4 ms·

I'm working on one of these projects, trying to make C4 photosynthesis an installable module. Happy to answer questions.

by Blahah 11y ago

seszett 11y ago
Are C3 and C4 really simply interchangeable mechanisms? What about CAM, would it be possible to "install a CAM module" into maize to make it drought resistant, though less productive? Also, but that might not be directly related to your work, the article says "plants already absorb more sunlight than they can use" but still goes on to talk about how they could be more efficient if they used a larger part of the light spectrum. Would it serve any purpose, then?
- Blahah 11y ago
  You can think of C3, C4 and CAM as interchangeable functions, yes. They take in CO2 and energy from sunlight, and they output sugar: def photosynthesis(co2, energy) # C3, C4 or CAM return sugar end to your second question, plants absorb photons that are not converted to biomass because all the light harvesting machinery is saturated. But this is only true at the parts of the plant that are most exposed to light. The idea is that we could reduce the absorption in those parts and let some light through to other parts of the plant, where it could be absorbed at a different wavelength if we install that ability.
  - pvaldes 11y ago
    Maybe interchangeable is not the right word here (defun edible.in.large.amounts? (plant) (if (equal plant "CAM-plant") (print "Not, unless you really know what are doing")))
murbard2 11y ago
I was under the impression that nitrogen fixation was still the limiting factor in plant growth. If that's the case, will improving photosynthesis really improve yields?
- afarrell 11y ago
  I'm a vast gaping maw of ignorance here, but I thought we had solved nitrogen fixation with the fritz-Haber process at the cost of using fossil fuels. Am I wrong, or are we just trying to keep farmers from having to buy ammonium nitrate?
  - murbard2 11y ago
    What I've been told is that, while fertilizers obviously help a lot, they aren't a panacea and the plant still needs to do some expensive nitrogen chemistry which will set limits to its growth, regardless of how much energy it gets from photosynthesis.
  - Blahah 11y ago
    Supplementing nitrogen comes with a whole host of environmental trade-offs. In particular there are problems with pollution, where nitrogen added to fields gets washed off in the rain and ends up in waterways. There it can totally destabilise ecosystems by introducing a flood of nitrogen which is usually a scarce resource, leading to massive population explosions of some kinds of organisms, which in turn can leave huge buildups of toxic byproducts. This is called eutrophication. https://en.wikipedia.org/wiki/Eutrophication https://en.wikipedia.org/wiki/Eutrophication
- Blahah 11y ago
  Yes, it will. Plants need nitrogen to make proteins, and the most abundant protein in plants is RuBisCO - the one that fixes CO2 in the air into carbohydrates to store the energy from sunlight. Most plants have to produce a vast amount of RuBisCO to make up for the fact that photosynthesis is so inefficient. By making it more efficient, we reduce the amount of RuBisCO needed and therefore reduce the nitrogen required. C4 plants are much more nitrogen efficient than C3 plants.
david-given 11y ago
Would improved photosynthesis be liable to find its way into nearby weeds via horizontal gene transfer? It sounds like a really advantageous modification, and so something that's likely to be picked up on. (Whereas, say, a modification for higher yields wouldn't be, because it wouldn't be advantageous for a weed.)
- Blahah 11y ago
  I think this is extremely unlikely. This is because the engineering projects we are talking about involve co-ordinating the regulation of dozens of genes (at least 40 in my project). To build the system we have to transfer in the components separately in many different plants and then carefully stack the changes using breeding techniques. The probability of this happening in nature would be infinitessimally small, especially because we have found that by taking only some of the changes you actually get a decrease in photosynthesis.

I'm working on one of these projects, trying to make C4 photosynthesis an installable module. Happy to answer questions.

by Blahah 11y ago

I'm working on one of these projects, trying to make C4 photosynthesis an installable module. Happy to answer questions.

seszett 11y ago

Are C3 and C4 really simply interchangeable mechanisms? What about CAM, would it be possible to "install a CAM module" into maize to make it drought resistant, though less productive? Also, but that might not be directly related to your work, the article says "plants already absorb more sunlight than they can use" but still goes on to talk about how they could be more efficient if they used a larger part of the light spectrum. Would it serve any purpose, then?

Blahah 11y ago
You can think of C3, C4 and CAM as interchangeable functions, yes. They take in CO2 and energy from sunlight, and they output sugar: def photosynthesis(co2, energy) # C3, C4 or CAM return sugar end to your second question, plants absorb photons that are not converted to biomass because all the light harvesting machinery is saturated. But this is only true at the parts of the plant that are most exposed to light. The idea is that we could reduce the absorption in those parts and let some light through to other parts of the plant, where it could be absorbed at a different wavelength if we install that ability.
- pvaldes 11y ago
  Maybe interchangeable is not the right word here (defun edible.in.large.amounts? (plant) (if (equal plant "CAM-plant") (print "Not, unless you really know what are doing")))

murbard2 11y ago

I was under the impression that nitrogen fixation was still the limiting factor in plant growth. If that's the case, will improving photosynthesis really improve yields?

afarrell 11y ago
I'm a vast gaping maw of ignorance here, but I thought we had solved nitrogen fixation with the fritz-Haber process at the cost of using fossil fuels. Am I wrong, or are we just trying to keep farmers from having to buy ammonium nitrate?
- murbard2 11y ago
  What I've been told is that, while fertilizers obviously help a lot, they aren't a panacea and the plant still needs to do some expensive nitrogen chemistry which will set limits to its growth, regardless of how much energy it gets from photosynthesis.
- Blahah 11y ago
  Supplementing nitrogen comes with a whole host of environmental trade-offs. In particular there are problems with pollution, where nitrogen added to fields gets washed off in the rain and ends up in waterways. There it can totally destabilise ecosystems by introducing a flood of nitrogen which is usually a scarce resource, leading to massive population explosions of some kinds of organisms, which in turn can leave huge buildups of toxic byproducts. This is called eutrophication. https://en.wikipedia.org/wiki/Eutrophication https://en.wikipedia.org/wiki/Eutrophication
Blahah 11y ago
Yes, it will. Plants need nitrogen to make proteins, and the most abundant protein in plants is RuBisCO - the one that fixes CO2 in the air into carbohydrates to store the energy from sunlight. Most plants have to produce a vast amount of RuBisCO to make up for the fact that photosynthesis is so inefficient. By making it more efficient, we reduce the amount of RuBisCO needed and therefore reduce the nitrogen required. C4 plants are much more nitrogen efficient than C3 plants.

david-given 11y ago

Would improved photosynthesis be liable to find its way into nearby weeds via horizontal gene transfer? It sounds like a really advantageous modification, and so something that's likely to be picked up on. (Whereas, say, a modification for higher yields wouldn't be, because it wouldn't be advantageous for a weed.)

Blahah 11y ago
I think this is extremely unlikely. This is because the engineering projects we are talking about involve co-ordinating the regulation of dozens of genes (at least 40 in my project). To build the system we have to transfer in the components separately in many different plants and then carefully stack the changes using breeding techniques. The probability of this happening in nature would be infinitessimally small, especially because we have found that by taking only some of the changes you actually get a decrease in photosynthesis.