Multi-Environment Testing Based G × E Interactions Reveal Stable Host-Plant Resistance against Sterility Mosaic Disease in Pigeonpea

Round 1

Reviewer 1 Report

Abstract section

The abstract provides a concise overview of a seemingly comprehensive study, and its contributions to the field of SMD resistance in pigeonpea are evident. Minor clarifications and slight elaborations at specific points will further enhance its clarity, completeness, and impact.

1.     Instead of using the vague term "moderate to high levels of resistance," it would be more informative to specify the criteria or quantitative measurements that determined these levels of resistance. This added detail can give readers a clearer understanding of the genotypes' resistance performance.

2.     The sentence "Genotype variance contributed the greatest effect (63.56%) to the total variation and it represents the maximum disease variation." could be cleared up a bit. If the authors are saying that genotype variance accounts for approximately 64% of the observed variation in SMD resistance, this implication could be spelled out a little more explicitly for the reader.

3.     Include more specific information about the correlation between SMD incidence and environmental factors (maximum temperature, rainfall), if possible. While the mention of these correlations is useful, concrete data or values could enrich their findings.

4.     In the context of the G × E (Genotype by Environment) interaction, please make sure to properly define terms such as PC1 and PC2 if they are to be included in the abstract. It is critical to be explicit about what they stand for - presumably Principal Components 1 and 2.

5.     The sentence "This research will broaden the area of phenotyping and sources of stable resistance that can be used in future SMD resistance breeding projects." is perfectly fine, although by opting for "This research broadens the area of phenotyping and identifies stable resistance sources .." might ensure cohesion since it aligns the verb tense with the rest of the text.

6.     Finally, there's a minor typographical error in "The results revealed a significance variation (P˂0.05)". Here, it should be "significant" rather than "significance."

 

 

Introduction section

The Introduction section of the manuscript provides a detailed background and a justified context for the research work. The authors have shown a thorough understanding of the pigeonpea crop, the significance of its production, the challenges in its cultivation, particularly the Sterility Mosaic Disease (SMD), and the importance and complexity of finding resistant varieties. However, the reviewer has some suggestions to further improve the clarity and effectiveness of this section:

1.     The authors describe the huge areas under pigeonpea production in India but also state that average yield productivity is relatively less due to major biotic challenges, including Fusarium wilt, Phytophthora blight, and SMD. Here, the authors could provide more details on why these challenges have not been effectively addressed yet, is it due to the lack of technological implementations, economic factors, or any other reasons?

2.     The discovery of two different strains of the Pigeonpea sterility mosaic virus (PPSMV) is well described, but a further elaboration on their unique characteristics - why they cause different symptoms or why a mixed infection leads to a more severe form of SMD - would be beneficial to non-specialist readers.

3.     In the discussion about the failure of chemical management of SMD, the authors simply mention it to be not economically feasible and ecologically sound. A bit more explanation, possibly with the aid of a couple of references, would provide the reader with a more comprehensive understanding of why chemical management is not a favorable option.

4.     When addressing the challenges due to the genomic plasticity of the virus and the presence of distinct PPSMV strains throughout India, consider providing some insights into the breakthroughs or research efforts towards understanding this plasticity in more detail. Such information would be of interest to many readers and add weight to your study.

5.     Finally, the authors intend to use GGE biplot analysis. It would be helpful if the authors could explain a little more why GGE biplot analysis is most suited for their research objective among all other available biostatistical methods. An added link to the aims of the study could strengthen the methodology.

 

 

Materials and Methods section

This section provides a detailed description of the experimental design, screening procedures, data collection, and statistical analysis used in the study. However, there are a few areas where additional information would be valuable to enhance the clarity and comprehensiveness of the methods employed.

1.     Preliminary SMD Field Screening (section 2.1): The authors conducted a preliminary screening of 75 pigeonpea genotypes at ICRSAT, Patancheru during the 2020/2021 season. This preliminary screening aimed to assess the reaction of these genotypes to SMD under epiphytotic conditions. The selected genotypes with moderate to high levels of SMD resistance were then advanced for multi-environment testing. The location of the preliminary screening is well-mentioned. It would be beneficial to provide some details regarding the conditions under which these screenings were conducted – any controls, temperature, moisture, etc. Additionally, please clarify the criteria for how the 21 genotypes were specifically chosen based on the preliminary screening.

2.     Genotype Assessment at Multi-Environment Locations (section 2.2): The multi-environment locations for assessing the selected genotypes were ICRISAT and Bidar, and the assessment was carried out over two consecutive crop seasons (2021/2022 and 2022/2023). The experimental design employed a randomized complete block design (RCBD) with two replications. Each replication consisted of genotypes sown in two rows with specific spacing. The authors also mentioned the use of resistant and susceptible check lines for reference. It would be beneficial if the authors could provide further information about the specific measures taken to control any confounding factors during the experiment, such as pest management or environmental control.

3.     Data Observation and Statistical Analysis (section 2.3): The authors observed disease symptoms and calculated the percent incidence of SMD at different time points following inoculation. The genotypes were categorized into four groups based on the levels of SMD incidence: resistant (R), moderately resistant (MR), susceptible (S), and highly susceptible (HS). The authors employed analysis of variance (ANOVA) to analyze the variation and examined the stability of genotypes and environments using the GGE biplot analysis. It would be helpful for the authors to provide more information on the specific statistical methods used for the ANOVA and GGE biplot analysis, including any assumptions made and the significance level employed.

4.     Association between Environments and Genotypes (section 2.3): The authors used principal component analysis (PCA) to identify the association between environments based on the angles formed between environment vectors. Additionally, the distance of the vector represented genotypic diversity in the relevant environment. It would be beneficial if the authors could provide more details on how the association between environments was determined using the angles and the specific interpretation of the genotypic diversity based on distance.

5.     Weather Factors and Impact on Disease Incidence (section 2.3): The authors recorded several weather factors, including temperature, relative humidity, rainfall, and wind speed, from two meteorological observatories to study their impact on disease incidence. It would be helpful if the authors could provide more information on how these weather factors were collected and analyzed. Additionally, it would be beneficial for the authors to discuss the relevance and potential influence of these weather factors on SMD incidence.

 

 

Results section

The Results section is comprehensive and provides a structured presentation of the findings. It is well-organized into sub-sections, making it reader-friendly.

1.     3.1. Disease Symptoms and Impact: This section provides a detailed description of the disease symptoms and their impact on pigeonpea. The inclusion of Figure 1 offers a good visual representation to complement the textual details. The reviewer suggests that the authors further clarify if these symptoms and impacts are consistent across all pigeonpea cultivars or if there are exceptions.

2.     3.2. Preliminary SMD Field Screening: The use of the phrase "data not shown" raises questions. It would be beneficial if the authors could either provide the said data, perhaps as a supplementary table, or give a reason for its exclusion.

3.     3.3. Multi-Environmental Testing of SMD: This section is detailed and offers insights into the performance of various genotypes across different environments. The range of SMD incidence for the susceptible check line (ICP 8863) is provided, but it might be useful to also include the range for the resistant lines to give readers a complete picture. 

4.     Tables and Figures: All tables and figures presented are comprehensive and informative. 1) Table 1: The column titles and data are clear. It might be helpful to include a key or legend for abbreviations such as MR, S, HS, etc., even if they have been explained elsewhere on Lines 114-117 in the manuscript. 2) Table 2 and Table 3: These tables effectively summarize the ANOVA results and Spearman’s rank correlation. Ensure that readers can easily relate the data in these tables to the corresponding narrative in the text. 3) Table 4: Correlation coefficients are well-tabulated. It would be beneficial to briefly discuss in the text the implications of these correlations.

5.     3.4. Stability Analysis of Genotypes and Environments: The findings from the GGE biplot analysis seem to be cut off. It would be essential to include the complete details for this section, including the interpretation of Figures 4, 5, and 6.

6.     Grammar and Syntax: A few minor grammatical errors were noted. It would be beneficial to have the manuscript proofread to enhance understanding. For instance, in section 3.2, instead of "22 genotypes (G1–G22) that comprised 21 resistant-to-moderate reaction genotypes and a national highly susceptible check line, ICP 8863 (G22) were selected," it would be clearer to mention "22 genotypes, including 21 resistant-to-moderate reaction genotypes and a national highly susceptible check line (ICP 8863, G22), were selected." For instance, it should be ‘Based on this’, not ‘Based of this’ on Line 277.

7.     Additional Considerations: 1) When discussing genotype performance across environments, consider providing insights into the possible reasons behind the observed performance variability. 2) The relationship between environmental factors and disease incidence is crucial. Consider elaborating on how these factors, such as temperature and rainfall, may influence SMD.

 

 

Discussion section

The overall structure of the discussion is well-organized and follows a logical progression, addressing the importance of the study, the results obtained, the implications of these results, and comparisons with previous studies. There are still a few minor comments to polish this section.

1.     Line 307-308: Consider rephrasing "Although many scientists have been developed resistant cultivars against SMD in the long back," to "Although many scientists developed resistant cultivars against SMD in the past," for clarity.

2.     Line 312: “present investigation is focus on” should be “present investigation focuses on.”

3.     Line 315: Ensure that the references are cited consistently. Some references have multiple numbers e.g., “(32,13,10,33).” Please standardize the format for clarity.

4.     Line 335: It would be clearer if a list format or semicolons are used to separate the reasons for differential responses in pigeonpea genotypes to SMD in multi-environment trials.

5.     Line 358: A reference is cited as “[37]” without any preceding context or statement. Consider adding context or integrating the reference more smoothly into the text.

6.     The importance of plant resistance as a viable management strategy against viral diseases is emphasized. The paper discusses the potential benefits of genetic resistance to SMD and addresses the complexities of the SMD interaction due to the vector-mediated transmission. It might be beneficial to provide more concrete recommendations for breeders and farmers based on the findings.

 

Conclusion section

The Conclusion section effectively summarizes the key findings of the study and provides insights into the significance of multi-locational trials, GGE biplot analysis, and genotypic resistance for managing SMD in pigeonpea. However, it would be advantageous to provide additional details and context to enhance the clarity and impact of the conclusion.

1.     The mention of a significant positive association observed for SMD incidence levels among the tested environments is intriguing. It would be helpful to include the rationale behind this association and its potential impact on future breeding programs or disease screening trials.

2.     The acknowledgment of Bidar and ICRISAT as suitable locations for natural screening of pigeonpea genotypes against SMD and the development of resistant cultivars in future breeding programs is important. It would be informative to elaborate on the specific factors that make these locations suitable and how they align with the objectives of the study.

3.     The statement highlighting the importance of genotypic resistance as the basis for managing SMD in pigeonpea is well-supported by the study's findings. It would be beneficial to briefly discuss the potential implications of these findings for future disease management strategies and the development of resistant cultivars.

Comments for author File: Comments.pdf

Minor editing of English language is required.

Author Response

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Reviewer 2 Report

The manuscript deals with an interesting leguminous crop and one of its most important diseases, the PPSMV and it studies the genetic resistance in pigeon pea as a tool to counteract the viral disease.

The introduction includes all the information needed to a good reading, also considering that the crop is not cultivated all over the world.

Materials and methods are described very clearly, allowing an easy understanding of the results obtained.

However, it is crucial to clarify if the symptoms of the disease observed are related to PPSMVI or PPSMVII. The Authors reported something about the identification of the virus al line 52 but, as far as I understood, diagnostic analyses on plants are not reported in the manuscript.

Finally, some point-by-point comments follow:

Line 17: “kharif” is an English word?

Line 115: viz.?

Figure 2: it is suggested to use other colour for the histogram

Line 235: “arow” should be “arrow”

Line 311: focused?

Line 331: influenced

Table 1: the authors should explain how they define the Reaction type in the table. As a mean of the incidence in the four trials? Please, explain this point in materials and methods.

Results and discussions: the authors wrote that some random observations were done to detect mites on the leaves. Did the authors verify if the genotypes can be considered resistant/susceptible to viruses or to mites? Were mite population number evaluated? Did the authors observe a positive correlation of number of mites and disease severity? Could the authors mention this point and discuss it?

Finally, due to the scientific soundness, in my opinion, the manuscript fits better with the “Communication” type.

Author Response

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Reviewer 3 Report

The work by Mediga et al. advances our understating of host plant Against Sterility Mosaic Disease in Pigeonpea. The report is well written and condensed, as well as technically appropriate. However, before being able to recommend acceptance, I invite authors to address the following amendments.

Please improve the language of the manuscript.

First, the introduction section properly closes with an explicit goal. I just would recommend adding a short sentence before to emphasize the research gap that inspired pursuing this work. Please read and include (https://doi.org/10.47278/journal.ijab/2023.059).

Please acknowledge that the modest diversity panel utilized in the study, with only 21 pigeonpea genotypes, may preclude concluding in this regard.

Last but not least, please envision any other recommendation by adding a short perspectives section before the conclusions . Specifically, what is the next step to study and utilize disease tolerance in studied genotypes?  What is the future potential of marker assisted selection (MAS), and genomic-assisted back crossing (GABC) to leverage disease resistance in diverse genotypes.

Please add latitude and altitude of experimental site

Please improve discussion section of the manuscript by reading (https://doi.org/10.47278/journal.ijab /2023.042)

Moderate revision

Author Response

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Reviewer 4 Report

Q1: 2. Materials and Methods，2.1. Preliminary SMD Field Screening, “A total of 75 pigeonpea genotypes comprising ICRISAT germplasm accessions and breeding lines of mid-early to long duration were assessed for their reaction to SMD under epiphytotic conditions.”What are the criteria for pigeonpea genotypes selection? Were all types included?

Q2: 2. Materials and Methods，2.2. Genotype Assessment at Multi-Environment Locations , “Multi-environment locations were conducted at ICRISAT and Bidar for two successive crop seasons during 2021/2022 and 2022/2023. 21 genotypes selected from the preliminaryscreening were assessed by considering two replications in randomized complete block design (RCBD)..”What are the criteria for the selection of Multi-environment locations? What are the differences? Are they reflected?

Q3: 2. Materials and Methods，2.3. Data Observation and Statistical Analysis. How do you weed out large deviations in the selection of data and on what basis?

Q4: 4 Discussion，“Therefore, present investigation is focus on the impact of the genotype and the environmental causes on the pigeonpea-sterility mosaic virus interaction.”The importance of genes and environmental influences is not sufficiently componentized, and it is recommended that the relevant content be added.

Q5: 5. Conclusions,Suggested areas of application and future prospects for some of these additions.

Q6: Is it a bit low to have only 43 references, some relevant additions could be added.

Minor editing of English required

Author Response

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Round 2

Reviewer 2 Report

The manuscript seems substantially improved, also thank to the contribution of all the reviewers. It is acceptable in the present form.

Reviewer 3 Report

Authors must read and include suggested studies. Overall authors did great efforts to improve the article according to the suggestions.