Plant Cuticle or: where the algae attaches. Research review paper

http://www.plantstress.com/Articles/up_general_files/Stress%20and%20cuticular%20wax.pdf

Of note, CO2 and the % of CO2 used for cutin production.
Seems like this material can be sloughed off as diatoms and other algae grow on this non living EW layer. This may explain the long term lack of algae on some longer lived leaves, as well as microinvertebrate herbivores and large algae herbiviores.

Most aquatic weeds simple drop or aloow the leaves to get covered with algae epiphytes and grow faster and new fresh leaves instead of sticking around a fighting the problem. We prune the nice fresh tips and toss the old alage covered lower older sections.

So CO2 it's stability might be a key factor in the algae free state of many plants.
Mostly via good growth/trimming but perhaps via the cutin itself.

A poor/weak, cutin layer might make a good place for a spore to recruit and grow without getting sloughed off. Same for fungal attack on plant leaves etc.

Anubias and many other susceptible algae prone plants have cutin layers, whereas things like Egeria are lacking significant cutin. One might slough off, whereas one species might just outgrow the algae.

Regards,
Tom Barr

 

Well a bit like your skin that sloughs off the dead skin on the top and the new living skin under neath replaces it.
At the whole plant level, leaves simply drop and are replaced by new runners/new growth at the tip of meristem.
Why bother replacing it if it's easier to simple grow a new leaf that's closer to the surface/light/CO2?

You can have several mechanisms to avoid algae, herbivores at the micro scale are yet another not noticed by aquarist
Current knocking it off, lower light tolerances etc.

Regards,
Tom Barr

 

Well, allelopathic compounds imbedded in the cutin layer, now that makes more sense as far as reduced algae recruitment.

Adding AC would not have any effect on them there.
Nor would they get washed away.
They'd have to be stuck on a healthy leaf, but be released on a not so healthy leaf and thereby alloow algae recruitment to occur.

That I could speculate. The other?
No, I see little evidence.

Some plants also seem to get algae and others do not near as much, this would explain it in the chemical context.
But you'd need a plant that does not product this compound and have it localized at the EW layer.
A molecular approach using a knock out mutant and 35s promoter+ a GFP to the protein that deposits this would be a potential way to see and verify.
Got 200K$?

Regards,
Tom Barr

 

As far as imbedded protection from pathogens or epiphytes, I'd say this is much more likely than chemicals just released out into the water column.........to only be washed away....... and much easier to change and alter as conditions change.
I'm not saying it's right or wrong...........

So the methods of detection need to reconsidered greatly.

Aslo, there is certainly selectivity in plants that are much more prone to algae epiphytes than others.
This may be related to their ability to acquire and sequester carbon as CO2 in a mixed community.
Some plants will still grow pretty well and not get any algae, others will very quickly in the same tank.

So it might be a two part issue occuring, both CO2 uptake/competition for CO2 and some ability differences with prevention of epiphytes from the EW layer.
There are holes in this EW layer BTW, it's got weak spots and that's where most of these things attach.

I'd suggest there's more weak spots on a CO2 limited plant that a non limited plant.

Regards,
Tom Barr