Bioengineered yeast feed on agricultural waste

Result sets the stage for biomanufacturing of biofuels and other products with a very low carbon footprint

Peer-Reviewed Publication

TUFTS UNIVERSITY

 

IMAGE: BIOENGINEER NIKHIL NAIR AND HIS TEAM AT TUFTS UNIVERSITY SCHOOL OF ENGINEERING DEVELOPED BIOSYNTHETIC YEAST THAT CAN FEED ON SUGARS FROM AGRICULTURAL WASTE. THE INNOVATION SETS THE STAGE FOR MORE SUSTAINABLE METHODS FOR THE PRODUCTION OF BIOFUELS AND OTHER BIOSYNTHETIC PRODUCTS view more 

CREDIT: PHOTO BY ALONSO NICHOLS

Yeast has been used for thousands of years in the production of beer and wine and for adding fluff and flavor to bread. They are nature’s tiny factories that can feed on sugars found in fruit and grains and other nutrients – and from that menu produce alcohol for beverages, and carbon dioxide to make bread rise.

Researchers at Tufts University School of Engineering report making modified yeast that can feed on a wider range of materials, many of which can be derived from agricultural by-products that we don’t use – leaves, husks, stems, even wood chips – what is often referred to as “waste biomass”.

Why is it important to make yeast that can feed on these agricultural leftovers?

In recent years, scientists have modified yeast to make other useful products like pharmaceuticals and biofuels. It’s a clever way to let nature do our work in a way that does not require toxic chemicals for manufacturing. The technology – referred to as “synthetic biology” – is still young, but looking ahead to a future where biosynthetic production from yeast would operate at a very large scale, we need to feed yeast on something other than what we ourselves need to eat.

A lot to chew on – engineering yeast to grow on biomass sugars

The novel yeast made by the Tufts team can feed on sugars like xylose, arabinose and cellobiose which can be extracted from the indigestible woody parts of crops that are often tossed aside after harvesting, like corn stalks, husks and leaves, and wheat stems. About 1.3 billion tons of this waste biomass is produced each year, providing more than enough sugars to drive a vast industry of yeast biosynthesis.

“If we can get yeast to feed on waste biomass, we can create a biosynthetic industry with a low carbon footprint,” said Nikhil Nair, associate professor of Chemical and Biological Engineering at Tufts School of Engineering. “For example, when we burn biofuels made by yeast, we produce a lot of carbon dioxide, but that carbon dioxide is re-absorbed into crops the following year, which the yeast feed on to make more biofuel, and so on.”

Minimal engineering for maximum output

Nair and his team thought that the best chance for efficient consumption of waste biomass sugars might be to modify an existing genetic “dashboard” that the yeast uses to regulate galactose consumption (a sugar commonly found in dairy products). The dashboard, called a regulon, includes genes for sensors that detect the presence of sugar, and triggers enzymes for the chemical breakdown of sugar so its carbon and oxygen components can be rebuilt into new components. The new components are mostly small molecules and proteins that the yeast itself needs to survive, but they can also be novel products that scientists might have engineered into the yeast.

In an earlier study, the researchers modified the galactose regulon so that the sensor detects the biomass sugar xylose, and triggers enzymes to process xylose instead of galactose.

“Getting yeast to grow on xylose was an important advance,” said Sean Sullivan, a graduate student in the Nair lab who co-led the recent study, “but re-engineering different yeast organisms to grow on each biomass sugar is not the best approach. We wanted to design a single yeast organism that can feed off a complete, or nearly complete menu of biomass sugars.”

Sullivan made only minimal changes to the regulon already designed for xylose, by changing the sensor protein to more generally accept xylose, arabinose and cellobiose. Apart from a few more minor changes, the new regulon allowed the yeast organism to grow on these three sugars at rates comparable to yeast grown on native sugars glucose and galactose.

“By using native regulatory networks linked to cell growth and survival, we could take a minimal engineering approach to modifying and optimizing sugar consumption,” said Vikas Trivedi, a post-doctoral researcher who co-led the study. “It just so happens that yeast has the machinery to grow on non-native sugars, as long as we adapt sensors and regulons to recognize those sugars.”

Improving the back end of production

Remodeling yeast to grow on waste biomass sugars sets the stage for improved production of biosynthesized products, which includes drugs such as insulin, human growth hormone and antibodies. Yeast has also been engineered to produce vaccines by expressing small fragments of virus that stimulate the immune system.

In fact, yeast can be re-engineered to produce natural compounds used to make drugs, which are otherwise difficult to source because they have to be extracted from rare plants. These include scopolamine used for relieving motion sickness and postoperative nausea, and atropine used to treat Parkinson’s disease patients, and artemensin, used to treat malaria.

Ethanol is a well-known biofuel produced by yeast, but researchers have also engineered the organism to produce other fuels such as isobutanol and isopentanol, which can deliver more energy per liter than ethanol.

Bioengineered yeast can also produce building blocks of bioplastics, such as polylactic acid, which can then be used to make a variety of products, including packaging materials and consumer goods, without having to draw from petroleum sources.

“While the research community continues to innovate yeast to make new products, we are preparing the organism to grow efficiently on agricultural waste biomass, closing a carbon cycle that has so far eluded the manufacturing of fuels, pharmaceuticals and plastics,” said Nair.

 

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JOURNAL

Metabolic Engineering

DOI

10.1016/j.ymben.2023.07.001 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Towards universal synthetic heterotrophy using a metabolic coordinator

ARTICLE PUBLICATION DATE

18-Jul-2023

 

Can we predict if a plant species will become exotic?

Peer-Reviewed Publication

PENSOFT PUBLISHERS

 

IMAGE: AGRICULTURAL LANDSCAPE DOMINATED BY EXOTIC SPECIES OF EUROPEAN ORIGIN (MERCED VERNAL POOL AND GRASSLAND RESERVE, CALIFORNIA, U.S.A.). view more 

CREDIT: DR JAVIER GALÁN DÍAZ

Plant species become exotic after being accidentally or deliberately transported by humans to a new region outside their native range, where they establish self-perpetuating populations that quickly reproduce and spread. This is a complex process mediated by many factors, such as plant traits and genetics, which challenges the creation of general guidelines to predict or manage plant invasions. Scientists from Spanish and Australian institutions have now defined a new framework to find the predictors of invasiveness, investigating species that have succeeded or failed to establish abroad after following similar historical introduction routes.

Dr Javier Galán Díaz, University of Seville, Spain, Dr Enrique G. de la Riva, University of León, Spain, Dr Irene Martín-Forés, The University of Adelaide, Australia, and Dr Montserrat Vilà, Doñana Biological Station (EBD-CSIC), Spain, described their findings in a new paper in the open-access journal NeoBiota.

“While current policies exert strong control on the import and export of living organisms, including pests, across countries, until only a few decades ago, very little attention was paid to this issue. This means that many species were translocated to new regions without any consideration of their potential impacts,” says Dr Javier Galán Díaz.

An example of this is the massive plant exchange among Mediterranean‐type regions as a consequence of European colonialism: crops and cattle were exported, along with tools and materials, potentially bringing along the seeds of many plant species.

“So far, most studies on plant invasions have tried to explain the success of exotic species by comparing their traits with those of the native plant communities where they arrive, or by comparing the traits of plant species that have achieved different levels of invasion in the same region. But, if we take into account that the most common plant species from European agricultural landscapes have been in contact with humans and have therefore had the potential to be inadvertently transported to other Mediterranean regions, then only those that have successfully invaded other regions have something different in them that allowed them to establish and spread abroad,” Dr Galán Díaz explains.

Following this approach, the scientists found that, when comparing plant species transported from the Mediterranean Basin to other Mediterranean-climate regions (California, Central Chile, the Cape Region of South Africa and Southwestern and South Australia) in the search of predictors of invasiveness, only those species with large distribution ranges that occupy climatically diverse habitats in their native region became exotic. Also, species with many dispersal vectors (for instance those that have seeds dispersed by animals, water or wind), long bloom periods and acquisitive above- and belowground strategies of resource use are most likely to become exotic. Most of this plant information is readily available or easy to obtain from free and open-access repositories.

“Determining the factors that pre-adapt plant species to successfully establish and spread outside of their native ranges constitutes a powerful approach with great potential for management,” the researchers write in their paper. “This framework has the potential to improve prediction models and management practices to prevent the harmful impacts from species in invaded communities.”

“Using the existing information, we can identify the key species to monitor. This is especially encouraging in the era of Big Data, where observations from citizen science applications add to those of scientists, increasing the potential of screening systems,” Dr Galán Díaz says in conclusion.

  

Ancient agricultural landscape dominated by plant species introduced in other Mediterranean regions (Parque Natural de Los Alcornocales, Andalucía, Spain).

CREDIT

Dr Javier Galán Díaz

Original source:

Galán Díaz J, de la Riva EG, Martín-Forés I, Vilà M (2023) Which features at home make a plant prone to become invasive? NeoBiota 86: 1-20. https://doi.org/10.3897/neobiota.86.104039

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JOURNAL

NeoBiota

DOI

10.3897/neobiota.86.104039 

ARTICLE TITLE

Which features at home make a plant prone to become invasive?

Ultra-processed foods largely missing from US food policy

Few federal and state policies consider ultra-processed foods, but policy activity is growing

Peer-Reviewed Publication

NEW YORK UNIVERSITY

Ultra-processed foods—including industrially produced packaged snacks, fruit-flavored drinks, and hot dogs—have been linked to health issues ranging from weight gain to certain cancers. So where are the food policies helping Americans to steer clear of these foods?

 

A new study published in the American Journal of Preventive Medicine finds that only a small number of U.S. policies consider ultra-processed foods, lagging behind countries such as Belgium, Brazil, and Israel. 

 

“In some countries, ultra-processed foods have been directly integrated into national dietary guidelines and school food programs, but in the U.S., few policies directly target ultra-processed foods,” said Jennifer Pomeranz, associate professor of public health policy and management at NYU School of Global Public Health and the first author of the study.

 

After decades of focusing on single nutrients such as protein, fat, and carbohydrates in nutrition science and food policy, a growing body of evidence shows that there is more to dietary quality than nutrients.

 

“It’s clear that the extent of processing of a food can influence its health effects, independent of its food ingredients or nutrient contents. Ultra-processed foods generally contain ‘acellular nutrients’—nutrients lacking any of the natural intact food structure of the source ingredient—and other industrial ingredients and additives that together can increase risk of weight gain, diabetes, and other chronic diseases,” said study co-author Dariush Mozaffarian, the Jean Mayer Professor of Nutrition at the Friedman School of Nutrition Science and Policy at Tufts.

 

Only a few countries around the world directly regulate ultra-processed foods, but those that do have limited its consumption in schools and recommend eating less ultra-processed food in dietary guidelines. The U.S. Dietary Guidelines for Americans, which inform the country’s food and nutrition policies, do not currently mention ultra-processed food. However, the scientific advisory committee for the 2025-2030 U.S. Dietary Guidelines has been tasked with evaluating research related to ultra-processed foods consumption as it relates to weight gain. 

 

To understand how U.S. policymakers have already addressed ultra-processed foods in policies, the researchers gathered all federal and state statutes, bills, resolutions, regulations, proposed rules, and Congressional Research Services reports related to “highly processed” and “ultra-processed” food. 

 

They identified only 25 policies—eight at the federal level and 17 at the state—that were proposed or passed between 1983 and 2022. The vast majority (22 of 25) were proposed or passed since 2011, showing that U.S. policy making on ultra-processed foods is quite recent.

 

The U.S. policies on ultra-processed foods tend to mention them as contrary to healthy diets. Most policies had to do with healthy eating for children, including limiting ultra-processed foods in schools and teaching kids about nutrition. Another common theme was the relatively higher price of healthy food versus ultra-processed foods. Only one policy (a Massachusetts school food bill) actually defined ultra-processed foods, and three policies sought to address the broader food environment by providing incentives to small retailers to stock healthy foods. 

 

“The emerging policy language in the U.S. on ultra-processed foods is consistent with international policies on the topic. We would urge a more robust discussion and consideration of ultra-processed foods for future policymaking,” added Pomeranz. “The United States should consider processing levels in school food policies—especially to update the ‘Smart Snack’ rules—and to ensure the U.S. Dietary Guidelines reflect the evidence on ultra-processed foods and health.”

 

Jerold Mande of the Harvard T.H. Chan School of Public Health and Nourish Science was also a co-author of the study. The research was supported by the National Institutes of Health (2R01HL115189-06A1).

 

About the NYU School of Global Public Health

At the NYU School of Global Public Health (NYU GPH), we are preparing the next generation of public health pioneers with the critical thinking skills, acumen, and entrepreneurial approaches necessary to reinvent the public health paradigm. Devoted to employing a nontraditional, interdisciplinary model, NYU GPH aims to improve health worldwide through a unique blend of global public health studies, research, and practice. The School is located in the heart of New York City and extends to NYU's global network on six continents. Innovation is at the core of our ambitious approach, thinking and teaching. For more, visit: publichealth.nyu.edu

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JOURNAL

American Journal of Preventive Medicine

DOI

10.1016/j.amepre.2023.07.006 

ARTICLE TITLE

U.S. Policies Addressing Ultra-processed Foods, 1980-2022

 

New research sheds light on factors influencing trust and bias in societies

Peer-Reviewed Publication

SOCIETY FOR PERSONALITY AND SOCIAL PSYCHOLOGY

People with more positive perceptions of their nation’s institutions are more likely to show favoritism toward fellow citizens, according to new research in Social Psychological and Personality Science. This research suggests that support for national institutions could pose a challenge for establishing trust across borders.

Researchers also found that people who identify strongly with their own nation are likely to favor their fellow citizens, which aligns with previous studies. The possible role of trust in national institutions, however, was an unexpected development for researchers.

“We observed greater favoritism in trust toward fellow citizens (as opposed to foreigners) from participants who yielded more positive perceptions of institutions as trustworthy, benevolent, and able to provide security,” says author Dr. Giuliana Spadaro, of Vrije Universiteit Amsterdam.

Researchers asked more than 3,200 participants in 17 societies to play a game that measured the level of trustworthiness they expect from a fellow citizen, someone not from their country, and an unidentified stranger.

Previous research has shown that institutions offering more support and security can guarantee safe interactions with others outside of a person’s in-group. Based on these findings, Dr. Spadaro’s team hypothesized that people with a more positive opinion of their country’s institutions would be less likely to show favoritism toward other citizens. Researchers were surprised to find that people with more faith in institutions were more likely to favor their fellow citizens.

“Trust among strangers is an essential feature of functioning societies,” says Dr. Spadaro. “Our findings can inform citizens about the potential factors that might be associated to discrimination, such as national identification or being embedded in well-functioning institutions.”

Dr. Spadaro emphasized that these findings do not show the cause of in-group favoritism, but rather that it is associated with positive opinions of national institutions. As a result, these findings should be considered preliminary and an encouragement for further investigation.

Looking ahead, Dr. Spadaro also believes that researchers should examine how people’s attitudes toward institutions within their own local communities play a role in favoritism.

“More attention should be paid to perceptions of local (compared to national) institutions, as citizens have a higher chance to interact first hand with local institutional representatives (e.g., police, municipalities, bureaucrats), and might actively rely on these perceptions,” says Dr. Spadaro.

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JOURNAL

Social Psychological and Personality Science

DOI

10.1177/19485506231172330 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Identity and institutions as foundations of ingroup favoritism: An investigation across 17 countries.

ARTICLE PUBLICATION DATE

20-Jul-2023

How eelgrass spread around the world

An international research team led by GEOMAR reconstructs the worldwide colonisation history of the most widespread marine plant

Peer-Reviewed Publication

HELMHOLTZ CENTRE FOR OCEAN RESEARCH KIEL (GEOMAR)

Seagrasses evolved from freshwater plants and use sunlight and carbon dioxide (CO2) for photosynthesis and are able to thrive in depths down to 50 metres. In contrast to algae, they possess roots and rhizomes that grow in sandy to muddy sediments. The grass-like, leaf-shoots produce flowers and complete their life cycle entirely underwater. Seeds are negatively buoyant but seed-bearing shoots can raft, thus greatly enhancing dispersal distances at oceanic scale.

As a foundational species, eelgrass provides critical shallow-water habitats for diverse biotas and also provides numerous ecosystem services including carbon uptake. Seagrasses have recently been recognised as one of the important nature-based contributions to store carbon in the ocean. The sediment below seagrass meadows can sequester between 30 and 50 times more carbon annually that the roots of forests on land. Unfortunately, the continuing loss of seagrass beds worldwide – including eelgrass – is of acute concern.

An international group of researchers coordinated by Professor Thorsten Reusch, Head of the Research Division Marine Ecology at GEOMAR Helmholtz Centre for Ocean Research Kiel, used complete nuclear and chloroplast genomes from 200 individuals and 16 locations to reconstruct and date the colonisation history of the eelgrass Zostera marina from its origin in the Northwest Pacific Ocean to the Pacific, Atlantic and the Mediterranean. The findings described in a peer-reviewed publication and a Research Briefing published today in the scientific journal Nature Plants beg the question, “How well will eelgrass adapt to our new, rapidly changing climate?”

Using a phylogenomic approach the scientists were able to determine that eelgrass plants first crossed the Pacific from west to east in at least two colonization events, probably supported by the North Pacific Current. The scientists then applied two DNA “molecular clocks” – one based on the nuclear genome and one based on the chloroplast genome – to deduce the time when eelgrass populations diverged into new ones. The DNA mutation rate was calculated and calibrated against an ancient, whole genome duplication that occurred in eelgrass.

Both nuclear and chloroplast genomes revealed that eelgrass dispersed to the Atlantic through the Canadian Arctic about 243 thousand years ago. This arrival is far more recent than expected – thousands of years versus millions of years, as is the case with most Atlantic immigrant species during the Great Arctic Exchange some 3.5 million years ago. Reusch explains: “We thus have to assume that there were no eelgrass-based ecosystems – hotspots of biodiversity and carbon storage – in the Atlantic before that time. Recency was also mirrored in an analysis of the associated faunal community, which features many fewer specialised animals in the Atlantic as compared to the Pacific eelgrass meadows. This suggests that there was less time for animal-plant co-evolution to occur”, said Reusch. Mediterranean populations were founded from the Atlantic about 44 thousand years ago and survived the Last Glacial Maximum. By contrast, today’s populations found along the western and eastern Atlantic shores only (re)expanded from refugia after the Last Glacial Maximum, about 19 thousand years ago – and mainly from the American east coast with help from the Gulf Stream.

In addition, the researchers further confirmed the huge difference in genomic diversity between the Pacific and Atlantic, including latitudinal gradients of reduced genetic diversity in northern populations. “Both Atlantic compared to Pacific populations, and northern versus southern ones are less diverse on a genetic level than their ancestors by a factor of 35 among the most and least diverse one”, summarised postdoctoral scientist Dr. Lei Yu, first author of the publication which was a chapter in his doctoral thesis. “This is due to bottlenecks arising from past ice ages, which raises concerns as to how well Atlantic eelgrass, will be able to adapt to climate change and other environmental stressors based on its genetic capacity.”

“Warming oceans have already caused losses of seagrass meadows at the southern range limits, in particular North Carolina and southern Portugal. In addition, heat waves have also caused losses in shallow waters in some the northern parts of the distribution,” noted Reusch. “This is not good news because seagrass meadows form diverse and productive ecosystems, and no other species is able to take on the role of eelgrass if meadows cannot persist under future conditions.”

“One possibility for restoration might be to borrow some genetic diversity from Pacific eelgrass to fortify diversity in the Atlantic. Our next step is to interrogate the eelgrass pangenome. A new reference genome from Pacific eelgrass is currently under development and should tell us more about the adaptive ecotypic capacity across its global range of habitats,” said Prof. Jeanine Olsen, emeritus professor from the University of Groningen who initiated the study and coordinated the work between the Joint Genome Institute (JGI) and the research team. Thus, the verdict on rapid adaptation is out but there’s reason for optimism.

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JOURNAL

Nature Plants

DOI

10.1038/s41477-023-01464-3 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Ocean current patterns drive the worldwide colonization of eelgrass (Zostera marina)

ARTICLE PUBLICATION DATE

20-Jul-2023

Reducing food waste is a smaller environmental win

New CU Boulder-led study finds gains in food security would come at cost for the environment

Peer-Reviewed Publication

UNIVERSITY OF COLORADO AT BOULDER

 

IMAGE: A NEW CU BOULDER STUDY SUGGESTS THAT ELIMINATING FOOD LOSS AND WASTE WOULD NOT FULLY ELIMINATE THE ENVIRONMENTAL COST OF THAT WASTE; IT WOULD, HOWEVER, IMPROVE FOOD SECURITY, GLOBALLY. view more 

CREDIT: WIKIMEDIA, CREATIVE COMMONS CC0 1.0

Decreasing food loss and food waste may not have the environmental benefits researchers, advocates, and policymakers expect, but it could increase access to more affordable food for people worldwide, a new University of Colorado Boulder study suggests.

For years, eliminating food loss and food waste has been promoted as one of the most important actions humans can take to reduce the environmental impacts of the food system. And not without reason: food loss and waste along the supply chain account for as much as 24% of global food system GHG emissions and 6% of total emissions worldwide. The total loss and waste worldwide amount to an average of 527 calories per person per day.

The paper, published in Nature Food, suggests decreasing food loss and waste will have less of an environmental benefit than previously thought. Instead, food prices will go down, and people will eat more.

For the new work, a CIRES-led team considered the full impacts of reducing food loss and food waste, using guidelines set by the United Nations Sustainable Development Goals in 2021. The study looked at food loss (damaged or spoiled before reaching retailers) with waste (spoiled or thrown away by consumers or retailers). Using these definitions, loss occurs on the supply side, while waste takes place on the demand side.

Margaret Hegwood, lead author of the study, and a CIRES/CU Boulder PhD candidate, explained to understand the environmental benefits of reducing food waste and food loss, one must also consider the full picture of reducing waste: More food available would lead to lower prices, and that would create predictable changes in people’s behavior. 

“Let's say the price of cereals goes down because of improvements in food system efficiency, now you can afford to eat the same amount more often,” said Hegwood. “Consumers respond to these price decreases, purchasing more than they had before, which offsets some of the benefits of reducing the food loss and waste.” 

The authors used a simple model that looked at supply and demand responses to reducing food waste and food loss. 

“Our model basically formalized ECON 101: reducing food loss and waste shifts the supply and demand curves, respectively,” says Matt Burgess, co-author of the study and CIRES/CU assistant professor.  “How sensitive supply and demand are to prices–which we get from previous research–then determines how much we project food prices and consumption will change” 

The offset is significant, and the authors found that reducing food loss and waste by 100%, decreases 1/2 to 2/3 of the predicted environmental benefits.

While the study modeled what might happen if food waste and loss are reduced, the authors don’t make assumptions about how both will be reduced. There are various solutions, and they all depend on food type, region, consumption habits, access to technology, politics, and dietary needs. 

Similar studies have looked at the impacts of decreasing food loss and food waste at the regional or country scale, but Hegwood and Burgess say it’s the first study they know of that looks at the global level. 

Overall, Hegwood hopes this study can shift the conversation from its focus on the environmental benefits of reducing food waste and loss to recognizing the food security benefits.

“And I think likely, at least to some extent, that this could mean that our efforts to reduce food loss and waste could actually not be as beneficial for the environment as we think they could be, but it’s super beneficial in terms of food security,” said Hegwood. “And I think that is very important for people to think about.”

 

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JOURNAL

Nature Food

DOI

10.1038/s43016-023-00792-z 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Rebound effects could offset more than half of avoided food loss and waste

ARTICLE PUBLICATION DATE

20-Jul-2023

Buzzing down the primrose path: Specialist bee species prefer abundant host plants

Peer-Reviewed Publication

ECOLOGICAL SOCIETY OF AMERICA

 

IMAGE: A BEE ON A WILLOW NEAR OTTAWA. PLANTS IN THE WILLOW GENUS SUPPORT BOTH GENERALIST BEE SPECIES, AS WELL AS POLLEN SPECIALISTS. view more 

CREDIT: PHOTO BY JESSICA FORREST

How do bees choose which flowers to visit? Some bees will visit almost any bloom, while others are more discerning. How, and whether, bees choose to specialize in one kind of flower or pollen is a question entomologists and ecologists have puzzled over for years.

Now, a team of scientists led by ecologist Colleen Smith – who is currently based at the University of California, Santa Barbara, but conducted the research while working at the University of Ottawa – is deciphering why some species of bees specialize in visiting one type of plant over others. They concluded that bees who specialize tend to focus on the most abundant species in an ecosystem – at least in the eastern United States. The findings were published last month in the Ecological Society of America’s journal Ecology.

“Most environments have a few common species that are really abundant, so most plants that a bee encounters will be from a few common plants,” Smith explained. “Bees are much less likely to encounter rare plants. Plant abundance could be a mechanism that promotes specialization – and thus speciation.”  

Of the thousands of bee species in the United States, about one-quarter of them are pollen specialists that only use pollen from plants in one genus, species or family. Only a tiny percentage of plants are hosts to these pollen specialists.

“Some plant taxa, like willows and sunflowers, support tons of bee species, and most don’t support any species of specialist bees,” Smith said. “Why do some plants support specialists? What causes a bee to specialize in one plant type? That’s what we set out to measure.”

Two competing hypotheses held sway in the field: One proposes that bees might specialize when the plants they favor have low pollen quality. The other posits that bees specialize on the most abundant taxa or types of plants in their ecosystem.

To decide between the two, Smith’s team tested each hypothesis. First, they conducted a field study in Ottawa to see if generalist bees also collected pollen from the host plants of specialist bees. If specialist bees target host plants with low quality or actively toxic pollen, generalists would avoid those plants. That’s not what they found, indicating that pollen quality did not affect specialization.

To test the plant-abundance hypothesis, they turned to a large public data source: citizen scientists uploading pictures to the iNaturalist app.

“It’s hard to get standardized measures of plant abundance of all the plant genera in the Eastern United States if you’re going out sampling yourself,” Smith said. “We used data from a phone app, iNaturalist. Because people are recording where they see different plant species, we were opportunistically able to use this data to get regional plant abundance.

“Our research showed that specialist bees are more likely to use abundant plants than rare plants,” Smith said. “This is strong support for what many people had suspected anecdotally. This is the first time, though, that there has been a quantitative test of a broad range of plants. One of the things that is interesting about this study is that it supports some ecological theories suggesting why specialization evolves in the first place.”

Future research might test the same hypotheses in the western United States – a hotspot for specialist bee diversity – to see if the pattern holds true there as well.

For non-researchers the implication for boosting bee species is clear: Plant your garden with those plants that host both specialists and generalist bees.

“By planting these abundant host plants that both the specialists and the generalist species visit, you're supporting these potentially more vulnerable bee species in addition to the largest number of bees,” Smith said. “By paying attention to what plants specialists need, you’ll be helping more bee species.”

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The Ecological Society of America, founded in 1915, is the world’s largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 9,000 member Society publishes five journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society’s Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at http://www.esa.org.

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JOURNAL

Ecology

DOI

10.1002/ecy.4122 

ARTICLE TITLE

Regional plant abundance explains patterns of host use by pollen-specialist bees in eastern North America

 

New advances in integrating mechanisms of multiple stress response in conifers

Peer-Reviewed Publication

NANJING AGRICULTURAL UNIVERSITY THE ACADEMY OF SCIENCE

The proper response to various abiotic stresses is essential for plants’ survival to overcome their sessile nature, especially for perennial trees with very long-life cycles. However, in conifers, the molecular mechanisms that coordinate multiple abiotic stress responses remain elusive.

This article has been published on Horticulture Research with title: An ethylene-induced NAC transcription factor acts as a multiple abiotic stress responsor in conifer.

Here, the transcriptome response to various abiotic stresses like salt, cold, drought, heat shock and osmotic were systematically detected in Pinus tabuliformis (P. tabuliformis) seedlings. We found that four transcription factors were commonly induced by all tested stress treatments, while PtNAC3 and PtZFP30 were highly up-regulated and co-expressed. Unexpectedly, the exogenous hormone treatment assays and the content of the endogenous hormone indicates that the upregulation of PtNAC3 and PtZFP30 are mediated by ethylene. Time-course assay showed that the treatment by ethylene immediate precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), activated the expression of PtNAC3 and PtZFP30 within 8 hours. We further confirm that the PtNAC3 can directly bind to the PtZFP30 promoter region and form a cascade. Overexpression of PtNAC3 enhanced unified abiotic stress tolerance without growth penalty in transgenic Arabidopsis, and promote reproductive success under abiotic stress by shortening the lifespan, suggesting it has great potential as a biological tool applied to plant breeding for abiotic stress tolerance.

This study provides novel insights into the hub nodes of the abiotic stress response network as well as the environmental adaptation mechanism in conifers, and provides a potential biofortification tool to enhance plant unified abiotic stress tolerance.

###

References

Authors

Fangxu Han, Peiyi Wang, Xi Chen, Huanhuan Zhao, Qianya Zhu, Yitong Song, Yumeng Nie, Yue Li, Meina Guo, Shihui Niu

Affiliations

Beijing Forestry University

About Shihui Niu

Professor Niu from Beijing Forestry University has extensive experience in conducting research on the genetic regulation of essential traits in conifers. In recent years, he has made substantial contributions to the field by applying genetic research strategies and methods to overcome the bottleneck of conifer giga-genomes assembly and gene annotation. He has also established a high-quality genetic information platform for Pinus tabuliformis, successfully solved several difficulties in the genetic analysis of important conifer traits, and expanded the research area focusing on the genetic regulation of conifer juvenility and reproduction. Professor Niu's research has advanced of the academic frontier in this field.

Now, Professor Niu serves as deputy director of the National Engineering Research Center of Tree Breeding and Ecological Restoration, deputy secretary general and standing member of the Pine Branch of the Chinese Society of forestry. He was selected as the national young top-notch talent of "Ten Thousand Talents Program", leading talent of forest and grassland and technology innovation of the National Forestry and Grassland Administration (NFGA), outstanding young scholarship of "Beilin Scholars Program" of Beijing Forestry University, etc. He also served as an evaluation committee member of the General Project meeting of the Life Science Department which belongs to the National Natural Science Foundation of China. His research findings have been published in prestigious academic journals in the field of biology, such as Cell, Plant Physiology, Trends in Genetics, and New Phytologist. His achievements exert extensive influence in the scientific community. He has been awarded as the author of  "ESI Highly cited Papers", "Research Advances on Plant Science in China in 2015", "Achievements and Advances in the Plant Sciences Field China in 2021", "Ten Major Events in Forests and Grasslands Science and Technology in 2021", and "Ten Major Advances in Forests and Grasslands Science and Technology during the 13th Five-Year Plan Period", etc.

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JOURNAL

Horticulture Research

DOI

10.1093/hr/uhad130 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

An ethylene-induced NAC transcription factor acts as a multiple abiotic stress responsor in conifer