Secondary Metabolites, Other Prospective Substances, and Alternative Approaches That Could Promote Resistance against Phytophthora infestans
and Martin Černý 1,*Round 1
Reviewer 1 Report
This review aims to summarize the key points regarding late blight disease caused by Phytophthora infestans in potato plants and the challenges associated with developing resistant cultivars. By in large, the review is well documents with some important details on the given topic however, i have some minor comments to further improve it before publication.
Minor comments:
In section 2. Phytophthora infestans
1.It might be useful to provide more specific details regarding the different taxa within the genus Phytophthora and their relevance to agricultural and ecological plant diseases.
2. Elaborating on the role of global trade and unintended transport of infected tubers in the spread of P. infestans would provide additional insight into the pathogen's ability to rapidly disseminate across regions and continents.
3. Providing more information on the factors influencing the area-specific occurrence of sexual reproduction in P. infestans, as well as the consequences of shifting ploidy levels, would enhance the understanding of the pathogen's life cycle and population dynamics.
In section 3.2 .Chemicial treatment:
4. Expanding on the optimal timing and duration of fungicide applications, as well as the factors influencing treatment periods (such as weather conditions and cultivar resistance), would provide a better understanding of the practical aspects of chemical control methods.
5. The section mentions phosphite treatment as a potentially less effective but complementary option to conventional fungicides. Elaborating on the benefits, limitations, and potential integration of alternative treatments (such as phosphite) alongside fungicides would provide a more balanced perspective on chemical control methods.
In Section
6. Provide more details about the potential of these potato endophytes as effective biological control agents. Discussing their specific mechanisms of action, their interactions with P. infestans, and any limitations or challenges associated with their use would enhance the discussion.
7. More specific examples and elaborate on the different ways in which endophytes interact with the pathogen and the host plant.
8. The identification of factors such as dosage, application methods, compatibility with fungicides, and persistence in the field would provide a more comprehensive understanding of the limitations and considerations involved.
9. Too many references, I suggest to remove at least half of the references, which is really not necessary.
10. The authors have not explained the effect Phytophthora on the growth and developemtal processes in other important crops. I think the following paper provides some insights in this regard which could be referenced in this review:
https://doi.org/10.3390/genes14020369
11. Minor english editing is still required.
English is fine. Minor corrections are needed.
Author Response
We thank the reviewer for the positive evaluation of our manuscript and helpful suggestions to improve our work.
1.It might be useful to provide more specific details regarding the different taxa within the genus Phytophthora and their relevance to agricultural and ecological plant diseases.
Our response to comment 1:
We agree with the reviewer that this information could be of interest. However, the sheer amount of Phytophthora-related research is too broad to fit within the scope of our review, and it would likely require a separate article. That said, we have updated our manuscript and replaced the reference [15] with a recently introduced database of Phytophthora and supplemented our text with a list of the most important Phytophthora pathogens for agriculture:
It includes more than 200 taxa distributed across twelve clades, and pathogens with a significant negative impact on agricultural production are found in several of these. For example, P. infestans belongs to clade 1, together with P. parasitica, P. nicotianae, and P. cactorum. The second clade includes P. capsici, and the representants of clade 4 are the pathogens P. megakarya and P. palmivora. Finally, P. sojae and P. cinnamomi are found in clade 7 [15].
2. Elaborating on the role of global trade and unintended transport of infected tubers in the spread of P. infestans would provide additional insight into the pathogen's ability to rapidly disseminate across regions and continents.
Our response to comment 2:
We thank the reviewer for this comment. We have expanded the paragraph as follows:
The long-distance movement and spreading of the pathogen are mainly anthropomorphic due to global trade and unintended transport of infected tubers for use as seed potatoes [19]. P. infestans may overwinter in tubers which then serve as the primary inoculum in the field. In parallel, contact between infected tubers and healthy tubers in storage promotes infection spread, and careful removal of infected tubers before storage, forced air ventilation, controlled temperature and humidity, and disinfectants are commonly used to protect the harvest and mitigate disease transmission [20].
3. Providing more information on the factors influencing the area-specific occurrence of sexual reproduction in P. infestans, as well as the consequences of shifting ploidy levels, would enhance the understanding of the pathogen's life cycle and population dynamics.
Our response to comment 3:
We have modified and extended the paragraph, but the knowledge on this topic predominantly originated in a study published in 2017 (referenced).
Sexual reproduction is area specific and seems to be preferred under stress conditions. Interestingly, the most aggressive known P. infestans isolates are triploid clonal lineages US-1 and 13_A2, and under stress, the triploid genotype can change to a diploid one [28].
4. Expanding on the optimal timing and duration of fungicide applications, as well as the factors influencing treatment periods (such as weather conditions and cultivar resistance), would provide a better understanding of the practical aspects of chemical control methods.
Our response to comment 4:
The reviewer is correct in commenting on these aspects of chemical treatments. We have expanded the text to indicate that this information is available in the referenced manuscript:
Traditional treatment depends on preventive fungicides applied regularly during the growing season, and the treatment period depends on weather conditions, cultivar resistance, as well as fungicide characteristics and efficacy. Readers interested in these aspects and the benefits of precision agriculture in the fight against late blight are referred to the report published by Yangxuan Liu et al. (2017) [54].
5. The section mentions phosphite treatment as a potentially less effective but complementary option to conventional fungicides. Elaborating on the benefits, limitations, and potential integration of alternative treatments (such as phosphite) alongside fungicides would provide a more balanced perspective on chemical control methods.
Our response comment 5:
We thank the reviewer for the suggestion. The manuscript already included the reference to studies describing the effects of the combination of phosphite and fungicides, and we have expanded the information with a new reference to recently published work and indicated that this treatment is more environmentally safe:
A less effective but more environmentally friendly than a conventional fungicide is a treatment with phosphite (e.g., KPO3). Interestingly, its application can reduce the dosage of fungicides without compromising protection against late potato blight [58–60]. A similar effect was found with the direct application of phosphorous acid when a significant reduction in the severity of the disease was observed even at half the recommended concentration of fungicides [61].
6. Provide more details about the potential of these potato endophytes as effective biological control agents. Discussing their specific mechanisms of action, their interactions with P. infestans, and any limitations or challenges associated with their use would enhance the discussion.
7. More specific examples and elaborate on the different ways in which endophytes interact with the pathogen and the host plant.
Our response to comments 6-7:
We believe that these issues are already addressed in our manuscript, as the required information about the general effects of biological control is referenced:
The protective effect of these microbes can originate from different mechanisms, including a simple competition for nutrients and space, the production of antifungal compounds, and the priming of the host’s defense mechanisms [71].
and the observed impact is listed in Table 1.
The exact molecular mechanisms of promoted resistance are in most cases unknown, and more research is needed to comprehend the effect. For instance, recent evidence (including our own unpublished data) indicates that temperature and phytohormone production by microbes could be one of the critical factors impacting resistance in plants, but these studies are not targeted at P. infestans.
8. The identification of factors such as dosage, application methods, compatibility with fungicides, and persistence in the field would provide a more comprehensive understanding of the limitations and considerations involved.
Our response to comment 8:
We are uncertain as to which section this points to. However, we agree with the reviewer that this is a critical step in transferring lab experiments into the field, and it does apply to all listed compounds and alternative techniques. The following sentence was added to the revised manuscript in the conclusion section:
The available data indicate that the dosage of the fungicide could be decreased by combining it with more environmentally friendly substances. However, the identification of factors such as dosage, application methods, compatibility with the given fungicide, and persistence in the field is needed.
9. Too many references, I suggest to remove at least half of the references, which is really not necessary.
Our response to comment 9:
We are uncertain as to which section the reviewer addresses this comment. However, we believe that all listed references are relevant, and the number of references is well within the range of standard review. We have tried to keep the number, even though the requested modifications required additional references.
10. The authors have not explained the effect Phytophthora on the growth and developemtal processes in other important crops. I think the following paper provides some insights in this regard which could be referenced in this review:
https://doi.org/10.3390/genes14020369
Our response to comment 10:
We thank the reviewer for the suggestion, the reference does not seem to fit in the scope of our review, as its primary objective is Phytophthora infestans, but we included the reference in the last section of the manuscript.
The problem is also due to our limited knowledge of resistance mechanisms and their interaction with abiotic factors. These interactions could be critical, as illustrated in the regulation of RWP-RK transcription factors in soybean infected with P. sojae [219].
11. Minor english editing is still required.
Our response to comment 11:
We thank the reviewer for the suggestion, we have proofread the manuscript and corrected some issues.
Reviewer 2 Report
Dear Authors,
Thank you for your significant contribution to the systematization of knowledge about the fight against late blight, this is really a very important problem of modern agriculture.
The review is excellent, there is only one remark: check the Latin names in the text, it is enough to write the full name at the first mention, then correct it in the text with the abbreviated.
Author Response
We thank the reviewer for the highly positive evaluation of our manuscript. We have abbreviated the Latin names where appropriate, as recommended.
