Posts Tagged ‘genetics’

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.

Rebuttal letter sets the record straight on crop breeding for climate change resilience

Crop scientists refute the flawed findings of a study questioning climate resilience in modern wheat breeding.

This article by Marcia MacNeil was originally posted on May 28, 2019 on cimmyt.org.

CIMMYT field workers working on wheat crossing as part of the breeding process. (Photo: CIMMYT)

In early 2019, an article published by European climate researchers in the Proceedings of the National Academy of Science (PNAS) journal questioned the climate resilience of modern wheat varieties. The article suggested that modern wheat varieties showed reduced climate resilience as a direct result of modern breeding methods and practices, a claim that researchers at the International Maize and Wheat Improvement Center (CIMMYT) vehemently rebuke

In a rebuttal letter published in the June issue of PNAS a group of scientists, including CIMMYT’s Susanne Dreisigacker and Sarah Hearne, strongly contradict the finding that breeding has reduced climate resilience in European wheat, citing significant flaws in the authors’ methodology, data analyses and interpretation.

“This article discredits European plant breeders and wheat breeders in general, who have been working over many decades to produce a wide range of regionally adapted, stable varieties which perform well under a broad range of climate change conditions,” said CIMMYT wheat molecular geneticist Susanne Dreisigacker.

Among other flaws, they found a number of omissions and inconsistencies.

  • The article shows a lack of understanding of commonly used terms and principles of breeding theory, criticizing newer wheat varieties for demonstrating a decrease in “climatic response diversity.” Less diversity in wheat response — that is, more stable yields despite the influence of climate change — is a benefit, not a threat, to farmers.
  • The article authors contradict the common knowledge among farmers and plant breeders that new elite wheat varieties are generally more productive than older varieties; new cultivars are only approved if they show added value in direct comparison to existing varieties.
  • The article’s claim of long-term losses of climate resilience in “European wheat” is unsubstantiated. The authors extensively used data from three small countries — the Czech Republic, Denmark and Slovakia — which contribute less than five percent of Europe’s wheat supply. Three of the five most important wheat producers in Europe — Russia, Ukraine and the United Kingdom — were not accounted for in the analysis.
  • The authors failed to report the actual wheat yields in their study, neglected to publish the underlying data with the manuscript and have up to now declined requests to make the data available.

Europe is one of the world’s major wheat producers and threats to its wheat production due to climate change would have serious consequences for world’s food security. Luckily, say the scientists who published the rebuttal letter, this fear is unfounded.

“Wheat producers and bread consumers around the world will be relieved to learn that breeders have not ignored climate change after all,” said letter lead-author Rod Snowdon, from the Department of Plant Breeding at Justus Liebig University of Giessen, Germany.

The full rebuttal letter by 19 international plant breeders, agronomists and scientists, is available on the PNAS site and reprinted in its entirety below.

Reduced response diversity does not negatively impact wheat climate resilience

Kahiluoto et al. (1) assert that climate resilience in European wheat has declined due to current breeding practices. To support this alarming claim, the authors report yield variance data indicating increasingly homogeneous responses to climatic fluctuations in modern wheat cultivars. They evaluated “response diversity,” a measure of responses to environmental change among different species jointly contributing to ecosystem functions (2). We question the suitability of this measure to describe agronomic fitness in single-cultivar wheat cropping systems. Conclusions are made about “long-term trends,” which in fact span data from barely a decade, corresponding to the duration of a single wheat breeding cycle. The authors furthermore acknowledge increasing climate variability during the study period, confounding their analysis of climate response in the same time span.

The underlying data are not published with the manuscript. Thus, the assertion that there is “no inherent trade-off between yield potential and diversity in weather responses” (1) cannot be verified. Inexplicably, the analysis and conclusions ignore absolute yields, which increase over time through breeding (3–6). Furthermore, incompatible data from completely different ecogeographical forms and species of wheat are apparently considered together, and the dataset is strongly biased toward a few small countries with minimal wheat production and narrow agroclimatic gradients.

The study assumes that increased response diversity among different cultivars is associated with yield stability. In contrast, the common, agronomic definition of yield stability refers to the ability of a single cultivar to stably perform well in diverse environments, without excessive responses to fluctuating conditions. Response diversity measures that ignore absolute yield do not support statements about food security or financial returns to farmers.

Cultivar yield potential, stability, and adaptation are enhanced by multienvironment selection over long breeding time frames, encompassing climate fluctuations and a multitude of other relevant environmental variables. Translation to on-farm productivity is promoted by national registration trials and extensive, postregistration regional variety trials in diverse environments. The unsurprising conclusion that planting multiple cultivars enhances overall production stability mirrors longstanding farming recommendations and practice (7). The availability of robust performance data from a broad range of high-performing cultivars enables European farmers to manage their production and income risks.

Kahiluoto et al. (1) speculate about “genetic erosion” of modern cultivars due to a “lack of incentives for breeders to introduce divergent material.” To substantiate these claims, the authors cite inadequate genetic data from non-European durum wheat (8), while explicitly dismissing clearly opposing findings about genetic diversity in European bread wheat (9). Short-term reductions in response diversity in five countries were misleadingly reported as a “long-term decline” in climate resilience in “most European countries,” although six out of seven countries with sufficient data showed no long-term decline. The article from Kahiluoto et al. and the misrepresentation of its results distorts decades of rigorous, successful breeding for yield potential and stability in European wheat and misleads farmers with pronouncements that are not supported by relevant data.

References:

1 H. Kahiluoto et al., Decline in climate resilience of European wheat. Proc. Natl. Acad. Sci. USA 116, 123–128 (2019).

2 T. Elmqvist et al., Response diversity, ecosystem change, and resilience. Front. Ecol. Environ. 1, 488–494 (2003).

3 S. De Schepper, M. De Loose, E. Van Bockstaele, P. Debergh, Ploidy analysis of azalea flower colour sports. Meded. Rijksuniv. Gent. Fak. Landbouwkd. Toegep. Biol. Wet. 66, 447–449 (2001).

4 I. Mackay et al., Reanalyses of the historical series of UK variety trials to quantify the contributions of genetic and environmental factors to trends and variability in yield over time. Theor. Appl. Genet. 122, 225–238 (2011).

5 F. Laidig et al., Breeding progress, environmental variation and correlation of winter wheat yield and quality traits in German official variety trials and on-farm during 1983-2014. Theor. Appl. Genet. 130, 223–245 (2017).

6 T. Würschum, W. L. Leiser, S. M. Langer, M. R. Tucker, C. F. H. Longin, Phenotypic and genetic analysis of spike and kernel characteristics in wheat reveals long-term genetic trends of grain yield components. Theor. Appl. Genet. 131, 2071–2084 (2018).

7 P. Annicchiarico, “Genotype x environment interactions: Challenges and opportunities for plant breeding and cultivar recommendations.” (Food and Agriculture 201 Organisation of the United Nations, Rome, Italy, 2002), FAO Plant Production and Protection Paper 174.

8 F. Henkrar et al., Genetic diversity reduction in improved durum wheat cultivars of Morocco as revealed by microsatellite markers. Sci. Agric. 73, 134–141 (2016).

9 M. van de Wouw, T. van Hintum, C. Kik, R. van Treuren, B. Visser, Genetic diversity trends in twentieth century crop cultivars: A meta analysis. Theor. Appl. Genet. 120, 1241–1252 (2010).

$20 million in grants for research to boost wheat yield potential

Wheat Remote Sensing-flip

Photo: Alfredo Saénz/CIMMYT

By Mike Listman/CIMMYT

COLLEGE STATION, Texas (October 30, 2015)- The International Wheat Yield Partnership (IWYP) will recommend around US $20 million in grants awards from its funders for a selection of 8 research projects by leading institutes to increase wheat’s photosynthetic and energy-use efficiency and harness the genetics behind key components of yield.

Resulting from a January 2015 call for competitive research proposals, the projects fit the IWYP goal of raising the genetic yield potential of wheat by up to 50% in the coming 20 years.

To read more about the projects, IWYP, and the Initiative’s funders, click here.