Posts Tagged ‘DNA Fingerprinting’

New genetic analysis advances the global quest for yellow rust resistant wheat

A wheat leaf infected with yellow rust, also known as stripe rust. Photo: Thomas Lumpkin/CIMMYT

Yellow rust, also known as stripe rust, is a tenacious and widespread fungal disease that threatens wheat all over the world. The fungal pathogen that causes the rust — Puccinia striiformis — is prevalent in more than 60 countries, and an estimated 88% of the world’s wheat production is considered vulnerable, with up to 100% losses. 

A number of factors – including favorable weather conditions, the adaptation of existing races and emergence of new ones, and a changing climate – have caused a recent uptick in severe outbreaks. Farmers can use fungicides and farming management practices to battle the fungus, but sowing resistant seeds is widely considered as the most cost-effective, environmentally-safe and sustainable way to beat it.

A new analysis by wheat scientists at the International Maize and Wheat Improvement Center (CIMMYT) published in Scientific Reports provides valuable insights and a deep resource of genetic information to increase the speed and accuracy of efforts to breed yellow rust resistant wheat.

To understand the shared genetic basis of yellow rust resistance over time and in three geographic regions, CIMMYT scientists performed a large genome-wide association study leveraging a dataset of 43,706 observations on 23,346 wheat lines evaluated between 2013 and 2019 at sites in India, Kenya and Mexico.

Photo: Flickr/ Wheat Genetics Lab

They found more than 100 repeatable –that is, statistically significant in multiple datasets — genome-wide markers associated with yellow rust that aligned to the reference genome of wheat.

 “These findings represent a significant advancement in our knowledge about the genetics of yellow rust resistance in bread wheat and provide exciting opportunities for designing future genomics-based breeding strategies for tackling yellow rust,” said CIMMYT wheat scientist Philomin Juliana, the lead author of the paper.

CIMMYT wheat scientists have been breeding for yellow rust resistance since the early 1970s. Breeding for resistance is a painstaking process involving crossing parents with slow rusting genes, selecting early-generation plants which exhibit resistance in Toluca, Mexico, and then subjecting the advanced generations to intense screening in sites like Karnal (in collaboration with the Indian Institute of Wheat and Barley Research) and Ludhiana (in collaboration with the Borlaug Institute for South Asia) in India; Njoro in Kenya; and Celaya (in collaboration with the Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias), El Batan and Toluca in Mexico. Identifying genes related to resistance can increase the efficiency of this selection process, giving breeders a head start by allowing them to begin the crossing process with varieties that are more likely to have resistance genes.

In the study, the wheat scientists also conducted “allelic fingerprinting” on the largest panel of wheat breeding lines to date — 52,067 lines, genomically characterizing them for yellow rust resistance.  The resulting data creates opportunities using molecular markers to identify varieties with desired combinations of resistance genes.

“This information advances our knowledge on the genetics of yellow rust resistance in thousands of wheat lines, and has important implications for the future design of resistant crosses and varieties,” Juliana said.

Overall, the markers and fingerprints identified in this study are a valuable resource not only for CIMMYT breeders but also for the global wheat breeding community in its efforts to accelerate yellow rust resistance breeding.

This work was made possible by the generous support of the Delivering Genetic Gain in Wheat (DGGW) project funded by the Bill & Melinda Gates Foundation and the UK  Department for International Development (DFID) and managed by Cornell University; the U.S. Agency for International Development’s Feed the Future Initiative; and the genotyping support of Dr. Jesse Poland from the innovation lab at Kansas State University.

Read the full article here:
https://doi.org/10.1038/s41598-020-67874-x

Juliana, P., Singh, R.P., Huerta-Espino, J. et al. 2020. “Genome-wide mapping and allelic fingerprinting provide insights into the genetics of resistance to wheat stripe rust in India, Kenya and Mexico.” Nature Scientific Reports.

Scientists use DNA fingerprinting to gauge the spread of modern wheat in Afghanistan

New study finds that wheat farmers often do not accurately identify their varieties.

Wheat is Afghanistan’s number-one staple crop, but the country does not grow enough and must import millions of tons of grain each year to satisfy domestic demand.

Despite the severe social and political unrest that constrain agriculture in Afghanistan, many farmers are growing high-yielding, disease resistant varieties developed through international, science-based breeding and made available to farmers as part of partnerships with national wheat experts and seed producers.

These and other findings have emerged from the first-ever large-scale use of DNA fingerprinting to assess Afghanistan farmers’ adoption of improved wheat varieties, which are replacing less productive local varieties and landraces, according to a paper published yesterday in the science journal BMC Genomics.

The study is part of an activity supported between 2003 and 2018 by the Australian Department of Foreign Affairs and Trade, through which the Agricultural Research Institute of Afghanistan and the International Maize and Wheat Improvement Center (CIMMYT) introduced, tested, and released improved wheat varieties.

“As part of our study, we established a ‘reference library’ of released varieties, elite breeding lines, and Afghan wheat landraces, confirming the genetic diversity of the landraces and their value as a genetic resource,” said Susanne Dreisigacker, wheat molecular breeder at CIMMYT and lead author of the new paper.

“We then compared wheat collected on farmers’ fields with the reference library. Of the 560 wheat samples collected in 4 provinces during 2015-16, farmers misidentified more than 40%, saying they were of a different variety from that which our DNA analyses later identified.”

Wheat is the most important staple crop in Afghanistan — more than 20 million of the country’s rural inhabitants depend on it — but wheat production is unstable and Afghanistan has been importing between 2 and 3 million tons of grain each year to meet demand.

Over half of the population lives below the poverty line, with high rates of malnutrition. A key development aim in Afghanistan is to foster improved agronomic practices and the use of high quality seed of improved wheat varieties, which together can raise yields by over 50%.

“Fungal diseases, particularly yellow rust and stem rust, pose grave threats to wheat in the country,” said Eric Huttner, research program manager for crops at the Australian Centre for International Agricultural Research (ACIAR) and co-author of the present paper. “It’s crucial to know which wheat varieties are being grown where, in order to replace the susceptible ones with high-performing, disease resistant varieties.”

Varietal adoption studies typically rely on questionnaires completed by breeders, extension services, seed producers, seed suppliers, and farmers, but such surveys are complicated, expensive, and often inaccurate.

“DNA fingerprinting resolves uncertainties regarding adoption and improves related socioeconomic research and farm policies,” Huttner explained, adding that for plant breeding this technology has been used mostly to protect intellectual property, such as registered breeding lines and varieties in more developed economies.

This new study was commissioned by ACIAR as a response to a request from the Government of Afghanistan for assistance in characterizing the Afghan wheat gene bank, according to Huttner.

“This provided the reference library against which farmers’ samples could be compared,” he explained. “Accurately identifying the varieties that farmers grow is key evidence on the impact of introducing improved varieties and will shape our future research

Joint research and development efforts involving CIMMYT, ACIAR, the Food and Agriculture Organization (FAO) of the United Nations, the International Centre of Agricultural Research in Dry Areas (ICARDA), French Cooperation, and Afghanistan’s Ministry of Agriculture, Irrigation and Livestock (MAIL) and Agricultural Research Institute (ARIA) have introduced more than 400 modern, disease-resistant wheat varieties over the last two decades. Nearly 75% of the wheat grown in the areas surveyed for this study comes from these improved varieties.

“New gene sequencing technologies are increasingly affordable and their cost will continue to fall,” said Dreisigacker. “Expanded use of DNA fingerprinting can easily and accurately identify the wheat cultivars in farmers’ fields, thus helping to target breeding, agronomy, and development efforts for better food security and farmer livelihoods.”


For more information, or to arrange interviews with the researchers, please contact:

Marcia MacNeil, Wheat Communications Officer, CIMMYT
M.MacNeil@cgiar.org, +52 (55) 5804 2004, ext. 2070

Rodrigo Ordóñez, Communications Manager, CIMMYT
r.ordonez@cgiar.org, +52 (55) 5804 2004, ext. 1167

About CIMMYT
The International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly funded maize and wheat research and related farming systems. Headquartered near Mexico City, CIMMYT works with hundreds of partners throughout the developing world to sustainably increase the productivity of maize and wheat cropping systems, thus improving global food security and reducing poverty. CIMMYT is a member of CGIAR and leads the CGIAR Research Programs on Maize and Wheat, and the Excellence in Breeding Platform. The center receives support from national governments, foundations, development banks and other public and private agencies.

About ACIAR
As Australia’s specialist international agricultural research for development agency, the Australian Centre for International Agricultural Research (ACIAR) brokers and funds research partnerships between Australian scientists and their counterparts in developing countries. Since 1982, ACIAR has supported research projects in eastern and southern Africa, East Asia, South and West Asia and the Pacific, focusing on crops, agribusiness, horticulture, forestry, livestock, fisheries, water and climate, social sciences, and soil and land management. ACIAR has commissioned and managed more than 1,500 research projects in 36 countries, partnering with 150 institutions along with more than 50 Australian research organizations.

About Afghanistan’s Ministry of Agriculture, Irrigation and Livestock
The Ministry of Agriculture, Irrigation and Livestock (MAIL) of the Islamic Republic of Afghanistan works on the development and modernization of agriculture, livestock and horticulture. The ministry launches programs to support the farmers, manage natural resources, and strengthen agricultural economics. Its programs include the promotion and introduction of higher-value economic crops, strengthening traditional products, identifying and publishing farm-tailored land technologies, boosting cooperative programs, agricultural economics, and export with marketing.