical aspects of maize breeding from Terry.”
Looking ahead, Andrade sees herself continuing as a plant breeder. “I don’t see myself working in anything else. I would eventually like to lead my own program but, at this point in my career, I’m happy to help transfer landrace traits to modern maize varieties.”
Figure: Maize-producing counties in the USA that are vulnerable to Tar Spot Complex (TSC) of maize, developed based on climate analogue model analysis procedure matching historic climatic data of 13 counties where TSC has been detected.
A new study shows that nearly 12 million hectares of the maize-growing USA, approximately 33 percent of the entire maize-growing area of the country, might be vulnerable to a disease called Tar Spot Complex (TSC).
Native to Latin America, one of the two major fungal pathogens involved in TSC of maize was detected for the first time in the United States in 2015. In Latin America, TSC can cause up to 50 percent losses in maize yields, but the impact of one fungal pathogen alone on maize yields unknown. There is a hypothetical likelihood that the second fungal pathogen involved in TSC, could migrate to the US. If this happens, the devastating TSC disease in the US could cause significant economic damages.
Even a one percent loss in maize production caused by the disease in this area could lead to a reduction in maize production of 1.5 million metric tons of grain, or approximately $231.6 million in losses. Such production losses would not only affect the $51.5 billion US maize industry, but also the food security in a number of low-income countries that are heavily dependent on maize imports from the US.
The emergence and spread of new crop diseases or new variants of already established diseases around the globe over the last decades have generated serious threats for food safety and security. Therefore, the improvement of crop disease resistance has become one of the key focus topics of research at the International Maize and Wheat Improvement Center (CIMMYT).
The intent of this study is to raise public awareness regarding potential TSC outbreaks and to develop strategies and action plans for such scenario.
This study was published by an interdisciplinary team of CIMMYT scientists in the journal of Mitigation and Adaptation Strategies for Global Change regarding the potential threats of TSC in the US and its global consequences. Within this article, ex-ante impact assessment techniques were combined with climate analogue analysis to identify the maize growing regions that may be vulnerable to potential TSC outbreaks in the USA.
Felipa Martinez shows off some of her family’s maize from last year’s harvest. Photo: Matthew O’Leary
Felipa Martinez, an indigenous Mexican grandmother, grins as she shows off a bag bulging with maize cobs saved from last harvest season. With her family, she managed to farm enough maize for the year despite the increasing pressure brought by climate change.
Felipa’s grin shows satisfaction. Her main concern is her family, the healthy harvest lets her feed them without worry and sell the little left over to cover utilities.
“When our crops produce a good harvest I am happy because we don’t have to spend our money on food. We can make our own tortillas and tostadas,” she said.
Her family belongs to the Chatino indigenous community and lives in the small town of Santiago Yaitepec in humid southern Oaxaca. They are from one of eleven marginalized indigenous communities throughout the state involved in a participatory breeding project with the International Maize and Wheat Improvement Center (CIMMYT) to naturally improve the quality and preserve the biodiversity of native maize.
These indigenous farmers are custodians of maize biodiversity, growing seeds passed down over generations. Their maize varieties represent a portion of the diversity found in the 59 native Mexican races of maize, or landraces, which first developed from wild grasses at the hands of their ancestors. These different types of maize diversified through generations of selective breeding, adapting to the environment, climate and cultural needs of the different communities.
In recent years, a good harvest has become increasingly unreliable, as the impacts of climate change, such as erratic rainfall and the proliferation of pests and disease, have begun to challenge native maize varieties. Rural poor and smallholder farmers, like Martinez and her family, are among the hardest hit by the mounting impacts of climate change, according to the Food and Agriculture Organization of the United Nations.
These farmers and their ancestors have thousands of years of experience selecting and breeding maize to meet their environment. However, climate change is at times outpacing their selection methods, said CIMMYT landrace improvement coordinator Martha Willcox, who works with the community and coordinates the participatory breeding project. Through the initiative, the indigenous communities work together with professional maize breeders to continuously improve and conserve their native maize.
Despite numerous challenges, farmers in the region are unwilling to give up their maize for other varieties. “The native maize, my maize grows best here, it yields well in our environment. The maize is sweeter, it is heavier,” said Don Modesto Suarez, Felipa’s husband. “This maize has been grown by our grandfathers and this is why I will not change it.”
Una mujer de la comunidad Chatino prepara tortillas muy grandes de maíz criollo que son muy apreciadas en los mercados locales. Foto: Matthew O’Leary
This is because a community’s native maize varieties are adapted to their specific microclimate, such as elevation and weather patterns, and therefore may perform better or be more resistant to local pests and diseases than other maize varieties. They may also have specific characteristics prized for local culinary traditions — for example, in Santiago Yaitepec the native maize varieties have a specific type of starch that allows for the creation of extra-large tortillas and tostadas that are in high demand in local markets.
Other varieties may not meet farmers’ specific needs or climate, and many families do not want to give up their cultural attachment to native maize, said Flavio Aragon, a genetic resources researcher at the Mexican National Institute for Forestry, Agriculture and Livestock Research (INIFAP) who collaborates with Willcox.
CIMMYT and INIFAP launched the four-year participatory plant breeding project to understand marginalized communities’ unique makeup and needs – including maize type, local climates, farming practices, diseases and culture – and include farmers in breeding maize to suit these needs.
“Our aim is to get the most out of the unique traits in the native maize found in the farmer’s fields. To preserve and use it to build resistance and strength without losing the authenticity,” said Aragon.
“When we involve farmers in the process of selection, they are watching what we are doing and they are learning techniques,” he said. “Not only about the process of genetic selection in breeding but also sustainable farming practices and this makes it easier for farmers to adopt the maize that they have worked alongside breeders to improve through the project.”
Suarez said he appreciates the help, “We are learning how to improve our maize and identify diseases. I hope more farmers in the community join in and grow with us,” he said.
When disease strikes
Chatino men stand in a maize field in Santiago Yaitepec, Oaxaca, Mexico. Tar spot complex threatened harvests, but work in participatory breeding with CIMMYT has helped local communities to improve their native maize without loosing preferred traits. (Photo: Matthew O’Leary)
Changes in weather patterns due to climate change are making it hard for farmers to know when to plant their crops to avoid serious disease. Now, a fungal disease known as tar spot complex, or TSC, is increasingly taking hold of maize crops, destroying harvests and threatening local food security, said Willcox. TSC resistance is one key trait farmers want to include in the participatory breeding.
Named for the black spots that cover infected plants, TSC causes leaves to die prematurely, weakening the plant and preventing the ears from developing fully, cutting yields by up to 50 percent or more in extreme cases.
Caused by a combination of three fungal infections, the disease occurs most often in cool and humid areas across southern Mexico, Central America and into South America. The disease is beginning to spread, possibly due to climate change, evolving pathogens and introduction of susceptible maize varieties.
“Our maize used to grow very well here, but then this disease came and now our maize doesn’t grow as well,” said Suarez. “For this reason we started to look for maize that we could exchange with our neighbors.”
A traditional breeding method for indigenous farmers is to see what works in fields of neighboring farmers and test it in their own, Willcox said.
Taking the search to the next level, Willcox turned to the CIMMYT Maize Germplasm Bank, which holds over 7000 native maize seed types collected from indigenous farmers. She tested nearly a thousand accessions in search of TSC resistance. A tedious task that saw her rate the different varieties on how they handled the disease in the field. However, the effort paid off with her team discovering two varieties that stood up to the disease. One variety, Oaxaca 280, originated from just a few hours north of where the Suarez family lives.
Farmer Modesto Suarez (left) and neighbors were originally cautious to plant Oaxaca 280 in their fields, but were pleased with the results. (Photo: Matthew O’Leary)
After testing Oaxaca 280 in their fields the farmers were impressed with the results and have now begun to include the variety in their breeding.
“Oaxaca 280 is a landrace – something from Mexico – and crossing this with the community’s maize gives 100 percent unimproved material that is from Oaxaca very close to their own,” said Willcox. “It is really a farmer to farmer exchange of resistance from another area of Oaxaca to this landrace here.”
“The goal is to make it as close as it can be to what the farmer currently has and to conserve the characteristics valued by farmers while improving specific problems that the farmers request help with, so that it is still similar to their native varieties and they accept it,” Aragon said.
Expanding for impact
Willcox and colleagues throughout Mexico seek to expand the participatory breeding project nationwide in a bid to preserve maize biodiversity and support rural communities.
“If you take away their native maize you take away a huge portion of the culture that holds these communities together,” said Willcox. Participatory breeding in marginalized communities preserves maize diversity and builds rural opportunities in areas that are hotbeds for migration to the United States.
“A lack of opportunities leads to migration out of Mexico to find work in other places, a strong agricultural sector means strong rural opportunities,” she said.
To further economic opportunities in the communities, these researchers have been connecting farmers with restaurant owners in Mexico City and the United States to export surplus grain and support livelihoods. A taste for high-quality Mexican food has created a small but growing market for the native maize varieties.
The next generation: The granddaughter of Felipa Martinez and Modesto Suarez stands in her grandparent’s maize field. (Photo: Matthew O’Leary)
Native maize hold the building blocks for climate-smart crops
Native maize varieties show remarkable diversity and climate resilience that grow in a range from arid to humid environments, said Willcox. The genetic traits found in this diversity are the building blocks that can be used to develop varieties suitable for the changing crop environments predicted for 2050.
“There is a lot of reasoning that goes into the way that these farmers farm the land, the way they decide on what they select for,” said Willcox. “This has been going on for years and has been passed down through generations. For this reason, they have maize of such high quality with resistance to local challenges, genetic traits that now can be used to create strong varieties to help farmers in Mexico and around the world.”
It is key to analyze the genetic variability of native maize, and support the family farmers who conserve it in their fields, she added. This biodiversity still sown and selected throughout diverse microclimates of Mexico holds the traits we need to protect our food supplies.
To watch a video on CIMMYT’s work in this community, please click here.
This work has been conducted as part of the CIMMYT-led MasAgro project in collaboration with INIFAP, and supported by Mexico’s Department of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA) and the CGIAR Research Program MAIZE.
Felix Corzo Jimenez , a farmer in Chiapas, Mexico, examines one of his maize plants infected with tar spot complex. Photo: J. Johnson/CIMMYT.
CHIAPAS, Mexico — In southern Mexico and Central America a fungal maize disease known as tar spot complex (TSC) is decimating yields, threatening local food security and livelihoods. In El Portillo, Chiapas, Mexico, local farmer Felix Corzo Jimenez sadly surveys his maize field.
“It’s been a terrible year. We’ll be lucky if we harvest even 50 percent of our usual yields,” he said, examining a dried up maize leaf covered in tiny black dots, and pulling the husk off of an ear to show the shriveled kernels, poorly filled-in. “Tar spot is ruining our crops.”
Named for the black spots that cover infected plants, TSC causes leaves to die prematurely, weakening the plant and preventing the ears from developing fully, cutting yields by up to 50 percent or more in extreme cases. Caused by a combination of three fungal infections, the disease occurs most often in cool and humid areas across southern Mexico, Central America and South America. The disease is beginning to spread – possibly due to climate change, evolving pathogens and susceptible maize varieties – and was reported in important maize producing regions of central Mexico and the northern United States for the first time last fall. To develop TSC resistant maize varieties that farmers need, the Seeds of Discovery (SeeD) initiative is working to “mine” the International Maize and Wheat Improvement Center’s (CIMMYT) genebank for native maize varieties that may hold genes for resistance against the disease.
The first stage of fungal maize disease TSC, with tiny, black “tar spots” covering the leaf. The spots will soon turn into lesions that kill the leaf, preventing photosynthesis from occurring. Photo: J. Johnson/CIMMYT.
The majority of maize varieties planted in Mexico today are susceptible to TSC, meaning that farmers would have to spray expensive fungicides several times each year to protect their crops against the disease, a huge financial burden that few can afford. Creating varieties with natural resistance to tar spot is an economical and environmentally friendly option that will protect the livelihoods of the region’s smallholder maize farmers.
“This project targets the many farmers in the region with limited resources, and the small local seed companies that sell to farmers at affordable prices,” says Terry Molnar, SeeD maize breeder.
The key to developing maize varieties with resistance to TSC lies in the genetic diversity of the crop. For thousands of years, farmers have planted local maize varieties known as landraces, or descendants from ancient maize varieties that have adapted to their environment. Over centuries of selection by farmers these landraces accumulated specific forms of genes, or alleles, which helped them to resist local stresses such as drought, heat, pests or disease.
These novel genetic traits found in landrace maize can help breeders develop improved maize varieties with resistance to devastating diseases such as TSC. However, it is quite challenging for breeders to incorporate “exotic” landrace materials into breeding programs, as despite their resistance to stresses found in their native environment, they often carry unfavorable alleles for other important traits.
A maize ear with shriveled kernels that are poorly filled, a major side effect of TSC that reduces farmer’s yields. Photo: J. Johnson/CIMMYT.
To help breeders incorporate this valuable genetic diversity into breeding programs, SeeD works to develop “bridging germplasm” maize varieties, which are created by transferring useful genetic variation from landraces held in the CIMMYT genebank into plant types or lines that breeders can readily use to develop the improved varieties farmers need. These varieties are created by crossing landrace materials with CIMMYT elite lines, and selecting the progeny with the genetic resistance found in a landrace without unfavorable traits breeders, farmers and consumers do not want.
“The CIMMYT maize genebank has over 28,000 maize samples from 88 countries, many of which are landraces that may have favorable alleles for disease resistance,” Molnar says. “We all know that there is good material in the bank, but it’s scarcely being used. We want to demonstrate that there are valuable alleles in the bank that can have great impact in farmers’ fields.”
A susceptible maize variety infected with TSC (left) compared to a healthy maize plant , a resistant variety immune to the disease (right). Photo: J. Johnson/CIMMYT.
SeeD scientists began by identifying landrace varieties with genetic resistance to TSC. Trials conducted in 2011, 2012 and 2014 evaluated a “core set” – a genetically diverse subset of the maize germplasm bank – in search of resistant varieties. Of the 918 landrace varieties planted in 2011 and 2012, only two landraces—Oaxaca 280 and Guatemala 153—were outstanding for tolerance to the disease. Genotypic data would later confirm the presence of unique resistant alleles not currently present in maize breeding programs that could be deployed into SeeD’s bridging germplasm. This bridging germplasm will be available to breeders for use in developing elite lines and varieties for farmers.
“As a breeder, I’m excited to work with SeeD’s bridging germplasm as soon as it is available,” said Felix San Vicente, CIMMYT maize breeder working with the CGIAR Research Program on Maize and the Sustainable Modernization of Traditional Agriculture (MasAgro) project.
Terry Molnar, maize breeder with SeeD, and Enrique Rodriguez, field research technician with SeeD, evaluate bridging germplasm for resistance to TSC. Photo: J. Johnson/CIMMYT.
Up to this point, most breeders have only used elite lines to develop hybrids, because landraces are extremely difficult to use. This practice, however, greatly limits the genetic diversity breeders employ. Using novel alleles from maize landraces allows breeders to develop improved hybrids while broadening the genetic variation of their elite germplasm. This novel genetic diversity is very important to protect crops from evolving pathogens, as it means the varieties will have several resistant alleles, including alleles that have never been used in commercial germplasm before.
“The more alleles the better,” said San Vicente, “as it protects the line longer. It provides a form of insurance to smallholder farmers as these varieties will have more genes for resistance, which reduces their risk of losing their crop.”
To ensure that farmers can access this improved seed, CIMMYT works with small local seed companies. “The price of seed will be very affordable,” according to San Vicente. “As CIMMYT is a non-profit, we provide our improved materials to seed companies at no cost.”
The TSC resistant bridging germplasm developed by SeeD has been tested in on-farm trials in TSC-prone sites in Chiapas and Guatemala, with promising results, and will be publicly available to breeders in 2017. In the meantime, local farmers look forward to seeing the results of this research in their own fields. “A variety with the disease resistance of a landrace and the yield and performance of a hybrid is exactly what we need,” says Corzo Jimenez.
Corzo Jimenez in his maize field infected with TSC. Varieties made from SeeD bridging germplasm would allow him to protect his crop without applying expensive fungicides. CIMMYT/Jennifer Johnson.
SeeD is a multi-project initiative comprising: MasAgro Biodiversidad, a joint initiative of CIMMYT and the Mexican Ministry of Agriculture (SAGARPA) through the MasAgro (Sustainable Modernization of Traditional Agriculture) project; the CGIAR Research Programs on Maize (MAIZE CRP) and Wheat (WHEAT CRP); and a computation infrastructure and data analysis project supported by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC). To learn more about the Seeds of Discovery project, please go to http://seedsofdiscovery.org/.
