Exceptional warm air intrusions and omnipresent aerosol layers in the stratosphere.

First results of one year of cloud research at the German polar station Neumayer III published.

Peer-Reviewed Publication

Leibniz Institute for Tropospheric Research (TROPOS)

 

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Clouds in Antarctica. Midnight sun at Christmas 2022 looking south "towards the South Pole".

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Credit: Martin Radenz, TROPOS

Leipzig/Bremerhaven. Extremely clean air on the ground, warm air intrusions and sulphate aerosol at high altitudes - a Leipzig research project has gained new insights into clouds in Antarctica. From January to December 2023, the vertical distribution of aerosol particles and clouds in the atmosphere above the German Neumayer Station III of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) was investigated from the ground for the first time. The height-resolved measurements were the first of their kind in Queen Maud Land, the area of the Antarctic that borders the Atlantic and covers an area larger than Greenland.

The observations were performed with the OCEANET-Atmosphere platform from the Leibniz Institute for Tropospheric Research (TROPOS). OCEANET-Atmosphere demonstrated its robustness already while it was drifting in the Arctic for a whole year on the RV Polarstern during the international MOSAiC expedition 2019/20. During the 12 months of operation in Antarctica, the platform was supervised on-site by TROPOS scientist Martin Radenz. Initial results have now been published in the renowned journal Bulletin of the American Meteorological Society (BAMS). The measurements were funded by the German Research Foundation (DFG) and carried out in close co-operation with the AWI.

 

The Antarctic continent and the Southern Ocean are important components of the global climate system. While Antarctica's climate was considered relatively stable in the last century, significant changes are now being observed. Climate projections indicate that the interior of the Antarctic will warm by more than 3 Kelvin, the sea ice extent will decrease by around 30 per cent and precipitation will increase in the 21st century. However, such projections are subject to major uncertainties and the global atmospheric circulation models are not yet able to correctly reproduce the cloud cover and radiative forcing over the Southern Ocean. This incorrect representation of clouds leads to distorted estimates of thermal radiation and sea surface temperature, which are a prerequisite for estimating the energy fluxes between the ocean and atmosphere. In addition, in order to be able to document any change in an environment, such as Antarctica, also its current state needs to be documented as good as possible.

Gaining knowledge about cloud formation in Antarctica is an essential need, as this takes place differently in the clean air of the southern hemisphere than in the northern hemisphere with more abundant land surfaces. A second major source of uncertainty is the transport of moisture and particles from the mid-latitudes and subtropics to the pole. The relatively flat surface between the Weddell Sea and the South Pole might be a kind of highway for warm and humid air masses.

In order to learn more about the clouds in Antarctica, the instrumentation at the German research station Neumayer III of the AWI were supplemented by remote-sensing measurements such as an atmospheric lidar and a cloud radar for around a full year in the framework of the project COALA (Continuous Observations of Aerosol-Cloud Interactions in the Antarctic). The importance of the project was well recognized by the priority program ‘Antarctic Research’ of the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG), which provided the funding for the endeavour. Carrier of the instrumentation was the TROPOS OCEANET-Atmosphere container. The platform had previously drifted through the Arctic for a year on RV Polarstern during the MOSAiC expedition led by AWI in 2019/20. " The MOSAiC observations allowed us to show for the first time that the atmosphere at the North Pole is more polluted than previously assumed. But what about over the Antarctic? Fortunately, we had the opportunity to operate our OCEANET container there for a year," explains Dr Ronny Engelmann from TROPOS. OCEANET was installed 300 meters south of the German Antarctic Neumayer Station III at the beginning of 2023. OCEANET-Atmosphere is an autonomous, polar-tested, specially equipped 20-foot container packed with state-of-the-art atmospheric observation equipment. It is currently the only polar-capable single container platform that combines multiwavelength lidar, a cloud radar, a microwave radiometer, and a Doppler lidar to observe clouds and aerosols, including turbulent air motions.

OCEANET was supplied with power from the research station, where the researcher from Leipzig also lived and spent a year making sure that all the devices measured without interruption: Dr Martin Radenz from TROPOS joined the station's core team. He was one of the 10 people who spent the winter in the dark polar night at Neumayer Station III. "Being able to spend a year in Antarctica with the community of our small team, the fascinating nature, snowstorms and isolation was a unique experience," reports Martin Radenz. The green laser beam of the multiwavelength lidar, which scanned the atmosphere above Neumayer Station III, was a novelty in this part of Antarctica. A lidar, also known as a "light radar", sends short laser pulses from the ground into the atmosphere and receives the backscattered light with a special receiver. Information about the height, quantity and type of suspended particles (aerosols) in the atmosphere can be derived from the travel time, intensity and polarisation of the backscattered signals. To date, related measurements with cloud radar and aerosol lidar have only been carried out at McMurdo station on the other side of Antarctica, 3500 kilometres away, bordering the Pacific Ocean. Contrary to Neumayer III on the ice shelf, the US McMurdo station there is built on rock. The researchers also hope that the measurements taken at Neumayer Station III over ice shelves will provide them with new insights into cloud formation over the vast expanses of ice in the Antarctic. "It is particularly pleasing that, following COALA, the AWI now permanently deploys similar remote sensing devices at Neumayer Station III in cooperation with TROPOS. This will make an important contribution to recording the short-lived climate components aerosols and clouds in the Antarctic," says Prof Andreas Macke, Director of TROPOS and Head of the "Remote Sensing of Atmospheric Processes" department.

In January 2024, the OCEANET container was dismantled, transported to the edge of the ice shelf and loaded onto the resupply vessel. The devices arrived in Leipzig in March, the DFG COALA project was completed and the researchers took stock: "All the devices held out and recorded valuable data. We are particularly pleased about this because it would have taken months for a replacement part to arrive during the polar night. Our experience from the MOSAiC expedition three years earlier in the Arctic was a great help. Nevertheless, it was a real challenge to make the devices storm-proof and clean them of snow almost every day," reports Martin Radenz. For Radenz and his team, however, the effort was worth it. The measurements provided three new insights into the Antarctic under climate change:

Atmosphere only clean close to the surface
The lidar measurements provided an insight into how many particles are floating above this part of Antarctica and at which altitudes. The lower part of the atmosphere (troposphere) with pristine conditions was mostly comparatively clean. In contrast, the team observed an unexpectedly large number of particles between an altitude of around 9 km and 17 km (stratosphere). "The optical properties of the aerosol derived from the lidar clearly indicate sulphate aerosol, which is mainly caused by volcanic eruptions. These aerosols were observed in the stratosphere since January 2023 and are therefore most likely related to the eruption of Hunga Tonga-Hunga Ha'apai in January 2022," says Martin Radenz. "The fact that volcanic dust can persist for a very long time over the south polar region surprised us just as much as the forest fire smoke over the north polar region, which we were able to observe for the first time during the MOSAiC expedition in 2020," reports Ronny Engelmann. The lidar measurements from the ground are particularly important, as the volcanic aerosol over Antarctica has apparently not been observed sufficiently from space before. At least no aerosol was detectable in the standard products of NASA's CALIOP satellite lidar. Aerosol in the stratosphere has an influence on the occurrence of polar stratospheric clouds (PSCs), where complex chemical processes take place and which are suspected of contributing to the hole in the ozone layer over the polar regions.

Aerosol-cloud interaction in shallow mixed-phase clouds
While more aerosol was observed in the upper layers of the atmosphere than expected, the lower layers proved to be about as clean as assumed. The continuous measurements enabled the team to "watch" the clouds grow. For example, a stable mixed-phase cloud consisting of ice crystals and water droplets embedded in a layer of marine aerosol was observed for a period of 10 hours. "Our measurements confirm that practically all particles serve as cloud nuclei, to either form cloud droplets or ice crystals. Cloud growth is therefore limited by the amount of particles. If there were more particles, for example because more polluted air flows into the Antarctic, then there would also be more droplets and ice crystals in the clouds, which would change their lifespan and lead to yet unknown effects on weather and climate," explains Dr Patric Seifert from TROPOS.

Unusual warm air intrusions
Warm air from lower latitudes could intensify climate change in Antarctica. It was therefore important to be able to analyse two extreme warm air intrusions in detail: One with intense snowfall in April, which brought 10 per cent of the snowfall of an entire year, and a second with record-breaking maximum temperatures and heavy ground icing due to supercooled drizzle in July. During this warm spell, the temperature rose to -2.3 degrees Celsius on 6 July 2023. "This is the highest temperature recorded in July at the German Antarctic Neumayer Station since continuous observations began in 1982. This means that it has never been so warm there in the middle of the polar night, the peak of the Antarctic winter," explains Martin Radenz. These unusually high temperatures led to supercooled drizzle. On the surface, a layer of clear ice of around 2 millimetres formed on top of the snow from the previous day. "What often happens here in Central Europe in winter is very unusual for the Antarctic during the dark polar night. Normally, temperatures at Neumayer Station III are below -30 degrees Celsius in July. Our observations over ice shelves are the first of their kind," emphasizes Radenz.

It took not long until the value of the remote sensing measurements was also recognized by the Alfred Wegener Institute that operates the Neumayer station. The deployment of OCEANET-Atmosphere was only the start of a long-term time series of profile measurements in this part of Antarctica: at the beginning of 2024, the Alfred Wegener Institute expanded the permanent observation capacities with a lidar and radar, thus ensuring that the unique OCEANET data set is continued. “The long-term climatology of aerosol and cloud parameters for the Neumayer station will thus be permanently extended to the vertical dimension," explains Dr Holger Schmithüsen from AWI.

The provision of an overview of the obtained results in the BAMS journal demonstrates the potential of the 1-year dataset for shedding light on the still barely characterized properties of clouds and aerosols above Antarctica. “But the BAMS article only provides a first glimpse into the highlights obtained during the measurements. Detailed statistics and process studies will follow in a subsequent step,” says Radenz. Over the next few months, the extensive data from Antarctica will be further analysed and compared with existing data sets from southern Chile, Cyprus, Germany and the Arctic. The researchers hope to gain new insights into why the clouds in the far south differ so much from those in the northern hemisphere. Plenty of datasets from key-regions of climate research are available for a comparison. As part of the DFG Transregio "Arctic Amplification" (AC3-TR), TROPOS has been investigating clouds in the Arctic together with the University of Leipzig since 2016. In addition, processes in the southern hemisphere have also become the focus of attention in recent years: in 2016/17, cloud researchers from Leipzig took part in the international Antarctic circumnavigation ACE. In 2018-2021, extensive measurements took place in southern Chile. Two major measurement campaigns in and around New Zealand are currently being prepared for 2025 and 2026: goSouth at the southern tip of the South Island, accompanied by HALO-South with the German research aircraft HALO and an expedition around New Zealand with the research vessel Sonne are the placemarks of the next series of experiments under the lead of TROPOS. "TROPOS is about to contribute important novel insights for improving the understanding of aerosol-cloud-climate processes in the clean and maritime southern hemisphere," concludes Prof Andreas Macke.

Tilo Arnhold

Twilight over Antarctica.

Credit

Martin Radenz, TROPOS

 

COALA-3 (IMAGE)

Leibniz Institute for Tropospheric Research (TROPOS)

Aurora Australis above the OCEANET container at the German research station Neumayer III in Antarctica.

Credit

Martin Radenz, TROPOS

COALA-4 [VIDEO] | 

The observations were performed with the OCEANET-Atmosphere platform from the Leibniz Institute for Tropospheric Research (TROPOS).

Journal

Bulletin of the American Meteorological Society

DOI

10.1175/BAMS-D-22-0285.1 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Ground-Based Remote Sensing of Aerosol, Clouds, Dynamics, and Precipitation in Antarctica: First Results from the 1-Year COALA Campaign at Neumayer Station III in 2023

 

New method in the fight against forever chemicals

ETH Zurich

 

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The piezoelectric nanoparticle acts as a catalyst and initiates a chemical reaction: 90.5 % of the PFOS molecule is degraded and 29 % is defluorinated. 

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Credit: Andrea Veciana / ETH Zurich

What do firefighting foam, non-stick cookware, water-repellent textiles and pesticides all have in common? They all contain per- and polyfluoroalkyl substances, or PFAS – human-made chemicals that don’t break down naturally. It’s no wonder, then, that PFAS are now contaminating soil and water and can also be detected in the bodies of humans and animals. The dangers are well known: these forever chemicals can damage the liver, trigger hormonal disorders and cause cancer, to mention just a few of their effects.

Researchers in the group under Salvador Pané i Vidal, Professor at ETH Zurich’s Institute of Robotics and Intelligent Systems, have developed a new method to break down a subgroup of PFAS called perfluorooctane sulfonates, or PFOS. Due to their toxicity, PFOS are now severely restricted or even banned. “The main problem is that the molecules consist of long carbon chains surrounded by fluorine atoms. This carbon-fluorine bond is so strong that you need a lot of energy to break it,” says Andrea Veciana, a doctoral student of Pané i Vidal’s.

Breaking down molecules with ultrasound and nanoparticles

To break up the PFOS molecules and thus degrade them in water, the researchers used piezocatalysis for the first time. “Piezo” refers to piezoelectricity, an electrical charge that is generated during mechanical deformation, and “catalysis” means accelerating a chemical reaction with suitable substances. “We’ve developed nanomaterials that are piezoelectric. To the naked eye, this material looks a bit like sand,” Veciana says. In the ultrasonic bath, these particles become electrically charged and act as a catalyst. Pané i Vidal adds: “It’s this electrical charge that sets the whole chain of reaction in motion and breaks down the PFOS molecules piece by piece. That’s why the nanoparticles are called piezoelectric.”

To measure the PFOS concentration in their samples, the researchers worked with Samy Boulos, analytical specialist from the Laboratory of Food Biochemistry. Using a mass spectrometer, the researchers were able to prove that 90.5 percent of the PFOS molecules were degraded. “However, we should point out that we were working with a very high concentration of 4 milligrams per litre,” Veciana says. “In the natural world, such as in lakes and rivers, the PFOS concentration is less than 1 microgram per litre. And the lower the concentration, the longer it takes for the PFOS to degrade.” Some of the technologies currently in development first concentrate the water and then destroy the PFOS. This would also be a key step in the piezocatalysis, one that would have to be implemented in a specific application such as a chemical industry effluent.

Better than previous methods

The potential of the new method becomes clear when considering the existing options for degrading PFAS. “One method is thermal decomposition, but that requires a temperature of over 1,000 degrees Celsius, which makes it highly energy intensive,” Veciana says. PFAS can also be degraded by photocatalysis. This process is similar to piezocatalysis but uses light for activation of the catalyst instead of mechanical energy. The main problem with this method is that in practice, the objective is to treat wastewater, and since wastewater is cloudy, there is a low light penetration. Veciana mentions a third method: “There’s also absorption, where you use a kind of sponge to soak up the pollutants from the water. But this merely shifts the problem from one place to another; now you need a solution for the PFAS-permeated sponge.”

The disadvantages of the existing methods were one of the reasons the ETH researchers went looking for a new way to break down PFAS. Piezocatalysis has the advantage of being able to work with different sources of mechanical energy. “If water has to be purified in wastewater treatment plants and there’s already turbulence in the water, that energy could perhaps be harnessed to break down the PFAS in it,” Veciana says.

Combating PFAS together

Unfortunately, what the researchers have achieved in the laboratory with water samples of 50 millilitres hasn’t yet been transferred into practice. “The scalability of our method is one of the biggest challenges,” Pané i Vidal says. “However, we’ve succeeded in showing that piezocatalysis works as a method for degrading PFOS and has advantages over previous methods.” Furthermore, their method can not only be used on PFOS, but on any other PFAS and micropollutant.

In general, methods for degrading PFAS should be used before the chemicals get into the environment, i.e. in industrial wastewater treatment plants, or on collected agricultural water for reuse. “Companies should take all possible measures to ensure that the water they release into the environment is as clean as possible,” Pané i Vidal says. Veciana adds: “PFAS are a global problem that should be tackled first and foremost through policy change and more transparency.” There’s already a lot of media coverage about a PFAS ban and stricter regulations to force the industry to be more transparent about the use of these chemicals. Veciana says: “Nevertheless, it’s also important to continue to innovate through research in order to reduce and remediate the existing exposure to PFAS as much as possible.”

Reference

Veciana A, Steiner S, Tang Q, Pustovalov V, Llacer-Wintle J, Wu J, Chen X, Manyiwa T, Ultra Jr. V, Garcia-Cirera B, Puigmartí-Luis J, Franco C, Janssen D, Nyström L, Boulos S, Pané S: Breaking the Perfluorooctane Sulfonate Chain: Piezocatalytic Decomposition of PFOS Using BaTiO3 Nanoparticles. Small Science 2400337. 28 August 2024, doi: 10.1002/smsc.202400337

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Journal

Small Science

DOI

10.1002/smsc.202400337 

Article Title

Breaking the Perfluorooctane Sulfonate Chain: Piezocatalytic Decomposition of PFOS Using BaTiO3 Nanoparticles

 

Characterization of microbial structure and function in the rhizosphere of Boehmeria nivea L.：A comparative study of volcanic cone and crater

Higher Education Press

 

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a shows the relative abundance of phyla bacteria and fungi based on circular visualization (Circos). b shows the taxonomic characteristics of asv microbial community composition between the two sites based on the Manhattan map. The structural equation model (SEM) in c shows the direct and indirect effects of nivea rhizosphere microbial versatility in volcanic cones and craters.

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Credit: Jin Chen, Yiming Zhang, Qingchen Xiao , Boyan Wang, Zishan Li, Keqing Lin, Xiaowan Geng, Xiaoyu Li

Volcanic activity alters the Earth's surface and promotes the development of new ecosystems, providing valuable models for studying soil formation processes such as microbial composition and vegetation succession. Increasing evidence suggests that soil microbes are pivotal in numerous ecological and biogeochemical processes, encompassing carbon mineralization, humus formation, and nutrient cycling. Given the intricate and dynamic interactions between soil properties, plant life, and soil microbial communities, a comprehensive understanding of soil microbial communities is critical to improving our understanding of ecosystem processes. The study shows that the rhizosphere microbial communities of volcanic Boehmeria nivea L. in Nvshan, Anhui Province shows significant spatial differences in diversity, structure, and function. Volcanic soil plays a key role in the formation of microbial community diversity and subsequently influences the diversity of microorganisms residing in the rhizosphere of ramie. The researchers’ finding appeared July 26, 2024 in Soil Ecology Letters.

Li Xiaoyu's team at Anhui Agricultural University conducted a series of studies on different sites of rhizosphere microbial communities in volcanic B. nivea, and obtained many interesting findings. For example, their findings suggest that fungal communities show greater vulnerability to changes in geography and environment. In addition, there were differences in the structural and functional diversity of the rhizosphere microbial communities in volcanic pits and volcanic cones, suggesting that the rhizosphere microbial communities were mainly affected by volcanic sites.

Professor Chen said: "We chose to study the Nvshan region in Anhui Province, a dormant volcano recognized globally as one of the best preserved ancient craters, located in the subtropical monsoon climate zone, with an average annual precipitation of 939.9 mm and an average annual temperature of 15 °C. The Nvshan volcanic area has obvious geomorphic features, including craters, lava platforms, lava flows and volcanic cones. The volcano has experienced many eruptions during its geological evolution, forming its unique landform landscape. Therefore, Nvshan Volcano provides a suitable, high-quality platform for the study of volcanic activity and environmental disturbances, and B. nivea, as a plant of important economic and ecological value, plays a key role in its rhizosphere microbial community."

In this study, they found that it was easier to support bacteria rather than fungi at various sites in the rhizosphere soil of B. nivea, a phenomenon that could be attributed to increased disturbance intensity, which could lead to the disappearance of rare fungal species and thus a decline in biodiversity. The Zi-Pi chart illustrates the critical role of key species one step supports this observation, showing that the proportion of bacterial generalist species is higher than that of fungi in both the crater (15.5% vs. 11.7%) and the cone (19.2% vs. 13.9%). Actinomycetes and Acidobacteria dominate the bacterial community, while ascomycetes and basidiomycetes dominate the fungal community. Actinomycetes play a crucial role in the breakdown of humus because they have multiple enzyme-mediated degradation capabilities and are able to thrive under nutritionally restricted conditions. In contrast, fungi show a greater ability to break down complex organic polymers, such as polyphenols, hemicellulose, and refractory cellulose, compared to bacteria.

Professor Chen added: "We also used RMT random matrix theory to establish bacterial and fungal co-occurrence networks to study cooccurrence patterns of microbial communities in volcanic pits and cones." Compared to bacterial networks, fungal networks have a more complex microbial community structure with greater modularity, with tightly connected nodes. Compared with crater, cone has lower avgCC value and higher avgK value in their respective bacterial networks. However, in its respective fungal networks, the cone had lower avgK and avgCC values, suggesting that it reduced the complexity of microbial symbiosis. In addition, based on the SEM results, we found that the influence of microbial α diversity on microbial versatility was more obvious than that of microbial β diversity. The α diversity of microorganisms in craters has a direct and positive impact on their respective multifunctional capabilities.

“By investigating the impact of volcano on rhizosphere microbial community of ramie, the mechanism of volcanic activity on soil ecosystem can be deeply understood, and scientific basis can be provided for the protection of ecological environment around volcano and rational use of land resources. In addition, the research on rhizosphere microbial community of ramie is helpful to explore the mechanism of microbial action in plant growth and soil ecosystem, and provide theoretical support and technical guidance for agricultural production and soil health management."

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Journal

Soil Ecology Letters

DOI

10.1007/s42832-024-0259-x 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Characterization of microbial structure and function in the rhizosphere of Boehmeria nivea L.: A comparative study of volcanic cone and crater

 BOTANY

From Mount Etna to the UK: genetics unveil the Oxford ragwort unique journey and resilience

Faculty of Sciences of the University of Lisbon

 

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Senecio squalidus.

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Credit: Bruno Nevado

A descendant of Sicilian progenitors, this daisy-family plant appeared in the UK, escaped from a botanical garden, and began its conquest of the region during the Industrial Revolution.

It is rare to uncover the details of a story as fascinating as this, especially since there are few cases where the emergence of a new species can be traced across just 300 years. The Oxford ragwort, Senecio squalidus, a yellow-flowered plant from the daisy family, first appeared in the 17th century at the Oxford Botanic Garden after a crossbreeding of two plants native only to Mount Etna in Sicily.

Bruno Nevado, researcher at the Centre for Ecology, Evolution, and Environmental Changes (CE3C) at the Faculty of Sciences of the University of Lisbon (CIÊNCIAS), leads the study now published in the scientific journal Current Biology. The research reveals key moments in the existence of this species—from its origins to its colonization of the United Kingdom during the Industrial Revolution—through the lens of genetics.

Between the late 17th and early 18th centuries, Senecio chrysanthemifolius and Senecio aethnensis, plants endemic to the rugged slopes of Mount Etna in Italy, were introduced to the gardens of the Duchess of Beaufort in Gloucestershire, England, by botanists Francesco Cupani and William Sherard. On Mount Etna, these plants rarely mingled due to their distinct habitats — S. chrysanthemifolius at altitudes below 1,000 meters and S. aethnensis above 2,000 meters. However, in the UK, conditions brought them into closer proximity, resulting in hybrid individuals. By the first two decades of the 18th century, these hybrids were cultivated in the renowned Oxford Botanic Garden, where they eventually gave rise to a new hybrid species, Senecio squalidus (hence Oxford ragwort). By the end of the 18th century, S. squalidus had escaped its confines and spread into the urban environment of Oxford, beginning its naturalization and eventual colonization of the UK.

Possibly due to its descent from species adapted to the harsh volcanic landscape, this hybrid species managed to thrive, later spreading via the expanding railway network of the Industrial Revolution in the 19th century. It was “by train” that the yellow flowered Oxford ragwort reached nearly every corner of the UK over a span of 150 years. Today, the species can be found from Scotland to Wales, and even in Ireland, thriving along railway lines, roadsides, footpaths, industrial zones, and other disturbed habitats.

Senecio squalidus is one of a few hybrid species with a very recent origin. Bruno Nevado highlights this rarity: “Normally, hybrid species are much older, and it’s difficult to disentangle the processes that contributed to speciation from those that affected the hybrid species later on during its evolution. But with this species, we can study the processes involved in the very early stages of speciation”.

In this new study, conducted in collaboration with researchers from several British universities and the Wellcome Sanger Institute in Cambridge, the genome of S. squalidus was sequenced. Genetic analysis of both S. squalidus and its parental species revealed a rapid reorganization of the hybrid species' genome, driven by the resolution of genetic incompatibilities between the parental species and natural selection. These processes shaped a unique genome, combining traits from both parents, allowing the new species to thrive in an environment where neither parent could survive. Thanks to this unique evolutionary journey, “The Oxford ragwort serves as a small, exceptional laboratory for studying hybridization and its role in the emergence of new species and the colonization of challenging environments,” concludes Bruno Nevado.

Senecio squalidus

Credit

Bruno Nevado

Senecio squalidus

Credit

John Baker

Journal

Current Biology

DOI

10.1016/j.cub.2024.08.009 

Article Title

Genomic changes and stabilization following homoploid hybrid speciation of the Oxford ragwort Senecio squalidus

Super golden lettuce richer in vitamin A

A team from the IBMCP (UPV-CSIC) has developed a technique that multiplies the beta-carotene content in plant leaves.

Universitat Politècnica de València

 

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A team from the IBMCP (UPV-CSIC) has developed a technique that multiplies the beta-carotene content in plant leaves.

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Credit: UPV

The work demonstrates that by using biotechnological techniques and treatments with high light intensity, the levels of beta-carotene in leaves can be multiplied up to 30 times by creating new places to store it without affecting vital processes such as photosynthesis. The results are published in the Plant Journal.

Beta-carotene is one of the main carotenoids, pigments found naturally in plants and other photosynthetic organisms that benefit health, with antioxidant, immunostimulant and cognitive-enhancing properties.

Specifically, beta-carotene is the primary precursor of retinoids, chemical compounds with essential bodily functions (vision, cell proliferation and differentiation, immune system...), including vitamin A.

Using tobacco plants (Nicotiana benthamiana) as a laboratory model and lettuce (Lactuca sativa) as a cultivation model, the team led by Manuel Rodríguez Concepción, CSIC researcher at the IBMCP, has managed to increase the beta-carotene content in the leaves without negatively affecting other vital processes such as photosynthesis.

'Leaves need carotenoids such as beta-carotene in the photosynthetic complexes of chloroplasts for their proper functioning,' explains the CSIC researcher. 'When too much or too little beta-carotene is produced in the chloroplasts, they stop functioning, and the leaves eventually die. Our work has successfully produced and accumulated beta-carotene in cellular compartments where it is not normally found by combining biotechnological techniques and treatments with high light intensity,' he summarises.

Higher accumulation and bioaccessibility

The results of this study, published in the Plant Journal, show that it is possible to multiply beta-carotene levels in leaves by creating new places to store them outside the photosynthetic complexes. On the one hand, they have managed to store high levels of beta-carotene in plastoglobules, and fat storage vesicles are naturally present inside chloroplasts. These vesicles do not participate in photosynthesis and do not usually accumulate carotenoids.

‘Stimulating the formation and development of plastoglobules with molecular techniques and intense light treatments not only increases the accumulation of beta-carotene but also its bioaccessibility, i.e. the ease with which it can be extracted from the food matrix to be absorbed by our digestive system,’ says Luca Morelli, first author of the study.

Biofortification of vegetables

The study also shows that beta-carotene synthesis in plastoglobules can be combined with its production outside chloroplasts by means of biotechnological approaches. In this case, co-author Pablo Pérez Colao says, 'beta-carotene accumulates in vesicles similar to plastoglobules but located in the cytosol, the aqueous substance that surrounds the organelles and nucleus of cells’.

The combination of both strategies achieved up to a 30-fold increase in accessible beta-carotene levels compared to untreated leaves. The massive accumulation of beta-carotene also gave the lettuce leaves a characteristic golden colour.

According to the researchers, the discovery that beta-carotene can be produced and stored at very high levels and in a more bioaccessible form outside the places where it is usually found in leaves 'represents a very significant advance for improving nutrition through biofortification of vegetables such as lettuce, chard or spinach without giving up their characteristic scent and flavour'.

 

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Journal

The Plant Journal

DOI

10.1111/tpj.16964 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Boosting pro-vitamin A content and bioaccessibility in leaves by combining engineered biosynthesis and storage pathways with high-light treatments

 

Plant-derived secondary organic aerosols can act as mediators of plant-plant interactions

University of Eastern Finland

A new study published in Science reveals that plant-derived secondary organic aerosols (SOAs) can act as mediators of plant-plant interactions. This research was conducted through the cooperation of chemical ecologists, plant ecophysiologists and atmospheric physicists at the University of Eastern Finland.

It is well known that plants release volatile organic compounds (VOCs) into the atmosphere when damaged by herbivores. These VOCs play a crucial role in plant-plant interactions, whereby undamaged plants may detect warning signals from their damaged neighbours and prepare their defences. “Reactive plant VOCs undergo oxidative chemical reactions, resulting in the formation of secondary organic aerosols (SOAs). We wondered whether the ecological functions mediated by VOCs persist after they are oxidated to form SOAs,” said Dr. Hao Yu, formerly a PhD student at UEF, but now at the University of Bern.

The study showed that Scots pine seedlings, when damaged by large pine weevils, release VOCs that activate defences in nearby plants of the same species. Interestingly, the biological activity persisted after VOCs were oxidized to form SOAs. The results indicated that the elemental composition and quantity of SOAs likely determines their biological functions.

“A key novelty of the study is the finding that plants adopt subtly different defence strategies when receiving signals as VOCs or as SOAs, yet they exhibit similar degrees of resistance to herbivore feeding,” said Professor James Blande, head of the Environmental Ecology Research Group. This observation opens up the possibility that plants have sophisticated sensing systems that enable them to tailor their defences to information derived from different types of chemical cue.

“Considering the formation rate of SOAs from their precursor VOCs, their longer lifetime compared to VOCs, and the atmospheric air mass transport, we expect that the ecologically effective distance for interactions mediated by SOAs is longer than that for plant interactions mediated by VOCs,” said Professor Annele Virtanen, head of the Aerosol Physics Research Group. This could be interpreted as plants being able to detect cues representing close versus distant threats from herbivores.

The study is expected to open up a whole new complex research area to environmental ecologists and their collaborators, which could lead to new insights on the chemical cues structuring interactions between plants.

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Journal

Science

DOI

10.1126/science.ado6779 

Article Title

Biogenic secondary organic aerosol participates in plant interactions and herbivory defense.

Unbiased look at plants uncovers how surprisingly transcription is regulated in plants

Gregor Mendel Institute of Molecular Plant Biology

 

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A GATC-motif downstream of the transcription start site acts like a rheostat, finetuning transcription in different cell types. 

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Credit: GMI

Our world today is populated by multicellular organisms, from big trees to climate-wrecking humans. This multicellularity arose independently in plants and animals. Both animals and plants cope differently with the challenges of corralling individual cells together to form a larger organism, such as the need to communicate and coordinate between cells, to share and transport nutrients, and to form specialized structures. One challenge posed by multicellularity is that all cells carry the same genetic code, but the cells look and behave differently: A root cell needs to elongate towards water sources and gravity, while cells in the leaves drive photosynthesis. To achieve different outcomes from the same underlying code, cells tinker with how the code is read out, in what is called transcriptional regulation. Plants and animals also differ fundamentally in how they achieve this transcriptional regulation, as a new paper by the group of Magnus Nordborg at the GMI shows. The results, published in Nature Genetics on September 12, open a new perspective on how plants achieve transcriptional regulation.  

New perspective from studying plants

“Much of what we know about transcriptional regulation in plants so far is informed by research on animals and yeast”, says Yoav Voichek, postdoc in the lab of Magnus Nordborg and co-author of the study. “We wanted to look at plants in an unbiased way, thereby making it possible to uncover mechanisms and processes that are unique to plants.” Using a parallel reporter assay in four plant species – maize, Arabidopsis, tomato and Nicotiana benthamiana – the researchers searched for sequences that influence transcription. The transcription start site (TSS) is the specific location on a gene where transcription begins. The researchers identified a region downstream of the TSS that is central for transcriptional regulation.

Looking more closely at how the sequences regulate transcription, the researchers uncovered a novelty in transcriptional regulation. “Most surprisingly, when we swap the position of this regulatory sequence, placing it upstream of the transcriptional start site, it no longer drives transcription”, Voichek says. This finding runs counter to what would be expected from looking at transcriptional regulation in animals: In animals, regulatory sequences are position-independent, as swapping their position does not change how they regulate transcription.

Fine-tuning transcription

Within the regulatory sequence, the scientists uncovered a sequence-motif, consisting of the bases GATC, that strongly drives gene expression. “The sequence motif has a more potent influence on transcription than any DNA motif identified upstream of the transcriptional start site”, Voichek explains. The motif is evolutionarily conserved and found in all vascular plants, i.e. all land plants except for mosses, hornworts and liverworts.

The way in which the GATC-motif influences transcription illustrates how regulatory sequences can fine tune transcription in different cell types. “The higher the number of these motifs downstream of the TSS, the more strongly the gene is expressed”, Voichek says. “The motif acts like a rheostat, finely tuning genes that need to be expressed in all cell types, but at different levels.” In the future, Voichek plans to investigate how the GATC-motif exerts control over transcription. “Our study not only shifts the understanding of transcription regulation in plants but also underscores that we need to study transcription in a diverse set of organisms to broaden our understanding of biology.”

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Journal

Nature Genetics

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Widespread position-dependent transcriptional regulatory sequences in plants