Is it true that plants begin to consume oxygen around 45°C?
I used to work with a guy who had three PhD's. (two in Europe, one in the US). He had them in math, chemistry and biology. He said a few fairly outlandish things over the timeframe that I knew him, but every one I ever dug into it turned out was basically accurate.
One of the things he mentioned in passing, but which I haven't been able to confirm to my satisfaction is that when plants reach certain high temps, they start producing H2O2 instead of H2O. (around 45 Celcius)
I've read a few papers that seem to indicate that part at least is true, but I've never found anything that says whether or not this puts plants into the 'consumer' column for oxygen.
Anyone here able to point me to something that has this answer? or anyone here know the answer, even if it's not specifically been published yet?
Interesting question!
I don't think it would be fair to call them "consumers" of oxygen, in that if you put plants in a sealed chamber and apply heat stress, they wouldn't suddenly start sucking in massive quantities of O2 and change the composition of the air in the chamber in a major way. However, heat stress does cause a buildup of "reactive oxygen species" (ROS), which includes H2O2, O2, and ions thereof.
If you were to subject animal tissue to conditions where cells weren't able to respire efficiently, you'll see buildups of CO2. For example, ABG testing is a commonly-used indicator in ICU medicine for overall patient health, because the human body's overall ability to operate effectively is closely correlated to its ability to expel CO2 as waste. This heat stress response in plants is basically the mirror image of the CO2 buildup you'd expect to see in humans/other animals.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7795586/
Plants consume oxygen when they are metabolizing actively but not photosynthesizing.
For instance from the time a seed germinates to the time it leafs out it is consuming oxygen to burn carbohydrates and fats stored in the seed.
Yeah, and I know that because of this, they aren't as huge of a net producer of oxygen as people might think. (since they consume it at night)
This guy was saying though, that by having to produce H2O2 instead of H2O to protect from heat stress and damage during the day, they become net consumers of oxygen over a 24 hour cycle.
I can't find anything to refute or back that up, and I don't see anything that did enough work on heat stressed trees (it's mostly food crop research for obvious reasons) to know if that's true or not.
Was hoping someone here knew where the science was to educate myself further on the subject.