How some plant architectures mimic subway system designs
What do tomato plants and subway systems have in common? It’s not the start to a joke… it’s a legitimate question – and one that might have a definitive answer.
Scientists from the Salk Institute used 3D laser scans of growing plants to discover that the same design principles humans use to engineer subway systems also follow a similar pattern to the shape of plant branching systems. Both networks work to make a similar trade off between cost and performance.
“The idea for this work really started with an engineering question,” says Saket Navlakha, senior author of the paper and assistant professor in Salk’s Center for Integrative Biology. “How do transportation networks like a subway system or an electric grid resolve the tension between two competing objectives, such as cost and performance? And do plants resolve similar competing objectives in the same way?”
For subway systems, the design is a balance between the cost of construction and providing sufficient transportation. The transportation system should provide enough efficient transport to get people where they need to go quickly, but not so much that resources are wasted. For plants, nutrients need to get between roots and leaves as quickly as possible, while limiting the cost of extra branches and root systems.
The research team analyzed three agriculturally valuable crops: sorghum, tomato, and tobacco. They grew the crops under half a dozen conditions, scanning each plant every 20 days to analyze the growing network of branches, stems, and leaves. From these scans, they were able to create and graph theoretical plant shapes that could either prioritize efficient routes for nutrients, minimal branch length, or a variety of tradeoffs between the two.
When they placed real plants into this similar model, they found that the plants fell perfectly within the range of the digital models. This shows that plants are attempting to find the best balance between cost and performance for their specific environment.
“Our hypothesis was that if total length and travel distance were important evolutionary criteria for plants, there would be evolutionary pressure to minimize the criteria together, and that’s actually what we found,” says Ullas Pedmale, who was a postdoctoral researcher on the project and is now an assistant professor at Cold Spring Harbor Laboratory.
The plants also clustered by species, but within those species they made different tradeoffs base on their growth environment. Plants grown certain light conditions would find a different balance between cost and performance than other plants grown in different conditions.
“This means the way plants grow their architectures also optimizes a very common network design tradeoff. Based on the environment and the species, the plant is selecting different ways to make tradeoffs for those particular environmental conditions,” says Navlakha. “By understanding these tradeoffs we may be able to dynamically tune our crop varieties to a changing climate.”
Timing is everything for stopping pesky weeds
Herbicide-resistant weeds are increasing in dramatic numbers, which doesn’t bode well for farmers. Now, a new study from Cambridge University has found that “superweeds” are on the rise in the Midwest where farming and agriculture are a core part of the economy.
It’s not all bad news though. The research also found that it’s not just about what you put on your weeds, it’s when you till the soil that has a huge impact on weed growth.
Tillage is the process of preparing the land for seeds and planting through digging, turning, and mixing up the soil. And the time tillage occurs may play a crucial role in hindering weeds from taking over.
The study, published in the journal Weed Science, looked at tillage and weed growth in the Northeastern United States. Researchers examined 196 random plots and monitored tillage that occurred every two weeks through the growing season on these sites, later coming back to test weed growth on the plots.
The research team discovered that if tillage happens early in the season, there is an increase in weed growth. More than 50 percent more weeds grew in soil tilled early compared to later season tilled soil.
And it’s not just the number of weeds that are affected by timed tillage. Scientists found that early tilling produced an uneven distribution of species, with some particular weeds holding sway over the soil. Late tilling had an even amount of the types of weeds represented.
This is great news for farmers who are frustrated by weed growth, thanks to herbicide resistance increasing.
Mathew Ryan, a member of the research team from Cornell University said, “Our results suggest that farmers may be able to better manage weed communities and to mitigate the impact of weeds on crop yields by adjusting the timing of their tillage, crop rotation, and other cultural management practices.”
Despite the fact that “superweeds” are on the rise, science is working on finding ways to help farmers manage their crops and cutting back on weed density via timed tillage could be hugely beneficial.
Non-photosynthesizing plant discovered on Japanese island
Some plant species attach to other plants and feed off of their roots instead of photosynthesizing. Fungi such as mushrooms and mold are most often hosts to these parasitic plants. On Ishigaki Island in Okinawa, Japan, a new species of non-photosynthesizing plant has been identified and named Sciaphila sugimotoi.
Non-photosynthesizing plant species, known as myco-heterotrophs, only emerge from under ground when flowering or bearing fruit. Many plants of this species are extremely small with short flowering periods, making them difficult to find and classify.
Professor Kenji Suetsugu of Kobe University, who is involved in documenting the distribution and classification of the mycoheterotrophic plants in Japan, led the team that recognized Sciaphila sugimotoi.
In October 2016, Professor Suetsugu was informed of a sighting of an unknown myco-heterotroph near Mount Omoto on Ishigaki Island. Professor Suetsugu meticulously investigated the morphological characteristics of the plant. The results showed that it was a relative of Sciaphila nana, which has three spherical nubs on the head of the male flower. The study revealed that the new species has six nubs.
Sciaphila sugimotoi is named after Mr. Takaomi Sugimoto of Kyushu University, who played a key role in the identification of the species. Specimens of S. sugimotoi collected by Mr. Sugimoto reveal that the plant stands 5-10 centimeters above ground with violet flowers that are roughly 2 millimeters in diameter.
Due to their parasitic nature, mycoheterotrophic plants need a healthy, stable ecosystem with abundant resources in order to thrive. The discovery of new mycoheterotrophic species suggests that a rich habitat resides beneath the forest floor. The existence of S. sugimotoi is further evidence of the value of the Mount Omoto area.
The findings of this study will be published on July 25 in Phytotaxa.
Source: Kobe University
Image: SUGIMOTO Takaomi
Why invasive coastal plants are better than no plants at all
Invasive plants can be valuable in some coastal areas where native plants are declining, a new study concludes.
“With the progressive decline of coastal habitats worldwide, our findings suggest it’s better to have a non-native habitat than no habitat at all,” said Aaron Ramus, a PhD student at the University of North Carolina-Wilmington, who led the research. “There’s a good chance that many invaders don’t have the negative effects that we often think they do.”
On otherwise barren mudflats, invasive species such as non-native seaweed can offset the loss of native species and be useful in other ways. These plants can provide storm protection and food production, on which nearly half the human population depends, the researchers found.
The study focused on Gracilaria vermiculophylla, a Japanese seaweed affecting lagoons and estuaries throughout coastlines of the North Atlantic. Recent research suggests that it came to North Carolina with the export of oysters from Japan.
The research was conducted over 10 months in 48 large plots with different densities of Gracilaria. The team measured monthly changes in seven functions for which coastal ecosystems are highly valued. This included soil stabilization and erosion control, storm surge and flood protection, biodiversity, food production, and a habitat for economically important seafood species such as shrimp, crab, and fish.
The invasive plants can help on many of these measures, the researchers found.
“Conservation practitioners are investing millions of dollars to eradicate invasive species, but what if some of those invasive species are actually benefiting native species and ecosystem services?” said Brian Silliman, professor at Duke University who co-authored the study. “Our experimental study shows for the first time that this can be the case.”
Conservationists “must now begin the hard conversation about changing their black-and-white picture of invasive species impacts,” Silliman said.
The study was published in Proceedings of the National Academy of Sciences.
Some plant-based diets can increase risk of heart disease
Plant-based diets that include lots of sweets and refined grains could increase the risk of heart disease, a new Harvard University study found.
Previous research on the impact of plant-based diets treated plant foods equally, even though some such as refined grains and sugar-sweetened beverages are associated with a higher risk of heart disease.
In the new study, the researchers created three versions of a plant-based diet: an overall plant-based diet consisting of of all plant food and reduced animal food intake; a diet that consisted of healthy plant foods such as whole grains, fruits and vegetables; and a plant-based diet consisting of less healthy plant foods such as refined grains.
Researchers used a baseline sample of 73,710 women from the Nurses’ Health Study, 92,320 women from the Nurses’ Health Study 2, and 43,259 men from the Health Professionals Follow-Up Study. Participants with coronary heart disease at baseline were excluded along with those with cancer, stroke, and coronary artery surgery.
The research showed that 8,631 participants developed coronary heart disease. A higher intake of a more healthy plant-based diet rich in whole grains, fruits, and vegetables, was associated with a substantially lower risk of heart disease. But a plant-based diet that emphasized less healthy plant foods like sweetened beverages, refined grains, potatoes and sweets had the opposite effect, the study found.
“It’s apparent that there is a wide variation in the nutritional quality of plant foods, making it crucial to take into consideration the quality of foods in a plant-based diet,”said Ambika Satija, a postdoctoral fellow at the Harvard University School of Public Health and the study’s lead author.
The study was published in the Journal of the American College of Cardiology.
Source: American College of Cardiology
How plants protect themselves from sunshine overdose
A new study has unravelled mysteries of a key protein that allows moss and green algae to protect themselves from too much sunshine.
Most plants absorb far more sunlight than they can use, the study said. In very sunny conditions, they convert only about 30 percent of the available sunlight into sugar.
If green plants absorb too much sunshine, the extra energy from photosynthesis destroys their tissue. As a defense, plants have mechanisms to release the extra energy as heat.
“These photoprotective mechanisms have evolved from the fact that sunlight is not constant. There are sunny days; there are cloudy days,” said Gabriela Schlau-Cohen, a Massachusetts Institute of Technology Assistant Professor of Chemistry and the senior author of the study.
Several years ago, researchers discovered that the protein LHCSR1 is the key player in photoprotection that occurs over short timescales (seconds to minutes) in green algae and moss. It is embedded in the membranes in the chloroplast and interacts with chlorophyll and carotenoids, another type of light-absorbing pigment. However, the mechanism of how this photoprotection works was not known.
In the new study, researchers used a very sensitive microscope that can analyze single proteins to determine how the LHCSR1 protein found in moss reacts to different light conditions. The protein can assume three distinct conformations, which correspond to different functions, the researchers discovered.
Under cloudy or shady conditions, LHCSR1 simply absorbs photons and passes the energy on to the rest of the photosynthetic machinery, the researchers said. When the sun comes out and energy intake rises, LHCSR1 switches to another conformation within seconds. The switch is caused by a decrease in pH, which occurs when too many hydrogen ions are generated by water-splitting during photosynthesis.
The researchers are now creating mutated versions of LHCSR1, which they plan to test to see if they have the ability to produce more biomass while still offering some photoprotection.
Learning more about how the protein works could allow scientists to alter it in a way that would promote more photosynthesis, potentially increasing the biomass yield of crops and algae grown for biofuels, Schlau-Cohen said.
The study was published in the journal Nature Chemistry.
Humans domesticated plant seeds thousands of years ago
Researchers using high-resolution X-ray technology have been able to document the revolution of thinning seed coats, a major marker of domestication of seeds by humans.
“Seed coat thickness is a great indicator of domestication, as thinner coats will mean faster germination of a seed when it is watered,” said Dorian Fuller of University College London, co-author of the paper.
The researchers found evidence of seed coat thinning between 2,000 BC and 1,200 BC in the legume horsegram, a bean commonly eaten in southern India.
Using the high-resolution X-ray computed tomography technique (HRXCT) at the UK’s synchrotron facility, Diamond Light Source, allowed researchers to measure thickness without breaking and destroying archaeological specimens.
“Being able to look at the seed coat thickness without breaking the sample is possible by other methods, but you can only look at a spot on the seed,” said Charlene Murphy, co-author on the paper.
Researchers analysed 12 samples, putting the seeds into two distinct groups: thicker (wild type) seed coats, with averages thicknesses above 17 micrometres, and thinner (more domesticated) seed coats between 10 and 15 micrometers.
The findings show the potential for HRXCT to be used to look at a variety of domesticated grains and pulses, such as peas, the authors said.
“We’re continuing to work with Diamond to look at other interesting archaeological seeds, and how they’ve become domesticated,” said Fuller. “Peas are a great example of this – wild peas are ejected from their pods naturally, but domesticated peas only leave the pod when the cultivator removes them – a quite symbiotic relationship.”
Source: Diamond Light Source
Ingredient in magic mushrooms could help psychiatric therapies
Psilocybin, the active ingredient in psychedelic mushrooms, may be more effective than traditional psychiatric therapies for depression, anxiety, and substance abuse disorders, a new study found.
Researchers at Touro University California reviewed seven published psilocybin clinical trials and concluded that psilocybin-assisted psychotherapy has strong potential in improving patient outcomes, particularly for those who haven’t responded to other treatments.
Patients can also show improvement after just a few six-hour “medicated” therapy sessions and a few weeks of follow-up therapy, the review found.
The studies all investigated the use of psilocybin in strictly controlled clinical conditions under the supervision of therapists and other health professionals.
“Additional studies are required to determine if psilocybin will be deemed safe and effective enough to gain FDA approval,” the researchers wrote. “While psilocybin’s clinical utility still remains uncertain, it should be investigated further to determine if this novel treatment paradigm has the potential to dramatically improve outcomes in patients with psychiatric disorders.”
As psychological and psychiatric researchers have gained greater access to brain imaging technologies, they are forming new hypotheses about the physiological roots of psychological disorders. One is the idea that major depression is rooted in atypical connections between regions of the brain that aren’t usually connected, which may in turn underlie the fixation and rumination on thoughts that characterizes depression.
Recent studies have found that psilocybin from mushrooms significantly affects connectivity among different brain regions.
In most of the United States psilocybin is still classified as a Schedule I substance, meaning it has “a high potential for abuse, no currently accepted medical use in treatment in the United States, and a lack of accepted safety for use under medical supervision,” according to the U.S. Drug Enforcement Administration.
Whether the DEA will take the most recent scientific data into account, remains to be seen, the authors said.
The study is published in the Journal of Psychoactive Drugs.
Source: Touro University California
Warmer Arctic is weakening vegetation growth in North America
Warmer Arctic temperatures have triggered cooler winters and springs in North America, which has weakened vegetation growth and lowered carbon uptake capacity in its ecosystems, according to a new study.
Researchers analyzed an index of sea surface temperatures from the Bering Sea and found that in years with higher-than-average Arctic temperatures, changes in atmospheric circulation affected climate throughout North America.
In years of intense cold and low precipitation, the team found that the unfavorable conditions adversely affected vegetation growth—including crop yields—which decreased carbon uptake capacity by about 14 percent, the study said.
“If current warming trends continue, it is feasible to conclude that the ecosystems in regions affected by the anomalous climate will suffer greater damages due to the cold and dry spells,” the authors saId.
Further research is needed to obtain a “general conclusion” on the matter, but the research “delivers important implications for climate adaptation,” the authors added.
The study was conducted by Jin-Soo Kim and Jong-Seong Kug at Pohang University of Science and Technology (POSTECH), in collaboration with Su-Jong Jeong from South University of Science and Technology in China. It is published in the journal Nature Geoscience.
How plants can turn caterpillars into cannibals
Tomato plants can turn caterpillars into cannibals, a new study found.
The plants can release a chemical that makes themselves so distasteful that the normally vegetarian insects will resort to eating their own kind, the University of Wisconsin Madison study said.
“We struck upon a way that plants defend themselves that nobody had really appreciated before,” saId postdoctoral researcher Brian Connolly. “It’s grisly and macabre, but it’s energy transfer.”
The researchers set up experiments using tomato plants and a species of caterpillar called the beet armyworm.
“Beet armyworms are important agricultural pests, in part because they can feed on a variety of plants,” Connolly says. “And early, influential work describing plant responses to herbivore attacks used tomato and beet armyworm. We build on that work here.”
Many plants can produce defensive chemicals such as jasmonate to deter their attackers.
This allows other plants to detect the airborne substances emitted and begin to invest in their own defenses.
In the new study, researchers sprayed tomato plants in plastic containers with either a control solution or a range of concentrations of methyl jasmonate – low, medium and high — and then added eight caterpillar larvae to each container.
Caterpillars living with the well-defended plants became cannibalistic much sooner than their counterparts with access to the less-well-defended plants, the study found.
“From the plant’s perspective, this is a pretty sweet outcome, turning herbivores on each other,” said University of Wisconsin-Madison integrated biology Professor John Orrock, author of the study. “Cannibals not only benefit the plant by eating herbivores, but cannibals also don’t have as much appetite for plant material, presumably because they’re already full from eating other caterpillars.”
The research found that cannibalistic caterpillars on defended plants grew at similar rates to caterpillars given access to undefended plants.
However, caterpillars on well-defended plants with no fresh caterpillar carcasses ate less plant and grew slowly.
“The next step in this work is to figure out whether accelerated cannibalism would slow, or increase, the rate of spread of insect pathogens,” said Orrock.
Researchers also hope to better understand whether caterpillars are as quick to turn to cannibalism when they are not trapped with a single plant, as they were in the lab, he said.
The study was published in Nature Ecology & Evolution.
Source: University of Wisconsin Madison
Baker’s yeast could help battle soil contamination
Toxic chemicals found in the soil as a result of human activities can cause major issues for the development and growth of plants. But now, researchers have discovered two genes in baker’s yeast that are capable of increasing plant resistance to a broad range of contaminants. This could allow plants and crops to thrive despite soil pollution.
Soil contamination is due in large part to heavy metals and organic pollutants that are leaked during industrial activity. Soil is also frequently polluted by improper use of pesticides and other agricultural chemicals. A research team led by Paula Duque from the Instituto Gulbenkian de Ciencia took a new approach to this environmental issue by analyzing the properties of baker’s yeast, most commonly used for making bread and beer.
“Current strategies to decontaminate soils are very expensive and not so effective. The scientific community has been looking for alternative strategies to make plants more resilient to toxic compounds,” said Duque. “A possible solution may lie in Saccharomyces cerevisiae, a species of yeast used for baking, brewing, and winemaking.”
Saccharomyces cerevisiae is known to be resistant to herbicide and other chemicals. Isabel Sa-Correia of the Universidade de Lisboa and her colleagues identified two genes that give this particular species of yeast its resistance. Duque’s team put the two genes to the test on a small flowering plant known as Arabidopsis thaliana.
“These two yeast genes produce proteins that are able to expel molecules from cells. So we hypothesized that they could play a similar role in plants, eliminating toxic molecules and allowing normal growth,” said Duque.
The researchers discovered that once either of the two yeast genes were inserted, the plants became more resistant to herbicides, fungicides and heavy metals. These plants were able to grow and develop significantly better with the modifications.
The study, published in Scientific Reports, will continue with further testing of the Arabidopsis thaliana and other plant species. The team hopes to extend the application of the genes to major crops. Duque expressed that the findings of this study “hold much promise to help solve a difficult environmental problem.”
Source: Instituto Gulbenkian de Ciencia
How ancient virus species helped each other by exchanging DNA
Ancient virus species infecting the same plant helped each other by exchanging DNA, according to a new study.
The team led by Yuji Kishima analyzed the sequences of PRVs in 20 grass genomes including Oryza sativa, also known as rice. The team found DNA of five non-autonomous PRVs lacking some essential genes and therefore incapable of functioning on their own. All previously identified PRVs have been autonomous.
Viruses including “pararetroviruses” can insert their DNA into their host’s genome, the study said. For some viruses, this is a required step for replication, while in others, the DNA is inserted accidently and is passed from one generation to the next.
Inherited viral DNA sequences serve as fossil records for ancient viruses and studying them has revealed valuable data about the evolutionary dynamics of host-virus interactions, the authors said. However, little is known about the evolution of virus-virus interactions.
The study suggests that non-autonomous PRVs adopted two strategies to maintain their life cycles. One involves a “commensal” partnership with another species of autonomous PRV. The other strategy involves a “mutualistic” partnership with another species of non-autonomous PRV in which both PRVs compensate for a function they are each lacking.
“In both strategies, exchanging DNA between the virus species plays an important role in establishing the partnership,” said Kishima “We suggest that the exchange of noncoding regulatory sequences is an important mechanism driving concerted evolution of the viruses.”
The same type of partnerships could be used in existing non-autonomous PRVs, Kishima added.
“Whether plant or human, further studies are needed to better understand the mechanisms of viral evolution and pathology.”
Source: Hokkaido University
Image Credit: Chen S. et al., PLOS Pathogens, June 29, 2017