Professor Stephen Long FRS is Ikenberry University Chair of Plant Biology and Crop Sciences, University of Illinois and a world leading expert in how global climate change is affecting plants and how photosynthetic efficiency may be improved to affect sustainable yield increase.
In this discussion, he describes his research, which is being supported by CTRF, and how it aims to both improve photosynthesis and importantly increase the durability of CO2 storage in soil and outlines the enormous potential to scale this within global agricultural systems.
Tell us about your project?
In outline, what we’re trying to achieve is to boost carbon uptake initially by crops, although this work could move into forestry and other areas, by increasing the efficiency of the process of photosynthesis. And secondly, and most importantly, to move some of that material into chemicals which cannot be easily broken down so that they would reside in the soil for a long period of time.
In terms of the permanence and durability of storage, what is the potential to use biotechnology to improve that?
One way to look at this is that there some parts of plants can remain in the soil and some can, become fossilized for millions of years. So these long lasting components are the ones that we aim to boost. These include, for example, waxes and forms of lignin. Lignin is a carbohydrate polymer, it gives the strength to plants. It’s why trees can grow to many meters in height We and many others have researched how to make lignin more easily degradable in the quest for lignocellulosic fuels. In doing so we have also learnt how to make lignin and associated polymers less easily degraded and we are employing that here. First, we are using metabolic pathway models to learn where to intervene to make for waxes and more resilient lignin complexes.
Given that there is likely to be an improvement in that durability and permanence of storage, what’s the potential to scale that up? And what are the routes to scale up?
To me, the obvious realm is arable agriculture. If you just take the four main crops of maize, rice, soybean and wheat, they occupy 720 million hectares of land worldwide. Now farmers replant these crops at least once a year and in some parts of the world it’s twice a year. So as a new innovation comes in, it’s very easy for farmers to just adopt that.
Obviously they won’t do it if it’s going to cost them more, for example. They need to be incentivised but if it’s simply in the seed, it doesn’t cost them productivity. Then to me that’s quite a win, once you’ve got the technology there is a quick way to introduce this.
In terms of soil health, are there potential benefits to changing the constitution of the soil to store carbon more durably?
There are very significant benefits. A lot of agronomic management of crop land aims to preserve organic matter because for example the lignin residues are very good at binding nutrients so that they don’t wash through the soil. Organic matter is also important in holding water, by slowing drainage, particularly on light soils. So there are large benefits in increasing the organic matter in soil.
Why do you and your team believe this has potential?
Well, if you look at arable crop production globally and I just focus on those four crops maize, rice, soy and wheat, then in aggregate, the average yield globally is about 4.3 tonnes of biomass per hectare. This is a huge amount of biomass if you multiply that up by 720 million hectares. Half remains on the field either as crop residue, such as straw and chaff after the combine has taken off the seed, plus the roots in the soil. That is about equivalent to two gigatons of carbon. If we could keep more of that two gigatons in the soil, that could offset a substantial portion of emissions.
Last year, fossil fuels emitted about nine gigatons of carbon. We hope of course that emissions will go down and that this removal into soil organic matter will be an even bigger proportion. So in the global perspective, this could be one very large offset. Obviously it’s not going to offset everything, but it has the potential to be one important part of the solutions needed to remove CO2 from the atmosphere.
How scalable at speed is this given that we have an existing agricultural system that is cycling carbon through the soil ?
I think it’s very quickly scalable. If we look at past innovations in seed, for example the Bt genes, which offset insect damage in these crops in countries which allow genetically engineered crops, they spread very quickly partly because farmers quickly see the advantage. For example, they may see my neighbour’s crop is not damaged and theirs is, so they will want that technology for the next planting season. Innovations like this have been widely adopted across the countries allowing the technology within just a few years. The beauty of plants is that they are natural CO2 absorbers and they’re distributed globally, whereas if you’re using chemical atmospheric CO2 capture facility it is impossible to disperse them in the way that plants already are.
So there is an important climate justice element to this. Does that universality apply to different types of farming in different parts of the world?
Actually the benefits of being able to retain more carbon in the soil is particularly important in many of the semi-arid areas of the world, which are threatened with climate change and suffer some of the poorest production. Those areas could benefit considerably from this due to improved water retention and nutrient use efficiency with more organic matter in the soil.
Can you describe the steps and the processes involved in your work?
It’s twofold. One element is to increase photosynthetic efficiency so that plants remove more CO2 from the atmosphere and make more biomass. Some of that biomass is available to go into compounds which we then intend to stay in the soil for much longer. In both of these areas of work, we’re using mathematical modelling of the metabolic pathways to then pick out the targets to allow us to increase photosynthesis, accumulation of waxes and formation of less degradable lignin complexes, each by up or down-regulation of genes through DNA editing.
How optimistic are you, given time and funding that this is possible, that a significant benefit in terms of retaining carbon within the soil can be achieved?
I’m very optimistic because if we look at the theory for this and what we know about the metabolic pathways, both aspects of this appear perfectly doable. It’s just a question of time, hands and money to support that.
What body of work does this project build on from your team and elsewhere.
We’re also conducting work funded by the Gates Foundation and the Department of Energy here in the United States on improving photosynthetic efficiency in in crops of various types. That has been primarily transgenic work. We have identified opportunities from mathematical modelling that we then targeted by adding extra copies of genes and these have given us improvements in photosynthetic efficiency and in turn crop productivity.
Colleagues also working in the Gates Foundation funded project have made other improvements in this way. And of course, the modelling is identifying many targets beyond those used in these projects.
Given what you’re describing and the common sense that, shouldn’t we be throwing a lot of effort, funding and support from as many different avenues as possible at maximizing those pathways and working out the best possible solution as quickly as possible, given the scale of the challenge ?
I’d absolutely agree, we and others could go much faster, explore more opportunities, and put pilots into place, given more people, teams and support. We’re doing this engineering in tobacco. Tobacco sounds a very odd choice. It’s a crop which is, fortunately on the decline. The reason we’re using it is that tobacco is very amenable to bioengineering. It also produces a large amount of seed, which crops like maize, rice, soy, don’t do. So it is a pathfinder allowing us to scale very quickly to field trials where we can see whether our strategies work and are then worth applying to these other crops.
Importantly, the process of photosynthesis is largely the same in all of these crops, as are the pathways that affect lignin composition and wax content in the plant. So if we can show this to work in tobacco then it very likely that it will work broadly and in far more important crops.
From a personal and professional perspective. How exciting is this to you and how important is this work to you?
It’s extremely important to me. I’ve been working on climate change impacts and impacts of rising CO2 for almost 40 years, way before it was fashionable. It is just such a threat to us and in particular future generations, including my five grandchildren. I don’t want to be seen as part of the generation that caused the problem, I’d like to be part of the generation that sowed solutions.
Anthony Blinken, the Secretary Of State, talking at the United Nations Climate Conference (COP28) and quoting President Biden said “If parents can’t feed their children, nothing else matters.” He added .’ “If you get the seeds right, if you get the soil right, then you have your agricultural foundation” That captures in a nutshell our aim here from this small beginning.
Building on something we spoke about earlier, given more funding and more support, what more could be done?
There are many more targets and that we can see from modelling so with more support, you could then go to much higher throughput testing of many, many more targets, and move to pilot scale with successes and trials at more locations. From the modelling, we’ve opted for what we think are the best targets but the modelling is based on the information we have and with more funding, you could get much more detailed information on that to make the models better, and to make many more tests to move into the crops which count more quickly as well.
Nature has a carbon removal system. Do you think that there is logic in looking at effectively supercharging that, using bioengineering and biotechnology, to adjust the cycle of that carbon within our within our planet and within our biosphere ?
Oh, absolutely. Right now, photosynthesis, just on land, is drawing down 130 gigatonnes of carbon, according to the most recent IPCC report. So even a small increase on that, would have benefit. Much of that, of course, is natural forests, but a very large part of the planet is covered by managed systems where we can implement changes quickly.
How important is it that we as a society are visionary, entrepreneurial and innovative when we look at the scale of the challenge that climate change is presenting ?
It really needs a realization that climate change is ruining our planet, not least in damaging our capacity to produce food. I think IPCC is often criticized as being alarmist, but in fact they’ve actually always been on the conservative side. They said extreme events that we’re now seeing were going to occur, at least in the original reports which I was a part of.
Now we’re seeing there’s more energy in the atmosphere, the jet streams are becoming more disrupted and today we’re seeing record-breaking wildfires in Texas at the same time as snowstorms in the mountain West, and globally more extreme droughts in some locations simultaneous with extreme flooding elsewhere.
A lot is going to depend on society really waking up. This is a problem that we’ve got to do something about and as quickly as possible.
In earlier crises technological development and deployment has been rapid. Take World War II, within 6 years military aviation went from propeller biplanes to near supersonic jets. To achieve carbon removal by crops we do not need miracles, just iterative technological improvements and deployment.