you are right, when I wrote that post I was kinda baked and it's been quite imprecise. It's designed more like an "advertisement" (for UVB), and I wanted to SNIPE into many LED manuf. claims of "full spectrum" or "sun-like" but are then missing 2/5 of colors, and that does even not include real heat radiation, as in around ~1500nm or +2500nm. AFAIK only Amare & Valoya...?
Unfortunately I cannot edit that post anymore to formulate it in another way... but I do firmly believe that the extreme response you see -in the UVB region- is because of the UVR-8 receptor because, as you've stated, is the region where he will only work as a light-absorbing chromophore. By its sheer looks of it this is somewhat a strong indicator, and the scientists in the attached .pdfs do actually also voice this opinion. Problem is that this signal transducting pathway has not been figured out yet. So validation is lacking, but the UVR-8 receptor is only known for 10 years and in current research - there are many studies from only recent years.
The plants responses to DNA damage or otherwise cellular-damage from ROS are all non-photomorphogenetic. This is so because these things can have many many reasons - and it wouldn't be helpful if e.g. a PM infestation would trigger an UVB response, like building up of a sun screen layer of pigments. The photomorphogenic responses of UVB - hyponastic shape, steeper petiole angle & stomatal conductance (which has many other influences) are all due to the photoreceptor response IMO. In one of the .pdfs scientists have tested this in order to inquire if a low UVB constant dosage, such one which just doesn't damage DNA anymore once the initial protective layer has been established, could trigger this response - and they confirmed that, although only at low irradiance levels.
This is because photoreceptors are more sensitive to their target radiation as they've been deliberately designed so. Our skin can tolerate UVA after some adaptation, but our eyes...?
It seems like all plants do or did possess the UVR-8 receptor as the conditions a few hundred million years ago were with more UVB, and even UVC. It's peak nearly marks the cross into UVC. Today 290nm is all it gets at sea-level, and not even very long.
I'll upload the studies once I'm at the homedesk.
koraylights.com
