Advances in Genetic Enhancement of Nutritional Quality of Tropical Maize in West and Central Africa
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
This review paper deals with the advances in genetic enhancement of the nutritional quality of tropical maize in West and Central Africa. The paper is of interest and addresses an important aspect of hidden hunger in one of the most affected regions. In general, the paper is good; however, a thorough and careful revision is needed. I made all my comments and edits directly in the MS (attached). The most important points are:
I think the title of the review implies that there should be some background information on what was going on before presenting what the situation is now and how to move forward.
Please try to rewrite the abstract more coherently and comprehensively.
As a review paper, one expected more on the hidden hunger (some figures) in Africa and the targeted West and Central Africa compared to the rest of the world.
Before moving on to modern breeding, it might be appropriate to indicate the efforts (if any) made to develop varieties with enriched micronutrients through conventional breeding.
Please make your review more comprehensive and inclusive. I have the feeling that you are reviewing the work that is going on at IITA in this regard. Even if you have to do so because there is no such type of work elsewhere in the target regions, you should at least link your work to what is going on elsewhere.
I also believe that providing data on different aspects of the review will be more informative for readers, especially in the target regions and Africa as a whole.
Since this review covers West and Central Africa, it would have been better to provide a table showing the number of maize varieties (especially those with enhanced nutritional quality) in these areas.
Sometimes under a general subtitle (e.g. 3.2), an almost very specific study is presented. At least some general statements should be provided and then such specific study can be given as an example.
I think you need to consolidate your conclusion in a better way, rather than repeatedly mentioning the same statement in different forms and phrases.
Please update your references with more similar works done in Africa and similar environments. Please check your citation style.
Please provide the full name before mentioning the abbreviations.
Some additional edits and comments can be found in the MS.
Comments for author File: 
Comments.pdf
Comments on the Quality of English Language
Minor English language editing is required.
Author Response
Response to Reviewer 1:
This review paper deals with the advances in genetic enhancement of the nutritional quality of tropical maize in West and Central Africa. The paper is of interest and addresses an important aspect of hidden hunger in one of the most affected regions. In general, the paper is good; however, a thorough and careful revision is needed. I made all my comments and edits directly in the MS (attached). The most important points are:
1· I think the title of the review implies that there should be some background information on what was going on before presenting what the situation is now and how to move forward.
Response: Section 2. "Breeding for Enhance Nutritional Quality" addresses the current situation and the number of OPVs and hybrids released so far as listed at the HarvestPlus website (hyperlink provided). Several publications from IITA and partners have shown the success of conventional breeding of biofortified maize. The intention of this review is about harnessing available and emerging tools and techniques that could accelerate the breeding of biofortified maize.
2· Please try to rewrite the abstract more coherently and comprehensively.
Response: Abstract was rewritten to address the reviewers' comments.
3· As a review paper, one expected more on the hidden hunger(some figures) in Africa and the targeted West and Central Africa compared to the rest of the world.
Response: Figure 1 was added to shed light on the hidden hunger situation in selected African countries.
4· Before moving on to modern breeding, it might be appropriate to indicate the efforts (if any) made to develop varieties with enriched micronutrients through conventional breeding.
Response: Section 2 is all about achievements through conventional breeding, including number of OPVs and hybrids released. Evidences for the success of conventional breeding are abound. Here, the focus is about modernizing the conventional breeding to develop biofortified cultivars with multiple nutrients efficiently and effectively.
5· Please make your review more comprehensive and inclusive. I have the feeling that you are reviewing the work that is going on at IITA in this regard. Even if you have to do so because there is no such type of work elsewhere in the target regions, you should at least link your work to what is going on elsewhere.
Response: As the reviewer noted, major breeding work is done at IITA and CIMMYT, whereas NARS perform regional trials and evaluations for release of hybrids and OPVs. Based on this comment, a statement was added that IITA collaborates with other CG centers, NARS, and private seed companies to complete the breeding pipeline.
5· I also believe that providing data on different aspects of the review will be more informative for readers, especially in the target regions and Africa as a whole.
Response: The hyperlink provided (section 2, line 85-144 in the revised version) takes to the Harvestplus database where there is comprehensive data about crops, varieties, type of biofortification. We avoided duplicating the same information in this review but provided the cross reference for interested readers.
6· Since this review covers West and Central Africa, it would have been better to provide a table showing the number of maize varieties (especially those with enhanced nutritional quality) in these areas.
Response: Under Section 2, a hyperlink to the HarvestPlus web page has been provided. The HP database have excellently prepared interactive graphs and Tables with respect to crops, number of varieties, level of nutrient, countries, etc. We wanted to avoid duplication of the same data in this review.
7· Sometimes under a general subtitle (e.g. 3.2), an almost very specific study is presented. At least some general statements should be provided and then such specific study can be given as an example.
Response: Thanks for this valuable comment. For subheading 3.2., for example, an introductory statement was added preceding the specific work on population improvement.
8· I think you need to consolidate your conclusion in a better way, rather than repeatedly mentioning the same statement indifferent forms and phrases.
Response: This is valuable suggestion. The section "Future Directions" was eliminated some contents merged with "Prospect and Perspective". Also, the Conclusion was modified by adding new, non-redundant, statements. Some reptations were deleted.
9· Please update your references with more similar works done in Africa and similar environments. Please check your citation style.
Response: Three wrongly formatted citations were corrected and formatted according to the template.
10· Please provide the full name before mentioning the abbreviations
Some additional edits and comments can be found in the MS.
Response: Several acronyms/abbreviations were fully defined on the first instance.
*N.B. Additional comments and suggestions on the MS-pdf were duly addressed.
Reviewer 2 Report
Comments and Suggestions for Authors
In general, this is an interesting manuscript (agriculture-2886803-peer-review-v1) focuses on the significant issue of micronutrient deficiencies in developing countries and proposes biofortified cultivars developed through breeding as a sustainable solution. It highlights recent advancements in genomics and molecular tools that have enabled the rapid identification and development of maize cultivars enriched with essential micronutrients like provitamin A, iron, and zinc. The review emphasizes the importance of integrating multi-omics approaches and new technologies such as genome editing and nutrigenomics to accelerate the genetic improvement of maize for enhanced nutrition.
Suggestions for improvement are listed below.
Consistently apply the journal's designated font throughout the entire text.
Lines 24-57 : In addition to vitamin A, it is necessary to identify specific nutritional deficiencies common in the diets of populations in West and Central Africa, such as iron and zinc deficiencies. It is essential to enhance the literature review by conducting a thorough examination of current research on genetic enhancement methods, with a specific focus on those aimed at enhancing the nutritional content of maize, support all this with references.
Line 59: International Institute of Tropical Agriculture (IITA) should be written in full before using the abbreviation, as well as for all other abbreviations mentioned in the text.
Line 61: high levels of β-carotene and other carotenoids, please indicate the level or range within parentheses.
Line 63: high provitamin A content, please indicate the level or range within parentheses.
Lines 58-84: It is necessary to do a detailed assessment of the genetic diversity of maize germplasm available in West and Central Africa, with a focus on identifying sources of variation for key nutritional traits, support all this with references. Are molecular tools and genomic resources used to identify and characterize candidate genes associated with the biosynthesis and accumulation of target nutrients in maize? What are the molecular tools and genomic resources used to identify and characterize candidate genes associated with the biosynthesis and accumulation of target nutrients in maize? This paragraph should be dedicated to breeding approaches for enhancing the nutritional quality of tropical maize varieties in West and Central Africa. By combining scientific expertise with stakeholder engagement and capacity-building efforts. Therefore, I suggest rewriting that this paragraph from 58-85 to make it more readable, and by adding the text from 116-136, because it all refers to the same topic.
Lines 86-99 and 163-190: Paragraph line 87-99 is difficult to read and suggest that it be rewritten so that the text would be easier to read and that the text be combined with paragraph line 163-190 and that the title be changed in accordance with the changes to something like this " Advancing Agricultural Solutions: Breeding Strategies for Multi-Nutrient Enriched Tropical Maize to Address Micronutrient Deficiencies in Sub-Saharan Africa".
Line 137: I would suggest another title of the type “Understanding the Impact of Processing Methods on Micronutrient Content in Maize: Implications for Breeding Strategies” the title provided does not follow the text provided (lines 138-148).
Line 151: Absence of references may indicate the need for inclusion of some of these. I recommend considering the incorporation of some of these references:
Suwarno, W. B., Hannok, P., Palacios-Rojas, N., Windham, G., Crossa, J., & Pixley, K. V. (2019). Provitamin A carotenoids in grain reduce aflatoxin contamination of maize while combating vitamin A deficiency. Frontiers in Plant Science, 10, 30.
Purar, B., Djalovic, I., Bekavac, G., Grahovac, N., Krstović, S., Latković, D., ... & Živančev, D. (2022). Changes in Fusarium and Aspergillus Mycotoxin Content and Fatty Acid Composition after the Application of Ozone in Different Maize Hybrids. Foods, 11(18), 2877.
Line 246: I suggest that the title "Forward Breeding" be changed to reflect the text below in something like "Enhancing Maize Improvement through Forward Breeding and Trait-Linked Marker Assisted Selection in Maize Breeding Programs".
Line 334-355: This paragraph is difficult to read, I suggest that it be rewritten in such a way as to present the continuous research and development of advanced genetic tools such as technologies for genetic editing of the genome (like CRISPR-Cas9) will enable precise modifications to key genes involved in nutrient biosynthesis pathways. This can lead to the creation of maize varieties with optimized nutritional profiles tailored to address specific nutrient deficiencies prevalent in the region. Then it is necessary to mention Integration of Multi-Omics Approaches: Embracing multi-omics approaches, including genomics, transcriptomics, proteomics, and metabolomics, will provide comprehensive insights into the complex interactions governing nutritional traits in maize. By elucidating the molecular mechanisms underlying nutrient accumulation and metabolism, researchers can identify novel targets for genetic enhancement and accelerate breeding efforts. It is certainly worth mentioning in this part that exploiting the rich genetic diversity present in maize germplasm collections, both locally adapted landraces and exotic germplasm, will be crucial for broadening the genetic base and introducing novel alleles associated with enhanced nutritional traits.
Author Response
Response to Reviewer 2:
In general, this is an interesting manuscript (agriculture-2886803-peer-review-v1) focuses on the significant issue of micronutrient deficiencies in developing countries and proposes biofortified cultivars developed through breeding as a sustainable solution. It highlights recent advancements in genomics and molecular tools that have enabled the rapid identification and development of maize cultivars enriched with essential micronutrients like provitamin A, iron, and zinc. The review emphasizes the importance of integrating multi-omics approaches and new technologies such as genome editing and nutrigenomics to accelerate the genetic improvement of maize for enhanced nutrition.
Suggestions for improvement are listed below.
- Consistently apply the journal's designated font throughout the entire text.
Response: All fonts of the body and the heading are corrected.
- Lines 24-57: In addition to vitamin A, it is necessary to identify specific nutritional deficiencies common in the diets of populations in West and Central Africa, such as iron and zinc deficiencies. It is essential to enhance the literature review by conducting a thorough examination of current research on genetic enhancement methods, with a specific focus on those aimed at enhancing the nutritional content of maize, support all this with references.
Response: Three more references were added as a review with a focus on Zn and Fe. (Line 65-73 in the revised version).
- Line 59: International Institute of Tropical Agriculture (IITA) should be written in full before using the abbreviation, as well as for all other abbreviations mentioned in the text.
Response: Corrected (now Line 86 in the revised version)
- Line 61: high levels of β-carotene and other carotenoids, please indicate the level or range within parentheses.
Response: As suggested " >15 μg g-1" has been added (line 97 on the revised version).
- Line 63: high provitamin A content, please indicate the level or range within parentheses.
Response: As suggested " >15 μg g-1" has been added (line 100 on the revised version).
- Lines 58-84:It is necessary to do a detailed assessment of the genetic diversity of maize germplasm available in West and Central Africa, with a focus on identifying sources of variation for key nutritional traits, support all this with references. Are molecular tools and genomic resources used to identify and characterize candidate genes associated with the biosynthesis and accumulation of target nutrients in maize? What are the molecular tools and genomic resources used to identify and characterize candidate genes associated with the biosynthesis and accumulation of target nutrients in maize? This paragraph should be dedicated to breeding approaches for enhancing the nutritional quality of tropical maize varieties in West and Central Africa. By combining scientific expertise with stakeholder engagement and capacity-building efforts. Therefore, I suggest rewriting that this paragraph from 58-85 to make it more readable, and by adding the text from 116-136, because it all refers to the same topic.
Response: The genetic diversity of maize germplasm, with respect to carotenoids, has been discussed in section 3.1. Publication evidences has been throroughly discussed in this section. The key publication of all our works in WCA have been cited.
- Lines 86-99 and 163-190: Paragraph line 87-99 is difficult to read and suggest that it be rewritten so that the text would be easier to read and that the text be combined with paragraph line 163-190 and that the title be changed in accordance with the changes to something like this " Advancing Agricultural Solutions: Breeding Strategies for Multi-Nutrient Enriched Tropical Maize to Address Micronutrient Deficiencies in Sub-Saharan Africa".
Response: Thanks for the suggestion. Some modification were made in the first paragraph to improve readability. Also, paragraph line 163-169 (Iron and Zinc) has been merged with paragraph line 87-89.
- Line 137: I would suggest another title of the type “Understanding the Impact of Processing Methods on Micronutrient Content in Maize: Implications for Breeding Strategies” the title provided does not follow the text provided (lines 138-148).
Response: The subheading was modified as follows "Impact of Processing Methods on Degradation and Losses of Micronutrient Content"
- Line 151: Absence of references may indicate the need for inclusion of some of these. I recommend considering the incorporation of some of these references:
Suwarno, W. B., Hannok, P., Palacios-Rojas, N., Windham, G., Crossa, J., & Pixley, K. V. (2019). Provitamin A carotenoids in grain reduce aflatoxin contamination of maize while combating vitamin A deficiency. Frontiers in Plant Science, 10, 30.
Purar, B., Djalovic, I., Bekavac, G., Grahovac, N., Krstović, S., Latković, D., ... & Živančev, D. (2022). Changes in Fusarium and Aspergillus Mycotoxin Content and Fatty Acid Composition after the Application of Ozone in Different Maize Hybrids. Foods, 11(18), 2877.
Response: The first reference "Suwarno et al." is already cited. However, Purar et al. don't seem to be relevant for this review as it discusses about the effect of Ozone treatment on mycotoxin content.
- Line 246: I suggest that the title "Forward Breeding" be changed to reflect the text below in something like "Enhancing Maize Improvement through Forward Breeding and Trait-Linked Marker Assisted Selection in Maize Breeding Programs".
Response: To use a more concise subheading, we modified it to "Forward Breeding using Trait-linked Molecular Markers".
- Line 334-355: This paragraph is difficult to read, I suggest that it be rewritten in such a way as to present the continuous research and development of advanced genetic tools such as technologies for genetic editing of the genome (like CRISPR-Cas9) will enable precise modifications to key genes involved in nutrient biosynthesis pathways. This can lead to the creation of maize varieties with optimized nutritional profiles tailored to address specific nutrient deficiencies prevalent in the region. Then it is necessary to mention Integration of Multi-Omics Approaches: Embracing multi-omics approaches, including genomics, transcriptomics, proteomics, and metabolomics, will provide comprehensive insights into the complex interactions governing nutritional traits in maize. By elucidating the molecular mechanisms underlying nutrient accumulation and metabolism, researchers can identify novel targets for genetic enhancement and accelerate breeding efforts. It is certainly worth mentioning in this part that exploiting the rich genetic diversity present in maize germplasm collections, both locally adapted landraces and exotic germplasm, will be crucial for broadening the genetic base and introducing novel alleles associated with enhanced nutritional traits.
Response: Based on both reviewers' comments, this paragraph was modified and merged with the preceding section (subheading) to improve readability.
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
Dear authors,
Thank you for your great efforts to improve the quality of your review paper. I think your MS is in better shape now. However, some minor issues may need your attention.
- As I mentioned before, the paper's title implies that you provide background information about what has been done (even before Harvestplus). I am not sure if there is enough background information in section 2.
-The authors argued that they wanted to avoid duplicating the same data in this review. To me, since this is a review paper for specific areas, it deserves to have a summarized table or figure that gives a clear picture of the current situation and the gaps that need to be addressed. I agree that the hyperlinks provided are good sources, but readers should get the information directly from your review and specifically for the areas covered in this review.
- Please provide reference(s) to what was mentioned in L109-112.
- I still believe that the paper missed similar work that, if included, would add more insight to the review. I think the authors are well aware of this.
Comments on the Quality of English Language
Minor English editing might be required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
