I had an interesting query: what would occur to a submersed aquatic weed if there was a sudden decline in CO2 under high light/non limiting nutrients?
What would happen in the Light reactions?
There would be a back up of NADPH, ATP and lots and lots of high energy electrons, which can over load the light reactions causign the formation of reactive oxygen radicals.
These ROS's in turn destroy the very enzymes that are suppose to gather light energy and feed it into the light reactions to send to the dark reactions where the CO2 is fixed.
By decoupling these light and dark reactions..........this causes a severe back up of incoming light energy => biochemical reactions begin to back up=> these expose the enzymes more and more to ROS's which attack and destroy the enzymes required for photosynthesis.
http://www.biosensitivefutures.org.au/overviews/principles/images2/photosynthesis.gif
See the part that splits the water?
See the electron carriers and the PQ- and PQ?
There's a few others, but all these are overloaded with electrons.........they have to go somewhere, so a few start attacking the D1 enzyme that splits the water into O2 and e-.
Plants can regulate this balance somewhat under optimal conditions, but if the temp goes way up, say 40C, or the CO2 is suddenly gone.........or some other stresses.........then this ROs effect occurs and can be intense.
Since there is little CO2, there's little food for plants.
Plants can adapt to some degree, but this takes time and sudden large CO2 changes seems to really cause a lot of issues within submersed plants that are simply not present with terrestrial species.
We enrich the CO2 so this difference is even larger in many cases. Going up higher in CO2 seems okay, but not dropping or bobbing between high and low.
I passed BTW(the exam).
Regards,
Tom Barr
What would happen in the Light reactions?
There would be a back up of NADPH, ATP and lots and lots of high energy electrons, which can over load the light reactions causign the formation of reactive oxygen radicals.
These ROS's in turn destroy the very enzymes that are suppose to gather light energy and feed it into the light reactions to send to the dark reactions where the CO2 is fixed.
By decoupling these light and dark reactions..........this causes a severe back up of incoming light energy => biochemical reactions begin to back up=> these expose the enzymes more and more to ROS's which attack and destroy the enzymes required for photosynthesis.
http://www.biosensitivefutures.org.au/overviews/principles/images2/photosynthesis.gif
See the part that splits the water?
See the electron carriers and the PQ- and PQ?
There's a few others, but all these are overloaded with electrons.........they have to go somewhere, so a few start attacking the D1 enzyme that splits the water into O2 and e-.
Plants can regulate this balance somewhat under optimal conditions, but if the temp goes way up, say 40C, or the CO2 is suddenly gone.........or some other stresses.........then this ROs effect occurs and can be intense.
Since there is little CO2, there's little food for plants.
Plants can adapt to some degree, but this takes time and sudden large CO2 changes seems to really cause a lot of issues within submersed plants that are simply not present with terrestrial species.
We enrich the CO2 so this difference is even larger in many cases. Going up higher in CO2 seems okay, but not dropping or bobbing between high and low.
I passed BTW(the exam).
Regards,
Tom Barr