Plants Emit Ultrasound Signals When Under Stress
Researchers at Tel Aviv University have recorded and analyzed sounds distinctly emitted by plants. The click-like sounds, similar to the popping of popcorn, are emitted at a volume similar to human speech, but at high frequencies, beyond the hearing range of the human ear.
“We found that plants usually emit sounds when they are under stress, and that each plant and each type of stress is associated with a specific identifiable sound. While imperceptible to the human ear, the sounds emitted by plants can probably be heard by various animals, such as bats, mice and insects,” the researchers noted.
The paper was published in the scientific journal Cell.
Previous research indicated that plants vibrate. Scientists didn’t know, though, whether those vibrations became airborne soundwaves that could be recorded from a distance.
In the first stage of the study, the researchers placed plants in an acoustic box in a quiet, isolated basement with no background noise. Ultrasonic microphones recording sounds at frequencies of 20-250 kilohertz (the maximum frequency detected by a human adult is about 16 kilohertz) were set up at a distance of about 10 cm from each plant. The study focused mainly on tomato and tobacco plants, but wheat, corn, cactus and henbit were also recorded.
According to lead researcher Professor Lilach Hadany, “Before placing the plants in the acoustic box we subjected them to various treatments: some plants had not been watered for five days, in some the stem had been cut, and some were untouched. Our intention was to test whether the plants emit sounds, and whether these sounds are affected in any way by the plant’s condition. Our recordings indicated that the plants in our experiment emitted sounds at frequencies of 40-80 kilohertz. Unstressed plants emitted less than one sound per hour, on average, while the stressed plants — both dehydrated and injured — emitted dozens of sounds every hour.”
The recordings collected in this way were analyzed by specially developed machine learning (AI) algorithms. The algorithms learned how to distinguish between different plants and different types of sounds and were ultimately able to identify the plant and determine the type and level of stress from the recordings. Moreover, the algorithms identified and classified plant sounds even when the plants were placed in a greenhouse with a great deal of background noise. In the greenhouse, the researchers monitored plants subjected to a process of dehydration over time and found that the quantity of sounds they emitted increased up to a certain peak, and then diminished.
“Our findings suggest that the world around us is full of plant sounds and that these sounds contain information — for example, about water scarcity or injury,” said Professor Hadany. “We assume that in nature, the sounds emitted by plants are detected by creatures nearby, such as bats, rodents, various insects and possibly also other plants, that can hear the high frequencies and derive relevant information. We believe that humans can also utilize this information, given the right tools — such as sensors that tell growers when plants need watering.”
Ultrafast Spectroscopy Reveals Processes at Beginning of Photosynthesis
Scientists researching the earliest stages of photosynthesis — the natural mechanism that powers the vast majority of life on Earth — have discovered new ways to extract energy from the process, a finding that could lead to new ways of generating clean fuel and renewable energy.
An international team of physicists, chemists and biologists, led by the University of Cambridge, was able to study photosynthesis — the process by which plants, algae and some bacteria convert sunlight into energy — in live cells at an ultrafast timescale: a millionth of a millionth of a second.
Despite the fact that it is one of the most well-known and well-studied processes on Earth, the researchers found that photosynthesis still holds secrets. Using ultrafast spectroscopic techniques to study the movement of energy, the researchers found the chemicals that can extract electrons from the molecular structures responsible for photosynthesis do so at the initial stages, rather than much later, as was previously thought. This understanding of photosynthesis could help create new and more efficient ways of using its power. The results are reported in the journal Nature.
“We didn’t know as much about photosynthesis as we thought we did, and the new electron transfer pathway we found here is completely surprising,” said Dr. Jenny Zhang from Cambridge University, who coordinated the research.
While photosynthesis is a natural process, scientists have also been studying how it could be used as to help address the climate crisis, by mimicking photosynthetic processes to generate clean fuels from sunlight and water, for example.
Zhang and her colleagues were originally trying to understand why a ring-shaped molecule called a quinone is able to “steal” electrons from photosynthesis. Quinones are common in nature, and they can accept and give away electrons easily. The researchers used a technique called ultrafast transient absorption spectroscopy to study how the quinones behave in photosynthetic cyanobacteria.
“No one had properly studied how this molecule interplays with photosynthetic machineries at such an early point of photosynthesis; we thought we were just using a new technique to confirm what we already knew,” said Zhang. “Instead, we found a whole new pathway and opened the black box of photosynthesis a bit further.”
Using ultrafast spectroscopy to watch the electrons, the researchers found that the protein scaffold where the initial chemical reactions of photosynthesis take place is “leaky,” allowing electrons to escape. This leakiness could help plants protect themselves from damage from bright or rapidly changing light.
“The physics of photosynthesis is seriously impressive,” said co-first author Tomi Baikie, from Cambridge’s Cavendish Laboratory. “Normally, we work on highly ordered materials, but observing charge transport through cells opens up remarkable opportunities for new discoveries on how nature operates.”
“Since the electrons from photosynthesis are dispersed through the whole system, that means we can access them,” said co-first author Dr. Laura Wey. “The fact that we didn’t know this pathway existed is exciting, because we could be able to harness it to extract more energy for renewables.”
The researchers say that being able to extract charges at an earlier point in the process of photosynthesis could make the process more efficient when manipulating photosynthetic pathways to generate clean fuels from the sun. In addition, the ability to regulate photosynthesis could mean that crops could be made more able to tolerate intense sunlight.
“Many scientists have tried to extract electrons from an earlier point in photosynthesis, but said it wasn’t possible because the energy is so buried in the protein scaffold,” said Zhang. “The fact that we can steal them at an earlier process is mind-blowing. At first, we thought we’d made a mistake: it took a while for us to convince ourselves that we’d done it.”
Key to the discovery was the use of ultrafast spectroscopy, which allowed the researchers to follow the flow of energy in the living photosynthetic cells on a femtosecond scale — a thousandth of a trillionth of a second.
Genomic Difference Can Detect Naturally vs. CAFO-Raised Meat
Free-range organic chicken or factory farmed? Scientists at the German Cancer Research Center (DKFZ) have developed a new detection method that can reveal how an animal was raised. The epigenetic method is based on the analysis of the characteristic patterns of chemical markers on the genome of the animals.
Current food analysis laboratories can only answer such questions to a limited extent. They usually require time-consuming tests that combine several different assays. A team led by Frank Lyko of DKFZ, together with colleagues from the chemical company Evonik, is now presenting a simpler solution: analyzing the characteristic fingerprint of chemical markers on the genome of animals.
“The question of the origin of food is increasingly becoming a purchasing argument for consumers — especially when it comes to animal products, and thus also to the wellbeing of animals,” said Lyko. “We have now established an amazingly sensitive detection method that maps many of the environmental factors that are relevant to animal wellbeing.”
Our DNA is studded with millions of chemical markers. These so-called methyl groups perform important biological functions. They decide which genes are translated into proteins.
In contrast to the lifelong stable sequence of DNA building blocks, the methyl labels can be reattached or removed again. This happens in adaptation to biological requirements. In humans, for example, the methyl pattern — the “methylome” — changes in the course of disease or age. The totality of these reversible control elements on the genome is referred to as epigenetics.
The influence of environmental factors on the methylome is not always easy to prove. The laboratory at DKFZ used the marble crayfish in its experiments. “All marble crayfish have an identical genome, which means they are a single clone. Therefore, the study of environmentally induced changes in the methylation pattern is not falsified by deviating genetic factors,” explained Lyko.
For the methylome analysis, the researchers use a special DNA sequencing technique that allows them to identify each methylated DNA building block. Lyko and colleagues were thus able to unambiguously identify marble crayfish populations from different parts of the world. They were able to distinguish animals from clean or eutrophic waters or from laboratory husbandry. The researchers were also successful in tracking the time course of the adaptation of the methylation pattern when switching between two types of husbandry.
Encouraged by these unambiguous results, the team successfully extended the methylome analyses to animals that are part of the human diet. They conducted this project in collaboration with colleagues at Evonik.
The researchers were able to distinguish shrimp from different rearing facilities. The methylome of salmon from slow-flowing rivers differs from that of their conspecifics that lived in mountain streams. In chickens, the farm and its feed supply affected the pattern of methylation. “The environmental and living conditions leave a specific fingerprint in the methylome of all organisms studied. This turns out differently in a free-range chicken than in a factory farm,” said Lyko.
“Methyl fingerprints could expand the possibilities of food analysis as an important biomarker,” said DKFZ researcher Sina Tönges, one of the study’s authors. “However, sequencing as we applied it in this study is a laborious procedure that cannot be routinely performed in food analysis. We are therefore working with Evonik to develop a test system for methylome fingerprinting that can also find its way into laboratories on a broad scale.”
Moths May Be More Efficient Pollinators Than Bees
Moths are more efficient pollinators at night than day-flying pollinators such as bees, new research from the University of Sussex has shown.
Amid widespread concern about the decline of wild pollinating insects like bees and butterflies, the researchers discovered that moths are particularly vital pollinators for nature.
Studying 10 sites in the southeast of England throughout July 2021, the Sussex researchers found that 83 percent of insect visits to bramble flowers were made during the day. While the moths made fewer visits during the shorter summer nights — only 15 percent of the visits — they were able to pollinate the flowers more quickly.
As a result, the researchers concluded that moths are more efficient pollinators than day-flying insects such as bees, which are traditionally thought of as hard-working. While day-flying insects have more time available to transfer pollen, moths were making an important contribution during the short hours of darkness.
“Bees are undoubtedly important, but our work has shown that moths pollinate flowers at a faster rate than day-flying insects,” said Professor Fiona Mathews, a co-author of the study. “Sadly, many moths are in serious decline in Britain, affecting not just pollination but also food supplies for many other species ranging from bats to birds. Our work shows that simple steps, such as allowing patches of bramble to flower, can provide important food sources for moths, and we will be rewarded with a crop of blackberries.”
Researchers studied the contribution of both nocturnal and non-nocturnal insects to the pollination of bramble. They monitored the numbers of insects visiting flowers using camera traps and worked out how quickly pollen was deposited at different times of day by experimentally preventing insects from visiting some flowers but not others.
Additionally, the study indicates the importance of bramble, a shrub widely considered as unfavorable and routinely cleared away, but which is in fact critical for nocturnal pollinators.
Both night- and day-flying pollinators need to be protected in order to allow natural ecosystems to flourish. As a result, researchers are also calling for the U.K. public to do their bit to protect moths by planting white flowers, growing patches of scrub and rough grass, and turning off night lights.
