enrich section on photoprotection

[teixeirak]

from R2: "I was eager to see the part of the manuscript about photoprotection and also its relationship to heat damage. The opening sentence (l. 384) was obvious to the point of being painful to read. Of course photoprotection is higher in the upper canopy: radiation levels are higher! Can this first sentence get revised to increase information content? This is one of the more exciting topics of the review, yet is handled only in a cursory fashion. If the authors could manage a bit more discussion of this topic it would be useful – instead they move (in the same paragraph) to VOC emissions, something I view as a separate capability of some plants. This is also confused in Fig. 1 where VAZ and VOC are placed on the same line. I’d like to see a more complete discussion of photoprotection and heat dissipation by NPQ first, and a separate paragraph about VOC. Also, there is nothing about critical temperature until late in the manuscript even though the authors skirt the issue in their text about photoprotection. This kind of thermal sensitivity is different from gas exchange (the section where the text about Tcrit occurs, l. 530-555), and should have been discussed earlier in the manuscript."

(separated out from issue #87)

[teixeirak]

@NidhiVinod , a lot of this seems fairly straightforward. I'll let you get started on it, and please reach out if you have questions.

[NidhiVinod]

from R2: "I was eager to see the part of the manuscript about photoprotection and also its relationship to heat damage. The opening sentence (l. 384) was obvious to the point of being painful to read. Of course photoprotection is higher in the upper canopy: radiation levels are higher! Can this first sentence get revised to increase information content? This is one of the more exciting topics of the review, yet is handled only in a cursory fashion. If the authors could manage a bit more discussion of this topic it would be useful – instead they move (in the same paragraph) to VOC emissions, something I view as a separate capability of some plants. This is also confused in Fig. 1 where VAZ and VOC are placed on the same line. I’d like to see a more complete discussion of photoprotection and heat dissipation by NPQ first, and a separate paragraph about VOC. Also, there is nothing about critical temperature until late in the manuscript even though the authors skirt the issue in their text about photoprotection. This kind of thermal sensitivity is different from gas exchange (the section where the text about Tcrit occurs, l. 530-555), and should have been discussed earlier in the manuscript."

(separated out from issue #87)

@SlotMartijn and @tyeentaylor , wondering if you have papers I could read and cite for this NPQ section? and also please let me your thoughts on the reviwer's comment here!

[SlotMartijn]

I think the reviewer makes a fair point about splitting the photoprotection and VOCs into different paragraphs. I'm thinking that the best way to connect photoprotection and heat damage is by focusing on heat damage often being expressed as an oxidative stress response, and that photoprotection includes antioxidant activity. Therefore, higher levels of photoprotection in upper canopy leaves, should have greater antioxidant activity, which would also serve as thermoprotection and postpone heat damage. Other aspects of photoprotection, such as leaf angle adjustments to reduce the radiation load, would likewise protect against leaves reaching very high temperatures. If this is an approach you all think appropriate in response to this reviewer, I can write a few sentences and find some references to support the arguments

[NidhiVinod]

@SlotMartijn, I think this makes sense to me! then would it make sense to include perhaps a line or so about NPQ in the heat damage section, you think? @SlotMartijn, here is the google document for the response: https://docs.google.com/document/d/1SArr765O39LtwLlKDxomlWur8gmtBzq8/edit#bookmark=id.gjdgxs

[NidhiVinod]

I have added some information on this. Ty is still working on adding a few more lines to this.

[NidhiVinod]

@krista, do you think we should move Tcrit section to the top? from our discussion with Martijn in the document https://docs.google.com/document/d/1SArr765O39LtwLlKDxomlWur8gmtBzq8/edit#

[teixeirak]

I have a suggested rearrangement, also involving section 3.2. Basically, we could move Tcrit up to traits, and reorganize traits thematically rather than intra-spedific/ inter-specific (which better parallels section 4). I'll push a copy of the word doc with track changes and you can see what you think.

In the end, it could go either way, and you should go with what you like.

[NidhiVinod]

@teixeirak, yes, I agree. I actually like this arrangement too. Maybe by doing this, we can also address R1's points in #99 about inter and intra-canopy more generally.

[teixeirak]

Good! Do you want to take a first pass at implementing it? I'm happy to help-- let me know.

[NidhiVinod]

I have to go to walk to lab now, but i was hoping to work more on the review at 2pm. Maybe then i can try to then, but if you want to do it now that's okay too.

[teixeirak]

I think we can close this, right?

[NidhiVinod]

yes, this can be closed.