Matrilineal Composition of the Reconstructed Stock of the Szekler Horse Breed

Round 1

Reviewer 1 Report (New Reviewer)

The issues in the manuscript are very topical from the point of view of biodiversity protection and animal genetic resources. It concerns the rescue of a specific breed of horses whose stud book no longer exists. The manuscript is prepared at a very good level, covering all required chapters. The objectives are clearly defined, fulfilled and properly discussed in the "Discussion" chapter. The list of used literature is found and sufficient.

The aim of the manuscrip was to evaluate the mitochondrial D-loop sequence (608 bp) of the founder population (n=59) in 2021 of a breed reconstruction project started in 2012 in Hungary, because  characteristics of the Szekler Horse remained scattered in remote areas. 

Abstract:The abstract is concise, written simply but comprehensibly. It contains the goal, methodology, results. A more concise summary, conclusion is missing. 

Introduction:The Introduction is very well written, it discusses the history of the issue, a detailed description, characteristics of the Szekler Horse breed as well as genetic analysis methods. It is sufficient as an introduction to the issue. 

Results: 

The authors declared that since the HG Q is characteristic of Asian horses, the exam- ined stock haplotype distribution reflects the eastern origin of the Hungarian horses brought from the East in 896 AD. It is complemented by the gene pool of horses from Europe (L) and the Middle East (B). 

Discussion 

The achieved results are discussed in a suitable form, compared with data published so far, with sufficient citations of domestic and foreign authors. 

Literature: 

Appropriately use literary sources of domestic and foreign authors. The list of used literature corresponds to the instructions for authors.

Author Response

Authors say thanks for the careful proof-reading and the supporting review.

Reviewer 2 Report (New Reviewer)

In the study, the authors studied the matrilineal composition of the reconstructed stock of the  Szekler Horse breed with mtDNA. The results are meaningful for the conservation and utility of the local horse breed.

The manuscript is well written and organized. However, I have following suggestions for the authors:

To investigate the origin of the maternal lines of the Szekler horses, the authors compared their results with those of Achilli et al. (2012). It could provide some useful information to do so, but it is not enough for drawing a convinced conclusion. I would like to suggest that the authors analyze Fst between the local horse breed and other populations in Asia centre, Middle East, and Europe, whose mtDNA data could be downloaded from the public database，and the neighbor joining phylogenetic tree (or UPGMA phylogenetic tree) should be constructed with the mtDNA data.

The “J-K 1.7”could not be found in Table 1. In the table, only the frequency of haplogroup J is showed. The authors should make necessary revision to it .

In line 313-314, the phrase“Also, to achieve the genetic and phenotypic surveillance of the breed reconstruction process” is not a complete sentence, and the author should make necessary modification to it.

Author Response

In the study, the authors studied the matrilineal composition of the reconstructed stock of the  Szekler Horse breed with mtDNA. The results are meaningful for the conservation and utility of the local horse breed.

The manuscript is well written and organized. However, I have following suggestions for the authors:

To investigate the origin of the maternal lines of the Szekler horses, the authors compared their results with those of Achilli et al. (2012). It could provide some useful information to do so, but it is not enough for drawing a convinced conclusion. I would like to suggest that the authors analyze Fst between the local horse breed and other populations in Asia centre, Middle East, and Europe, whose mtDNA data could be downloaded from the public database, and the neighbor joining phylogenetic tree (or UPGMA phylogenetic tree) should be constructed with the mtDNA data.

Your reviewer's suggestion has been considered with thanks. GenBank contains about 9000 D-loop sequences. These vary in size, ranging from 200 to 1200 bp. As a test, we downloaded those that covered the 608 base pair long sequence we were investigating. Unfortunately, the resulting median joining tree figure is not usable due to its huge size and lack of transparency.

We did not see it feasible to create a new haplotype grouping alongside Achilli as part of this study. Therefore, the Fst was also not determined.

The “J-K 1.7”could not be found in Table 1. In the table, only the frequency of haplogroup J is showed. The authors should make necessary revision to it .

It is corrected.

In line 313-314, the phrase“Also, to achieve the genetic and phenotypic surveillance of the breed reconstruction process” is not a complete sentence, and the author should make necessary modification to it.

It is corrected.

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

Gáspárdy et al. examined the maternal background and genetic structure of the reconstructed stock based on the D-loop (control region) of the mitochondrial DNA. Their findings suggest that the eastern origin of the Hungarian horses brought from the East in 896 AD. This is complemented by the gene pool of horses from Europe (e.g., L) and the Middle East (e.g., B).

1.        Line 143, “the reconstructed population (n=59)”, what is the reconstructed population?

2.        As for figure 1, it difficult to distinguish the dominate haplotype, because the size of the circles can be greatly influenced by sample size, how many samples were used, also what approach was used for haplotype network construction.

3.        “Figure 2. Percentual haplogroup composition (outer ring) of the Szekler horse according to the haplogroup most”, the description of figure2 was difficult to understand. More description about figure should provide to help to make it easier to understand.

4.        Line 319-320, “We hope that selection work can begin in the increased stock and with more”, this sentence may not relate to current study, please remove.

5.        Line 324, No need to break sentences.

6.        The discussion part should be compressed to include the most important findings.

Reviewer 2 Report

The author presented the analyzed results of mitochondrial D-loop in 59 Szekler horse. Nevertheless, this work was designed and evaluated with simple. In particular, we see that more results presented in this study were nor supported by the Figure or Table. Here, the author only listed two Figure and one Table. Moreover, the author cited the published results, but this information was not described in the Method section. In this regards, I recommend rejecting it.

Reviewer 3 Report

This manuscript described genetic diversity of the Szekler Horse, which are recently re-constructed, by sequencing mtDNA D-loop region.

Major

As the author noted in the Introduction, the maternal lineage of horses is diverse. Therefore, it may be difficult to simply estimate the origin (genetic background) of Szekler Horse from the structure of the haplotype. M&M and Results to prove this are not listed. Therefore, the discussion is an ambiguous description. In particular, from the data in Table 1, it is not possible to see which regions the Szekler Horse has similarities to.

Minor

The introduction is redundant, long, and has unnecessary descriptions. Each paragraph should be shorter and more concise.

Lines 33-38: Unnecessary description.

Line 109-119: This is an unnecessary description.

M&M

Line 149: The authors should include gender information.

Results:

Line 184-188: Does this position information indicate a position within the 688 bp? Since the description is ambiguous, the location information of the reference sequence in the public DB should be described.

Line 198-202: How did the authors identify the haplogroups? For example, have you compared the previously reported haplotypes with the sequences?

Lines 208-216: These descriptions are more subjective than the results.

Line 220-221: How did you define "the haplogroup most characteristic of the geographical areas."?

Discussion

Line 241-287: Considering the haplotype composition of other breeds, but finally not clearly considering the relationship to the research results of the authors.