Brassica oleracea var. sabellica: A New Host of Agroathelia delphinii in Soilless Cultivation Systems in Central Thailand
and Chainarong Rattanakreetakul 6,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript is well written, describing the status and importance of the pathogen in Kale production. The methodology for the characterization and identification of the pathogen is clear and convincing with well documented and graphed results. However, it describes the formation of reproductive structure to the formation of sclerotia, it should be resting structure.
In the Introduction it is described that the pathogen Agroathelia delphini had already been described in Thailand (Line 78-80), but it is not clear why it is a first report. The area where the pathogen is described in this document presents different environmental conditions, is it a phytosanitary protection zone? It is recommended to expand on this comment.
The discussion of the paper is interesting but confusing in relation to the results, focusing on the sources of infection and epidemiology (line 321-330). The paper does not show detection results in the plant substrates from which the isolates were obtained.
The paper describes as the first report of Agroathelia delphini on Kale in soilless systems, even though the pathogen had already been described in the country, insinuating that it is due to the use of recycled material as substrate. Perhaps the main focus of this paper should be on epidemiology and integrated management, highlighting that the main source of inoculum is the substrate in this case (line 361-371). I suggest the author clarify why this is considered a first report of the pathogen on kale in Thailand.
Author Response
1. The manuscript is well written, describing the status and importance of the pathogen in Kale production. The methodology for the characterization and identification of the pathogen is clear and convincing with well documented and graphed results. However, it describes the formation of reproductive structure to the formation of sclerotia, it should be resting structure.
Response: Thank you so much for your comments. The description of sclerotia has been corrected, it is now read “Under stress conditions such as nutrient limitation, the fungal forms sclerotia that appeared as rounded, and ranged in color from yellowish-brown to reddish-brown (Figure 1c-1d).
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2. In the Introduction it is described that the pathogen Agroathelia delphini had already been described in Thailand (Line 78-80), but it is not clear why it is a first report. The area where the pathogen is described in this document presents different environmental conditions, is it a phytosanitary protection zone? It is recommended to expand on this comment.
Response: It has been reported elsewhere (Lines 80-81). This study is the first report in Thailand. We have described it in Lines 376-378: “This research is the first to report that Agroathelia delphinii can infect kale in Thailand. Our study utilized soilless cultivation systems to rule out other soil-borne root rot pathogens.”
In addition, we have added the following statement to the manuscript: “There have been reports of Sclerotium fungi in Thailand, with Sclerotium rolfsii being the most identified species. This fungus is responsible a wide range of economically important crops, including legumes and plants grown in diverse conditions, both in conventional agricultural systems and soilless systems. It is the cause of several plant diseases, in-cluding root and collar rot. Nevertheless, no conclusive reports or unambiguous identi-fication of Agroathelia delphinii in Thailand have been reported [27]. “(Line 81-86).
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3. The discussion of the paper is interesting but confusing in relation to the results, focusing on the sources of infection and epidemiology (line 321-330). The paper does not show detection results in the plant substrates from which the isolates were obtained.
Response: We apologize for this confusion. We have revised it to “Currently, it is acknowledged that diseases affecting kale are understudied, and the identification of phytopathogenic agents remains inconclusive. This poses a significant challenge in managing plant diseases and pathogens, particularly in relation to the abnormalities observed in kale cultivated in soilless system within the greenhouse in the central region of Thailand. This region has seen an increase in the cultivation of vegetables, including kale, in greenhouses and soilless systems [50,51], (now lines 336-341).
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4. The paper describes as the first report of Agroathelia delphini on Kale in soilless systems, even though the pathogen had already been described in the country, insinuating that it is due to the use of recycled material as substrate. Perhaps the main focus of this paper should be on epidemiology and integrated management, highlighting that the main source of inoculum is the substrate in this case (line 361-371). I suggest the author clarify why this is considered a first report of the pathogen on kale in Thailand.
Response: We hope by now, we have convinced you that it is the first report in Thailand. We have added the epidemiology and integrated management and source of inoculum, as suggested (lines 376-392). It is now read “This research is the first to report that Agroathelia delphinii can infect kale in Thailand. Our study utilized soilless cultivation systems to rule out other soil-borne root rot pathogens. The data show that Agroathelia delphinii can persist in these systems and may be resistant to environmental conditions in a temperate region like Thailand. In support of this, our investigation into culturing the fungus at four different temperatures indicated that its optimum temperature from this study, is at 25 °C and above (Figure 4). Potential sources of the pathogen could include contaminated seeds produced using rice straw, which may be contaminated with Agroathelia delphinii, to cover the plant beds, contaminated water as well as infected tools and equipment. To minimize the risk of fungal pathogens in soilless systems, practices such as sterilizing equipment and media, filtering water, maintaining proper system hygiene, and using disease-resistant cultivars can be effective. Regular monitoring and early detection of fungal symptoms also help in managing outbreaks. The findings provide valuable insights that will contribute not only to the development of research but also to the advancement of kale production processes, ensuring they are effective and meet the consumer demand. This includes exploring effective disease management strategies in greenhouse and soilless cultivation systems, which are becoming increasingly important due to significant changes in weather and environmental conditions.
Reviewer 2 Report
Comments and Suggestions for Authors- Some sentences are not fluently expressed and are rather awkward. For example, the expression "The economic value of kale has surged, driven by rising consumer demand for health-promoting and organic foods." seems a bit stiff. It can be optimized to "The economic value of kale has surged due to the rising consumer demand for health-promoting and organic foods.", which makes the expression more natural.
- In the discussion section, discussions on how to prevent and control this pathogen should be added. Meanwhile, although the article points out that agricultural waste may carry pest residues due to inadequate disinfection and these wastes are used in soilless cultivation, it fails to provide direct evidence of an inevitable link between them and the infection of Brassica oleracea var. sabellica by Agroathelia delphinii.
- It is not necessary to place Table 1 in the main text.
Author Response
1. Some sentences are not fluently expressed and are rather awkward. For example, the expression "The economic value of kale has surged, driven by rising consumer demand for health-promoting and organic foods." seems a bit stiff. It can be optimized to "The economic value of kale has surged due to the rising consumer demand for health-promoting and organic foods.", which makes the expression more natural.
Response: We thank you for your thorough review, comments, and suggestions. We have revised it as suggested.
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2. In the discussion section, discussions on how to prevent and control this pathogen should be added. Meanwhile, although the article points out that agricultural waste may carry pest residues due to inadequate disinfection and these wastes are used in soilless cultivation, it fails to provide direct evidence of an inevitable link between them and the infection of Brassica oleracea var. sabellica by Agroathelia delphinii.
Response: Per your suggestion, we have added these sentences in our discussion: lines 381-391 “Potential sources of the pathogen could include contaminated seeds produced using rice straw, which may be contaminated with Agroathelia delphinii, to cover the plant beds, contaminated water as well as infected tools and equipment. To minimize the risk of fungal pathogens in soilless systems, practices such as sterilizing equipment and media, filtering water, maintaining proper system hygiene, and using disease-resistant cultivars can be effective. Regular monitoring and early detection of fungal symptoms also help in managing outbreaks. The findings provide valuable insights that will contribute not only to the development of research but also to the advancement of kale production processes, ensuring they are effective and meet the consumer demand. This includes exploring effective disease management strategies in greenhouse and soilless cultivation systems, which are becoming increasingly important due to significant changes in weather and environmental conditions.”
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3. It is not necessary to place Table 1 in the main text.
Response: While you prefer Table 1 to be in the supplemental documents, other reviewers have suggested including it in the main text. This is due to the inclusion of accession numbers for our isolates, as well as the GenBank data used in our phylogenetic analysis. We will leave this decision to the editors.
Reviewer 3 Report
Comments and Suggestions for Authorsthis manuscript give some new disease and pathogen reports, in general, this text has been well organzied and written. However, it may be better to considered as Short communiction due to not enough data were included in the current version.
- Some tables and figures could be merged, for example the pathonicity in Figure 1 and Figure 6, Table 1 can be integrated into Figure 5.
- Some figures such as Figure 4 is too simple, which can be deleted or included more data.
- In addition, the presentation need consistent throughout the text such as hr and minutes, if full name which should be applied for all units.
- Supplementary Materials should include this information that sequences data in this study have been submitted to NCBI with accession numbers.
- this style of references is not consistent, which need carefully check and improve.
Author Response
1. This manuscript gives some new disease and pathogen reports, in general, this text has been well organized and written. However, it may be better to considered as short communication due to not enough data were included in the current version.
Response: We thank you for your thorough review, comments, and suggestions. We greatly appreciate your feedback and have made the necessary corrections as per your remarks.
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2. Some tables and figures could be merged, for example the pathogenicity in Figure 1 and Figure 6, Table 1 can be integrated into Figure 5.
Response: We respectfully disagree because Figure 1a & 1b show the symptoms of the initial infections from greenhouses located in the three provinces, while Figure 6 presents data from our Kochs’ postulates experiment using soilless system. Regarding Table 1 and Figure 5, although both present the same dataset, we have chosen to include Table 1 in the main manuscript to provide clear information on the host plants, the source of the isolates, accession numbers for our isolates, as well as isolates from other researchers used to construct the phylogenetic tree. We believe this will enhance clarity and provide valuable reference data for researchers and readers.
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3. Some figures such as Figure 4 are too simple, which can be deleted or included more data.
Response: We thank you for your suggestion. While the data in Figure 4 may appear simple, we believe it is important to include it as it highlights the optimal temperature for Agroathelia delphinii infection. This information is valuable for researchers who may want to study this pathogen further. Additionally, it is relevant to the current global climate change situation, where temperature variations can significantly impact pathogen behavior.
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4. In addition, the presentation need consistent throughout the text such as hr and minutes, if full name which should be applied for all units.
Response: We have changed to using hr. and min. throughout.
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5. Supplementary materials should include this information that sequences data in this study have been submitted to NCBI with accession numbers.
Response: All sequences from this study have been submitted to NCBI and the accession numbers are provided in Table 1.
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6. This style of references is not consistent, which need carefully check and improve.
Response: We apologize for the oversight and have corrected this issue to ensure consistency.
Reviewer 4 Report
Comments and Suggestions for AuthorsReviewer Comments:
The article " Brassica oleracea var. sabellica: A New Host of Agroathelia delphinii in Soilless Cultivation Systems in Central Thailand" presents an intriguing study. This study marks the first documentation of A. delphinii affecting this plant in the region. It provides essential insights for accurate disease diagnosis and developing effective management strategies, which are key to enhancing productivity in soilless cultivation systems amid increasingly variable environmental conditions. While I found the article interesting, I have some suggestions for the authors. If they incorporate these suggestions, I recommend it for publication in MDPI:horticulturae.
- What is the significance of reporting Agroathelia delphinii on kale? Has it been reported on other Brassica species?
- How does this finding impact kale production in soilless systems?
- What were the environmental conditions (humidity, temperature, pH, EC) for pathogen growth in soilless media?
- Could other plant stress factors (e.g., nutrient imbalance, high humidity) have contributed to pathogen susceptibility?
- Why do you prefer using Bayesian inference analyses (BI) to construct phylogenetic trees?
- What benefits does coconut coir media offer for plant growth and disease resistance? Did you amend the media with any additional ingredients?
- How do you calculate disease incidence and severity, and should formulas be included in the supplementary file?
- The authors should include plant data (biomass, etc.).
- Conclusions need to be improved.
Author Response
1. The article "Brassica oleracea var. sabellica: A New Host of Agroathelia delphinii in Soilless Cultivation Systems in Central Thailand" presents an intriguing study. This study marks the first documentation of delphinii affecting this plant in the region. It provides essential insights for accurate disease diagnosis and developing effective management strategies, which are key to enhancing productivity in soilless cultivation systems amid increasingly variable environmental conditions. While I found the article interesting, I have some suggestions for the authors. If they incorporate these suggestions, I recommend it for publication in MDPI: Horticulturae.
Response: We thank you for your thorough review, comments, and suggestions. We greatly appreciate your feedback and have made the necessary corrections as per your remarks.
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2. What is the significance of reporting Agroathelia delphinii on kale? Has it been reported on other Brassica species?
Response: Globally, A. delphinii has been isolated from several hosts, including ornamental plants and other crops, but reports on Brassica species are limited and not well-documented. While A. delphinii has previously been reported from warm regions such as parts of China and the United States, there has been no clear identification of this pathogen on kale or other Brassica species in Thailand. Therefore, our study provides important new insights into the host range and potential risks posed by this pathogen. We utilized soilless cultivation systems to rule out other soil-borne root rot pathogens. The significance of this study lies in the fact that this is the first confirmed report of the A. delphinii affecting kale (Brassica oleracea var. sabellica) in Thailand.
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3. How does this finding impact kale production in soilless systems?
Response: The pathogen affects the root system, critical for nutrient uptake. In controlled soilless environments, its spread could lead to widespread crop loss. Effective detection, management, and biosecurity measures will be essential to minimize yield losses and ensure the sustainability of kale production in these systems.
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4. What were the environmental conditions (humidity, temperature, pH, EC) for pathogen growth in soilless media?
Response: We have explained these details, please see Section 2.5 of the Materials and Methods.
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5. Could other plant stress factors (e.g., nutrient imbalance, high humidity) have contributed to pathogen susceptibility?
Response: Yes, it could. In our study, plants were kept under controlled conditions to avoid these abiotic factors.
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6. Why do you prefer using Bayesian inference analyses (BI) to construct phylogenetic trees?
Response: We selected Bayesian Inference (BI) for constructing the phylogenetic tree because it provides posterior probability (PP) values. This approach is more informative than methods that yield only a single best tree without quantifying confidence. Additionally, BI supports the use of complex evolutionary models such as GTR+G+I, enhancing the accuracy of phylogenetic analysis based on nucleotide sequence data. It is also well-suited for analyzing concatenated datasets involving multiple gene regions. Importantly, BI offers better resolution among closely related species, especially in cases where morphological characteristics alone are insufficient for species-level identification.
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7. What benefits does coconut coir media offer for plant growth and disease resistance? Did you amend the media with any additional ingredients?
Response: Coconut coir media provides excellent water retention and aeration, which helps in promoting healthy root development. The media has a naturally balanced pH and a high cation-exchange capacity (CEC), which helps in retaining essential nutrients and making them available to plants. These properties make it an ideal substrate for soilless cultivation. In the area where the samples were collected, only coconut coir was used as the growing medium. However, the growers ensured proper irrigation and fertilizer management to promote optimal plant growth. No additional ingredients were added to the coconut coir media, as it was deemed sufficient for supporting plant health under these conditions.
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8. How do you calculate disease incidence and severity, and should formulas be included in the supplementary file?
Response: We agreed and have included the formulas in the supplementary file.
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9. The authors should include plant data (biomass, etc.).
Response: We appreciate the suggestion to include plant data such as biomass. We agreed that including plant growth parameters like biomass can provide valuable insights into how the pathogen affects the overall plant health and productivity. In this study, we focused primarily on identification of the pathogen, disease incidence, and disease severity, which are critical for disease management. We plan to incorporate this data in future studies to provide a more comprehensive assessment of the pathogen's impact.
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10. Conclusions need to be improved.
Response: We have revised the Conclusion section. It is now read, “In this study, Agroathelia delphinii was isolated from stem rot of kale from three provinces. Koch’s postulates were performed using soilless cultivation systems to rule out other potential root rot pathogens, as well as to support growers using soilless systems, which have become popular in Thailand. The identification of the pathogen was conducted using a combination of multilocus sequence analysis (MLSA), morphological characteristics, and Kochs’ postulates, confirming that the causal pathogen is Agroathelia delphinii. This study represents the first report showing that Agroathelia delphinii causes stem rot in kale in Thailand. These findings contribute not only to the research community but also to risk assessments of soilless cultivation systems, highlighting the significance of contaminated fungal pathogens on materials used to produce seeds, such as rice straw, which is known to be an alternative host for Agroathelia.
