Peak Oil is You
Donate Bitcoins ;-) or Paypal :-)
Page added on July 15, 2015
Can scientists hack photosynthesis to feed the world as population soars?
The world population, which stood at 2.5 billion in 1950, is predicted to increase to 10.5 billion by 2050. It’s a stunning number since it means the planet’s population has doubled within the lifetimes of many people alive today.
At the same time, arable land is shrinking and crop productivity is stagnating.
The last time population outran agricultural productivity, we were rescued by the Green Revolution, an increase in the harvest index (the amount of the plant’s biomass partitioned into grain) achieved through classical plant breeding. Today’s ears of corn are huge compared to those harvested in the 1920s.
But the harvest index can be pushed only so far; a plant can’t be 100-percent grain. And as the harvest index approaches its theoretical limit, gains in crop productivity have plateaued.
Is there another rabbit plant scientists can pull out of the hat? One possibility is to redesign photosynthesis, the process by which plants convert sunlight and carbon dioxide into sugar and the ultimate source of all food, unless you’re a chemosynthesizing bacterium.
Photosynthesis, scientists will tell you, is stunningly inefficient. “We expect the solar cells we put on our rooftops to be at least 15- or 20- percent efficient,” said Robert Blankenship, PhD, the Lucille P. Markey Distinguished Professor of Arts and Sciences at Washington University in St. Louis. “A plant is at best one-percent efficient.”
Photosynthesis is the only determinant of crop yields that is not close to its biological limits, he said. It’s the one parameter of plant production that has not been optimized.
“A plant is probably never going to reach solar cell efficiencies, but solar cells are not going to make you lunch,” Blankenship said. “If we can double or triple the efficiency of photosynthesis—and I think that’s feasible—the impact on agricultural productivity could be huge.”
But how could this be done? In May 2013 Donald Ort and Sabeeha Merchant organized a workshop at Cold Spring Harbor Laboratory where a group of the world’s top plant scientists slipped the leash of scientific caution and tried to imagine what they would do if they could redesign plants at will. Blankenship was a workshop participant and agreed to summarize some of ideas that came out of the workshop, which are described in more detail in an article published in the July 14 issue of Proceedings of the National Academy of Sciences.
Layering the canopy
One clever idea was to design a smart canopy, a layered canopy of plants that would interact cooperatively to maximize photosynthetic efficiency. The canopy might exploit several tricks to wring the maximum productivity out of light as it filtered through the leaves to the ground.
Ironically, given that plants make use of only a fraction of the available sunlight, they have more light than they can handle for much of the day. During the early morning and in the evening they have the right amount of light but during the midday they have more light than they can process and they have to throw this excess energy away.
One way to minimize light saturation of the upper leaves and light starvation of the lower leaves is to vary the angle of the leaves in the canopy. Leaves in high light might be nearly vertical while those beneath might be horizontal.
The light is absorbed in each leaf by “antenna” pigments, typically chlorophyll and the carotenoids. These antennas channel the energy to reaction centers where the chemistry takes place. A plant can have up to several hundred pigment molecules per reaction center.
If plants had antenna complexes sized for the light intensity at their level of the canopy they could absorb light more judiciously. The upper leaves that get lots of light would have fewer antenna complexes feeding more reaction centers and would be pale green. Descending through the canopy the leaves would have larger antennas feeding fewer reaction centers and shade to darker green.
But it isn’t just the light intensity that changes with depth in the canopy; it’s also the solar spectrum. Plants only use a very narrow region of the solar spectrum, Blankenship said. “Basically the plant sees the same light we see with our eyes. Anything on either side of it is just completely wasted—not even absorbed—so it doesn’t even have a chance to do anything.”
That’s basically why solar cells are more efficient than plants, he said. They use some of the other light, the light in the near infrared.
So a third idea is to plug different light-absorbing pigments into different levels of the canopy. High up the antenna complexes might still be composed of the familiar chlorophyll a, which absorbs in the visible part of the spectrum, but farther down, where the leaves mainly receive infrared light, chlorophyll a might be replaced by chlorophyll d, whose absorption peaks deeper in the red.
Goosing a poky enzyme
Having explored ways to tailor light collection to the intensity and spectrum of the available light, the scientists then turned to the next major barrier to improving photosynthetic productivity. This is the infamous enzyme RuBisCO.
RuBisCO catalyzes the first major step in carbon fixation, the process by which the carbon atom in atmospheric carbon dioxide is added to a carbon molecule. RuBisCO has two flaws. One is that for a catalyst, a molecule whose job is to speed up reactions, it is very slow. “It turns over a few times a second,” Blankenship said, “which is really, really slow. Some enzymes will turn over tens of millions of times per second.”
RuBisCO is so poky that huge amounts of it (half the soluble protein in leaves) is required to support adequate photosynthetic rates.
The other flaw is that RuBisCO is not very good at discriminating between carbon dioxide and oxygen. If it latches on to oxygen, which happens 25 to 30 percent of the time, the carbon-fixation reactions spit out a compound called glycolate that is toxic and must be removed. The reaction cycle by which it is removed, called photorespiration, is long, complicated and a major drain on the efficiency of the plant, Blankenship said.
In many plants, a third of the carbon dioxide the plant fixes is lost again through photorespiration. “Sometimes people try to argue that photorespiration has some benefit but in the end I don’t think many people believe it,” he said.
There are many natural variants of RuBisCO, Blankenship said, which represent different tradeoffs between the enzyme’s rate and its specificity. If the enzyme distinguishes well between oxygen and carbon dioxide, then it tends to be slow, and if it works really fast, then it isn’t as selective.
So one idea would be to put RuBisCOs with a high catalytic rate in the upper canopy to make the most of the abundant light and ones with high specificity in the lower canopy to minimize losses through photorespiration where light is limited, he said.
Another is to equip plants with a specialized carbon fixation system found in a minority of plants. These plants concentrate their RuBisCO in specialized cells and pumping carbon dioxide into those cells to keep its concentration high. (They are said to have C4 metabolism, in contrast to the majority of plants, which have C3 metabolism; the names refer to the numbers of carbon atoms in intermediate products of the reactions that manufacture sugar.)
There’s a lot of interest in putting C4 metabolism (the carbon concentrating adaptation) into C3 plants like rice, said Blankenship. “That’s the big goal: to make C4 rice. It’s an international effort involving many groups. All of the enzymes needed to do C4 photosynthesis are already in the plant. It’s just a matter of putting them in the right place and turning them on at the right time.
In a smart canopy the top layers might be carbon-concentrating and the lower layers, where there is less energy to pump carbon dioxide, might settle for carbon dioxide transport by diffusion.
Some of these projects are fairly easy, Blankenship said, and could be accomplished within a few years, but others would require radical redesigns or a major rethinking of the architecture of photosynthesis.
The most attractive part, he said, is that photosynthesis is at the very front end of the process of capturing the sun’s energy. “If you lose the energy there, it’s gone, and you don’t have any chance to recoup that loss in later stages. So improving the front end seems to me the most desirable thing to do.”
32 Comments on "Can scientists hack photosynthesis to feed the world as population soars?"
Lawfish1964 on Wed, 15th Jul 2015 1:29 pm
Sounds an awful lot like genetic engineering to me. That experiment’s gone really well, so what could go wrong here? /sarc off.
PrestonSturges on Wed, 15th Jul 2015 1:59 pm
The thing is that evolution has had over 100,000,000 years to tinker with photosynthesis, so it’s very unlikely for us to tweak it significantly. Keep in mind it has to work using with whatever is lying around in your yard and without any manufacturing input, rare elements, or nanotechnology.
We would be better off focusing on the nutrition and agronomics of crop plants.
eugene on Wed, 15th Jul 2015 2:13 pm
My read is there’s absolutely no need to worry about limits of any kind. Aliens will arrive with endless energy, endless food and a 10 second solution to climate change. If we’re going to continue to live in fantasy world, lets do it right.
Boat on Wed, 15th Jul 2015 2:27 pm
End eating meat. No more exports I typed that in 4 sec.
Davy on Wed, 15th Jul 2015 2:46 pm
Why not do it the old fashion way including many of the best modern materials and technology that have resilience and sustainability. In other words a hybrid of the best of today’s AG included in the best of pre-industrial AG. We would acknowledge that best of today would be that which is sustainable and resilient first with efficiency and production least important.
We would stockpile logistics and do widespread education. At some point we would pull the trigger on an epic return to the land effort. Since this would destroy globalism because of the disruptive nature of the change we would ready the masses for widespread deaths.
We would then focus all this science and engineering shown in this article on ways to humanly reduce the world population to 2Bil in 10years. This would include the broad spectrum of technologies and policies from birth control to euthanasia. We would pay people to die. That’s a deal man. We gotta die anyway so let’s get paid for it.
Ok, I was being stupid like this article. The difference is people believe in technology and progress in this article. What I said would be dismissed as nutter. Can you see the challenges ahead?
There is zero chance of science and technology succeeding with a population over 2Bil. Actually we need to be around 1Bil. Yet we read in this article preparations for 10Bil. Folks this is an insane asylum we live in basically a bunch of lunatics parading as scientist.
dave thompson on Wed, 15th Jul 2015 2:47 pm
We are depleting the earths soils through agriculture made possible only with FF inputs.
Plantagenet on Wed, 15th Jul 2015 3:00 pm
Scientists are very close to being able to do genetic engineering at this level. There really isn’t any technical reason that the efficiency of photosynthesis can’t be redesigned and improved upon.
Scientists are also trying to jigger algae and bacteria to basically poop out hydrocarbons as a to create new kindd of biofuels to power the economy.
Davy on Wed, 15th Jul 2015 3:12 pm
Planter, I am in utter awe we will be saved by Scientist. Algae pooping hydrocarbons who would have thought. Next it will be people doing the hydrocarbon pooping that way we can justify more people. Thanks Planter for making my day your a PO site wise man.
apneaman on Wed, 15th Jul 2015 3:24 pm
Hey planty are these unnamed scientists working on any new crops whose proteins will not denature at 4C like all our current crops will? How about some special gizmo to halt and reverse the 6th mass extinction? Maybe crops that need no pollination since the birds and bees and bats and insects that do that are well on their way to extinction. Hey I know they can build a pollinator app.
Plantagenet on Wed, 15th Jul 2015 3:26 pm
@Daver
If you can figure out a way to start pooping hydrocarbons I’ll be very impressed. Although right now all it would do is add to the current oil glut.
Have a great day!
apneaman on Wed, 15th Jul 2015 3:30 pm
Hey planty know any scientists who have a plan to stop whats left of the worlds forests from burning? I mean other than chop them all down to make more shitty Ikea furniture destined for landfills.
Alaska’s 2015 Epic Burning is One Month Ahead of Previous Worst Year; Canada Conflagration Continues, Eastern Siberia Wildfires Light Off
“From Canada to Alaska to Siberia, an immense half-crescent of the Arctic is on fire. The hot spots along this zone include freakish fires with 50 mile fronts, fires that generate thunderstorms from the heat of their updrafts, and fires that paint smokescapes over the lake waters of Canada even as they light the sky red”
“Fires, overall, that have been vastly under-reported in the mainstream media. And, even when they are reported, they include often inaccurate qualifiers.
So what the heck is really going on? The human hothouse is generating an ever-greater burning potential throughout the Arctic. One that has erupted toward new levels of intensity this year. One that is plainly and painfully visible to any who care to look.”
“In Alaska, a massive area the size of one and one half Connecticuts (7,300 square miles) has already been consumed by fires. A zone of smoldering tundra, boreal forests turned to ash, smoking bogs, and smoldering, thawing permafrost.”
https://robertscribbler.wordpress.com/2015/07/15/alaskas-2015-epic-burning-is-one-month-ahead-of-previous-worst-year-canada-conflagration-continues-eastern-siberia-wildfires-light-off/
apneaman on Wed, 15th Jul 2015 3:43 pm
Hey planty, your hero scientists in the employ of big Ag don’t impress me one bit – they are a bunch of clueless career monkeys who do not understand or care about the big picture. They are not paid for that, So who does look at the big picture when it come to the highly complex and vast interconnected web of life? I’m glad you asked planty. That would be the research biologists, conservation, wildlife, marine and such and none of them share your optimism of the future.
Humans could be among the victims of sixth ‘mass extinction’, scientists warn
“If it is allowed to continue, life would take many millions of years to recover and our species itself would likely disappear early on,” lead author Gerardo Ceballos of the Universidad Autonoma de Mexico said.”
http://www.abc.net.au/news/2015-06-20/sixth-mass-extinction-impact-humans-study-says/6560700
planty do you think it is going to be allowed to continue?
Boat on Wed, 15th Jul 2015 3:44 pm
apneaman on Wed, 15th Jul 2015 3:30 pm
Hey planty know any scientists who have a plan to stop whats left of the worlds forests from burning? I mean other than chop them all down to make more shitty Ikea furniture destined for landfills
Not much is possible unless there is a profit in it.
penury on Wed, 15th Jul 2015 3:47 pm
The title asks a question which is simple to answer. NO
Plantagenet on Wed, 15th Jul 2015 3:55 pm
@penury
Won’t you be surprised when they award a Nobel prize to some deserving folks for improving plant photosynthesis.
Cheers!
Davy on Wed, 15th Jul 2015 4:38 pm
Planter, just like Obama I imagine. Planter you are so smart today you are blinding me with the light of your brilliance.
BobInget on Wed, 15th Jul 2015 4:39 pm
Oh, I’m sorry. Landed on fearofscience.com
by mistake.
PrestonSturges on Wed, 15th Jul 2015 4:56 pm
This page mentions converting rice to C4 photosynthesis, which seems like a more focused goal.
https://en.wikipedia.org/wiki/C4_carbon_fixation
hosj on Wed, 15th Jul 2015 5:44 pm
Drinking Game: Take a shot every time Plantagenet says: “Oil Glut”
Dredd on Wed, 15th Jul 2015 5:49 pm
No.
Greenland & Antarctica Invade The United States – 3
Dredd on Wed, 15th Jul 2015 5:50 pm
hosj on Wed, 15th Jul 2015 5:44 pm
Drinking Game: Take a shot every time Plantagenet says: “Oil Glut”
=============================
LOL !
freak on Wed, 15th Jul 2015 6:21 pm
It is horrifying to watch how fast the extinction rate and global warming is speeding up Exponentially. Scientist can not keep up with there modeling and have to keep adjusting there timeline to an ever faster rate of collapse.
https://www.youtube.com/watch?v=cmb5hn2X2ok
Davy on Wed, 15th Jul 2015 7:14 pm
Bob, you are damn right. Fear of science dot come in the hands of careless and incompetents. Nothing wrong with science in the proper hands. This is why you corns are so worrisome. You have sold your soul to progress in any form.
Makati1 on Wed, 15th Jul 2015 8:48 pm
Science as we know it today is a product of oil energy and will die when the excess energy oil provides is gone. So will go scientists and all of the other nonproductive careers like those below.
Most: lawyers, psychologists/psychiatrists, real estate salesmen, daycare, archeologists, architects, engineers, healthcare specialists, nursing homes, retirement/financial advisers, internet mechanics, airline employees, rocket scientists, chemists, biologists, retail clerks, professors, IT specialists,…
I’m sure you can add to the list if you think about it. Specialists of ALL kinds will disappear as there will not be the money/energy to support such people. The lack of the above careers prior to the 1800s was not due to stupidity but to the lack of excess wealth/energy that oil gave to mankind in the 1800s and made all of that possible. When that excess goes away, so will most of those careers.
Is your career dependent on BAU? If it is, you better diversify into something that isn’t unless you are retired or about to. Oh, and retirement is also going to be history soon as the underpinnings of that dream are already shaking.
BC on Wed, 15th Jul 2015 8:50 pm
@eugene: “My read is there’s absolutely no need to worry about limits of any kind. Aliens will arrive with endless energy, endless food and a 10 second solution to climate change. If we’re going to continue to live in fantasy world, lets do it right.”
http://www.hulu.com/watch/440883
Right on, eugene! I’m personally rooting for a large-scale visitation of Earth by our extraterrestrial brothers and sisters (unless they are asexual, or should that be non-gendered?) from The Rings of Uranus to “serve man” in the manner we truly deserve.
HARM on Thu, 16th Jul 2015 1:41 am
“Photosynthesis, scientists will tell you, is stunningly inefficient. “We expect the solar cells we put on our rooftops to be at least 15- or 20- percent efficient,” said Robert Blankenship, PhD, the Lucille P. Markey Distinguished Professor of Arts and Sciences at Washington University in St. Louis. “A plant is at best one-percent efficient.”
Actually photosynthetic efficiency varies from .1-8%, depending on the plant, but regardless, point taken. We’ve got to get those lazy bums working harder for humanity! Clearly the sole purpose of all organisms on this planet is to support ever greater numbers of people and make life more comfortable for us. Anything else is just “waste”, and organisms that can’t get with the program should be driven to extinction at an even *faster* rate –the sooner the better! Go people, rah…
meld on Thu, 16th Jul 2015 3:35 am
Once again an article that doesn’t understand the very basic and very fundamental laws of nature. Sure you might be able to “hack” nature into “improving” photosynthesis, but there is a 100% chance that you will create a new issue that hadn’t been thought about. Who do I trust, millions of years of the most harsh testing via evolution or a few graduates with pipettes and test tubes…..hmmmmmmm
Boat on Thu, 16th Jul 2015 7:00 am
meld, for ever yign there is a yang..https://gmoanswers.com/ask/what-difference-cost-production-gmo-vs-non-gmo…
Davy on Thu, 16th Jul 2015 7:17 am
Funny how we like to second guess nature and criticize her. I wonder if these buffoons parading as scientist ever think a little deeper into the whole enigma of life. Don’t you think nature is more concerned about sustainability and resilience of a complex system over time than strictly short term efficiency and gain? You know why this may be the case? Well every little action of a natural system has consequences to the whole system. We want to change that without knowing even what we are changing.
That is what idiots do. That is the definition of stupid is and stupid does. Humans are idiots. I see a typical large brain thinking it is larger than it really is. We are a hilarious creature especially when one looks at our exceptional feeling of ourselves. Our divine manifest destiny is really strange and interesting. We are going to buck a system of eons of evolution and extinction? We are going to outwit nature by being smarter than her. We are going to hog tie Nature into submission for our greedy ways.
ERRATA on Thu, 16th Jul 2015 8:39 am
PrestonSturges, Davy are right
Again a serious mistake here:
Wrong / unfair / incorrect comparison of leaf photosynthesis (plants) and solar (PV panel).
Leaf (green plant) consumes / needs a portion of the collected solar energy for self-maintenance!
It is important to understand this properly!
The plant exists / exists yourself!
Battery solar cells (PV panel) needs a “care” / maintenance / repairs to an external display unit, for which energy is required oil & coal!
This is an external, extra power, which does not take into account.
Kylon on Thu, 16th Jul 2015 4:57 pm
There is a reason that plan don’t absorb more light. The reason is a lack of magnesium necessary for cholorphyll.
If you add in Epsom salts to plants (magnesium plus sulfur) the plants supposedly grow really, really well. You end up with deeper greens, and more luscious fruit, larger fruit.
So what they need to do is classical selective plant breeding, in a soil that’s oversaturated with magnesium. The plants that have genes that maximize magnesium uptake and usage in the production of choloraphyll would be selected for and have more seeds. Over time you’d end up with plants that could use lots of sunlight so long as the soil was properly fertilized with enough magnesium. Magnesium can be extracted from the ocean, so theres no likelihood that it will be depleted.
At least this is my opinion.
Makati1 on Fri, 17th Jul 2015 10:02 pm
Kylon, in a capitalist world, if your idea had merit, wouldn’t it already be used for profit?
Perhaps the energy cost to extract it from the ocean is too expensive? After all, ocean water contains more gold than has ever been mined, yet it is impractical to recover it, even at $1,000+ per oz.