Effects of Magnesium Sulphate Fertilization on Glucosinolate Accumulation in Watercress (Nasturtium officinale)

Round 1

Reviewer 1 Report

This manuscript is a narrative review whose stated aim is to explore the occurrence of glucosinolates in watercress (Nasturtium officinale) as affected by sulfur supply in hydroponic cultivation. The topic is appealing, a substantial amount of information is synthesized, and the language is clear and understandable. In my opinion, this paper could represent a new and original contribution, and has strong potential to become a milestone in this area of plant research.

However, something essential seems to be missing, and in its current form, the review does not fully achieve its stated objective. 

My major concern relates to the organization and progression of paragraphs and subparagraphs. The manuscript is divided into eight main sections and several subsections. The first seven sections essentially serve as an extended introduction to what should be the core of the manuscript, namely, the part dedicated to the effects of sulfur addition on watercress cultivated hydroponically, which appears to be the central research question of the review.

Yet, the template crop (watercress) is mentioned only a few times, and almost always to emphasize the scarcity of related information. Similarly, hydroponic management, particularly with regard to glucosinolate production, is stated to have received limited attention. The inclusion of a section titled “Results” leads the reader to expect that it will provide answers to the many questions raised in the preceding sections. However, Sections 8.1 to 8.5 merely summarize previously discussed issues, leaving the reader with several unanswered questions. Ultimately, the role of MgSO₄ in glucosinolate biosynthesis and accumulation in hydroponically grown watercress, which is identified in the title and early sections (lines 47–48) as the key unexplored research point, remains unresolved by the end of the review (lines 445–446).

Hence, I recommend to rearrange the text, giving it a more convenient, clear and consequent structure. According to Litmaps (https://www.litmaps.com/articles/write-narrative-review#standard-outline-for-a-narrative-review), although other well-structured guidelines may also be used, a sound narrative review should include the following components:

• Introduction: outlines the main topics and research questions. In this manuscript, the introduction is well-written, fluent, and understandable.
• Background: provides the broader context of the research. Here, subdivision into subparagraphs could be helpful, each addressing a specific aspect of the topic (e.g., historical background of watercress, glucosinolates and their uses, etc.). This section is, however, already fairly strong.
• Thematic sections: organized around specific arguments that are analyzed and discussed in depth. This is where the most substantial restructuring is needed. The focus of the review should consistently remain on watercress; only when specific literature is lacking should examples from other species be introduced. Since a “Results” section is not typically required in a review article, the data and examples from Section 8 could be merged with those from Section 7, producing a set of coherent, self-contained sections centered on watercress but supported by references to related taxa when relevant.
• Discussion and conclusions: these can be combined or separated. This final part should synthesize the main findings and provide clear answers to the research questions raised in the introduction.

Additional minor adjustements are listed below.

Major concerns are listed in the frame above; find below some minor comments.

• Table 1: Consider expanding the table to include other glucosinolates (e.g., gluconasturtin), which is first mentioned a few lines later. If necessary, adjust the caption to refer to Brassicaceae rather than Brassica.
• Line 162: Correct to “Figure 3.”
• Line 235: Add the common name “(glucoraphanin)” in parentheses.
• Line 260: A verb appears to be missing.
• Lines 286–287: This statement repeats the idea expressed in lines 290–292; please consolidate.
• Line 303: Write the full name of L. latifolium at its first mention, ideally including the authority.
• Figures 2 and 5: These are not cited in the text.
• Figure 5: Correct misspellings (“or,” “cytochrome,” and “monooxygenase”).
• Line 319: Did you mean “studies on the production … are minimal”?
• Lines 340–341: Remove the quotation marks at the beginning and the bold formatting.
• Line 365: “In brassica plants, in brassica species”; one of these phrases is redundant, please choose one.

Author Response

Response to Reviewer 1 Comments
1. Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions in track changes in the re-submitted files.   Major comments
Comments 1: [Does the title describe the article's topic with sufficient precision, bearing in mind that it is a review article?] Not exactly, as the topics raised in the title are not fully explored in the manuscript. The title induces the reader to expect that the work will focus on “Biochemical Modulation of Glucosinolate Biosynthesis in Hydroponically Grown Watercress (Nasturtium officinale) in Response to Sulfate Fertilization”, whereas the template crop, i.e., watercress, is quoted very few times, and quite always to state that scarce related information is available. Similarly, hydroponic management, especially as concerns the glucosinolate production, is declared as addressed by scarce attention.
Response 1: Thank you for pointing this out. We agree to this comment. Therefore, we have changed the title on the paper as outlined in red on line 2 and 3, on page 1 on the revised manuscript. The changed title is now therefore: Effects of Magnesium Sulfate Fertilization on Glucosinolate Accumulation in Watercress (Nasturtium officinale).     Comment 2: The arguments are not properly developed; while many questions are raised at the beginning of the manuscript, few are effectively addressed. Consequently, the reader reaches the end of the paper with essentially the same uncertainties present at the beginning. Response 2: Valid appreciation for the comment. The arguments were strengthened in the following paragraphs as outlined in red. Line 360 to 370 on page 11: Impact of Magnesium Sulfate on Glucosinate Accumulation in Hydroponically Grown Watercress. Further, within the conclusion, we further strengthened the argument to remove uncertainties as outlined in lines 512 to 518 on pages 16. The revised font is also highlighted in red.   Comment 3: The template crop (watercress) is mentioned only a few times, and almost always to emphasize the scarcity of related information. Response 3: We have accordingly revised and have mentioned more information about watercress in the introduction, in the 2nd paragraph from lines 47 to 48 on page 2 and also on the 3rd paragraphs on lines 73 to 77, also on page 2. The revised font is also highlighted in red.     Comment 4: Similarly, hydroponic management, particularly with regard to glucosinolate production, is stated to have received limited attention. Response 4: Hyroponic management particularly with regard to glucosinolate production was added on lines 310 to 319 on page 10: First paragraph. Glucosinolate Accumulation Under Soilless Conditions, this was also written in red font.   Comment 5: Ultimately, the role of MgSO₄ in glucosinolate biosynthesis and accumulation in hydroponically grown watercress, which is identified in the title and early sections (lines 47–48) as the key unexplored research point, remains unresolved by the end of the review (lines 445–446). Response 5:  The role of MgSO₄ in glucosinolate biosynthesis and accumulation in hydroponically grown watercress was resolved initially in lines 336 to 339 on page 11 under the topic, 8.2. Impact of Magnesium Sulfate on Glucosinolate Accumulation. Further, from lines 345 to 359 we further explained, under the same tab: 8.2. Impact of Magnesium Sulfate on Glucosinolate Accumulation on page 11. Additionally, in lines 362 to 372 in the paragraph: Impact of Magnesium Sulfate on Glucosinate Accumulation in Hydroponically Grown Watercress more explanations were given. Further, within the conclusion, we resolve the research point as outlined in lines 516 to 526 on page 16.The revised font is also highlighted in red.   Comment 6: Thematic sections: organized around specific arguments that are analyzed and discussed in depth. This is where the most substantial restructuring is needed. The focus of the review should consistently remain on watercress; only when specific literature is lacking. Response 6: Thank you for pointing this out. This has since been corrected: The literature review revealed the impact of organic and inorganic amendments on the GSLs concentrations in various vegetable crops, however very few studies investigated the effect of MgSO4 in watercress.     Comment 7: Since a “Results” section is not typically required in a review article, the data and examples from Section 8 could be merged with those from Section 7, producing a set of coherent, self-contained sections centered on watercress but supported by references to related taxa when relevant. Response 7: Yes this has been justified and a formal results section has been removed to become thematic sections, with several revisions and additions in red font.   Comment 8: Discussion and conclusions: these can be combined or separated. This final part should synthesize the main findings and provide clear answers to the research questions raised in the introduction. Response 8: Yes the conclusion has been modified to include the overall findings as shown on lines 512 to 522 on page 16 , in red font.

Reviewer 2 Report

The objective of this review was to evaluate the effect caused by the addition of magnesium sulfate on glucosinolate production in watercress.

The relevance of this review lies in the fact that watercress contains bioactive compounds such as glucosinolates, which is why watercress has anti-inflammatory, antimicrobial, hepatoprotective and cardioprotective effects.

The first time "GSL" is written, its meaning must be described, even if it has already been described in the Abstract.

In addition to showing glucosinolate hydrolysis (Figure 2), the authors should focus on the names and chemical structures of the main glucosinolates in cruciferous plants.

In addition to "Table 1. Glucosinolate content in Brassica plants", the authors should include the chemical formulas of glucoraphanin, glucobrassicin, and sinigrin.

The manuscript lacks a clear sequence regarding the application of glucosinolates in agriculture and in the human diet. A more structured framework (with a schematic diagram or summary table) would improve coherence.

Since it is a review article, it is necessary to indicate how the article search was conducted, the databases consulted, and the period covered.

Furthermore, since this is a review article, chapter "8. Results" should not be included as it is not a research article.

Author Response

Responses to Reviewer 2

 

Comment 1: The first time "GSL" is written, its meaning must be described, even if it has already been described in the Abstract.

Response 1: Corrected in line 32 on page 1 of the introduction, in red font.

 

Comment 2: In addition to "Table 1. Glucosinolate content in Brassica plants", the authors should include the chemical formulas of glucoraphanin, glucobrassicin, and sinigrin.

Response 2: Chemical formulas added to the table under section 6: Glucosinolates in the Human Diet on page 9, lines 276 to 277. The revised font is also highlighted in red.

 

 

Comment 3: In addition to showing glucosinolate hydrolysis (Figure 2), the authors should focus on the names and chemical structures of the main glucosinolates in cruciferous plants.

Response 3: Names and chemical structures of the main glucosinolates in cruciferous plants added under Figure 2b: line 136 to 139 page 4. The revised font is also highlighted in red.

 

 

 

Comment 4: The manuscript lacks a clear sequence regarding the application of glucosinolates in agriculture and in the human diet. A more structured framework (with a schematic diagram or summary table) would improve coherence.

Response 4: A schematic diagram was added on line 480 to 481, on page 14 under section 9.4. Transcriptomic, Epigenetic and Metabolomic Factors Affecting Glucosinolate Biosynthesis. The revised font also highlighted in red.

 

 

Comment 5: Furthermore, since this is a review article, chapter "8. Results" should not be included as it is not a research article.

Response 5: Well noted. The results section was removed and thematic sections were adopted. The revised font is highlighted in red.

Reviewer 3 Report

Dear Authors,

Suggestions for correction are in the attached file.

Kind regards,

Dear Authors,

Suggestions for correction are in the attached file.

Kind regards,

Comments for author File: Comments.pdf

Author Response

Responses to Reviewer 3

Comment 1: I suggest replacing the phrase "Results show that increased sulfate enhances total and specific GSL content based on their genes and environment" with a statement indicating that the synthesis of the reviewed literature demonstrates that increased sulfate generally improves GSL content.

Response 1: Replaced as suggested in line 20 to 21, in the abstract on page 1, in red font. The revised font is also highlighted in red.

 

Comment 2: It would become more accessible and avoid overloading the Introduction if it were referenced more succinctly, with greater emphasis on the role of sulfation as a crucial final step and a reference to section 3 ("The Science Behind Glucosinolates").

Response 2: The role of sulfation as a crucial final step was emphasized in lines 215 to 220 on page 6 under section 4. The Science Behind Glucosinolates. Further, the introduction section made reference to The Science Behind Glucosinolates, where further details of the previously mentioned biochemical synthesis of glucosinolates was removed. This section now appears in lines 201 to 220 on page 6, in red font to show the rearrangement. The revised font is also highlighted in red.

 

Comment 3: Adding a formal Review Methodology section.

Response 3: Review section added from lines 96 to 109 on page 3.

 

Comment 4 : I suggest that subsections 8.1 and 8.2 be restructured to first discuss the influence of N and S on watercress, or metabolomic profiling in hydroponic systems, and then use data from other Brassicaceae as comparative support

Response 4: Sections 8.1 and 8.2 restructured accordingly. N and S first mentioned under section 9.1. Effect of Sulphur Fertilization on the Glucosinolate Content from lines 380 to 382 on page 12. Additionally, support data from Brassicaceae was added from lines 398 to 404. Metabolomic profiling information was added under section 8.1: Glucosinolate Accumulation Under Soilless Conditions, from lines 309 to 318, on page 10. The revised font is also highlighted in red.

 

Comment 5: It is important that you include a critical analysis and in-depth discussion of the potential trade-off between biofortification (increased GSLs) and the fresh and dry biomass performance metric of watercress, which is a relevant performance factor in cultivation systems.

Response 5: The critical analysis and in-depth discussion was added under section 8.2: Impact of Magnesium Sulfate on Glucosinolate Accumulation from lines 342 to 357, on page 11. The revised font is also highlighted in red.

 

Comment 6: Conclusion should include an actionable recommendation based on the synthesis. For example, based on evidence that sulfate modulation influences GSLs in various Brassica, the conclusion could suggest specific dosage parameters or concentration ranges of sulfate (e.g., based on concentrations used in analogous studies, such as 0.5 to 1.0 mM sulfate or 50 mM magnesium sulfate in broccoli) for future researchers to test in hydroponic watercress, turning the gap into a defined starting point.

Response 6 : An actionable recommendation was added in the conclusion from lines 519 to 522, on page 15. The revised font is also highlighted in red.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Round 2

Reviewer 3 Report

Dear Authors,

The paper has been improved sufficiently to justify its publication in the IJPB.

Kind regards,

The paper has been improved sufficiently to justify its publication in the IJPB.