Research at the University of Leeds has identified a key gene that assisted the transition of plants from water to the land around 500 million years ago.
The ANR gene is required to tolerate 'extreme dehydration' in the moss Physcomitrella patens, a land plant that is used as an experimental model.
Researchers at the Centre for Plant Sciences at the University found that the ANR gene - present in the most ancient land plants - was inherited from ancestral fresh water algae.
The ANR gene has since been lost in the evolution of seed plants. The results are published today in the American Society of Plant Biology's journal The Plant Cell.
Dr Andrew Cuming, who led the research, said: "This gene hadn't been identified so far because most research until now has focused on modern flowering plants.
From a quarter to half of Earth's vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, according to a new study published in the journal Nature Climate Change on April 25.
An international team of 32 authors from 24 institutions in eight countries led the effort, which involved using satellite data from NASA's Moderate Resolution Imaging Spectrometer and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer instruments to help determine the leaf area index, or amount of leaf cover, over the planet's vegetated regions. The greening represents an increase in leaves on plants and trees equivalent in area to two times the continental United States.
Green leaves use energy from sunlight through photosynthesis to chemically combine carbon dioxide drawn in from the air with water and nutrients tapped from the ground to produce sugars, which are the main source of food, fiber and fuel for life on Earth. Studies have shown that increased concentrations of carbon dioxide increase photosynthesis, spurring plant growth.
However, carbon dioxide fertilization isn't the only cause of increased plant growth--nitrogen, land cover change and climate change by way of global temperature, precipitation and sunlight changes all contribute to the greening effect. To determine the extent of carbon dioxide's contribution, researchers ran the data for carbon dioxide and each of the other variables in isolation through several computer models that mimic the plant growth observed in the satellite data.
Results showed that carbon dioxide fertilization explains 70 percent of the greening effect, said co-author Ranga Myneni, a professor in the Department of Earth and Environment at Boston University. "The second most important driver is nitrogen, at 9 percent. So we see what an outsized role CO2 plays in this process."
Climate change can influence everything from pine beetle outbreaks in the Rocky Mountains to rising sea levels in Papua New Guinea. In the face of a rapidly changing earth, plants and animals are forced to quickly deal with new challenges if they hope to survive. According to a recent paper by Jason Fridley, associate professor of biology in Syracuse University's College of Arts and Sciences, recently minted SU Ph.D. Catherine Ravenscroft, and University of Liverpool professor Raj Whitlock some species may be able to handle environmental changes better than others.
Fridley explains that species have a couple options to deal with stress associated with environmental change: they can pick up and move to more favorable areas, or they can stick it out and adapt to the new challenges. This ability to adapt to climate changes was the main focus of the researcher's study
Ribwort plantain and sheep fescue, two plants common in the study site, show signs of being able to respond to induced climate challenges. "There is evidence of genetic differentiation with a long term climate treatment," says Ravenscroft, explaining that genetic difference have built up between climate-treated versus untreated plants in the study site.
What's more, the gene-level changes have happened remarkably fast. Because these grasses are perennial species, meaning they live and reproduce for multiple growing seasons, Fridley estimates there have only been around 10 generations of plants over the 15-year experiment. While that may sound like a lot of generations if you think back to your great-great-great-great-great-great-great-great-grandparent, genetic splits happen on an evolutionary timescale - think in terms of hundreds or thousands of years.
Including plants' acclimation to changes in temperature could significantly improve the accuracy of climate models, a Purdue University study shows.
Plants are the largest drivers of carbon fluxes between land and the atmosphere, taking up and releasing carbon dioxide through the processes of photosynthesis and respiration. The rates at which these processes occur are sensitive to temperature and gradually adjust over time in response to long-term temperature shifts, a phenomenon known as acclimation.
Jeffrey Dukes, professor of forestry and natural resources and biological sciences, and a team of researchers found that adding formulas for acclimation into climate change models more closely aligns their simulations of carbon exchange with those observed in nature. The accuracy of model projections of carbon flux in tropical forests improved by 36 percent when acclimation was included.
"We want climate models to be as accurate as possible and represent the world in the way we know it to work," Dukes said. "We found that incorporating acclimation into a model helped it represent the tropics much more accurately. This won't dramatically reshape our big-picture understanding of climate change, but it gives us a better idea of how certain regions of the world will respond."
Because carbon dioxide traps heat in the atmosphere, it's important to accurately capture plant carbon exchange rates, said Dukes, who is also director of the Purdue Climate Change Research Center housed in Discovery Park. Less carbon stored in plants and soil means more carbon is in the atmosphere, leading to a warmer planet.
Increased atmospheric CO2 concentrations have already caused large-scale physiological responses of European forests. In particular, the efficiency of water-use of trees, which is coupled to the uptake of CO2 during photosynthesis of leaves and needles has changed significantly. According to the study of a large, interdisciplinary team of researchers, European broadleaf and coniferous trees have increased their water-use efficiency since the beginning of the 20th century by 14% and 22%, respectively.
During photosynthesis trees take up carbon dioxide (CO2) from the air. In return they loose water vapor (H2O) through tiny pores of their leaves or needles, so-called stomata. This gas exchange between trees and the atmosphere is regulated through the opening widths (aperture) of their stomata. Wider apertures of the stomata allow the uptake of higher numbers of CO2 molecules, but promote an increased loss of water vapor (transpiration) into the atmosphere. The opposite holds for narrowed stomatal apertures.
"Assuming that the trees demand for CO2 does not change, they can reduce the aperture of the stomates of their leaves and needles under increasing atmospheric CO2 concentrations. This should lower the rates of transpiration and minimize the tree's water loss", says Gerhard Helle at the GFZ German Research Centre for Geosciences, co-author of the study. "Nevertheless, a 5% increase in European forest transpiration was calculated over the twentieth century. This can likely be attributed to a lengthened growing season, increased transpiration due to a warmer environment, and an enhanced leaf area."
New evidence on the origin of carnivorous plants
Author:
Givnish
Abstract:
Carnivorous plants have fascinated scientists and the general public since the pioneering studies of Charles Darwin (1). No doubt part of their wide appeal is that carnivorous plants have turned the evolutionary tables on animals, consuming them as prey, with the green predators often equipped with remarkable lures, traps, stomachs, and—in a few cases—extraordinary speed of movement. To be considered carnivorous, a plant must be able to absorb nutrients from dead bodies adjacent to its surfaces, obtain some advantage in growth or reproduction, and have unequivocal adaptations for active prey attraction, capture, and digestion (2, 3). Some carnivorous species [e.g., Pinguicula (butterworts), Philcoxia] lack obvious attractants; some rely on passive pitfalls [e.g., Cephalotus (Australian pitcher plant), Sarracenia (American pitcher plants)] rather than active traps based on sticky tentacles [e.g., Byblis, Drosera (sundews)] or snap traps [e.g., Dionaea (Venus fly-trap), Utricularia (bladderworts)]; and some lack digestive enzymes and instead depend on commensal microbes or insect larvae to break down prey (e.g., Brocchinia, Darlingtonia, some species of Sarracenia). Based on these criteria, today we recognize at least 583 species of carnivorous plants in 20 genera, 12 families, and 5 orders of flowering plants (Table 1). Based on DNA sequence phylogenies, these species represent at least nine independent origins of the carnivorous habit per se, and at least six independent origins of pitfall traps, five of sticky traps, two of snap traps, and one of lobster-pot traps. To the extent to which molecular phylogenies have been calibrated against the ages of fossils of other plants, these origins of carnivory appear to have occurred between roughly 8 and 72 million years ago (Mya). In PNAS, Sadowski et al. (4) contribute to our understanding of the origins of plant carnivory by describing the first fossilized trap of a carnivorous plant, a fragment of a tentacled leaf preserved in Baltic amber from 35 to 47 Mya, and allied to modern-day Roridula of monogeneric Roridulaceae (Ericales) from South Africa.
Carnivorous plants catch and digest tiny animals in order and derive benefits for their nutrition. Interestingly the trend towards vegetarianism seems to overcome carnivorous plants as well. The aquatic carnivorous bladderwort, which can be found in many lakes and ponds worldwide, does not only gain profit from eating little animals but also by consuming algae and pollen grains. This results in survival in aquatic habitats where prey animals are rare, and in increased fitness if the animals and algae are caught in a well-balanced diet. An Austrian research group around Marianne Koller-Peroutka and Wolfram Adlassnig published these results in the respected journal Annals of Botany.
The bladderworts (Utricularia) are one of the largest genera in carnivorous plants with over 200 species. Aquatic bladderworts catch their prey with highly sophisticated suction traps consisting of little bladders that produce a hydrostatic under pressure. A valve-like trap door opens upon stimulation and the surrounding water including tiny organism flushes in rapidly within three milliseconds. Once inside the trap, the prey dies of suffocation and is degraded by digestive enzymes. Due to the minerals provided by prey organisms, bladderworts are able to live and propagate even in habitats that are extremely poor in nutrients.
Increased carbon dioxide in the atmosphere is known to boost vegetation cover at high latitudes — and this could accelerate Arctic warming year-round.
Grasses and shrubs have a warming effect because plant-covered areas reflect less sunlight than barren surfaces do. Baek-Min Kim at the Korea Polar Research Institute in Incheon, South Korea, Sang-Yoon Jun at the Korea Institute of Atmospheric Prediction Systems in Seoul and their colleagues used a climate model to study the impact of doubled CO2 concentrations and increased high-latitude plant growth on Arctic temperatures.
They found that increased vegetation in summer warms the surface and this heat moves to the Arctic, where it causes additional ocean warming and sea-ice melting in winter and spring. The exposed ocean then releases more heat, leading to a further boost in Arctic warming and promoting even more plant growth the following season, the team says.
It is difficult to find fault with a process that can create food from sunlight, water and air, but for many plants, there is room for improvement. Researchers have taken an important step towards enhancing photosynthesis by engineering plants with enzymes from blue-green algae that speed up the process of converting carbon dioxide into sugars.
The results, published today in Nature, surmount a daunting hurdle on the path to boosting plant yields — a goal that is taking on increasing importance as the world’s population grows.
“With the limited ability to increase land use for agriculture, there’s a huge interest in trying to improve yield across all the major crops,” says Steven Gutteridge, a research fellow at chemical firm DuPont’s crop-protection division in Newark, Delaware.
Researchers have long wanted to increase yields by targeting Rubisco, the enzyme responsible for converting carbon dioxide into sugar. Rubisco is possibly the most abundant protein on Earth, and can account for up to half of all the soluble protein found in a leaf.
But one reason for its abundance is its inefficiency: plants produce so much Rubisco in part to compensate for its slow catalysis. Some have estimated that tinkering with Rubisco and ways to boost the concentration of carbon dioxide around it could generate up to a 60% increase in the yields of crops such as rice and wheat.
Reconstructing the impact of human activities in a NW Iberian Roman mining landscape for the last 2500 years
Authors:
López-Merino et al
Abstract:
Little is known about the impact of human activities during Roman times on NW Iberian mining landscapes beyond the geomorphological transformations brought about by the use of hydraulic power for gold extraction. We present the high-resolution pollen record of La Molina mire, located in an area intensely used for gold mining (Asturias, NW Spain), combined with other proxy data from the same peat core to identify different human activities, evaluate the strategies followed for the management of the resources and describe the landscape response to human disturbances. We reconstructed the timing and synchronicity of landscape changes of varying intensity and form occurred before, during and after Roman times. An open landscape was prevalent during the local Late Iron Age, a period of relatively environmental stability. During the Early Roman Empire more significant vegetation shifts took place, reflected by changes in both forest (Corylus and Quercus) and heathland cover, as mining/metallurgy peaked and grazing and cultivation increased. In the Late Roman Empire, the influence of mining/metallurgy on landscape change started to disappear. This decoupling was further consolidated in the Germanic period (i.e., Visigothic and Sueve domination of the region), with a sharp decrease in mining/metallurgy but continued grazing. Although human impact was intense in some periods, mostly during the Early Roman Empire, forest regeneration occurred afterwards: clearances were local and short-lived. However, the Roman mining landscape turned into an agrarian one at the onset of the Middle Ages, characterized by a profound deforestation at a regional level due to a myriad of human activities that resulted in an irreversible openness of the landscape.
Fifty-five million years ago, when scientists believe the Earth was in a near-runaway state, dangerously overheated by greenhouse gases, the Arctic Ocean was also a very different place. It was a large lake, connected to the greater oceans by one primary opening: the Turgay Sea.
When this channel closed or was blocked nearly 50 million years ago, the enclosed body of water became the perfect habitat for a small-leaved fern called Azolla. Imagine the Arctic like the Dead Sea of today: It was a hot lake that had become stratified, suffering from a lack of exchange with outside waters. That meant its waters were loaded with excess nutrients.
Azolla took advantage of the abundant nitrogen and carbon dioxide, two of its favorite foods, and flourished. Large populations formed thick mats that covered the body of the lake. When rainfall increased from the changing climate, flooding provided a thin layer of fresh water for Azolla to creep outward, over parts of the surrounding continents.
Azolla bloomed and died like this in cycles for roughly 1 million years, each time laying down an additional layer of the thick blanket of sediment that was finally found in 2004 by the Arctic Coring Expedition.
The fact that the fern only needs a little over an inch of water under it to grow makes the whole scenario seem just within reason—that is, until you learn how much carbon this carbon dioxide-hungry plant sucked up over the course of those million years.
"Around half of the CO2 available at the time," said Jonathan Bujak, who studies dust and fine plant particles as a palynologist. "Levels dropped from between 25,000 and 35,000 [parts per million] to between 15,000 and 16,000 ppm."
While what ended the Azolla age remains unclear, the next 49 million years saw the Earth fall into a cycle that brought even more drastic drops in CO2 levels.
The southern continents broke up, and, as South America and India migrated north, the Antarctic become isolated and increasingly cold, absorbing more CO2 and creating a conveyor-belt-like effect of cold air that perpetuated ice. A succession of ice ages was triggered once the atmosphere's CO2 dropped below 600 ppm around 2.6 million years ago, just 200 ppm shy of the Earth's current estimate.
Cyclical glacial ages began, rotating between 100,000 years of massive glaciers, followed by 10,000-year breaks. By the mid-18th century, CO2 levels were at 280 ppm.
Elevated CO2 further lengthens growing season under warming conditions
Authors:
Reyes-Fox et al
Abstract:
Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2—which can delay annual life cycle events —on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles.
or those of us without a green thumb, growing even the most hardy plants in perfect conditions can seem impossible. How about trying to grow plants on a meteorite? Well, at least one scientist is doing it, with moderate levels of success.
The thinking goes—if we're going to have space colonies, we're going to need some way to eat. Transporting all food from Earth isn't realistic, and neither is bringing tons of bags of topsoil. Photos of asteroids, meteors, and other planets in our solar system look incredibly desolate, but, in fact, some of them contain many of the nutrients necessary to grow plants.
"People have been talking about terraforming, but what I'm trying to do is give some concrete evidence that it's possible to do this, that it's possible to grow in extraterrestrial materials," Michael Mautner, a Virginia Commonwealth University researcher and one of the world's only "astroecologists" told me. "What I've found is that a range of microorganisms—bacteria, fungi, and even asparagus and potato plants—can survive with the nutrients that are in extraterrestrial materials."
Asteroids and meteorites often contain phosphate, nitrates, and even water that plants can feed on. Mautner thinks it's not outside the realm of possibility to directly grow certain plants on other planets, in some sort of protected environment.
He's not simply tossing asparagus seeds onto a meteorite, however—he's grinding up the rock into something more closely resembling soil. His plan is to eventually find several different plants and extraterrestrial soils that make the most sense to farm, and use his experiments to develop a "rating system" for which are likely to fare best—a kind of interplanetary farmer's almanac, if you will.
Of course, Mautner is doing these experiments on Earth, and it's worth taking his results with more than a grain of salt—he's not considering the lack of oxygen on other planets and the different gravity conditions.
"The conditions outside Earth are presumably anaerobic—that's an order of magnitude harder to do," he said. "But, if we can find things that can grow in extraterrestrial materials under Earth conditions, you can start to talk about it. We can maybe start to use those materials in artificial, oxygen-containing environments."
Can plants and animals evolve to keep pace with climate change? A study published May 19 in the journal Proceedings of the National Academy of Sciences shows that for at least one widely-studied plant, the European climate is changing fast enough that strains from Southern Europe already grow better in the north than established local varieties.
Small and fast-growing, Arabidopsis thaliana is widely used as the "lab mouse" of plant biology. The plant grows in Europe from Spain to Scandinavia and because Arabidopsis is so well-studied, there is a reference collection of seeds derived from wild stocks across its native range. Originally collected from 20 to 50 years ago, these plants have since been maintained under controlled conditions in the seed bank.
Johanna Schmitt, formerly at Brown University and now a distinguished professor in the UC Davis Department of Evolution and Ecology, and colleagues took banked seed samples originally from Spain, England, Germany and Finland and raised all the plants in gardens in all four locations.
"The southern imports do better across the range than locals," Schmitt said. "This shows that the adaptive optimum has moved really fast."
Seed stocks banked decades ago may no longer be the best for their locations of origin, she said, although they still may be critical for preserving genetic diversity, especially from warmer parts of the species range that may facilitate adaptation to future climates.
Scientists from the University of the Philippines, Los Baños have discovered a new plant species with an unusual lifestyle — it eats nickel for a living — accumulating up to 18,000 ppm of the metal in its leaves without itself being poisoned, says Professor Edwino Fernando, lead author of the report. Such an amount is a hundred to a thousand times higher than in most other plants. The study was published in the open access journal PhytoKeys.
The new species is called Rinorea niccolifera, reflecting its ability to absorb nickel in very high amounts. Nickel hyperaccumulation is such a rare phenomenon with only about 0.5–1% of plant species native to nickel-rich soils having been recorded to exhibit the ability. Throughout the world, only about 450 species are known with this unusual trait, which is still a small proportion of the estimated 300,000 species of vascular plants.
The new species, according to Dr Marilyn Quimado, one of the lead scientists of the research team, was discovered on the western part of Luzon Island in the Philippines, an area known for soils rich in heavy metals.
Storytelling and story testing in domestication
Authors:
Gerbault et al
Abstract:
The domestication of plants and animals marks one of the most significant transitions in human, and indeed global, history. Traditionally, study of the domestication process was the exclusive domain of archaeologists and agricultural scientists; today it is an increasingly multidisciplinary enterprise that has come to involve the skills of evolutionary biologists and geneticists. Although the application of new information sources and methodologies has dramatically transformed our ability to study and understand domestication, it has also generated increasingly large and complex datasets, the interpretation of which is not straightforward. In particular, challenges of equifinality, evolutionary variance, and emergence of unexpected or counter-intuitive patterns all face researchers attempting to infer past processes directly from patterns in data. We argue that explicit modeling approaches, drawing upon emerging methodologies in statistics and population genetics, provide a powerful means of addressing these limitations. Modeling also offers an approach to analyzing datasets that avoids conclusions steered by implicit biases, and makes possible the formal integration of different data types. Here we outline some of the modeling approaches most relevant to current problems in domestication research, and demonstrate the ways in which simulation modeling is beginning to reshape our understanding of the domestication process.
During the age of the dinosaurs, the arrival of flowering plants as competitors could have spelled doom for the ancient fern lineage. Instead, ferns diversified and flourished under the new canopy -- using a mysterious gene that helped them adapt to low-light environments.
A team led by Duke University scientists has pinpointed the curious origins of this gene and determined that it was transferred to ferns from a group of unassuming moss-like plants called hornworts. The findings were announced today, April 14, in the Proceedings of the National Academy of Sciences.
For years, researchers have suspected that a gene called neochrome played a role in the evolution of ferns. Neochrome is a hybrid of two other plant genes which code for photoreceptor proteins that sense blue and red light.
"Neochrome is a 'chimeric' gene," said Fay-Wei Li, lead author and Ph.D. student in Duke's biology department. It produces a photoreceptor that senses both blue and red light, affording ferns a unique advantage in forests shaded by flowering plants. "Most plants sense and grow toward blue light, but under the canopy, the filtered light spectrum has more red light than blue."
"Neochrome helped ferns to 'see' better," Li said. What hasn't been crystal clear is the gene's origin. Li set out to investigate its evolution by systematically combing through plant genomes from the Duke Herbarium and 1000 Plants Initiative.
Neochrome turned up in a surprising place: the genomes of hornworts, a damp-loving plant group related to mosses.
Three scenarios could have explained how the gene came to be shared by ferns and hornworts: 1) a common ancestor that had the gene; 2) independent evolution of the gene in both groups; or 3) a process called horizontal gene transfer, which ferried neochrome from one group to the other.
To sort out these theories, the team looked not only at the evolutionary relationships of land plants and algae, but also at how all of their light-sensitive genes were related.
Ferns and hornworts diverged in evolution 400 million years ago. If neochrome came from a common ancestor, it would have been passed on to many other plant families, too. But then it had to have been lost in all but the ferns, since no seed plants still have it. The analysis also didn't support the idea that an unusual gene like neochrome evolved independently in both hornworts and ferns.
What the scientists found instead was strong evidence that the fern version of neochrome descended from the hornwort version. By looking at sequence changes in the gene's various spellings, they constructed a family tree of light-sensitive genes, in which fern neochrome "nested" neatly within the hornwort lineage. The analysis also showed that the gene versions separated about 179 million years ago.
Only one mechanism could explain how the gene hopped from hornworts to ferns so long after the lineages themselves diverged: horizontal gene transfer. But researchers have only just begun to explore how this occurs in plants.
link.
A team of researchers studying plants has assembled the largest dated evolutionary tree, using it to show the order in which flowering plants evolved specific strategies, such as the seasonal shedding of leaves, to move into areas with cold winters. The researchers, including University of Minnesota professor Peter Reich, will publish their findings Sunday, Dec. 22 in the journal Nature.
Early flowering plants are thought to have been woody— maintaining a prominent stem above ground across years and changing weather conditions, such as maple trees—and restricted to warm, wet tropical environments. But they have since put down roots in chillier climates, dominating large swaths of the globe where freezing occurs. How they managed this expansion has long vexed researchers searching for plants' equivalent to the winter parka.
"Freezing is a challenge for plants. Their living tissues can be damaged. It's like a plant's equivalent to frostbite. Their water-conducting pipes can also be blocked by air bubbles as water freezes and thaws," said Amy Zanne, the study's lead author and an assistant professor of biology in the George Washington University's Columbian College of Arts and Sciences.
More than 25 scientists with a wide variety of expertise worked together on this study.
"We wanted to understand more about how plants came to have evolved the traits that allow them to withstand cold," Reich said.
The newly sequenced genome of the Amborella plant addresses Darwin's "abominable mystery" -- the question of why flowers suddenly proliferated on Earth millions of years ago. The genome sequence sheds new light on a major event in the history of life on Earth: the origin of flowering plants, including all major food crop species. On 20 December 2013, a paper by the Amborella Genome Sequencing Project that includes a full description of the analyses performed by the project, as well as implications for flowering plant research, will be published in the journal Science. The paper is among three on different research areas related to the Amborella genome that will be published in the same issue of the journal.
Amborella (Amborella trichopoda) is unique as the sole survivor of an ancient evolutionary lineage that traces back to the last common ancestor of all flowering plants. The plant is a small understory tree found only on the main island of New Caledonia in the South Pacific. An effort to decipher the Amborella genome -- led by scientists at Penn State University, the University at Buffalo, the University of Florida, the University of Georgia, and the University of California-Riverside -- is uncovering evidence for the evolutionary processes that paved the way for the amazing diversity of the more than 300,000 flowering plant species we enjoy today.
This unique heritage gives Amborella a special role in the study of flowering plants. "In the same way that the genome sequence of the platypus -- a survivor of an ancient lineage -- can help us study the evolution of all mammals, the genome sequence of Amborella can help us learn about the evolution of all flowers," said Victor Albert of the University at Buffalo.
Scientists who sequenced the Amborella genome say that it provides conclusive evidence that the ancestor of all flowering plants, including Amborella, evolved following a "genome doubling event" that occurred about 200 million years ago. Some duplicated genes were lost over time but others took on new functions, including contributions to the development of floral organs.
In the life cycle of plants, most developmental processes are dependent on light. Significant biological processes such as germination, shade avoidance, circadian rhythms, and flower induction are all affected by light. Recent advancements in the use of LED lighting in plant and vegetable production systems has researchers looking for insights into the effects of these artificial lights on the growth and yield of crops. Scientists from the Department of Horticultural Science at Chungbuk National University published a study in HortScience that sheds some light on the advantages and challenges of LEDs in lettuce cultivation.
The increased use of LEDs in environmentally controlled closed-type plant production systems allows crop production throughout the year, regardless of external weather conditions. According to authors Ki-Ho Son and Myung-Min Oh, LEDs have some advantages over traditional lighting sources in plant cultivation. "LEDs have the advantages of high light-conversion efficiency with low radiant heat output, semipermanence, and small mass," they noted. "In addition, LEDs are available in a variety of narrow wavebands; hence, it is possible to optimize light quality to improve both crop yield and quality." They explained that blue and red LEDs are usually used for plant growth because chlorophyll a and b efficiently absorb wavelengths in the blue and red ranges.
The research design used red and green leaf lettuce subjected to six LED lighting treatments. The scientists examined growth characteristics including the fresh and dry weights of shoots and roots, shoot-to-root ratio, total leaf area, and chlorophyll content. Chlorophyll fluorescence, antioxidant capacity, phenolic concentration, and flavonoid concentration were also measured in the study. "The growth characteristic results for the two lettuce cultivars grown under various ratios of blue to red LEDs confirmed that red LED serves as a major light source that improves lettuce growth rate," the authors said.
The experiments confirmed that both blue and red LEDs have a positive effect on the accumulation of antioxidant phenolic compounds and lettuce growth, respectively. "Red light irradiation in the absence of blue light was effective at stimulating the biomass accumulation of lettuce plants; however, this lighting alone induced abnormal leaf shape and had a negative effect on polyphenolics and antioxidant levels," the scientists said. They recommended a mixture of blue and red LEDs to enhance lettuce crop quality and yield in closed-type plant production systems.
