Sessile Trichomes Play Major Roles in Prey Digestion and Absorption, While Stalked Trichomes Function in Prey Predation in Byblis guehoi

Round 1

Reviewer 1 Report

My comments are as follows,

1.      Introduction, What scientific question does this study want to address?

2.      The authors mentioned the prey utilization and the traps type of carnivorous plant in the introduction, so what kind of prey utilization and "traps" of Byblis guehoi ?

3.      Line 95-100, This paragraph about flower blooming is not relevant to the topic of this study, and can be deleted.

4.      Line 101-104, Do trichomes present on the flowers or inflorescences?

5.      Line 101, “B. guehoi has two kinds of glandular trichomes”, while “three kinds of trichomes" was mentioned in the abstract?

6.      Is there any other difference between long-stalked and short-stalked trichomes except for the head cells? Is it possible the same type at different developmental stages? Since the long stalk trichomes showed in Figure 1 and 3 are also of varying in lengths.

7.      Line 129-138, how many leaves and individuals were investigated in the study? Are the cell numbers of trichomes stable or unstable? Apart from the head cells, what about the stalk cells?

8.      Discussion, Line 331-341, In addition to absorbing nutrients, are the pores of the head cells of the sessile trichomes also the channels for digestive fluid?

9.      References : Missing page number in 13,23,26,31.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The present manuscript by Li and colleagues is generally very interesting and well-thought. The authors should take the following points into consideration during a revision:

 

My biggest problem with this submission is that the authors claim to be the first to proof the division of labour between the stalk types. However, when reading Lloyd (1942 - The carnivorous plants - Chapter VII, page 97), I see that this was already tested and referred back to, e.g., Fenner! The authors should clearly indicate what is novel in their study, and discuss the prior finding in a correct and appropriate manner!

 

My second major concern is the presentation of the stalk length and occurrence measurements. It is nowhere indicated where the stalks were located on the leaf (upper side, lower side; basal or apical part), which leaves were used (young leaf vs. old leaf), and if stalks were measured on the same leaf or on different leaves.

Table S1 mentions “length on the screen” – what does that mean? Why is a stalk on “the screen” several centimetres long? Honestly, this does not read like a reliable measuring method here…

The authors write that “the ratio of sessile, short-stalked, and long-stalked trichomes was about 10:3:1, and no obvious differences in trichome number would be detected between trichomes located on the upper and lower surfaces of the leaves.” Really? No discrepancy between the upper and lower side? Since the measurement location(s) are not indicated (see comment above), this statement is not comprehensible. What does the ratio relate to – the overall leaf? Much is quite unclear here, and the authors should be more precise.

 

The authors should read and discuss the article by Voigt and colleagues on the hierarchically structured Roridula traps. Although the adhesive system of Roridula (based on resin) is very different to Byblis (sugar-based), the trapping trichomes are otherwise very well investigated and explained in a biomechanical context, which I think is very relevant to the study under consideration here. In Roridula, the different trichomes and the different stickiness of the secreted glue constitute a multi-hierarchical capture system: the short and stiff trichomes secrete a very sticky glue and are adapted to strong, long-term adherence to prey insects, whereas the long and more flexible trichomes produce a less sticky glue, which is responsible for initial trapping and entanglement of prey. It is highly possible that a similar system has evolved in Byblis!

Voigt, D.; Gorb, E.; Gorb, S. Hierarchical organisation of the trap in the protocarnivorous plant Roridula gorgonias (Roridulaceae). J. Exp. Biol. 2009, 212, 3184–3191

 

The authors should check their manuscript for language. They mainly use past tense, which is not fitting everywhere. There are also many typos. Scientific names (e.g., Drosera) should always be written in italics, and so on. Additionally, the references are messed up a bit, please revise.

 

In the introduction, line 64 onwards, the authors write: “Although the structure and function of the glandular trichomes of Byblis were first reported long ago [2] and then further elaborated by Adlassnig [20], no experimental data or picture records were presented in these studies.” This is not correct, there are indeed very detailed figures in the Adlassnig publication. The authors should read carefully and discuss appropriately what is new in their study!

 

In the introduction, line 35 onwards, the authors mention the “carnivorous syndrome” by Juniper. However, “killing” as a feature is missing.

 

It is my view that Figure 1 can be reduced, since the information presented in the 5 sub-images can also be presented in one image.

 

Please avoid the term “dewdrop”; this is not established terminology in the carnivorous plant literature, where “glue drop” (or similar) is used.

 

In the discussion, the authors write that “Recently, the long-held theory that the traps of Byblis are nonmotile was disproved by Poppinga et al. [23].“ The authors of this publication were not the first to note that the stalks are motile, as mentioned by themselves in their article and referenced (Allan, G. Evidence of motile traps in Byblis. Carniv. Plant Newsl. 2019, 48, 51–63).

The authors furthermore write that stalk movement is “due to the reorientation of cellulose microfibrils”. This is not true, there is no re-orientation! The fixed orientation of the microfibrils dictates how the stalk cell deforms, a phenomenon widely known from many passive-hydraulically actuated plant movements, e.g., the pine cone and grass awns.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear authors,

Many thanks for providing a thoughtful revision of your beautiful and very interesting article! However, it came to my attention that now, due to the revised text, three additional issues have appeared, which require your attention. Therefore, I recommended a “minor revision”, but I am convinced that you can fix these important issues quickly.

 

1) You have re-measured stalk lengths very comprehensively and in the text you write that some stalks are “significantly longer” than others, and so on. However, it is nowhere mentioned which statistical tests were applied that warrant such statements. Would you please indicate how you tested for significance in your results?

 

2) You indicate that Roridula is protocarnivorous. Please check new literature; I am quite sure that Roridula is nowadays classified a full carnivore! See, for example, the Ellison & Adamec book on carnivorous plants (Oxford Academic, 2018).

 

3) You write that “…and further investigated by Poppinga et al. [28] at a molecular level.“ The authors of this article have not investigated the trapping system on a molecular level, but on a cellular- up to the tissue level.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Thanks for clarifying, and congratulations for this nice piece of work!