Utilization of Plant Genetic Resources of Bambara Groundnut Conserved Ex Situ and Genetic Diversification of Its Primary Genepool for Semi-Arid Production

Round 1

Reviewer 1 Report

The authors addressed most of the points raised earlier in the review and I therefore support publication of this paper.

minor editing spelling:

l347 "Technique"

l740. space missing in front of 1.

Reviewer 2 Report

All points noted in the previous version have been addressed adequately. I still find the illustration in Fig. 2 slightly confusing, however, it is now more in context with the text and quite useful to illustrate the interrelationships. The other changes to the text have been successful. The other revisions to the text have not reduced the character and quality of the work.

Reviewer 3 Report

I really like the manuscript in its current shape.

It is hard to check all changes because all changes are visible in the file, but taking into account the authors response to all reviewers I know they did their best to improve this manuscript. I really appreciate their efforts and professional approach to the matter.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Pasipanodya and colleagues submitted here a review on the state of conservation of the Bambara groundnut genetic resources. This review complements niecly with several recent works (Mayes et al., 2019, Tan et al., 2020) on the same crop and add a perspective for both ex situ and in situ conservation. Two main aspects may have been treated a bit more into details: from a conservation point of view, the actual state of conservation between various genbanks and the current state of use could have been described in more details.

Secondly, several times in the review, it is stated without clear reference that the local varieties from Bambara are actually low yield and therefore a good target for breeders. I wonder from an agronomic point of view whether the yield itself (or maybe rather its stability?) is the most prominent parameter that might be taken into account when growing leguminosae. Cotribution to long-term soil fertility and push-pull effects of mixed crops systems could be also very important target for bambara improvements.

As long as the existing genetic diversity of the bambara groundnut not been explored, I don't necessarily see the point harnessing complicated mutagenesis/tilling programs. There might be some "long hanging fruits" that could be harnessed in a more efficient way for pre-breeding programs.

Minor points:

l21. "breeding for adaptation" precise adaptation to what

l23. "research and policy priorization" is very vague

l24. see comment above, tone down taht sentence: "farmers often rely on traditional landraces which tends to ahve a low productivity and yield"

l31 and below occurences "ex situ" and "in situ" in 2 words (see the text of the FAO ITPGRFA for example).

l44 "or lesser" ?

l57-l63 this section can be removed. no particular added value

l67. "pathway components" needs a definition

l72 Cameroon

l84. link or definition needed for "Crops for Future" program

l95 "can be detrimental" to what?

l101. ref 20 might not be the appropriate one here.

l107. remove "approximatively" if 6145, this is not approximation

l115. replace "effected" by "regulated"

l121. "of Bambara groundnut"

l140. "Côte d'Ivoire"

l142. would be nice to provide more details on various CWR genepools from the bambara here ( a table for example).

l152. "nutrition"... protein levels?

l157. e.g spells "e.g."

l162. remove " in most institutions"

l162-164. these 2 sentences are not logic. either the diversity is big or not. please, rewrite.

l175. remove "about"

l199. germplams or PGR ? be consistent

l216. ex situ, in situ

l247-l251. this part can be made much shorter and refer to the corresp. literature.

l265 and/or

l321. utilisation, pre-breeding

l333 and l345. either there's a genome available or not, keep consistency here.

l382. Vigna subterranea

l438-l441. remove that section, to general

l455-463. this section can also be removed without altering the message.

l506. different

l510. selection for drought resistance (?)

l512 "breeding for drought" sounds weird.

l523-527. remove these sentence. no added value.

l562. replace polygenes by multiple

l579. Please merge future work and conclusion.

l584. I don't understand what these 50% are refering to?

l596. Again, I am not entirely convinced going to hard-core mutagenesis is needed as long as the existing genetic diversity has not been properly explored. See for ex the recent chickpea genomic study.

Author Response

The authors would like to thank the reviewer for a thorough introspection into our review manuscript. We have taken note of the various suggestions and are hopeful that this manuscript can contribute to the use of indigenous crops like bambara groundnut.

Author Response File: Author Response.pdf

Reviewer 2 Report

The work presents a very good overview of the state of research on Bambara Groundnut as a PGR. Starting from my professional focus, which, however, is not directly in the area of underutilized crops, like bambera, I have noticed only some minor points that can be optimised:

1. Of course, it is to be expected that the largest collection at IITA-GRC will also dominate the research. To give a more complete picture, it would be worth mentioning the next largest collections and their specificities.
2. It is not entirely clear to me whether the authors consider core sets and core collection to be synonymous.
3. Figure2: A clearer description of the different core set variants and the underlying tools would better support the text.
4. PGRs in genebanks are often heterogeneous, especially material collected as landraces. This is not specific to bambara, but should at least be mentioned.
   
5. The reference in line 441 should i. e. refer to [53].
6. For many crops, community driven approaches are being established to unlock PGR. Do such approaches exist for bambara or is something like this conceivable?
   

Author Response

The authors would like to thank and acknowledge the valuable comments and suggestions put forward by the reviewer. We are also thankful for the positive feedback, so far on our work on the state of bambara PGRs, and are hopeful that the work can realize the impact and contribute to better exploitation of indigenous species. 

Specific response

The work presents a very good overview of the state of research on Bambara Groundnut as a PGR. Starting from my professional focus, which, however, is not directly in the area of underutilized crops, like bambara, I have noticed only some minor points that can be optimised:

1. Of course, it is to be expected that the largest collection at IITA-GRC will also dominate the research. To give a more complete picture, it would be worth mentioning the next largest collections and their specificities.

Point 1 response

The authors have included the suggested information and provided the information as a table 1 in the revised manuscript

2. It is not entirely clear to me whether the authors consider core sets and core collection to be synonymous.

Point 2 response

Indeed, we as the authors considered core sets and core collections to be synonymous as they denote the reduced number or subset of accessions with maximum genetic diversity presentative of the full collection. Herein, we make reference to (Dutta et al., 2015), whereby core collection and core sets refer to an approach or approaches followed to reduce and assembly representative accessions of the targeted diversity from a whole collection. (see bold text underneath)

“Plant genetic resources, the source of genetic diversity provides a broad genetic foundation for plant breeding and genetic research, however, large germplasm resources are difficult to preserve, evaluate and use. Construction of core and mini core collections is an efficient method for managing genetic resources and undertaking intensive surveys of natural variation, including the phenotyping of complex traits and genotyping of DNA polymorphisms allowing more efficient utilization of genetic resources. A mega characterization and evaluation programme of the entire cultivated gene pool of wheat conserved in the National Genebank, India was undertaken. Wheat accessions with limited seed quantity, were multiplied in the off-season nursery at IARI Regional Station, Wellington during rainy season 2011 and the entire set of 22,469 wheat accessions were characterized and evaluated at CCS HAU, Hisar, Haryana during winter season 2011–12 for 34 characters including 22 highly heritable qualitative, and 12 quantitative parameters. The core sets were developed using PowerCore Software with stepwise approach and grouping method and validated using Shannon-Diversity Index and summary statistics. Based on Shannon-Diversity index, PowerCore with stepwise approach was found better than PowerCore with grouping. The core set included 2,208 accessions comprising 1,770 T. aestivum, 386 T. durum, and 52 T. dicoccum accessions as a representative of the total diversity recorded in the wheat germplasm. The core set developed will be further validated at different agro-climatic conditions and will be utilized for development of mini core set to enhance the utilization by wheat researchers and development of climate resilient improved varieties.”

3. Figure2: A clearer description of the different core set variants and the underlying tools would better support the text.

Point 3 response

The authors have noted the comment an incorporated the tools.

4. PGRs in genebanks are often heterogeneous, especially material collected as landraces. This is not specific to bambara, but should at least be mentioned.

Point 4 response
Authors inserted the phrase and acknowledge that bambara pgrs in Genebanks are derived from single seeds which are selected from seed mixtures in the landraces.

5. The reference in line 441 should i. e. refer to [53].

Point 5 response

The authors corrected the reference.

6. For many crops, community driven approaches are being established to unlock PGR. Do such approaches exist for bambara or is something like this conceivable?

Point 6 response

At this point in time, not much information is available for bambara. However, an NGO, Plant breeders without borders (http://pbwob.org/contact/) published on its website their work on training 30 farmers in Indonesia on how to make crosses of bambara. I have sought additional information seeking clarity on the framework of this project, if any conservation efforts are embedded, and what PGRs types are they improving, their sources etc. through an email, but, there is no response yet. Besides this report, information is not readily available. Like other crops, community driven approaches can be conceived for the bambara groundnut crop. Without a properly defined value chain which makes it unattractive for private seed houses and crop improvement purposes, and given that farmers have been preserving its genetic diversity, community driven approaches have potential to contribute to unlocking greater benefits from bambara PGRs.

Reviewer 3 Report

The title should be changed from 'Harnessing the Utilization of Plant Genetic Resources of Bambara Groundnut Conserved Exsitu and Genetic Diversification of its Primary Genepool for Semi-Arid Production' to 'Utilization of Plant Genetic Resources of Bambara Groundnut Conserved Exsitu and Genetic Diversification of its Primary Genepool for Semi-Arid Production '. The abstract requires the correction of linguistic errors, some of which I have highlighted in the attached manuscript, but left most of them for a native speaker to correct. The style is messy, the words and phrases repeat themselves. It is hard to understand the meaning of the abstract and to conclude what the work is about. The abstract is the most important part of the article, as it determines whether the reader decides to read the rest of the work.
The biggest drawback of the whole work, which makes it very difficult to evaluate it properly, is a very strange language. The English language definitely needs a correction. Reading is very difficult. There are fragments that are written better and then it is easier to focus on what the author wanted to say, but in other places, it is impossible to focus on the content. I am not sure if the introduction does not end after two or three paragraphs, as the sequel is already a description of the genre. In the end, there is a lot of information that is difficult to describe with a common denominator. Slightly messy.
Fig. 1 - Are you sure you can include it in your work? Moreover, the quality is very poor.
There is too little specific information in chapter two. What are these related species that can be used to expand variability? I still do not know what are the genetic resources in the species in question. The title of chapter three should be changed. I also don't like the contents of this chapter. I do not know if what was described corresponds to the assumptions, i.e. the characterization of genetic differentiation and the most important features. I believe that, similarly to the previous chapters, one should reflect on what the author wants to describe in the quotes from the paragraphs. In the current version of the text, there is a lot, little information and, in addition, there is no order in them. It is difficult to understand what is shown in Figure 2. Either add a detailed description to this diagram or simply delete Figure 2. In chapter four, I notice the same problem as in the previous ones. Too much unnecessary duplicate information has been included. In my opinion, the text needs to be read again and put together sentence by sentence. It should be considered whether all information is really needed. Unfortunately, this vital information is lost in the mass of text, which is completely unnecessary. The work should be cut in half to make it interesting and not boring for the reader. Chapter five is written in a surprisingly interesting way. Only here most of the text fits the topic. Unfortunately, the same cannot be said for chapter 5.3. It's hard to choose the information that applies only to the species in question. And what plants does the author want to introduce? Chapter six is written for the best. If the whole work was written this way, it would definitely be worth publishing. It contains a lot of information provided in a concise and understandable way. Even the number of stylistic and linguistic errors is smaller in this part. I believe that the manuscript should be read carefully again and reshaped. 

Comments for author File: Comments.pdf

Author Response

The authors would like to thank the reviewer for the critical review of our manuscript. 

Author Response File: Author Response.pdf