Presenting the Secrets: Exploring Endogenous Defense Mechanisms in Chrysanthemums against Aphids

Round 1

Reviewer 1 Report

The submitted review ‘Endogenous Defense Barriers: the War between Chrysanthemums and Aphids’ contains a summary of different mechanisms of plant defense against aphids. The topic of general aspects on plant-aphid interactions has been covered in many publications, books and journal articles. This manuscript is supposed to center on chrysanthemums. However, the Authors decided to include also general aspects. As a result, there is a mixture of information: general and chrysanthemum-centered. Unfortunately, there is confusion because these two aspects are not precisely separated and one does not know which information is of general nature and which refers precisely to chrysanthemums. Moreover, the information is in most cases very simple and with many imprecise statements. There are many errors in using English terms. The Authors should apply the terminology which is commonly used, especially in reference to aphid probing and feeding. The terminology is provided in the sources that are in the list of references. The descriptions are often very vague with few details which should be provided in a review paper. Specifically, the figure legends are imprecise and need correction and reference to the published material.

Below there are the most important aspects that should be corrected.

18-19: ‘constitutive defense, induced defense and aphid-resistance genes’ – I do not think this division is proper. Both the constitutive and induced defense mechanisms are genetically based.

38: On what basis is this statement? Literature data show a varied response of aphids to terpenoids. Some terpenoids are strong repellents.

42: The reference 10 deals with Medicago truncatula

51-63 (description to the figure 1):

-        What wavelength, please specify

-        'Inhale' means that the aphid is taking up the volatile into its respiratory system. Aphids do not inhale volatiles; aphids can sense the volatiles using the rhinaria on their antennae. Using the stylets, aphids can only ingest plant sap. The word 'ingest' is more appropriate in this context.

-        Aphids do not have a gustatory organ on the mouthparts. The gustatory organ is in the hypopharynx.

-        As above: aspiration of sap is not a proper expression.

-        What gap? Do you mean intercellular space?

-        Ingestion from sieve elements and not ‘aspiration’

-        Prokaryotic pathogens are not only located in the phloem, viruses infect also other tissues

-        References should be provided in the figure legend to support the presented information

65-75: Figure 2. The description is incomplete. It should include information on the two types of cycles: holocycle, which includes bisexual reproduction, and anholocycle, which includes only parthenogenesis. Aphids do not reproduce asexually: parthenogenesis is a sexual reproduction but using only female sex.

86: The saliva is not a type of damage: saliva can cause damage. Improper terminology

94: Imprecise statement. The publications 18 and 19 refer to aphids on legumes and not on chrysanthemums. It is not certain that the same mechanisms as in legumes exist also in chrysanthemums.

113: I suggest replace ‘slough’ with ‘aphid cuticle’

123: Aphid-transmitted plant viruses are not detrimental to aphids at all!

145-150: no reference provided; Latin names of species should be italicized

146, 164: Artemisia is not a chrysanthemum, so why it is included here.

169-173: Compare with the Introduction - lines 38 and 39 - where you state that terpenoids make chrysanthemums good hosts for aphids.

169-185: A lot of information, but does it all refer to Chrysanthemum?

-        175: Does Chrysanthemum synthesize the aphid alarm pheromone? It is not clear in this paragraph. Please, explain and provide reference if Chrysanthemum

-        181-182: Tanacetum is not a chrysanthemum. Italicize the Latin name

187-192: Figure 4d, please, explain what factors are responsible for ‘+’, ‘-‘, or ‘0’.

197: Why ‘oxidation’ has capital letter?

258: PAL is phenylalanine ammonia lyase

355: Figure 7, what do the colors mean in this scheme? The abbreviated names should be explained.

363: what is WRKY – please, explain

371: what is MYB – please, explain

 Scientific terminology should be corrected

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Overall, this is a nice review paper and will be useful to workers of aphids and particularly those in chrysanthemum management. 

I have just a few suggestions and comments.  English grammar and usage needs to be checked throughout.  For example, on line 54 it should say "ingests", not "inhales".  Line 82 should say "mechanisms" in plural, same for l. 83.  

The manuscript does present some inconsistencies in the level at which it presents different parts of the material, some very elemental while others very esoteric and complicated.  For example, the statement on l. 125 that viruses damage the plant more than the aphid is an elemental well-known phenomenon with most if not all insect-born plant viruses. 

In contrast, the entire section on the cell wall  (lines 272-285) has a great deal of chemical detail and technicality.  Is this necessary? As currently presented, it is excessively detailed and difficult to understand.  

l. 187.  Figure 4 d doesn't add much; the + and - arrows can be useful in ecological function diagrams but here are not associated with specific natural enemies or chemicals, so don't have much meaning.  Improve and specify more, or omit the diagram would be my suggestion. 

l. 234 How do toxic secondary metabolites alleviate cell damage?  Explain.

l. 318. Explain how salicylic acid can reduce chlorophyll content before aphid attach-- mediated how? Is this a naturally occurring mechanism?  Clarify.

l 386.  ABA?  Was this explained earlier and I missed it? Refresh meaning and importance

See comments above for minor corrections needed.

Author Response

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Reviewer 3 Report

Coments on an atached file.

Comments for author File: Comments.pdf

1.                Although I am not an English spoken, I still notice serious inaccuracies both in the expressions used and in the construction of the sentences, making much of the text difficult to understand. It needs a major English revision of the text.

Author Response

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Round 2

Reviewer 1 Report

The submitted version of the manuscript has been corrected by the Authors. Nevertheless, there are some points that need correction.

The title is better than the original one but refers to the defense mechanisms in general and the content is aphid-oriented. I suggest modifying it: Unveiling the Secrets: Exploring Endogenous Defense Mechanisms in Chrysanthemums against aphids.

L40: change ‘makes’ to; ‘make’ –

L44: change ‘which can better survival on the chrysanthemum’ to: ‘which can allow better survival on the chrysanthemum

Figure 2. This figure has been greatly improved. However, the present version refers only to species which do not alternate hosts. Among species infesting chrysanthemums there are ones that change hosts before winter. Your scheme excludes the host-alternating species. Myzus persicae, for example, shows host alternation depending on climate and photoperiod. In greenhouses, for example, it can develop without host alternation. Please, make necessary changes in the scheme because it is incomplete.

L 60: change ‘aspirates’ to ‘ingests’

L 149-150: Unclear, please correct the grammar

L 168: Replace ‘eglandular’ with non-glandular

L 174: ‘the hybrids of Artemisia ?

L 215-261. As plant defense mechanisms are induced by both abiotic and biotic stresses, I suggest changing the sentence into: ‘In contrast to constitutive defense, induced defense is only activated in response to biotic stresses.

Minor checks are required as indicated in the Comments for Authors

Author Response

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Reviewer 3 Report

Unveiling the Secrets:

 If it was an experimental result, it could be acceptable. But all you describe here, was already unveiled.

 Exploring Endogenous Defense Mechanisms in Chrysanthemums

I think you must put in the title aphids. Even if some defenses can be effective to other pests, aphids are the concern of your review.

Therefore, we only put the part of how aphids select host plants in the introduction mainly to reflect the fact that chrysanthemums are easily selected by aphids to become host plants, thus causing further infestation.

In this case, in the introduction a link should also be made between the different steps of aphid selection and the resistance of the plant (which is the goal of the review) – innate defenses and induced defenses. For example, in the body of the text, it is spoken of natural enemies, without ever having previously said that this also constitutes a kind of defense. After all, how can the plant affect aphid’s selection?

This, as I said earlier, mentions aphid biology mainly to explain why aphids damage chrysanthemums and why they do so much damage to chrysanthemums. The unique life history of aphids allows them to proliferate on chrysanthemums and cause damage to them. That is why it is more important for this paper to explore the endogenous defenses of chrysanthemums.

Line 43-49 - As you said, the “life story” of aphids explain the damage they cause and consequently the importance to explore new ways to control it, but it is not related to plant defenses (at least you don't give any reference about that). The way you mix this section, between plant defenses, gives a wrong idea. If you want to keep the life story, it should be moved on the previous section to understand the potential damage importance of aphids.

What do you mean by “agricultural methods” and “agricultural control”?

Do you mean cultural pest management methods or biological control?

 Line 90 - “offers the possibility of controlling aphids with molecular methods. “– you should better explain what you mean by molecular methods. You put these methods on an equal foot with other methods used by a plant producer. Is what you want to say about, or do you mean plant breeding?

  Reportedly, aphids require piercing cells to consume sap when selecting a host plant [13].

 I am not an English spoken but it seems clearer:

 When selecting a host plant (Figure 1), aphids must pierce the cells using their stylets, to access the sap [13].

Author Response

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