Review Reports - Histopathological Study of Chayote [<i>Sechium edule</i> (Jacq.) Sw.] Stems Infected with <i>Phytophthora capsici</i> Leonian

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a histological analysis of changes occurring in Sechium edule tissues during infection caused by Phytophthora capsici. The topic is relevant and potentially valuable from the perspective of crop phytopathology, particularly given the limited number of studies addressing the interaction between this pathogen and chayote. The manuscript addresses an important biological problem and provides experimental observations that may contribute to further research on defense mechanisms in this species. Nevertheless, several editorial and methodological issues should be addressed in order to improve the clarity, coherence, and scientific impact of the manuscript.

The Introduction is generally well structured and provides an appropriate background on the importance of Phytophthora capsici and its impact on crop plants. The authors successfully introduce the biological context of the pathogen as well as the agricultural importance of Sechium edule. However, some parts of the text contain overly detailed descriptions of the pathogen’s biology, which could be shortened to improve the clarity and flow of the narrative.

Another issue is the mixing of different levels of information, such as descriptions of infection mechanisms alongside agricultural production data. This somewhat weakens the overall coherence of the section. In addition, the use of examples from other pathosystems, such as Phytophthora cinnamomi infections in chestnut, is not fully justified in the context of the study and could be replaced with references more directly related to P. capsici.

It would also be beneficial to more clearly highlight the existing research gap regarding infection processes and histological changes in chayote, as this would strengthen the justification and objectives of the study.

The Materials and Methods section provides the basic information necessary to understand the experimental design, including plant preparation, pathogen inoculation, and histological analysis procedures. However, the description of the methods is somewhat inconsistent in places and combines different methodological elements within a single subsection, which reduces the clarity of the text.

In particular, the detailed description of chayote fruit morphology appears unnecessary in this section, as it is not directly related to the experimental procedures. Some aspects of the methodology also require further clarification, especially regarding pathogen identification, the number of samples analyzed, and the sampling strategy.

Additionally, the origin of the plant material is not entirely clear. The text refers both to plants from the greenhouse experiment and to samples collected from commercial orchards, which creates ambiguity about the source of the analyzed material. A clearer organization of this section, explicit information on sample numbers, and the reduction of unnecessary technical details would significantly improve the transparency and reproducibility of the methodology.

However, the section is somewhat overly detailed and contains repetitive descriptions of similar structures across successive sampling times, which makes it difficult to identify the most significant changes occurring during infection. In addition, certain passages include elements of biological interpretation that would be more appropriate in the Discussion section.

Another limitation is that the results are presented exclusively in a descriptive manner, without quantitative or semi-quantitative analyses that could strengthen the conclusions regarding pathogen colonization and plant defense responses. Reducing repetitive descriptions and emphasizing the key differences between successive stages of infection would improve the clarity and impact of this section.

The Discussion section provides an interpretation of the histological changes observed during infection and relates these findings to plant defense mechanisms described in the literature. The authors appropriately highlight the role of responses such as phenolic accumulation, lignification, callose deposition, and tylosis formation.

Nevertheless, some parts of the discussion are overly general and resemble a literature review rather than a direct interpretation of the study’s results. In particular, the opening paragraphs of the discussion and the section addressing the economic and medicinal importance of chayote are only loosely connected to the histological analysis presented in the study.

In several places, extensive definitions of biological processes are provided, which could be shortened by focusing more specifically on their relevance to the results obtained in this work. A more direct linkage between the observations presented in the Results section and the interpretation offered in the Discussion would improve the coherence and scientific focus of this section.

However, the conclusions remain somewhat general and do not clearly emphasize the novelty of the study, namely the histological characterization of infection processes in Sechium edule. It would be beneficial to more explicitly highlight the contribution of this work to the understanding of the S. edule–P. capsici pathosystem and to emphasize the significance of the observed sequence of tissue changes during infection.

However, many of the cited studies concern other plant species, particularly Capsicum annuum, while relatively few references directly address Sechium edule. Expanding the reference list to include additional studies specifically related to chayote or closely related cucurbit species would strengthen the contextual background of the work.

Overall, the manuscript addresses an interesting research topic and provides valuable histological observations related to the interaction between Phytophthora capsici and Sechium edule. However, improvements in the structure of the manuscript, clarification of methodological details, reduction of repetitive descriptions, and a stronger emphasis on the study’s novelty would significantly enhance the scientific quality and clarity of the work.

Comments on the Quality of English Language

The manuscript is generally understandable; however, several sentences require minor grammatical and stylistic corrections to improve clarity and readability. Careful language editing is recommended.

Author Response

Dear reviewer, thank you for your critical comments that enable us to improve the quality of our manuscript. All your comments have been addressed in full, and all the changes have been written in red.

Thank you for your comment. The information about the pathogen’s biology has been modified to improve the clarity of the introduction section.

Thank you for your comment. The information about P. cinnamomi has been removed to avoid potential confusion. Regarding your comment about using references about P. capsici and considering your following comments, we have modified the discussion section with examples about it among cucurbits while updating the reference list accordingly.

Thank you for your comment. The existing research gap has been mentioned in the revised version of the discussion section of the manuscript.

Thank you for your comment. The Materials and Methods section has been carefully revised and adjusted to improve the clarity of the text.

Thank you for your comment. The description about the chayote fruit morphology has been removed to improve the clarity of such section.

Thank you for your comment. Plant material used in this study originated from two clearly differentiated sources. For pathogen isolation and identification, samples were collected from two commercial chayote orchards in Huatusco, Veracruz. A total of 20 symptomatic plants were sampled (10 per orchard), selecting fruits and stem–root transition tissues exhibiting characteristic wilt and rot symptoms. From these plants, 60 infected tissue fragments were processed (30 from fruits and 30 from stem–root transition zones), and an additional five asymptomatic samples were included for comparison. The sampling strategy was targeted and symptom-based, ensuring balanced representation between orchards. In contrast, pathogenicity tests were conducted using healthy chayote plants grown under controlled greenhouse conditions; these plants were not sourced from the commercial orchards but were used exclusively to evaluate the virulence of the isolated Phytophthora capsici strain under controlled experimental conditions.

The Results section describes the temporal progression of Phytophthora capsici infection in Sechium edule stem tissues, including both macroscopic symptoms and histological changes observed at different time points after inoculation. The anatomical descriptions are detailed and include important elements of the plant defense response, such as the accumulation of phenolic compounds, callose deposition, and the formation of tyloses in the xylem. However, the section is somewhat overly detailed and contains repetitive descriptions of similar structures across successive sampling times, which makes it difficult to identify the most significant changes occurring during infection. In addition, certain passages include elements of biological interpretation that would be more appropriate in the Discussion section.

Thank you for your comment. We apologize if the original version seemed repetitive across successive sampling times. However, we kindly want to clarify that figures were originally designed to present just 12- and 22-days post inoculation since they constitute two time points where the most biological and epidemiologically meaningful transition stages where the infection process was observed. This is important to consider since we have noted that at 8, 16, and 30-days post inoculation the plants presented no visible symptoms, transitional vascular involvement, and plant death, respectively. Following this rationale and other reviewers’ comments together with yours, we have modified the figure legends to improve the explanation.

Thank you for your comment. Quantitative data has been added to the supplementary material of the revised version of the manuscript. Together with this, the discussion section of the revised version of our work has been modified to present this data.

Thank you for your critical observations and opportunity for improving the quality of our manuscript.

Thank you for your insightful comment. The information about the economic and medicinal importance of chayote has been removed to avoid potential confusions. Together with this, general statements have been revised to focus on the retrieved evidence. Still, it is important to mention that some of them were maintained since it was requested by other reviewers to provide information about how to observe such structures or determine their presence.

Thank you for your comment. it is important to mention that some of them were maintained since it was requested by other reviewers to provide information about how to observe such structures or determine their presence.

The Conclusions section concisely summarizes the main findings of the study, highlighting the activation of histological and biochemical responses in chayote following infection by Phytophthora capsici. The authors correctly emphasize the role of defense mechanisms such as phenolic accumulation, lignification, callose deposition, and tylosis formation, while also noting that these responses only partially limit pathogen progression. However, the conclusions remain somewhat general and do not clearly emphasize the novelty of the study, namely the histological characterization of infection processes in Sechium edule. It would be beneficial to more explicitly highlight the contribution of this work to the understanding of the S. edule–P. capsici pathosystem and to emphasize the significance of the observed sequence of tissue changes during infection.

Thank you for your critical comment and opportunity for improving the quality of our manuscript. The conclusion section has been rewritten accordingly.

The reference list includes literature relevant to the biology of Phytophthora capsici, plant defense mechanisms, and plant–pathogen interactions. The bibliography contains both classic review papers and more recent studies, which represents a strength of the manuscript. However, many of the cited studies concern other plant species, particularly Capsicum annuum, while relatively few references directly address Sechium edule. Expanding the reference list to include additional studies specifically related to chayote or closely related cucurbit species would strengthen the contextual background of the work.

Thank you for your comment. The reference list provided has been revised and updated as suggested.

Thank you for your time and comments, which have been addressed in full to improve the scientific quality and clarity of our manuscript.

Comments on the Quality of English Language

The manuscript is generally understandable; however, several sentences require minor grammatical and stylistic corrections to improve clarity and readability. Careful language editing is recommended.

Thank you for your comment. Grammar and style corrections have been performed throughout the revised version of the manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

The ms. Histopathological study of chayote Sechium edule (Jacq.) Sw

stems infected with Phytophthora capsici Leonian is generally presented, I just have some suggestions to further improve it:

Stem samples collected at 8, 12-, 16-, 22-, and 30-days post-inoculation , Figure 1provide only 12, and 22-days post-inoculation, Please add other three;
I suggest to present some data for disease severity or disease index for this five dates post-inoculation besides pictures in Figure 1 ;
Provide some information for how to observe those such as phenolic compounds (phe), callose (ca); starch (sta)to strengthen the self-explaination of figures. Meanhile, add the details and references in method part;
Line 317-318, Subsequently, 5 µL of the resulting supernatant was used as template DNA for PCR amplification of the internal transcribed spacer (ITS) regions. What did this mean?the objective?

Author Response

The ms. Histopathological study of chayote Sechium edule (Jacq.) Sw stems infected with Phytophthora capsici Leonian is generally presented, I just have some suggestions to further improve it:

Stem samples collected at 8, 12-, 16-, 22-, and 30-days post-inoculation , Figure 1provide only 12, and 22-days post-inoculation, Please add other three;

Thank you for your insightful comment. Figure 1 has been designed to present just 12- and 22-days post inoculation since they constitute two time points where the most biological and epidemiologically meaningful transition stages where the infection process was observed. This is important to consider since we have noted that at 8, 16, and 30-days post inoculation the plants presented no visible symptoms, transitional vascular involvement, and plant death, respectively. Following this rationale and deeply thanking your comment, we believe that the Figure 1 should be maintained as presented since they represent the critical transition stages which are in accordance with previous studies from our search group.

Andrade-Luna, Mauricio Iván, et al. "Severidad de una cepa de Phytophthora capsici en plantas de chayote Sechium edule a nivel de cámara de crecimiento." Revista mexicana de fitopatología 35.1 (2017): 40-57.

Aguirre-Medina, Juan Francisco, et al. "Co-inoculation of Sechium edule (Jacq.) sw. plants with rhizophagus intraradices and Azospirillum brasilense to reduce Phytophthora capsici damage." Agriculture 11.5 (2021): 391.

I suggest to present some data for disease severity or disease index for this five dates post-inoculation besides pictures in Figure 1 ;

Thank you for your comment. We have added supplementary material where we now present disease severity together with a new table where we enlist the parameters that we considered to assess it.

Provide some information for how to observe those such as phenolic compounds (phe), callose (ca); starch (sta)to strengthen the self-explaination of figures. Meanhile, add the details and references in method part;

Thank you for your information. The figure legends have been corrected as suggested by incorporating information about how to observe the mentioned parameters.

Line 317-318, Subsequently, 5 µL of the resulting supernatant was used as template DNA for PCR amplification of the internal transcribed spacer (ITS) regions. What did this mean?the objective?

Thank you for your observation. The mentioned information was added considering the comments from the Academic Editor. Still, from a methodological point of view, the ITS region is a standard genetic marker used to identify fungi and oomycetes. By amplifying and sequencing the ITS region, we compared (as already reported in ref. 16) the DNA sequence to sequences in GenBank (NCBI database), which allowed us to confirm that the isolate was Phytophthora capsici. Still the mentioned section has been revised accordingly to other reviewers suggestions.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper focuses on the histopathological characteristics of chayote stems infected by Phytophthora capsici. The topic has both theoretical and applied value. The authors basically achieved the research goal of histopathological observation. However, the paper has many scientific and normative problems in experimental design, result presentation and reference formatting. The research depth also needs to be improved.

1. Optimize the title. Place the Latin name of chayote in parentheses.
2. Information of the tested cultivar is incomplete. The experimental material is too single. The resistance level (susceptible/resistant) of the tested chayote cultivar is not specified. No other cultivars are set as controls. It is impossible to determine whether the observed pathological responses are cultivar-specific or common in chayote. Add chayote cultivars with significant differences in resistance and susceptibility for comparative analysis. This will better reveal the histopathological change rules after pathogen infection.
3. The description in the Materials and Methods section is inconsistent with the presented results. For example, the authors mentioned ITS amplification of Phytophthora capsici, but no relevant data and analysis are shown in the results. The number of biological replicates at each sampling time point is not specified. The experimental design lacks rigor.
4. The authors systematically observed stem sections at 8, 12, 16, 22 and 30 dpi, and described in detail the spatiotemporal dynamics of pathogen infection and host defense responses (e.g., phenolic compound accumulation, lignification, callose deposition and tylosis formation). However, the correlation between these histological changes and cultivar resistance/susceptibility is not clarified. The pathogen expansion rate is not quantified. Results are only presented by section photos with qualitative descriptions throughout. No image analysis software is used for quantitative statistics of diseased tissue area, hyphal density, vessel blockage ratio and other indicators. The experimental evidence is insufficient. Supplement relevant quantitative data.
5. The abbreviation system of symbols in the figures is confusing. The same tissue structure is given different abbreviations in different figures. For example, "hy" represents hyphae in epidermis in Figure 2, but hyphae in xylem in Figure 3. Unify the abbreviations of the same structure throughout the paper to ensure standardization and consistency.
6. Revise and polish the language of the full text. There are many grammatical and spelling errors, such as misspelling "capsici" as "capsica". Check and correct all errors one by one.
7. There are many formatting irregularities in the references, such as inconsistent use of italics for Latin names. Fully revise the references in strict accordance with the formatting guidelines of Horticulturae.

Author Response

Optimize the title. Place the Latin name of chayote in parentheses.

Thank you for your observation. The scientific name of the studied species has been revised and updated according to previous publications.

Cadena-Iñiguez, Jorge, et al. "Chayote [Sechium edule (Jacq.) Sw.] Fruit Quality Influenced by Plant Pruning." Horticulturae 11.8 (2025): 965.

Information of the tested cultivar is incomplete. The experimental material is too single. The resistance level (susceptible/resistant) of the tested chayote cultivar is not specified. No other cultivars are set as controls. It is impossible to determine whether the observed pathological responses are cultivar-specific or common in chayote. Add chayote cultivars with significant differences in resistance and susceptibility for comparative analysis. This will better reveal the histopathological change rules after pathogen infection.

Thank you for your insightful observations on this matter. We strongly believe that the experimental material, resistance levels, and use of other controls are required for improving the retrieved evidence from this study. However, although we deeply acknowledge your time and suggestion, we want to emphasize that this work was envisioned as an exploratory histopathological study. Still, we are committed to following your important suggestions in further studies from our research group.

The description in the Materials and Methods section is inconsistent with the presented results. For example, the authors mentioned ITS amplification of Phytophthora capsici, but no relevant data and analysis are shown in the results. The number of biological replicates at each sampling time point is not specified. The experimental design lacks rigor.

Thank you for your comment. We mentioned ITS amplification since it was information requested by other reviewers. However, we have added the appropriate reference where we performed such analysis, which served as the basis for executing this study.

The authors systematically observed stem sections at 8, 12, 16, 22 and 30 dpi, and described in detail the spatiotemporal dynamics of pathogen infection and host defense responses (e.g., phenolic compound accumulation, lignification, callose deposition and tylosis formation). However, the correlation between these histological changes and cultivar resistance/susceptibility is not clarified. The pathogen expansion rate is not quantified. Results are only presented by section photos with qualitative descriptions throughout. No image analysis software is used for quantitative statistics of diseased tissue area, hyphal density, vessel blockage ratio and other indicators. The experimental evidence is insufficient. Supplement relevant quantitative data.

Thank you for your comment. We have now added a supplementary material section where we have added quantitative data about the infection severity by P. capsici. This in accordance with other reviewers’ comments and yours.

The abbreviation system of symbols in the figures is confusing. The same tissue structure is given different abbreviations in different figures. For example, "hy" represents hyphae in epidermis in Figure 2, but hyphae in xylem in Figure 3. Unify the abbreviations of the same structure throughout the paper to ensure standardization and consistency.

Thank you for your observation. The abbreviations have been revised, being important to comment that the figure legends have been modified according to other reviewers’ suggestions to improve the clarity of our work.

Revise and polish the language of the full text. There are many grammatical and spelling errors, such as misspelling "capsici" as "capsica". Check and correct all errors one by one.

Thank you for your comment. We apologize for our mistake. The spelling errors have been revised and corrected as suggested.

There are many formatting irregularities in the references, such as inconsistent use of italics for Latin names. Fully revise the references in strict accordance with the formatting guidelines of Horticulturae.

Thank you for your observation. The Latin names and italics have been revised in the reference list of the revised version of the manuscript. However, it is important to mention that they have suffered from significant modifications when they are updated by the reference software manager. Still, we kindly request your understanding that this will not be the final format in the case of further revisions.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is scientifically sound; however, some interpretations should be slightly toned down due to the qualitative nature of the data. The revised version shows clear improvement compared to the previous submission. The Introduction has been substantially improved in terms of coherence and focus. The removal of references to Phytophthora cinnamomi was appropriate and strengthens the relevance of the background. Additionally, the description of the pathogen’s biology has been shortened, resulting in a more concise and focused narrative. The Introduction is now better aligned with P. capsici and cucurbit systems, and the research gap has been clearly articulated (e.g., the limited knowledge of the infection process in chayote). The Materials and Methods section has also been improved. The structure is clearer, with better separation of subsections. The authors have clarified key aspects such as the origin of plant material (greenhouse vs. orchards), sample size, and sampling strategy, which significantly enhances transparency and reproducibility. The removal of unnecessary elements, such as detailed fruit morphology and extended discussion on economic importance, has improved the overall focus of the manuscript. In addition, figure legends have been expanded and now provide clearer definitions of histological structures (e.g., callose, tyloses), which is a notable improvement. The Discussion is now more directly linked to the results, with fewer general, review-like passages and more explicit references to the observations presented in the study. However, some parts still contain excessive “textbpok-style” biological explanations (e.g., extended definitions of phenolics, lignification, and sporangia), which could be further reduced to maintain focus on the study’s findings. The Results section remains somewhat overly descriptive, with repetitive elements across time points. Although quantitative data have been added to the supplementary material, their integration into the main text is limited. The study still relies predominantly on qualitative descriptions, and the lack of statistical analysis, graphical representation, or clear quantitative indicators (e.g., percentage of colonization) remains a limitation. Finally, minor stylistic issues persist, including repetitive phrases (e.g., “it is important to mention that”), overly long sentences, and occasionally defensive tone in the text. Overall, the manuscript has improved significantly; however, minor revisions are still recommended to enhance clarity, conciseness, and the balance between qualitative and quantitative interpretation.

Comments on the Quality of English Language

The manuscript is generally understandable; however, several sentences require minor grammatical and stylistic corrections to improve clarity and readability. Careful language editing is recommended.

Author Response

The manuscript is scientifically sound; however, some interpretations should be slightly toned down due to the qualitative nature of the data.

Thank you for your comments and insightful suggestions that enabled us to improve the quality of our work. All your comments have been addressed or confirmed as follows.

The revised version shows clear improvement compared to the previous submission. The Introduction has been substantially improved in terms of coherence and focus.

Thank you for your comment.

The removal of references to Phytophthora cinnamomi was appropriate and strengthens the relevance of the background.

Thank you for your comment.

Additionally, the description of the pathogen’s biology has been shortened, resulting in a more concise and focused narrative.

Thank you for your comment.

The Introduction is now better aligned with P. capsici and cucurbit systems, and the research gap has been clearly articulated (e.g., the limited knowledge of the infection process in chayote).

Thank you for your comment.

The Materials and Methods section has also been improved. The structure is clearer, with better separation of subsections. The authors have clarified key aspects such as the origin of plant material (greenhouse vs. orchards), sample size, and sampling strategy, which significantly enhances transparency and reproducibility. The removal of unnecessary elements, such as detailed fruit morphology and extended discussion on economic importance, has improved the overall focus of the manuscript.

Thank you for your comment.

In addition, figure legends have been expanded and now provide clearer definitions of histological structures (e.g., callose, tyloses), which is a notable improvement.

Thank you for your comment.

The Discussion is now more directly linked to the results, with fewer general, review-like passages and more explicit references to the observations presented in the study. However, some parts still contain excessive “textbpok-style” biological explanations (e.g., extended definitions of phenolics, lignification, and sporangia), which could be further reduced to maintain focus on the study’s findings.

Thank you for your comment. The mentioned definitions have been removed to focus on the study’s findings.

The Results section remains somewhat overly descriptive, with repetitive elements across time points. Although quantitative data have been added to the supplementary material, their integration into the main text is limited.

Thank you for your observation. Considering this and your following comment, we want to clarify that the quantitative data has already been reported by our research group in past studies, as kindly referenced in the revised version of the manuscript. Therefore, we envisioned to integrate it in the discussion section to avoid potential confusions. Regarding the use of repetitive elements we kindly want to emphasize that they have been aligned with a histological analysis interpretation and presentation. We believe that it is important to maintain such elements to maintain consistency and coherence between the sampling and time points.

The study still relies predominantly on qualitative descriptions, and the lack of statistical analysis, graphical representation, or clear quantitative indicators (e.g., percentage of colonization) remains a limitation.

Thank you for your observation. In accordance with your previous comment, we have integrated the quantitative data in the results section, but we have aimed to represent it graphically in the supplementary section to maintain the aim of presenting just a histopathology analysis. Moreover, it is important to note that quantitative indicators were not included in this work since our main goal was to provide histological evidence about P. capsici on Sechium edule.

Finally, minor stylistic issues persist, including repetitive phrases (e.g., “it is important to mention that”), overly long sentences, and occasionally defensive tone in the text.

Thank you for your comment. The revised version of the manuscript has been revised again for style and grammar presentation. The use of repetitive phrases has been revised and modified when appropriate.

Overall, the manuscript has improved significantly; however, minor revisions are still recommended to enhance clarity, conciseness, and the balance between qualitative and quantitative interpretation.

Thank you for your comment. The manuscript has been modified accordingly.

Reviewer 2 Report

Comments and Suggestions for Authors

this revised ms. responsed to most of my concerns

Author Response

this revised ms. responsed to most of my concerns
Thank you for your comments and insightful suggestions that enabled us to improve the quality our work.

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you very much to the author for the revisions to the paper.

I believe they have been done appropriately.

Author Response

Thank you very much to the author for the revisions to the paper.

I believe they have been done appropriately.

Thank you for your comments and insightful suggestions that enabled us to improve the quality our work.