Methyl Jasmonate Applications in Viticulture: A Tool to Increase the Content of Flavonoids and Stilbenes in Grapes and Wines

Round 1

Reviewer 1 Report

This manuscript on the application of MeJ in viticulture is very well written and easy to follow. I only came across handful of minor points that could be addressed - see below.

In the abstract: Ln 14, replace study with interest. In the introduction: Ln 30, delete 'most'. Ln 83, delete are and remove the 'd' from accumulated. Ln 83, delete exclusive. Ln 87, add 'in red varieties' to the end of the sentence. 

The rest of the manuscript is quite nice and would not require a substantial adjustment

Author Response

 

This manuscript on the application of MeJ in viticulture is very well written and easy to follow. I only came across handful of minor points that could be addressed - see below.

 

In the abstract: Ln 14, replace study with interest. In the introduction: Ln 30, delete 'most'. Ln 83, delete are and remove the 'd' from accumulated. Ln 83, delete exclusive. Ln 87, add 'in red varieties' to the end of the sentence.

 

The rest of the manuscript is quite nice and would not require a substantial adjustment

 

Response: We appreciate the suggestion performed by the reviewer. Based upon the proposal, we have edited the sentences along the manuscript (please see lines: 17,37,92,95,97).

Author Response File: Author Response.docx

Reviewer 2 Report

I am sorry, but the MS deserve rejection because several not well explained points are present.

In order of importance:

Table 1 and 2. There is no indication of the concentration of MeJ applied, no clear information regarding the number of treatments and the timing of treatments. Without that the information present in the two tables cannot be understood. 

Chapter 2 does not provide a clear framework regarding phenolic substances produced in response to MeJ treatments, e.g. anthocyanidins, flavonols and flavanols are classes of flavonoids, but not stilbenes, so that at lines 214 it is not correct the phrase “improving the concentration of flavonols in wines”.

Some information of Chapter 3 should be used for Discussion, while other should be omitted e.g. “priming” or “callose deposition”.

Author Response

I am sorry, but the MS deserve rejection because several not well explained points are present.

 

Response: We regret the review that this reviewer has made as in his opinion there are several points explained incorrectly but she/he does not mention any that are wrong. However, based on reviewing it, we have noticed some missing information in the tables that we have carefully added into the manuscript and we appreciate this consideration (please see Tables 1 and 2). In this case, we would like to humbly request that the reviewer could deepen his review and tell us which are the incorrectly written paragraphs in order to improve the content of this manuscript. To our opinion, the considerations made in this review do not justify the rejection of the publication.

 

In order of importance:

 

Table 1 and 2. There is no indication of the concentration of MeJ applied, no clear information regarding the number of treatments and the timing of treatments. Without that the information present in the two tables cannot be understood.

 

Response: We appreciate the suggestion performed by the reviewer and we have added information about dosage and moment of MeJ applications of the reviewed manuscripts into the tables (please see Tables 1 and 2).

 

Chapter 2 does not provide a clear framework regarding phenolic substances produced in response to MeJ treatments, e.g. anthocyanidins, flavonols and flavanols are classes of flavonoids, but not stilbenes, so that at lines 214 it is not correct the phrase “improving the concentration of flavonols in wines”.

 

Response: Thank you for the suggestion and we have edited this little mistake as correspond (please see lines: 227,236-237). “More recent studies have reported that the foliar application of this elicitor to Tempranillo grapevines increased the anthocyanins and stilbenes content in grapes and wines compared to control (Tables 1 and 2), and also enhanced the concentration of flavonols in the produced wines [23,77].” In addition, the second section is introductory and as its title says it is called "biosynthesis and role of phenolic compounds in grapes". Here, there is no mention of flavonoid compounds that could misinterpret the introduction of stilbenes to this chapter.

 

Some information of Chapter 3 should be used for Discussion, while other should be omitted e.g. “priming” or “callose deposition”.

 

Response: We appreciate the suggestion performed by the reviewer. However, we will not consider it in our review manuscript since these are completely different sections.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The article ‘Methyl jasmonate applications in viticulture: a tool to increase the content of phenolic compounds in grapes and wines’, presented for review is verry interesting. The MeJ applications to grapevines improve the content of most of the families of phenolic compounds in grapes and wines. However, the effectiveness of this treatment depends on the variety and season factors. This is very important due to the beneficial effects of these compounds on health.

The some issues need to be clarified or supplemented. The comments are included below.

• Line 77-78: The anthocyanins are water-soluble pigments responsible for the red color and its tonality variations in grapes and red wines. These also contribute to the astringency and bitterness of grapes and wines [5]. – This is a debatable statement. There are other compounds responsible for the astringency and bitterness.
• The authors highlight the beneficial effect of MeJ on increasing anthocyanin content and synthesis of polyphenolic compounds. Are there studies on the effect of MeJ on the stability of these compounds? Sometimes a higher concentration of these compounds results in a higher rate of degradation, especially with longer storage. Regarding the final result, it is not always beneficial.
• Does the use of MeJ not have a negative impact on the shelf life of the fruit after harvest? Are there any research results on this?

Author Response

The article ‘Methyl jasmonate applications in viticulture: a tool to increase the content of phenolic compounds in grapes and wines’, presented for review is verry interesting. The MeJ applications to grapevines improve the content of most of the families of phenolic compounds in grapes and wines. However, the effectiveness of this treatment depends on the variety and season factors. This is very important due to the beneficial effects of these compounds on health.

 

Response: We really appreciate the suggestions performed by the reviewer since it motivates us to work harder on this issue.

 

Some issues need to be clarified or supplemented. The comments are included below.

 

Line 77-78: The anthocyanins are water-soluble pigments responsible for the red color and its tonality variations in grapes and red wines. These also contribute to the astringency and bitterness of grapes and wines [5]. – This is a debatable statement. There are other compounds responsible for the astringency and bitterness.

 

Response: We agree, and we have edited this sentence according to the suggested by the reviewer (please see lines: 85-86). “Recently, it has been demonstrated that these compounds also can contribute to the astringency and bitterness of grapes and wines”

 

The authors highlight the beneficial effect of MeJ on increasing anthocyanin content and synthesis of polyphenolic compounds. Are there studies on the effect of MeJ on the stability of these compounds? Sometimes a higher concentration of these compounds results in a higher rate of degradation, especially with longer storage. Regarding the final result, it is not always beneficial.

Does the use of MeJ not have a negative impact on the shelf life of the fruit after harvest? Are there any research results on this?

 

Response: The reviewer's suggestions are very interesting but are beyond the scope of our knowledge and the purposes of the review. In this case, our work is more focused on grapes for wine production and not on the table where we do not have much knowledge. We regret not being able to take the reviewer's suggestions, but this is beyond our knowledge.

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I am sorry, but still the MS deserve rejection because of several unclear points and mistakes

2. In chapter 2. “Biosynthesis and role of phenolic compounds in grapes” lacks a clear classification of phenolic compounds; of course various different classifications of phenolic compounds have been proposed over time by different researchers, so MS authors are free to introduce the classification they prefer citing the original source in order to avoid any inaccuracy. In fact, in the chapter 2 there is no mention about the existence of different classes of phenolic compounds so as to give the idea that phenols in vine are only anthocyanins, flavonols, flavanols and stilbenes. Such a simplification cannot be accepted in a review. to my knowledge Stilbenes are a class of phenolic compounds as are flavonoids which include the subclasses of anthocyanins, flavonols, flavanols; curiously the word flavonoid is only used as an adjective about enzymes or at line 117 without ever indicating the relationship with anthocyanins, flavonols, flavanols. Additionally, lines 226-228 indicate an "improvement in the content of flavonoids and non-flavonoids compounds, such as anthocyanins, flavonols, hydroxycinnamic acids, flavanols and stilbenes"; so what would the flavonoid and non-flavonoid compounds be?
3. There are several abbreviations/acronyms that should be eliminated because they are only mentioned once, e.g. AAT, AVI, FLS;
4. Table 1a, the legend indicates foliar treatments with MeJ, so it is not clear why in the table are indicated in some cases treatments "to grapes" and in others "to plants";
5. Table 1b, it is necessary to indicate the concentration of MeJ, the number of treatments and at what stage of development of the plant / fruit the treatments were carried out;
6. Table 1c, in the column "Effects" it is useless to repeat “MeJ applications” or “MeJ applications to grapevines”;
7. Table 1d, trans and cis-piceid, and trans-resveratrol are cited; of course they are stilbenes compounds, but why were these compounds not mentioned in Chapter 2? And where is it indicated that they are chemical compounds that are part of the class of stilbenes?
8. Table 2, see comments for Table 1, e.g It is really helpful to explain to the reader what ε-Viniferin is;
9. Other points would deserve comments but the above is already enough to justify rejection 

Author Response

Response to reviewer

1) I am sorry, but still the MS deserve rejection because of several unclear points and mistakes.

Response: We really appreciate the suggestions performed by the reviewer and we have corrected all the indications that the reviewer made us in the revision. Hopefully the new corrections are to the liking of the reviewer.

2) In chapter 2. “Biosynthesis and role of phenolic compounds in grapes” lacks a clear classification of phenolic compounds; of course various different classifications of phenolic compounds have been proposed over time by different researchers, so MS authors are free to introduce the classification they prefer citing the original source in order to avoid any inaccuracy. In fact, in the chapter 2 there is no mention about the existence of different classes of phenolic compounds so as to give the idea that phenols in vine are only anthocyanins, flavonols, flavanols and stilbenes. Such a simplification cannot be accepted in a review. to my knowledge Stilbenes are a class of phenolic compounds as are flavonoids which include the subclasses of anthocyanins, flavonols, flavanols; curiously the word flavonoid is only used as an adjective about enzymes or at line 117 without ever indicating the relationship with anthocyanins, flavonols, flavanols. Additionally, lines 226-228 indicate an "improvement in the content of flavonoids and non-flavonoids compounds, such as anthocyanins, flavonols, hydroxycinnamic acids, flavanols and stilbenes"; so what would the flavonoid and non-flavonoid compounds be?

Response: We agree and based on the reviewer’s suggestion we have edited and added information about the classifications of phenolic compounds to avoid any inaccuracy exposed by the reviewer. We have added the following paragraphs in the second chapter. “Based on the primary chemical structures of hydroxybenzenes, phenolic compounds can be classified into flavonoids and non-flavonoids compounds [3,17,22,13]. The most abundant flavonoids found in grapes include anthocyanins, flavonols and flavanols [17]. Hydroxycinnamic and hydroxybenzoic acids, volatile phenols and stilbenes are non-flavonoids compounds. Recent studies have been shown that anthocyanins, flavonols, flavanols and stilbenes are important elicitor activity markers that are synthesized after the affection of a pathogen in the plants [14,17,18]. Flavonoids and non-flavonoids compounds” (please, see lines 76 to 82). “The main stilbenes found in grapes are cis- and trans-resveratrol (3,5,4′-trihydroxystilbene), resveratrol-3-O-β-d-glucopyranoside (piceid), piceatannol (3,4,3′,5′-tetrahydroxy-trans-stilbene) and resveratrol dimers (viniferins) [17,18,37]. Hopeaphenol, resveratroloside, resveratrol-4′-O-β-d-glucopyranoside, and resveratrol di- and tri-glucoside derivatives are isomeric and glycosylated forms of resveratrol and piceatannol that have also been identified in trace amounts in grapes [17].” (please, see lines 131-136).

3) There are several abbreviations/acronyms that should be eliminated because they are only mentioned once, e.g. AAT, AVI, FLS;

Response: We have deleted all the acronyms that were only mentioned once.

4) Table 1a, the legend indicates foliar treatments with MeJ, so it is not clear why in the table are indicated in some cases treatments "to grapes" and in others "to plants";

Response: We have edited it for a better understanding of the table legend (please, see tables).

5) Table 1b, it is necessary to indicate the concentration of MeJ, the number of treatments and at what stage of development of the plant / fruit the treatments were carried out;

Response: This information was already added in the first revision. If there is no information that the reviewer satisfies, it is because it is not within the referenced article.

6) Table 1c, in the column "Effects" it is useless to repeat “MeJ applications” or “MeJ applications to grapevines”;

Response: Thank you for the suggestion. Based on the reviewer’s suggestion we have edited it in both tables (please, see tables).

7) Table 1d, trans and cis-piceid, and trans-resveratrol are cited; of course they are stilbenes compounds, but why were these compounds not mentioned in Chapter 2? And where is it indicated that they are chemical compounds that are part of the class of stilbenes?

Response: As was aforementioned stated, we have added the classification of phenolic compounds (please, see lines 131-136).

8) Table 2, see comments for Table 1, e.g It is really helpful to explain to the reader what ε-Viniferin is;

Response: We agree and as was aforementioned stated, we have added the classification of phenolic compounds (please, see lines 131-136).

9) Other points would deserve comments but the above is already enough to justify rejection

Response: This may be correct, but we think that the reviews are more in form and not in substance and do not relate much to the purpose of the review.

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

Very honestly the MS is not of sufficient quality for publication. There are still many points that have not been reviewed,

1. Writing " Based on the primary chemical structures of hydroxybenzenes, phenolic compounds can be classified into flavonoids and non-flavonoids compounds [3,17,22,13]" is a simplification taken from the introduction of reference 22, literally “These secondary metabolites are divided according to their structure in non-flavonoids (i.e. phenolic acids and stilbenes) and flavonoids (i.e. anthocyanins, flavonols, and flavanols)”. Anyway, such reference introduces at least some examples to indicate a non exhaustive classification. In the present MS, such classification appears exhaustive whereas only reference 3 shows a classification of phenolic compounds without a classification in “flavonoids and non-flavonoids” (cfr. attached fìgure from reference 3). A review on “the content of phenolic compounds” must correctly categorize phenolic compounds or alternatively change the title to "flavonoids and stilbenes". This was the strategy of reference 17 which was focused only on three classes of grape phenolics: anthocyanins, stilbenes and flavonols.
2. Chapter 3 appears to have little connection with the topic of the effects on flavonoids and non-flavonoids compounds of the MeJ treatments
3. Still several abbreviations/acronyms that should be explained or eliminated remain in the text (Authors cannot modify only the acronyms cited by the reviewer), e.g. JAI, MYC, WRKY, NAC, MYB, MYB, CHI, F3H.
4. Table 1 and 2, the column "Effects" could be named “Effects of MeJ treatments” deleting along column lines “MeJ icreased” or “MeJ wines showed”.
5. Line 147: “(Figure 1)” refers to Figure 1 of the reference 45 or whatever?
6. Some gene names are not written in Italic, e.g. Pr-1, Pr-2, Pr-5
7. Line 192: “Calose” must corrected in “Callose”.

Author Response

Very honestly the MS is not of sufficient quality for publication. There are still many points that have not been reviewed.

Response: We really appreciate the suggestions performed by the reviewer and we have corrected all the indications that the reviewer made us in the new revision. Hopefully the new corrections are to the liking of the reviewer even though we have big differences in relation to her/his revision. Honestly, we think that this manuscript should be accepted since a review regarding the use of this elicitor in viticulture has not yet been published and that we also provide guidelines for future research that have not been taken into account in other published reports. Another important fact is to take into account the crosstalk relations between hormones, which has been very little studied and that we indicate as a future study perspective in this manuscript.

 

Writing " Based on the primary chemical structures of hydroxybenzenes, phenolic compounds can be classified into flavonoids and non-flavonoids compounds [3,17,22,13]" is a simplification taken from the introduction of reference 22, literally “These secondary metabolites are divided according to their structure in non-flavonoids (i.e. phenolic acids and stilbenes) and flavonoids (i.e. anthocyanins, flavonols, and flavanols)”. Anyway, such reference introduces at least some examples to indicate a non exhaustive classification. In the present MS, such classification appears exhaustive whereas only reference 3 shows a classification of phenolic compounds without a classification in “flavonoids and non-flavonoids” (cfr. attached fìgure from reference 3). A review on “the content of phenolic compounds” must correctly categorize phenolic compounds or alternatively change the title to "flavonoids and stilbenes". This was the strategy of reference 17 which was focused only on three classes of grape phenolics: anthocyanins, stilbenes and flavonols.

 

Response: We really appreciate the suggestions performed by the reviewer and we have edited the tittle and some paragraphs along the manuscript as was proposed. “Methyl jasmonate applications in viticulture: a tool to increase the content of flavonoids and stilbenes in grapes and wines” (please see lines: 33-34, 490-491, 499). However, we still consider that the corrections performed by the reviewer do not address substantive issues that may justify a rejection of the article and rather address issues of form.

 

Chapter 3 appears to have little connection with the topic of the effects on flavonoids and non-flavonoids compounds of the MeJ treatments

 

Response: We do not agree because this section introduces the reader to the biochemical processes that involve the synthesis of phenolic compounds and that are of utmost importance to understand the effect of MeJ in its quantitative improvement. On the other hand, the reviewer in the corrections made above categorically points out that it is very important to explain an exact classification of phenolic compounds and explain some stilbenes in detail, which is addressed in this section.

 

Still several abbreviations/acronyms that should be explained or eliminated remain in the text (Authors cannot modify only the acronyms cited by the reviewer), e.g. JAI, MYC, WRKY, NAC, MYB, MYB, CHI, F3H.

 

Response: Thank you for the suggestion. Based on the reviewer’s suggestion we have edited it along the manuscript (please, see lines: 84-87, 166-168, 170-171, 173-174, 179-180, 184-185, 219-220, 246-247, 365-367).

 

Table 1 and 2, the column "Effects" could be named “Effects of MeJ treatments” deleting along column lines “MeJ icreased” or “MeJ wines showed”.

Response: Thank you for the suggestion. Based on the reviewer’s suggestion we have edited it in both tables (please, see tables).

 

Line 147: “(Figure 1)” refers to Figure 1 of the reference 45 or whatever?

Response: Thank you for the suggestion. This was a mistake and we have deleted this information.

 

Some gene names are not written in Italic, e.g. Pr-1, Pr-2, Pr-5

Response: Thank you for the suggestion. We have edited it according to the proposed (please, see lines: 233, 238, 242).

 

Line 192: “Calose” must corrected in “Callose”.

Response: Thank you for the suggestion. We have edited it according to the proposed (please, see line: 226).