Delphinidins and Naringenin Chalcone Underlying the Fruit Color Changes during Maturity Stages in Eggplant

Round 1

Reviewer 1 Report

The manuscript „Metabolites and gene expression analyses reveal key candidates underlying fruit color changes during maturity stages in eggplant“ by Wang et al. provides valuable results on differences between two eggplant genotypes in metabolites level and genes expression for metabolites involved in fruit color regulation during maturity. Manuscript might be interesting for all involved in modern vegetable breeding and may contribute to understanding of color changes processes during maturity. However, in its current form is not well balanced and requires major revision of its content and form, particularly in the sections Results and Discussion.

 

Abstract:

Abstract is well written and contains brief information on the goals, results and implications of findings.

 

Introduction:

Lines 83-89 – Please move description of genotypes to Materials subsection.

Lines 91-94 – Please add the purpose of your investigation. Also move the last sentence to the section Discussion.

 

Materials and Methods:

Lines 97-99 – As you suggested in the Introduction that origin may significantly influence the level of delphinidins, I strongly suggest to upgrade this section by information on origin of materials used as well as with morpho data written in previous section.   

 

Results:

In order to increase the clarity of this section and to upgrade the discussion section please move your comments on results (lines 186-191, 201-204, 214-217, 222-225, 251-257) to Discussion section. Leave just results.

 

Discussion

Generally, this section is incomplete and poorly balanced. The major findings of this research are not highlighted and not adequately compared with the findings of the other studies. There are just two intermediate paragraphs on naringenin chalcone and some structural genes findings.

I strongly suggest to follow results and write paragraphs on major findings (on fruit color comparison, phenylpropanoid metabolites results and genes involved in flavonoid pathway). Please, provide a general interpretation of the results in the context of other evidences and discuss more about implications of your findings for practice and future research.

Author Response

Reviewer #1

1. Abstract is well written and contains brief information on the goals, results and implications of findings.

Response: Thank you for your approval about the abstract, and we have simplified it within 200 words according to the instructions for authors.

2. Lines 83-89 – Please move description of genotypes to Materials subsection.

Response: Thank you for this comment. We have removed the description of genotypes to “Materials and Methods” section (Line 88-92).

3. Lines 91-94 – Please add the purpose of your investigation. Also move the last sentence to the section Discussion.

Response: The purpose of the investigations was added (Line 80-81) and the last sentence was moved to the end of Conclusion section to highlight the significance of the present study (Line 334-337).

4. Lines 97-99 – As you suggested in the Introduction that origin may significantly influence the level of delphinidins, I strongly suggest to upgrade this section by information on origin of materials used as well as with morpho data written in previous section.   

Response: We have added the origin of the materials and morpho data in the subsection of “2.1. Plant materials” (Line 87-89).

5. In order to increase the clarity of this section and to upgrade the discussion section please move your comments on results (lines 186-191, 201-204, 214-217, 222-225, 251-257) to Discussion section. Leave just results.

Response: Lines 186-191, 201-204, 214-217, 222-225 and 251-254 were moved to Discussion section. Of note, since Line 254-257 showed the results, not the comments, so it was kept in the revised manuscript.

6. Generally, this section is incomplete and poorly balanced. The major findings of this research are not highlighted and not adequately compared with the findings of the other studies. There are just two intermediate paragraphs on naringenin chalcone and some structural genes findings.

I strongly suggest to follow results and write paragraphs on major findings (on fruit color comparison, phenylpropanoid metabolites results and genes involved in flavonoid pathway). Please, provide a general interpretation of the results in the context of other evidences and discuss more about implications of your findings for practice and future research.

Response: This is a very good point. The previous discussion is incomplete and poorly balanced indeed. The discussion and conclusion were modified, including general interpretation, potential implications and possible future research, based on your comments 5 and 6 as well as the comments from Reviewer #2.

Reviewer 2 Report

The manuscript is very interesting. However, some issues need to be improved before the article is published. Several language and grammatical errors need to be corrected.

1) The title of the manuscript should be more concise, specific and relevant. Please, improve it

2) The abstract is well-written, but it is too long by losing its function as a summary of the complete article. The abstract should be a total of about 200 words maximum, as indicated in the instructions for authors.  Please, summarize it.

Introduction. The authors demonstrated a good introduction. However, some revisions are needed.

3) Lines 43-45 “Eggplant fruits show highly  diversity of in color, from purplish black and purple to green and white, with most commercial varieties are purple”.

Please, change “show highly diversity of in color, from purplish black”  to  “show a high diversity of color, from purplish-black.

The 3 and 4 literature references are not recent, while the number 5 reference does not appear appropriate to the provided information. I suggest updating these literature references.

4) Line 47 “fruit [6,7], leaves [8] and the plants with red to purple to blue colors [9]”.

Please, delete "the" before "plants".

5)  Line 49 “that benefits the human health”.

Please, correct as follows “that benefit human health”

6) Lines 49-50 “[…]the flavonoid pathway that are regulated by […]”. 

The plural verb “are” does not appear to agree with the singular subject “the flavonoid pathway”. Please, consider changing the verb form “are” to “is” for subject-verb agreement.

7) Line 51 “[…] of anthocyanin pathway”.

Please, correct to “of the anthocyanin pathway” 

8) Lines 52-56 “The early biosynthetic genes (EBGs) include CHS (Chalcone Synthase), CHI (Chal- 52

cone Isomerase), and […] and UFGT (Flavonoid 55 Glucosyltransferase)”.

Please, support this information with recent literature references.

9) Lines 57-58 “[…] composed of anthocyanidin backbone with […]”.

Please, add “an” before “anthocyanidin”

10) The two sections relating to lines 46-56 and 47-64 seem to be not well connected. The authors could provide the reader with links, making it easier to follow the train of the argument.

11) Line 68.

The literature reference 21 is outdated. Please, seek a more recent literary source, if possible.

12) Line 77 “non-photosensitive with D3R”.

It seems that preposition use may be incorrect here.

The authors could correct as follow “non-photosensitive to D3R”.

13) Line 80 “ […] which is severely influences the fruit quality and reduces the shelf life”.

It appears that the form of the verb “influences” does not works with “is” in this sentence. Please, correct follow as “which severely influences the …”

Please, support this information with recent literature references.

14) Line 94 “[…]fruit color changes, but also […]”.

The comma before the conjunction “but also” appears to be unnecessary. Consider removing it.

 

2.2. Fruit peel color evaluation

15) Lines 104-105. “The color index of purple eggplants was calculated by measuring the L*, a*, and b* values of the fruits […]”

Please, specify what the letters refer to “L*, a*, and b*” in the text.  For example, the authors could write as follows “[…] by measuring the L* (lightness), a* (red-greenness), and b* (blue-yellowness)”.

The authors may add the literature reference “Bakker et al., 1986” after “L*, a*, and b* values of the fruits”. (Bakker, J., Bridle, P. & Timberlake, C. F. (1986). Tristimulus measurements (CIELAB 76) of port wine colour. Vitis, 25, 67-78).

 

16) Line 106.

Please, define the C and H parameters of the equation. For example, the authors could insert the following sentence after the equation “where H is the hue angle and C is the chroma”.

 

3. Results

3.1. Comparison of fruit color between ‘14-345’ and ‘CGN23829’ using reflectance   spectrophotometer

 

17) Line 150.

Please, specify what DPA means

 

4. Discussion

18) Some information contained in the introduction is repeated in this paragraph. Remove repetitions, either from the intro or discussion.

 

19) Paragraph 4 is not adequately discussed. Please, improve it.  The authors should better discuss the results obtained and how these can be interpreted compared to previous studies. Please, discuss the carried out research implications extensively, and highlight the potential limitations of this research work. Please, mention future research directions, if possible.

5.Conclusions

20. Please, do not include images in this paragraph. The authors could move and discuss figure 5 in paragraph 4.
21. Please, check for any language or grammatical errors.

Author Response

Reviewer #2

1. The title of the manuscript should be more concise, specific and relevant. Please, improve it

Response: The title was changed to “Delphinidins and naringenin chalcone underlying the fruit color changes during maturity stage in eggplant”. The new title should be more concise and relevant than the old one.

2. The abstract is well-written, but it is too long by losing its function as a summary of the complete article. The abstract should be a total of about 200 words maximum, as indicated in the instructions for authors. Please, summarize it.

Response: Thank you for the comment on the abstract. The abstract was modified within 200 words.

3. Lines 43-45 “Eggplant fruits show highly diversity of in color, from purplish black and purple to green and white, with most commercial varieties are purple”.

Please, change “show highly diversity of in color, from purplish black” to “show a high diversity of color, from purplish-black.

The 3 and 4 literature references are not recent, while the number 5 reference does not appear appropriate to the provided information. I suggest updating these literature references.

Response: The “show highly diversity of in color, from purplish black” was changed to “show a high diversity of color, from purplish-black. In addition, the references were changed to papers that are published recently.

4. Line 47 “fruit [6,7], leaves [8] and the plants with red to purple to blue colors [9]”.

Please, delete "the" before "plants".

Response: Corrected accordingly.

5. Line 49 “that benefits the human health”.

Please, correct as follows “that benefit human health”

Response: Corrected accordingly.

6. Lines 49-50 “[…]the flavonoid pathway that are regulated by […]”.

The plural verb “are” does not appear to agree with the singular subject “the flavonoid pathway”. Please, consider changing the verb form “are” to “is” for subject-verb agreement.

Response: Corrected accordingly.

7. Line 51 “[…] of anthocyanin pathway”.

Please, correct to “of the anthocyanin pathway”

Response: Corrected accordingly.

8. Lines 52-56 “The early biosynthetic genes (EBGs) include CHS (Chalcone Synthase), CHI (Chal- 52cone Isomerase), and […] and UFGT (Flavonoid 55 Glucosyltransferase)”. Please, support this information with recent literature references.

Response: Two recent literatures were added as the references for the above-mentioned sentences.

9. Lines 57-58 “[…] composed of anthocyanidin backbone with […]”.

Please, add “an” before “anthocyanidin”

Response: Corrected accordingly.

10. The two sections relating to lines 46-56 and 47-64 seem to be not well connected. The authors could provide the reader with links, making it easier to follow the train of the argument.

Response: Thanks for your comment. The two paragraphs were not well connected indeed. We rearranged the two paragraphs with the introduction and classifications in the first paragraph (Line 39-50) and the synthesis of anthocyanin were put in the second paragraph (Line 51-61), which is more logic than the previous version.

11. Line 68.

The literature reference 21 is outdated. Please, seek a more recent literary source, if possible.

Response: Yes, the reference 21 is outdated. We found another reference that were published at 2002 about the yellow-flowered carnation. Although it is not a very recent paper, it is the one mostly related with the relationship between naringenin chalcone and the yellow-flowered carnation.

12. Line 77 “non-photosensitive with D3R”.

It seems that preposition use may be incorrect here.

The authors could correct as follow “non-photosensitive to D3R”.

Response: Corrected accordingly.

13. Line 80 “[…] which is severely influences the fruit quality and reduces the shelf life”.

It appears that the form of the verb “influences” does not works with “is” in this sentence. Please, correct follow as “which severely influences the …”

Please, support this information with recent literature references.

Response: The ‘is’ was removed and a recent literature (Lo et al., 2021) was added to support the information.

14. Line 94 “[…]fruit color changes, but also […]”.

The comma before the conjunction “but also” appears to be unnecessary. Consider removing it.

Response: Corrected accordingly.

15. Lines 104-105. “The color index of purple eggplants was calculated by measuring the L*, a*, and b* values of the fruits […]”

Please, specify what the letters refer to “L*, a*, and b*” in the text.  For example, the authors could write as follows “[…] by measuring the L* (lightness), a* (red-greenness), and b* (blue-yellowness)”.

The authors may add the literature reference “Bakker et al., 1986” after “L*, a*, and b* values of the fruits”. (Bakker, J., Bridle, P. & Timberlake, C. F. (1986). Tristimulus measurements (CIELAB 76) of port wine colour. Vitis, 25, 67-78).

Response: Thanks for your suggestion. The letters were specified and the reference was added. We also added a recent literature reference to support the information of “L*, a*, and b* values of the fruits”.

16. Line 106.

Please, define the C and H parameters of the equation. For example, the authors could insert the following sentence after the equation “where H is the hue angle and C is the chroma”.

Response: Corrected accordingly (Line 101-102).

17. Line 150.

Please, specify what DPA means

Response: The full name of DPA was added after it.

18. Some information contained in the introduction is repeated in this paragraph. Remove repetitions, either from the intro or discussion.

Response: Thank you for highlighting this issue. We have removed the repetitions from the discussion.

19. Paragraph 4 is not adequately discussed. Please, improve it. The authors should better discuss the results obtained and how these can be interpreted compared to previous studies. Please, discuss the carried out research implications extensively, and highlight the potential limitations of this research work. Please, mention future research directions, if possible.

Response: This is a very good point. The discussion was improved with more interpretations, limitations of the present study as well as the possible future studies.

20. Please, do not include images in this paragraph. The authors could move and discuss figure 5 in paragraph 4.

Response: Corrected accordingly.

Round 2

Reviewer 1 Report

The manuscript has been sufficiently improved to warrant publication in Agronomy. Congrats.

Author Response

Thanks for your comments that help a lot for our paper.