Not just CO2: Rising temperatures also alter photosynthesis in a changing climate

UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN, NEWS BUREAU

Research News

 

IMAGE: RISING TEMPERATURES ASSOCIATED WITH CLIMATE CHANGE AFFECT PLANTS' ABILITY TO MAINTAIN THEIR STRUCTURAL INTEGRITY, ABSORB CARBON DIOXIDE, RETAIN WATER, AND GROW AND REPRODUCE. view more 

CREDIT: GRAPHIC BY JULIE MCMAHON

CHAMPAIGN, Ill. -- Agricultural scientists who study climate change often focus on how increasing atmospheric carbon dioxide levels will affect crop yields. But rising temperatures are likely to complicate the picture, researchers report in a new review of the topic.

Published in the Journal of Experimental Botany, the review explores how higher temperatures influence plant growth and viability despite the greater availability of atmospheric CO2, a key component of photosynthesis.

Excessive heat can reduce the efficiency of enzymes that drive photosynthesis and can hinder plants' ability to regulate CO2 uptake and water loss, the researchers write. Structural features can make plants more - or less - susceptible to heat stress. Ecosystem attributes - such as the size and density of plants, the arrangement of leaves on plants or local atmospheric conditions - also influence how heat will affect crop yields.

The review describes the latest scientific efforts to address these challenges.

"It's important to have an understanding of these issues across scales - from the biochemistry of individual leaves to ecosystem-level influences - in order to really tackle these problems in an informed way," said lead author Caitlin Moore, a research fellow at the University of Western Australia and an affiliate research fellow at the Institute for Sustainability, Energy, and Environment at the University of Illinois Urbana-Champaign. Moore led the review with Amanda Cavanagh, another U. of I. alumna now at the University of Essex in the U.K.

"Historically, there's been a lot of focus on rising CO2 and the impact that it has on plants," said co-author Carl Bernacchi, a professor of plant biology and of crop sciences and an affiliate of the Carl R. Woese Institute for Genomic Biology at the U. of I. "And it is an important factor, because we are changing that carbon dioxide concentration enormously. But it's a small part of the bigger story. Once you throw changing temperatures into the mix, it completely messes up our understanding of how plants are going to respond."

"Take Rubisco, the key enzyme that fixes carbon dioxide into sugars, making life on Earth possible," Cavanagh said. "Rubisco speeds up as the temperature increases, but it's also prone to making mistakes."

Instead of fixing carbon dioxide by binding it to sugars, a key step in photosynthesis, Rubisco sometimes fixes oxygen, initiating a different pathway that wastes a plant's resources. Higher temperatures make this more likely, Cavanagh said. At even higher temperatures, the enzyme will begin to lose its structural integrity, making it ineffective.

Excessive heat can also undermine a plant's reproductive output. Other heat-sensitive enzymes are essential to the light-harvesting machinery of plants or play a role in moving sugars to different plant tissues, allowing the plant to grow and produce grains or fruits.

"If these little molecular machines are pushed out of the temperature range that's optimal, then they can't do their job," Cavanagh said.

When temperatures rise too high, plant leaves open the pores on their surfaces, called stomata, to cool themselves. Stomata also allow plants to absorb carbon dioxide from the atmosphere, but when they're fully open, the leaf can lose too much moisture.

"Temperature affects the atmosphere above the plant," Moore said. "As the atmosphere heats up, it can hold additional water, so it's pulling more water from the plants."

Scientists at Illinois and elsewhere are looking for ways to enhance crop plants' resilience in the face of these changes. Moore, whose work focuses on ecosystem-scale factors, said new tools that can help screen plants on a large scale are essential to that effort. For example, satellites that can detect changes in chlorophyll fluorescence in plants can indicate whether a crop is under heat stress. These changes in fluorescence are detectable before the plant shows any outward sign of heat stress - such as their leaves turning brown. Developing these tools may enable farmers to respond more quickly to crop stress before too much damage is done.

Cavanagh, who studies the molecular biology and physiology of plants, said some plants are more heat tolerant than others, and scientists are searching their genomes for clues to their success.

"For example, you can look at wild Australian relatives of rice that are growing in much harsher climates than most paddy rices," she said. "And you see that their enzymes are primed to work more efficiently at hotter temperatures."

One goal is to transfer heat-tolerant genes to cultivated rice varieties that are more susceptible to heat stress.

Other strategies include engineering structures that pump more CO2 to the site of carbon fixation to improve Rubisco efficiency; altering the light-gathering properties of leaves at the tops and bottoms of plants to even out distribution of sunlight and maintain moisture levels; and changing the density of stomata to improve their control of CO2 influx and moisture loss.

Collaboration between scientists focused on different scales of ecosystem and plant function - from the atmospheric to the molecular - is essential to the success of efforts to build resilience in crop plants, the researchers said.

"The world is getting hotter at a shocking rate," Cavanagh said. "And we know from global models that each increase in gross temperature degree Celsius can cause 3% to 7% losses in yield of our four main crops. So, it's not something we can ignore.

"What makes me optimistic is the realization that so much work is going into globally solving this problem," she said.

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From left, Caitlin Moore, Carl Bernacchi, Katherine Meacham-Hensold and their colleagues review how rising temperatures affect photosynthesis in plants and how scientists are addressing the challenges.

CREDIT

Photo by Claire Benjamin/RIPE project

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Co-author Amanda Cavanagh studies the molecular biology and physiology of plants.

CREDIT

Photo by Claire Benjamin/RIPE project

Cavanagh and Bernacchi are affiliates of the Realizing Increased Photosynthetic Efficiency project at the U. of I. Moore also is an affiliate of the Center for Advanced Bioenergy and Bioproducts Innovation at Illinois. Bernacchi is a research plant physiologist for the U.S. Department of Agriculture, Agricultural Research Service.

The paper "The effect of increasing temperature on crop photosynthesis: From enzymes to ecosystems" is available online and from the U. of I. News Bureau.

 

NTU Singapore scientists develop device to 'communicate' with plants using electrical signals

NANYANG TECHNOLOGICAL UNIVERSITY

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VIDEO: PLANT TALK: A TEAM OF SCIENTISTS LED BY #NTUSG? HAS DEVELOPED A DEVICE THAT CAN 'COMMUNICATE' WITH PLANTS BY DELIVERING ELECTRICAL SIGNALS TO AND FROM PLANTS. POTENTIAL USES OF THE... view more 

CREDIT: NTU SINGAPORE

A team of scientists led by Nanyang Technological University, Singapore (NTU Singapore) has developed a device that can deliver electrical signals to and from plants, opening the door to new technologies that make use of plants.

The NTU team developed their plant 'communication' device by attaching a conformable electrode (a piece of conductive material) on the surface of a Venus flytrap plant using a soft and sticky adhesive known as hydrogel. With the electrode attached to the surface of the flytrap, researchers can achieve two things: pick up electrical signals to monitor how the plant responds to its environment, and transmit electrical signals to the plant, to cause it to close its leaves.

Scientists have known for decades that plants emit electrical signals to sense and respond to their environment. The NTU research team believe that developing the ability to measure the electrical signals of plants could create opportunities for a range of useful applications, such as plant-based robots that can help to pick up fragile objects, or to help enhance food security by detecting diseases in crops early.

However, plants' electrical signals are very weak, and can only be detected when the electrode makes good contact with plant surfaces. The hairy, waxy, and irregular surfaces of plants make it difficult for any thin-film electronic device to attach and achieve reliable signal transmission.

To overcome this challenge, the NTU team drew inspiration from the electrocardiogram (ECG), which is used to detect heart abnormalities by measuring the electrical activity generated by the organ.

Transmitting electrical signals to create an on demand plant-based robot

As a proof-of concept, the scientists took their plant 'communication' device and attached it to the surface of a Venus flytrap - a carnivorous plant with hairy leaf-lobes that close over insects when triggered.

The device has a diameter of 3 mm and is harmless to the plant. It does not affect the plant's ability to perform photosynthesis while successfully detecting electrical signals from the plant. Using a smartphone to transmit electric pulses to the device at a specific frequency, the team elicited the Venus flytrap to close its leaves on demand, in 1.3 seconds.

The researchers have also attached the Venus flytrap to a robotic arm and, through the smartphone and the 'communication' device, stimulated its leaf to close and pick up a piece of wire half a millimetre in diameter.

Their findings, published in the scientific journal Nature Electronics in January, demonstrate the prospects for the future design of plant-based technological systems, say the research team. Their approach could lead to the creation of more sensitive robot grippers to pick up fragile objects that may be harmed by current rigid ones.

Picking up electrical signals to monitor crop health monitoring

The research team envisions a future where farmers can take preventive steps to protect their crops, using the plant 'communication' device they have developed.

Lead author of the study, Chen Xiaodong, President's Chair Professor in Materials Science and Engineering at NTU Singapore said: "Climate change is threatening food security around the world. By monitoring the plants' electrical signals, we may be able to detect possible distress signals and abnormalities. When used for agriculture purpose, farmers may find out when a disease is in progress, even before full?blown symptoms appear on the crops, such as yellowed leaves. This may provide us the opportunity to act quickly to maximise crop yield for the population."

Prof Chen, who is also Director of the Innovative Centre for Flexible Devices (iFLEX) at NTU, added that the development of the 'communication' device for plants monitoring exemplifies the NTU Smart Campus vision which aims to develop technologically advanced solutions for a sustainable future.

Next generation improvement: Liquid glue with stronger adhesive strength

Seeking to improve the performance of their plant 'communication' device, the NTU scientists also collaborated with researchers at the Institute of Materials Research and Engineering (IMRE), a unit of Singapore's Agency for Science, Technology and Research (A*STAR).

Results from this separate study, published in the scientific journal Advanced Materials in March, found that by using a type of hydrogel called thermogel - which gradually transforms from liquid to a stretchable gel at room temperature - it is possible to attach their plant 'communication' device to a greater variety of plants (with various surface textures) and achieve higher quality signal detection, despite plants moving and growing in response to the environment.

Elaborating on this study, co-lead author Professor Chen Xiaodong said, "The thermogel-based material behaves like water in its liquid state, meaning that the adhesive layer can conform to the shape of the plant before it turns into a gel. When tested on hairy stems of the sunflower for example, this improved version of the plant 'communication' device achieved four to five times the adhesive strength of common hydrogel and recorded significantly stronger signals and less background noise."

Co-lead author of the Advanced Materials study and Executive Director of IMRE, Professor Loh Xian Jun, said: "The device can now stick to more types of plant surfaces, and more securely so, marking an important step forward in the field of plant electrophysiology. It opens up new opportunities for plant-based technologies."

Moving forward, the NTU team is looking to devise other applications using the improved version of their plant 'communication' device

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Members of the research team include (top L-R) NTU Prof Chen Xiaodong, A*STAR Prof Loh Xian Jun, PhD students from the NTU School of Materials Science and Engineering, (bottom L-R) Li Wenlong and Luo Yifei.

CREDIT

NTU Singapo

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The plant 'communication' device is attached on the surface of a Venus flytrap plant.

CREDIT

NTU S

 

While drowning numbers soar, beach safety programs are largely unevaluated

Australia may be leading the way on coastal drowning research, but a study led by UNSW has identified the need for more evidence to support prevention strategies.

UNIVERSITY OF NEW SOUTH WALES

Research News

 

A global review of coastal drowning science has found there is only one study worldwide that has evaluated beach safety education programs in schools.

Researchers from UNSW's Beach Safety Research Group have conducted the first in-depth review specific to coastal drowning.

The study, published in PLOS ONE, reviewed 146 coastal drowning studies from around the world.

"We found that evaluation of coastal drowning prevention strategies is rare," said William Koon, the lead author of the study and a PhD candidate in the School of Biological, Earth and Environmental Sciences said.

"This means we simply don't have enough data showing what works and what doesn't work.

"There was only one study worldwide - involving a private primary school in Queensland - to see if beach safety education program is effective in schools."

Since the review, an additional school-based evaluation of water safety virtual reality programs in Victoria has been published.

Mr Koon said the review's findings are concerning as tens of thousands of Australian primary and secondary school students participate in beach or water safety programs from lifeguards and lifesavers every year.

"There is remarkably little information out there to say [firstly], does it work and [secondly], here's how it works best," Mr Koon said.

"We need to assess if programs function as intended, and continually refine them to improve effectiveness."

Researchers and UNSW Beach Safety Research Group founding members Dr Amy Peden, Dr Jaz Lawes and Professor Rob Brander were also involved in the study.

"I find it interesting that over the last 16 years we haven't really seen any improvement in the number of coastal drownings each year in Australia, despite lots of ongoing school and public education programs," Professor Brander said.

The study found that more than three-quarters (76.7%) of coastal drowning research was from high-income countries. Australia is leading the way with 49 studies, followed by the US (28 studies).

It also found that existing drowning prevention strategies are largely un-evaluated, with little research being done in low-income countries where a majority of drowning events occur.

Mr Koon said while there were 125 coastal drowning deaths in Australia last year, the World Health Organisation estimates that more than 90 percent of all drowning occurs in low-and middle-income countries.

He said to address this global health problem, researchers need to start looking to local data from lower-resourced settings to understand the coastal safety issues there and prioritise drowning prevention programs for different groups of people.

"Researchers like myself need to ask 'is what I learned from Australian coastal safety research applicable to a place like Ghana or Costa Rica or India, where similar hazards exist, but the cultural context is very different'," he said.

The researchers conducted the review to better understand the science driving safety initiatives and highlight gaps in the field of coastal drowning, in order to prioritise future studies and prevention initiatives that will ultimately save lives.

They focused on fatal unintentional coastal drowning that was unrelated to boating, disaster (ie cyclones) or occupational accidents (ie commercial fishermen or scuba divers).

They found studies inconsistently reported intentional, occupational and boating coastal drowning deaths, and the terminology used to describe coastal waters was also non-uniform.

"Reviews such as this one are so important as they highlight gaps in the current evidence base, identifying opportunities for future research to really make a difference, rather than more of the same," study co-author Dr Amy Peden, from the UNSW School of Population Health said.

Over 100 different risk factors related to coastal drowning were identified, but the data sources, outcomes used, and analyses employed were variable.

"What we learned is that the consistency in reporting and analysing of these different scenarios was just all over the place," Mr Koon said. "Not every place in the world is recording drowning in the same way.

Studies were also published in a variety of journals representing different disciplines.

Many studies recommended prevention measures, most frequently related to education, lifeguards and signage.?

"Is that enough? Are these efforts working? How well? We don't have enough data to answer these questions," Mr Koon said.

There are limited resources for evaluations on water safety programs, he said.

"But someone with a long-term view should start to see that investment in monitoring and evaluation is a way to really make sure the work is doing what it's supposed to do," he said. He says it is important to continue to refine school water safety programs.

"There are probably different lessons to be learned, such as messaging at different ages, whether that's stopping to look for rips or putting on sunscreen, avoiding alcohol or avoiding jumping off rocks and cliffs.

He said there has been "remarkably little information" studying prevention measures.

"Research on danger signs on beaches has already told us that people don't really look at signs, and if they do, are not really influenced to change decisions or behaviour," he said.

"We're still in the stage where most programs are driven by expert opinion without much supporting data."

He said Australia continues to lead the world in drowning prevention and water safety research because organisations like Surf Life Saving Australia and Royal Life Saving Society - Australia maintain robust databases, with some of the most detailed drowning data in the world.

UNSW Beach Safety Research Group researchers are currently working with Lake Macquarie lifeguards to evaluate a beach safety program which they deliver to high school students.

"We hope to be able to offer some recommendations on how other people in the industry can move forward with evaluating some of their school and other beach safety education programs," he said.

"As our review has shown, the kind of information this evaluation will yield addresses a massive gap in our understanding of what's effective and what's not in the drowning prevention education space," Dr Peden said.

"Identifying what can improving safety and reduce young people's risk of drowning during adolescence can result in positive behaviours throughout adulthood."

Deforestation taking a heavy toll on international bird haven

UNIVERSITY OF QUEENSLAND

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IMAGE: FORK-TAILED WOODNYMPH view more 

CREDIT: PABLO NEGRET

An analysis has found deforestation is severely affecting forest bird species in Colombia, home to the greatest number of bird species in the world.

University of Queensland-led research, steered by Dr Pablo Negret, analysed the impact of deforestation on 550 bird species, including 69 only found in the South American nation.

"Our study has shown an astonishing reduction in bird species habitat," Dr Negret said.

"One third of the forest bird species in Colombia have lost at least a third of their historical habitat, and that's just using the most recent data we have available - from 2015.

"Moreover, 18 per cent or 99 species have lost more than half of their historical habitat to date.

"By 2040, we expect this will increase to 38 per cent or 209 species.

"Sadly, many of those species are endemic to the country and are not currently classified as threatened by the International Union for Conservation of Nature, suggesting that there are many unlisted species that face an imminent extinction threat from ongoing habitat loss."

Dr Negret said the results were concerning but not surprising.

"Deforestation is one of the main drivers of habitat loss for many species in the tropics," he said.

"We know that deforestation affects thousands of species in these ecosystems, but our attention is usually focused on a tiny fraction - threatened and charismatic species.

"This study provides more data on species previously thought abundant that are actually dwindling - hopefully we can shine a light on them, so they can be recognised as under threat and don't fall through the cracks."

The researchers used historical and present satellite forest cover data, while collating spatial information on other variables associated with deforestation patterns.

UQ's Professor Martine Maron said the research would help predict future habitat loss for already-threatened species.

"This methodology, and the technologies behind it, allow us to identify places where future habitat loss is predicted.

"This means that we can reveal the locations where threatened species are most likely to lose precious habitat, and prioritise their protection.

"And, in a country with growing threats to rich bird diversity, it pays to be ahead of the game."

The authors hope the Colombian government and NGOs working in this space will use the research to guide conservation of Colombia's bird species.

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The study is published in Biological Conservation DOI: 10.1016/j.biocon.2021.109

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Golden-collared toucanet

CREDIT

Pablo Negret

 

Roof-tiles in imperial China: Creating Ximing Temple's lotus-pattern tile ends

Researchers from Kanazawa University and the Chinese Academy of Social Sciences cast light on the production of roof tiles during the Tang dynasty through a study of variations in lotus-pattern tile ends recovered from the Ximing Temple in Xi'an

KANAZAWA UNIVERSITY

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IMAGE: BASIC INFORMATION ABOUT TILE ENDS AND IMBRICES. THE FIGURE SHOWS THE STRUCTURE OF A TILE END AND HOW TILE ENDS AND IMBRICES ARE USED. view more 

CREDIT: KANAZAWA UNIVERSITY

Kanazawa, Japan -- Any visitor to China will have noticed the spectacular roofs on buildings dating from imperial times. However, the question of how these roof tiles were produced has attracted relatively little attention from archaeologists. Now, a team of researchers has conducted a major study of tile ends unearthed at the Ximing Temple in Xi'an, yielding exciting insights into their production.

In a study published in Archaeological Research in Asia, researchers from Kanazawa University and the Chinese Academy of Social Sciences have revealed the significance of minute variations in the tile ends used in the roof of the famous Ximing Temple in Xi'an, built during the Tang dynasty (618-907 AD) when Xi'an (then known as Chang'an) was the imperial capital.

The researchers conducted an investigation of 449 tile ends with lotus patterns from various periods during the Tang dynasty that had been recovered from the Ximing Temple. "We were interested in the variations in the tile ends, both those within the conscious control of the artisans who made the tiles, such as whether to use simple or complex lotus patterns, and those outside their control, such as the marks left by the deterioration of the molds used to make the tiles," says lead author of the study Meng Lyu.

"We discovered that the degree of minor variation in the tile ends increases significantly in the later samples," adds author Guoqiang Gong. "This suggests to us that there was a shift away from the centralized manufacturing of imperial building materials during the Early Tang period toward one in which small private artisans played an important role in the Late Tang period."

Intriguingly, the study has revealed traces of the coming together of two distinct cultural traditions. "We found that there were, in fact, two separate production systems at work to make the title ends," notes author Chunlin Li. "One produced tile ends with compound petal patterns and curved incisions, whereas the other made end tiles with simple petal patterns and scratched incisions." These two styles may ultimately have their origins during an earlier historical period when the Northern Wei dynasty was divided into two regimes on either side of the Taihang mountain range.

This study demonstrates that studying the roof tiles of China's grand imperial buildings can reveal a great deal about the circumstances of their production and yield insights into larger historical questions.

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Shaping stage in production process of tile end. The shaping stage in tile-end production process is most likely to have followed this sequence: 1. Design; 2. Making first-level mold; 3. Making ceramic second-level mold; 4. Making tile end. The use of two different levels of mold enabled artisans to produce the needed numbers over a relatively short period of time.

CREDIT

Kanazawa University

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Incisions on the back surfaces of tile ends and patterns on the front surfaces. Artisans firmly joined tile ends to imbrices through a process which left obvious traces on the back surfaces of the tile ends. Tile ends with simple petals mostly contain thin, radially oriented scratched incisions (Fig. 3.1), while those with compound petals usually contain wide, triangular-shaped curved incisions (Fig. 3.2). The correlation between pattern and processing technique identifies two production systems at the Ximing Temple workshop.

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Kanazawa University

Consumption of added sugar doubles fat production

UNIVERSITY OF ZURICH

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Sugar is added to many common foodstuffs, and people in Switzerland consume more than 100 grams of it every day. The high calorie content of sugar causes excessive weight and obesity, and the associated diseases. But does too much sugar have any other harmful effects if consumed regularly? And if so, which sugars in particular?

Even moderate amounts of sugar increase fat synthesis

Researchers at the University of Zurich (UZH) and the University Hospital Zurich (USZ) have been investigating these questions. Compared to previous studies, which mainly examined the consumption of very high amounts of sugar, their results show that even moderate amounts lead to a change in the metabolism of test participants. "Eighty grams of sugar daily, which is equivalent to about 0,8 liters of a normal soft drink, boosts fat production in the liver. And the overactive fat production continues for a longer period of time, even if no more sugar is consumed," says study leader Philipp Gerber of the Department of Endocrinology, Diabetology and Clinical Nutrition.

Ninety-four healthy young men took part in the study. Every day for a period of seven weeks, they consumed a drink sweetened with different types of sugar, while the control group did not. The drinks contained either fructose, glucose or sucrose (table sugar which is a combination of fructose and glucose). The researchers then used tracers (labeled substances that can be traced as they move through the body) to analyze the effect of the sugary drinks on the lipid metabolism.

Fructose and sucrose double fat production beyond food intake

Overall, the participants did not consume more calories than before the study, as the sugary drink increased satiety and they therefore reduced their calorie intake from other sources. Nevertheless, the researchers observed that fructose has a negative effect: "The body's own fat production in the liver was twice as high in the fructose group as in the glucose group or the control group - and this was still the case more than twelve hours after the last meal or sugar consumption," says Gerber. Particularly surprising was that the sugar we most commonly consume, sucrose, boosted fat synthesis slightly more than the same amount of fructose. Until now, it was thought that fructose was most likely to cause such changes.

Development of fatty liver or diabetes more likely

Increased fat production in the liver is a significant first step in the development of common diseases such as fatty liver and type-2 diabetes. From a health perspective, the World Health Organization recommends limiting daily sugar consumption to around 50 grams or, even better, 25 grams. "But we are far off that mark in Switzerland," says Philipp Gerber. "Our results are a critical step in researching the harmful effects of added sugars and will be very significant for future dietary recommendations."

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Sugar - Sidney Mintz

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I became awed by the power of a single taste, and the concentration of brains, energy, wealth and -- most of all, power -- that had led to its being supplied to so ..