University of California release

 

A team of scientists from University of California, Davis, have identified a new gene variant in wheat that can increase the amount of the grain produced, new research published in the journal PLOS Genetics finds.

 

Wheat is a staple of food diets worldwide and the gene discovery could allow farmers to grow more food without increasing land use. Increased yield could also lower consumer prices, making the crop more accessible.

 

“We have a growing human population that likes to eat every day,” said Jorge Dubcovsky, a plant sciences distinguished professor who led the research. “We need to produce more wheat in the same space so we need plants that are more productive.”

 

The researchers found a gene – WAPO1 – that controls the maximum number of grains in a wheat spike. Breeding the beneficial gene variant into the plants could delay the formation of the terminal spikelet, providing room for more grains to grow in each spike rather than ending production of grain.

 

WAPO1 is one of the first genes discovered that can affect wheat yield. “We are trying to make more productive wheat varieties and we are starting to understand how that trait is controlled,” Dubcovsky said.

 

Pasta Wheat Lacking the Gene

The gene variant for high grain number is found frequently in bread wheats but not in pasta wheats. By breeding the beneficial gene variant into those pasta wheat varieties, growers could increase yield by 4% to 5% in cultivars that have the biomass capacity to fill the extra grains.

 

“We developed molecular markers to select for the form of that gene to produce increased yield,” Dubcovsky said. “It’s a significant step forward.”

 

Previous research by the team mapped the gene and identified others that could affect yield. This research confirmed those findings for WAPO1.

 

Discovery on Path to Future Yield Increases

The WAPO1 gene is part of a network of genes that work together to control yield, and researchers need to identify the best variant combinations to maximize yield. Solving this puzzle can lead to better production rates.

“We will continue to try to understand the network of genes that control the yield of wheat,” he said.

 

Saarah Kuzay, Huiqiong Lin, Chengxia Li, Shisheng Chen, Daniel P. Woods and Junli Zhang from UC Davis also contributed to the research, as did scientists from Howard Hughes Medical Institute, Heinrich Heine University and Peking University Institute of Advanced Agricultural Sciences.

 

Funding was provided by USDAs National Institute of Food and Agriculture’s Food Research Initiative, the International Wheat Yield Partnership and Howard Hughes Medical Institute.

By Joan Conrow in Alliance for Science a publication from Cornell University

 

Genetically modified insects offer a sustainable solution for controlling fall armyworm, a devastating agricultural pest that has already developed resistance to both insecticides and Bt crops, a new study finds.

 

The peer-reviewed research, published in BMC Biotechnology Journal, found that Oxitec Ltd.’s Friendly technology can effectively reduce populations of fall armyworm, offering hope for long-term protection against the pest.

 

“Our results provide promise for a new and valuable addition to future integrated pest management programs for fall armyworm, and for other pests in which insecticide resistance has become a significant challenge for farmers,” the authors wrote. “Preservation of, and reducing over-reliance on, existing tools whilst minimizing their ecological impact will improve food security, farmers’ livelihoods, and environmental sustainability.”

 

The proprietary Friendly technology works by genetically modifying (GM) insects to introduce a gene that prevents offspring of the pests from surviving into adulthood. The modified male fall armyworms are released into areas of infestation where they mate with wild females, reducing the number of female offspring in the next generation and thereby dramatically reducing the population. The introduced gene is self-limiting.

 

One major benefit of the approach is that it targets the problem pests, sparing beneficial insects and avoiding the off-target effects on the wider ecology often seen with the application of insecticides. It also addresses the problem of pests developing resistance to the insecticides meant to control them.

 

“The development of a strain of fall armyworm engineered to show conditional, female-specific mortality offers a new pest management option and resistance management strategy where fall armyworm threatens the effectiveness of insecticides and Bt crops,” the authors concluded.

 

Oxitec has successfully used its Friendly self-limiting insect technology with mosquitoes to control dengue, Zika and other diseases in Brazil and is currently conducting field trials in the United States. Brazilian regulators also approved commercial use of the Friendly fall armyworm, finding it safe for people, animals and the environment.

 

Though native to the Americas, the fall armyworm has spread across the globe, destroying crops in Asia, Australia and now Africa. Adult moths lay their eggs on the crops and when the caterpillars hatch and start feeding, they are extremely destructive, causing billions of dollars in annual crop damage and losses. They are particularly attracted to corn (maize), rice and sorghum, but will feed on other crops and plants.

 

The researchers found that GM fall armyworm moths strongly compete with wild-type males for mates, which is key to the technology’s success in the field. They also confirmed the self-limiting nature of the transgene in laboratory populations. “The gene is self-limiting, declining to extinction within a few [four to seven] generations,” the authors wrote. “In future applications on crops, the OX5382G trait is therefore not expected to persist in fall armyworm populations after releases stop.”

 

Additionally, the researchers modelled the effect of releasing male-selecting, self- limiting adult moths into target fall armyworm populations. Their modelling shows that development of fall armyworm resistant to Bt corn is significantly delayed, leading to sustained fall armyworm management over a much longer period.

“Our simulations showed that without the release of OX5382G males, genetic resistance to insecticidal proteins increases rapidly due to natural selection,” the authors wrote. “The presence of insecticidal proteins in biotech crops suppresses fall armyworm populations initially, but as the resistance allele frequency increases, population size rebounds and returns to carrying capacity. To mitigate this threat, our simulations show that releases of OX5382G moths, even in relatively small numbers, have the potential to delay the accumulation of resistance alleles in a fall armyworm population, and suppress the size of that population. These findings are consistent with those of previous modelling studies and empirical studies with another lepidopteran.”

 

Oxitec officials heralded the results of the independent research. “These results demonstrate the immense promise of Oxitec’s fall armyworm to transform the effectiveness and sustainability of critical food crop production, in Brazil and across the world,” a company press release stated.

 

“Our Friendly fall armyworm is being prepared to transform the sustainability of corn production in Brazil and other countries, and to support food security for the long-term,” said Oxitec CEO Grey Frandsen in the release. “Having spent significant time across Brazil’s agricultural regions, I’ve seen first-hand the threat posed by fall armyworm on Brazilian farms. We now have a solution with the potential to protect existing tools and deliver truly long-term and environmentally friendly protection of corn against this threat.”

 

By Kathleen Hefferon Henry Miller

 

Much of the world is preoccupied with the ongoing coronavirus pandemic, but there are other global challenges, including climate change, food security, and degradation of the environment. Interestingly, and perhaps ironically, there is some good news regarding the latter three from a recent breakthrough in microbiology.  

 

Plants depend upon beneficial interactions between roots and root-associated microorganisms for growth promotion, disease suppression, and nutrient availability. Crops require nitrogen to grow, and although there is an abundance of it in the atmosphere, it is not available in a form that plants can readily use. Instead, the roots of most crops take up nitrogen in the form of ammonia, either as synthetic fertilizer or in biological waste such as manure or compost. The availability of nitrogen from any of those sources increases crop yield, which is in itself an important step toward achieving food security.

 

Before synthetic fertilizers became available, feeding the world’s population relied solely upon an endless demand for manure to such an extent that wars have been fought over it. For example, in 1864 a naval conflict broke out between Spain and Peru over the Chincha Islands, which were covered in guano deposits said to be over 100 feet high.

 

Some plants take up nitrogen with the help of soil bacteria that actually “fix” nitrogen gas (N₂) from the atmosphere, converting it into ammonia, which the plant’s roots can use. This process of biological nitrogen fixation (BNF) is tightly regulated by the bacteria that perform this action, so that the process is switched off if sufficient levels of nitrogen are available in a form that can be taken up by the plant. These microorganisms are found associated among the roots of certain leguminous crops, such as soybean, alfalfa or pea, which contain nodules within their root systems where these processes are carried out. Crops such as these can be rotated in the field with others which lack this ability, such as corn or wheat, for example, to obtain higher yields and for maintenance of soil health.

 

Synthetic fertilizers are now essential to feeding the world’s population, but they are costly and their production requires fossil fuels. While saving and enhancing the lives of countless people, synthetic fertilizers have had other, undesirable effects,

especially on the environment. Excess nitrogen in the form of ammonia can make its way out of farmland and into our waterways where it collects and forms anoxic dead zones, such as the one found where the Mississippi River Delta meets the Gulf of Mexico. Another aspect of the problem is that excess ammonia left on farmers’ fields can also be converted into nitrous oxide (N₂O), a stable, long-lived greenhouse gas with 300 times the potency of carbon dioxide.

Nitrous oxide represents six percent of greenhouse gas emissions, about three quarters of which is derived from agriculture. In addition, N₂O also diminishes the ozone layer, further exacerbating climate change.

 

A long-sought solution would be to replace synthetic fertilizers with bacteria that perform nitrogen fixation in the roots of crops other than legumes, which could reduce nitrogen runoff and the production of nitrous oxide. This has now been achieved, as described in an article published last December by a large group of academic and industrial researchers.

 

Their report described “the identification, development, and deployment of the first microbial product optimized using synthetic biology tools to enable BNF for corn (Zea mays) in fertilized fields, demonstrating the successful, safe commercialization of root-associated diazotrophs and realizing the potential of BNF to replace and reduce synthetic nitrogen fertilizer use in production agriculture.”

 

 

The bacterium chosen for this work already contained the genes that enabled it to fix atmospheric nitrogen via an enzyme called nitrogenase, so it comes by this ability naturally. However, because nitrogenase expression is switched off in the presence of ammonia, applying synthetic fertilizer would suppress bacterial BNF. By using a genome editing approach that employs CRISPR, the bacteria were tweaked to express the enzyme in the presence of fertilizer, which boosted the levels of nitrogen in a form available to the plant.

 

The study demonstrated that the need for applications of synthetic fertilizer was significantly less when this engineered bacterium was provided as an inoculum to the roots of non-leguminous crops such as corn. Most important, the authors showed that the system worked not just in the greenhouse but under a variety of real-world field conditions.

 

This elegant study could be a game-changer on many fronts. The process of generating synthetic fertilizer requires fossil fuel, and the simple act of applying it to farmers’ fields via tractor use burns even more fuel and thus exacerbates greenhouse gas emissions. Fewer applications of fertilizer (or manure) means fewer opportunities for nitrogen runoff and greenhouse gas emissions to be created, while maintaining the crop yields necessary to feed a burgeoning global population.

 

If the use of genetically engineered microorganisms could solve three of the major challenges in agriculture today, with no downside, who could possibly take issue with that? Unfortunately, there are numerous precedents for failing to embrace agricultural innovations. One egregious example was the saga of the genetically engineered “ice-minus” Pseudomonas syringae applied to plants such as strawberries to prevent frost damage.

 

The harmless wild-type bacterium, Pseudomonas syringae, which lives on many plants, contains an “ice nucleation” protein that promotes frost damage. (Ice nucleation proteins, which are found on the surface of certain bacteria, promote frost damage in plants by inducing the formation of ice crystals at a higher temperature than they would otherwise form.) In the early 1980s, scientists in the agricultural biotechnology industry and at the University of California, Berkeley, devised an ingenious approach to limiting frost damage, using recombinant DNA, or “gene-splicing,” techniques. They created a mutant of the bacterium that lacks the ice-nucleation protein, reasoning that spraying this variant bacterium (dubbed “ice-minus”) on plants might prevent frost damage by displacing the wild-type, ice-promoting variety. Using very precise recombinant DNA techniques, the researchers deleted the gene for the ice-nucleation protein and planned field tests with the ice-minus bacteria to see whether it would actually prevent frost damage under real-world conditions.

 

So far, so good. Then the government stepped in.

 

The Environmental Protection Agency (EPA) classified the innocuous ice-minus bacteria, which were to be tested in northern California on small, fenced-off plots of potatoes and strawberries, as a pesticide. The rationale was that because the naturally occurring, ubiquitous “ice-plus” bacterium promoted frost damage, it was, therefore, a “pest,” and other bacteria intended to mitigate its effects would be considered a pesticide. This is the kind of absurd, sophistic reasoning that could lead the EPA to regulate outdoor trash can lids as a pesticide because they deter or mitigate the actions of a “pest”—namely, raccoons.

 

At the time, scientists inside and outside the EPA agreed that the test posed negligible risk. The reasoning was that no new genetic material had been added—only a single gene whose function was well known had been deleted—and the organism was obviously harmless. Nonetheless, the field trial was subjected to an extraordinarily long and burdensome review, by both the National Institutes of Health and EPA, only because the organism had been genetically modified with recombinant DNA techniques.

 

It is noteworthy that small-scale field trials using bacteria with identical traits, but constructed with older, cruder techniques require no governmental review of any kind. (There are natural, ice-minus deletion mutants of P. syringae, but because the gene for the ice-nucleation protein is not completely deleted, the mutation isn’t permanent.) When field tested on less than 10 acres, non-engineered bacteria and chemical pesticides are completely exempt from regulation. Moreover, there is no government regulation at all of the vast quantities of the wild-type, “ice-plus” P. syringae organisms (which contain the ice-nucleation protein) that are commonly blown into the air during snow-making at ski resorts.

 

Although the ice-minus bacteria proved safe and effective at preventing frost damage in field trials, further research and commercialization were discouraged by the combination of onerous government regulation, the inflated expense of doing the experiments, the prospect of huge downstream costs, and the stigma of pesticide registration. As a result, the product was never commercialized, and plants cultivated for food and fiber remain vulnerable to frost damage.

 

The failure of the ice-minus P. syringae due to bureaucrats’ malfeasance might be thought of as a cautionary tale. In spite of the obstructionism of regulators and the opposition of activists, however, the innovations just keep on coming.

 

For years, farmers and scientists have been aware of a phenomenon known as “commensalism,” a long-term biological interaction in which members of one species gain benefits while those of the other species neither benefit nor are harmed; specifically, certain crops benefit from their intimate associations with their local soil microbial community. Thus, microorganisms are being developed for various agricultural applications, including as biopesticides; soil remediators to remove pollutants; and biosensors to detect crop stress or assess the microclimate of fields, orchards, and vineyards. The genomes of individual microorganisms as well as entire microbial communities are being examined using computational tools, including AI, to determine which can improve crop yield, reduce pest pressure, control weeds, and deliver nutrients.

 

For millennia, microorganisms have been used for fermentation of food and beverages, and, more recently, as a source of pharmaceuticals and industrial enzymes. They are truly part of the story of humanity. Using them to produce higher crop yields, which would feed more people at less expense, improve farmers’ bottom line, and reduce agriculture’s greenhouse gas footprint, is a logical and welcome extension.

 

Inevitably, however, there will be opposition to this innovation. The organic lobby, intransigent, anti-technology activists, and ignorant politicians won’t magically become enlightened. The recent fiasco in Sri Lanka, which tried to convert completely to organic farming, with disastrous results, is one example. Another is the European Union’s Farm to Fork strategy, which aspires to increase organic crop production 20% by 2030. Accomplishing that would require the conversion of more wild places into farmland, and a demand for compost, manure and other forms of biological waste that cannot possibly be met.

 

What will it take for policy makers to rethink their opposition to technologies such as genetically engineered plants and commensal microorganisms? Widespread famine? Astronomically inflated food prices? Extreme climate catastrophe? We hope not, but as with the sorry saga of nuclear power, history is not on our side.