Paper: Blue fluorescence in plants

[DaveO]

I recently found an interesting article on laser induced fluorescence (337 nm from a pulsed nitrogen laser)

 

http://naldc.nal.usd...nload/37970/PDF

 

It was done by NASA as studies for remote sensing.

 

I just found another article about UV induced fluorescence in grasses

 

 

UV induced visual clues in grasses

http://www.nature.co...f/srep02738.pdf

 

blue fluorescence is attributed to "ferulic acid" which is a hydroxycinnamic acid , an abundant phenolic phytochemical found in plant wall components according to Wiki. It is a component of lignin so perhaps this explains the blue fluorescence commonly observed in UVIVFL images. The UV absorption spectrum of ferulic acid has a maximum absorption at 321 nm and negligible above 400 nm where the blue fluorescence occurs.

 

Dave

[Andrea B.]

A nice find, this paper.

 

I have always been fascinated by the grasses, but find them difficult to study.

 

If the blue fluorescence attracting pollinators, then I'm wonder how it is seen in daylight?

 

In the discussion the authors state: We found grass inflorescences very attractive with UV-induced blue emission patterns. These blue emissions from critical floral parts of grasses are not known so far.

 

However I am not sure quite what they mean by that?

[DaveO]

"Ours is not to reason why" I'm just collecting UVIVFL images and as many papers which may or may not be relevant then one day, who knows I might get a light bulb moment. I find it interesting that at least some of the molecules which fluoresce in the "blue" region also have strong UV absorption around 330 - 360 nm ( which means a Stokes shift between absorption and fluorescence of around 100 nm). Is the real "purpose" to absorb harmful UV and re-emit as less harmful blue, so it's a self-protective mechanism by the plant for it's DNA?

 

Dave

[Andrea B.]

But then why wouldn't all plants do that to protect themselves against DNA damage?

Well, who knows!? But it is certainly interesting.

 

I looked at some of my old grass fotos and indeed found some blue fluorescence. Here is one example which also shows some chlorophyll fluorescence. Of course this photo is very broadband & uncontrolled, not like what was done in the paper under good experimental rules. The photo is as near to "white balanced" as I could get it at the time but is by no means perfect. I should perhaps try again this summer. :)

 

[DaveO]

We are probably six months away from flowering season for our native grasses, so I shall try to find something later.

Dave

[Damon]

There is a species of grass around my yard that fluoresce blue big time.

Fluorescence may have many roles. Maybe some do as the corals do below.

 

When watching Earth-A New wild on PBS

Dr. M Sanjayan said the following:

"By using UV light, we can now reveal the coral's built-in defenses to changes in ocean temperature.

Scientist studying reefs have found that those with more fluorescent coral will cope better with rising sea temperatures.

In warmer waters, the effects of sunlight become extremely dangerous for corals.

But the fluorescent cell absorb dangerous UV rays, acting as a sunscreen..."

 

-D

[DaveO]

Interesting. I suspect that there are many molecules which fluoresce blue under UV so this may be a common cause and effect. It will be interesting to make lists.

Dave