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Study: Global farming trends threaten food security

By | Agriculture, News

Citrus fruits, coffee and avocados: The food on our tables has become more diverse in recent decades. However, global agriculture does not reflect this trend. Monocultures are increasing worldwide, taking up more land than ever. At the same time, many of the crops being grown rely on pollination by insects and other animals. This puts food security at increased risk, as a team of researchers writes in the journal “Global Change Biology“. For the study, the scientists examined global developments in agriculture over the past 50 years.

The researchers analysed data from the United Nations’ Food and Agriculture Organization (FAO) on the cultivation of field crops between 1961 and 2016. Their evaluation has shown that not only is more and more land being used for agriculture worldwide, the diversity of the crops being grown has declined. Meanwhile, 16 of the 20 fastest growing crops require pollination by insects or other animals. “Just a few months ago, the World Biodiversity Council IPBES revealed to the world that up to one million animal and plant species are being threatened with extinction, including many pollinators,” says Professor Robert Paxton, a biologist at MLU and one of the authors of the new study. This particularly affects bees: honeybees are increasingly under threat by pathogens and pesticides, and populations of wild bees have been on the decline around the world for decades.

Fewer pollinators could mean that yields are much lower or even that harvests fail completely. However, risks are not spread equally across the world. The researchers used the FAO data to create a map showing the geographical risk of crop failure. “Emerging and developing countries in South America, Africa and Asia are most affected,” says Professor Marcelo Aizen of the National Council for Scientific and Technological Research CONICET in Argentina, who led the study. This is not surprising, he says, since it is precisely in these regions where vast monocultures are grown for the global market. Soy is produced in many South American countries and then exported to Europe as cattle feed. “Soy production has risen by around 30 percent per decade globally. This is problematic because numerous natural and semi-natural habitats, including tropical and subtropical forests and meadows, have been destroyed for soy fields,” explains Aizen.

According to the authors, current developments have little to do with sustainable agriculture, which focuses on the food security of a growing world population. And, although poorer regions of the world are at the greatest risk, the consequences of crop failure would be felt worldwide: “The affected regions primarily produce crops for the rich industrial nations. If, for example, the avocado harvest in South America fails, people in Germany and other industrial nations may no longer be able to buy them,” concludes Robert Paxton, who is also a member of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig.

The researchers advocate for a trend reversal: Care should be taken to diversify agriculture worldwide and make it more ecological. This means, for example, that farms in particularly susceptible countries should grow a diversity of crops. In addition, farmers all over the world would need to make the areas under cultivation more natural, for example by planting strips of flowers or hedgerows next to their fields and by providing nesting habitats on field margins. This would ensure that there are adequate habitats for insects, which are essential for sustainable and productive farming.

Read the paper: Global Change Biology

Article source: Martin-Luther-Universität Halle-Wittenberg

Image: Martin Husemann

Genetic breakthrough in cereal crops could help improve yields worldwide

By | Agriculture, News, Plant Science

A team of Clemson University scientists has achieved a breakthrough in the genetics of senescence in cereal crops with the potential to dramatically impact the future of food security in the era of climate change.

The collaborative research, which explores the genetic architecture of the little understood process of senescence in maize (a.k.a. corn) and other cereal crops, was published in The Plant Cell, one of the top peer-reviewed scientific journals of plant sciences. Rajan Sekhon, a plant geneticist and an assistant professor in the College of Science’s department of genetics and biochemistry, is the lead and corresponding author of the paper titled “Integrated Genome-Scale Analysis Identifies Novel Genes and Networks Underlying Senescence in Maize.”

“Senescence means ‘death of a cell or an organ in the hands of the very organisms it is a part of,’ ” Sekhon said. “It happens pretty much everywhere, even in animals. We kill the cells we don’t need. When the weather changes in fall, we have those nice fall colors in trees. At the onset of fall, when the plants realize that they cannot sustain the leaves, they kill their leaves. It is all about the economy of energy.”

As a result, the leaves die off after their show of color. The energy scavenged from the leaves is stored in the trunk or roots of the plant and used to quickly reproduce leaves next spring. This makes perfect sense for trees. But the story is quite different for some other edible plants, specifically cereal crops like maize, rice and wheat.

“These crops are tended very carefully and supplied excess nutrients in the form of fertilizers by the farmers,” Sekhon said. “Instead of dying prematurely, the leaves can keep on making food via photosynthesis. Understanding the triggers for senescence in crops like maize means scientists can alter the plant in a way that can benefit a hungry world.”

Sekhon, whose research career spans molecular genetics, genomics, epigenetics and plant breeding, established his lab in 2014 as an assistant professor. He has played a key role in the development of a “gene atlas” widely used by the maize research community. He has published several papers in top peer-reviewed journals investigating the regulation of complex plant traits.

“If we can slow senescence down, this can allow the plant to stay green – or not senesce – for a longer period of time,” Sekhon said. “Plant breeders have been selecting for plants that senesce late without fully understanding how senescence works at the molecular level.”

These plants, called “stay-green,” live up to their name. They stay green longer, produce greater yields and are more resilient in the face of environmental factors that stress plants, including drought and heat.

But even with the existence of stay-green plants, there has been little understanding about the molecular, physiological and biochemical underpinnings of senescence. Senescence is a complex trait affected by several internal and external factors and regulated by a number of genes working together. Therefore, off-the-shelf genetic approaches are not effective in fully unraveling this enigmatic process. The breakthrough by Sekhon and his colleagues was the result of a systems genetics approach.

Sekhon and the other researchers studied natural genetic variation for the stay-green trait in maize. The process involved growing 400 different maize types, each genetically distinct from each other based on the DNA fingerprint (i.e., genotype), and then measuring their senescence (i.e., phenotype). The team then associated the “genotype” of each inbred line with its “phenotype” to identify 64 candidate genes that could be orchestrating senescence.

“The other part of the experiment was to take a stay-green plant and a non-stay-green plant and look at the expression of about 40,000 genes during senescence,” Sekhon said. “Our researchers looked at samples every few days and asked which genes were gaining expression during the particular time period. This identified over 600 genes that appear to determine whether a plant will be stay-green or not.

“One of the big issues with each of these approaches is the occurrence of false positives, which means some of the detected genes are flukes, and instances of false negatives, which means that we miss out on some of the causal genes.”

Therefore, Sekhon and his colleagues had to painstakingly combine the results from the two large experiments using a “steams genetics” approach to identify some high-confidence target genes that can be further tested to confirm their role in senescence. They combined datasets to narrow the field to 14 candidate genes and, ultimately, examined two genes in detail.

“One of the most remarkable discoveries was that sugars appear to dictate senescence,” Sekhon said. “When the sugars are not moved away from the leaves where these are being made via photosynthesis, these sugar molecules start sending signals to initiate senescence.”

However, not all forms of sugar found in the plants are capable of signaling. One of the genes that Sekhon and colleagues discovered in the study appears to break complex sugars in the leaf cells into smaller sugar molecules – six-carbon sugars like glucose and fructose – that are capable of relaying the senescence signals.

“This is a double whammy,” Sekhon said. “We are not only losing these extra sugars made by plants that can feed more hungry mouths. These unused sugars in the leaves start senescence and stop the sugars synthesis process all together.”

The implications are enormous for food security. The sugars made by these plants should be diverted to various plant organs that can be used for food.

“We found that the plant is carefully monitoring the filling of the seeds. That partitioning of sugar is a key factor in senescence. What we found is there is a lot of genetic variation even in the maize cultivars that are grown in the U.S.”

Some plants fill seeds and then can start filling other parts of the plant.

“At least some of the stay-green plants are able to do this by storing extra energy in the stems,” Sekhon said. “When the seed is harvested, whatever is left in the field is called stover.”

Stover can be used as animal feed or as a source of biofuels. With food and energy demand increasing, there is a growing interest in developing dual-purpose crops which provide both grain and stover. As farmland becomes scarce, plants that senesce later rise in importance because they produce more overall energy per plant.

The genes identified in this study are likely performing the same function in other cereal crops, such as rice, wheat and sorghum. Sekhon said that the next step is to examine the function of these genes using mutants and transgenics.

“The ultimate goal is to help the planet and feed the growing world. With ever-worsening climate, shrinking land and water, and increasing population, food security is the major challenge faced by mankind,” Sekhon said.

In addition to Sekhon, other contributors include Rohit Kumar, Christopher Saski, Arlyn Ackerman, William Bridges, Barry Flinn and Feng Luo of Clemson University; Timothy Beissinger of the University of Gottingen; and Matthew Breitzman, Natalia de Leon and Shawn Kaeppler of the University of Wisconsin-Madison.

Read the paper: The Plant Cell

Article source: Clemson University

Image: Clemson University/College of Science

Plant nutrient detector breakthrough

By | Agriculture, News, Plant Science, Research

Findings from La Trobe University-led research could lead to less fertiliser wastage, saving millions of dollars for Australian farmers.

Published in the journal Plant Physiology, the findings provide a deeper understanding of the mechanisms whereby plants sense how much and when to take in the essential nutrient, phosphorus, for optimal growth.

Lead author Dr Ricarda Jost, from the Department of Plant, Animal and Soil Sciences at La Trobe University said the environmental and economic benefits to farmers could be significant.

“In countries like Australia where soils are phosphorus poor, farmers are using large amounts of expensive, non-renewable phosphorus fertiliser, such as superphosphate or diammonium phosphate (DAP), much of which is not being taken up effectively by crops at the right time for growth,” Dr Jost said.

“Our findings have shown that a protein called SPX4 senses the nutrient status – the ‘amount of fuel in the tank’ of a crop – and alters gene regulation to either switch off or turn on phosphorus acquisition, and to alter growth and flowering time.”

Using Arabidopsis thaliana (thale or mouse-ear cress) shoots, the research team conducted genetic testing by adding phosphorus fertiliser and observing the behaviour of the protein.

For the first time, the SPX4 protein was observed to have both a negative and a positive regulatory effect on phosphorus take-up and resulting plant growth.

“The protein senses when the plant has taken in enough phosphorus and tells the roots to stop taking it up,” Dr Jost said. “If the fuel pump is turned off too early, this can limit plant growth.

“On the other hand, SPX4 seems to have a ‘moonlighting’ activity and can activate beneficial processes of crop development such as initiation of flowering and seed production.”

This greater understanding of how SPX4 operates could lead to a more precise identification of the genes it regulates, and an opportunity to control the protein’s activity using genetic intervention – switching on the positive and switching off the negative responses.

La Trobe agronomist Dr James Hunt said the research findings sit well with the necessity for Australian farmers’ to be as efficient as possible with costly fertiliser inputs.

“In our no-till cropping systems, phosphorus gets stratified in the top layers of soil. When this layer gets dry, crops cannot access these reserves and enter what we a call a phosphorus drought,” Dr Hunt said.

“The phosphorus is there, but crops can’t access it in the dry soil. If we could manipulate crop species to take up more phosphorus when the top soil is wet, we’d be putting more fuel in the tank for later crop growth when the top soil dries out.”

The research team will now be investigating in more detail how SPX4 interacts with gene regulators around plant development and controlling flowering time.

The research was published in Plant Physiology with collaborators from Zhejiang University (China), Ghent University & VIB Center for Plant Systems Biology (Belgium), French Alternative Energies and Atomic Energy Commission (CEA) and the Australian Research Council Centre of Excellence in Plant Energy Biology.

Read the paper: Plant Physiology

Article source: La Trobe University

Image: Free-Photos / Pixabay

How much do climate fluctuations matter for global crop yields?

By | Agriculture, News

The El Niño-Southern Oscillation (ENSO) has been responsible for widespread, simultaneous crop failures in recent history, according to a new study from researchers at Columbia University’s International Research Institute for Climate and Society, the International Food Policy Research Institute (IFPRI) and other partners. This finding runs counter to a central pillar of the global agriculture system, which assumes that crop failures in geographically distant breadbasket regions such as the United States, China and Argentina are unrelated. The results also underscore the potential opportunity to manage such climate risks, which can be predicted using seasonal climate forecasts.

The study, published in Science Advances, is the first to provide estimates of the degree to which different modes of climate variability such as ENSO cause volatility in global and regional production of corn, wheat and soy. Such variability caused nearly 18 percent volatility in global corn production from 1980 to 2010, for example.

“Global agriculture counts on the strong likelihood that poor production in one part of the world will be made up for by good production elsewhere,” said Weston Anderson, a postdoctoral research scientist at the International Research Institute for Climate and Society and lead author on the study.

Of course, there’s always a chance—however small—that it won’t. The assumption until now has been that widespread crop failures would come from a set of random, adverse weather events, Anderson said.

He and his co-authors decided to test this idea by looking at the impact that the El Niño-Southern Oscillation, the Indian Ocean Dipole, and other well-understood climate patterns have had on global production of corn, soybeans and wheat. They analyzed how these modes of climate variability influenced drought and heat in major growing regions.

“We found that ENSO can, and has, forced multiple breadbasket failures, including a significant one in 1983,” said Anderson. “The problem with pooling our risk as a mitigating strategy is that it assumes failures are random. But we know that strong El Niño or La Niña events in effect organize which regions experience drought and extreme temperatures. For some crops, that reorganization forces poor yields in multiple major production regions simultaneously.”

How important is the influence of climate variability? The authors found that, on a global level, corn is the most susceptible to such crop failures. They found that 18% percent of the year-to-year changes in corn production were the result of climate variability. Soybeans and wheat were found to be less at risk for simultaneous failures, with climate variability accounting for 7% and 6% of the changes in global production, respectively.

“The bigger the uncertainty around climate drivers, the bigger the risk for those involved in the food systems,” said co-author Liangzhi You, a senior research fellow at the International Food Policy Research Institute. “The worst affected are poor farmers in developing countries whose livelihoods depend upon crop yields as they do not have an appetite for risks in absence of formal insurance products or other coping mechanisms.” The risk is further exacerbated by challenges posed by lack of infrastructure and resources in developing countries.

“ENSO may not be important in all years, but it is the only thing we know of that has forced simultaneous global-scale crop failures” said Anderson.

Within specific regions, the risk to agriculture by climate variability can be much higher. For example, across much of Africa and in Northeast Brazil, ENSO and other recurring climate phenomena accounted for 40-65% of the ups and downs of food production. In other regions, the number was as low as 10%.

While on the surface this may appear to mean that those areas more affected by ENSO and other climate patterns are more at risk to extreme events, the numbers actually reflect a link to climate patterns that can be monitored and predicted.

“What excites me about this work is that it shows how predictable modes of climate variability impact crop production in multiple regions and can scale up to influence global production, said co-author Richard Seager of Columbia’s Lamont Doherty Earth Observatory. “This should allow anticipation of shocks to global food prices and supplies and, hence, improve efforts to avoid food insecurity and provide emergency food assistance when needed.”

Read the paper: Science Advances

Article source: International Food Policy Research Institute IFPRI

Image: Laura Mendez / Pixabay