Bacillus velezensis HZ33 Controls Potato Black Scurf and Improves the Potato Rhizosphere Microbiome and Potato Growth and Yield
, Chao Wang 2, Yunpeng Tao 3, Aixia Dong 1, Yuzi Feng 1, Jiajia Li 1, Jin Cheng 1, Zhihong Xie 2, Yongqiang Tian 1 and Tong Shen 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReviewing agronomy-4049406 “Bacillus velezensis HZ33 controls Potato Black Scurf and improves the potato rhizosphere microbiome, growth and yield”.
The article is well structured. It is important to know how biological control agents such as Bacillus velezensis impact in the fields and crops where they are used. Although the findings are evident some observations are pointed out in the following.
1) Can the authors explain the incidence rates? Are the values in Table 1 normal, moderate, or severe?
2) Despite the high control efficiency of both HZ33 and MJZ in the Xindaping and Longshu 7 varieties, why isn't this reflected in a marked increase in potato yield (kg/ha) compared to the negative control? This isn't discussed.
3) What differences exist between the tested potato varieties? This discussion is not addressed. This is because Longshu 7 had a superior kg/ha yield,
4) Briefly mention the culture conditions for B. velezensis: were spores added along with the culture medium, or were they used alone?
5) Is common that lipopeptides produced by Bacillus genera in particular some of them as B. velezensis are used for biocontrol Fungi diseases, but why is so selective? This is mentiones by the discussion in line 411.
6) In the figure S2, regarding Venn diagrams in Xindaping variety, the fungal community structure according to the OTUs is superior in the experiment with the chemical control azoxystrobin. Please discuss.
Some writing considerations
- Define OTUs in text
- sp. must not be writing In italics
- Define that X was used for Xindaping variety and L was for Longshu 7
- Put space before each section.
Author Response
Reviewer 1: The article is well structured. It is important to know how biological control agents such as Bacillus velezensis impact in the fields and crops where they are used. Although the findings are evident some observations are pointed out in the following.
1. Can the authors explain the incidence rates? Are the values in Table 1 normal, moderate, or severe?
Our response: Thank you for your valuable suggestion. We have supplemented this formula in Lines 137-139 of the revised manuscript as follows: “The incidence rate, disease index and control efficacy were then calculated using the following formulas: , where A was the number of diseased tubers, B was the total number of tubers.” As shown in Table 1, the incidence rate of potato black scurf in the control group was severe, whereas it was moderate in the treatment group.
2. Despite the high control efficiency of both HZ33 and MJZ in the Xindaping and Longshu 7 varieties, why isn't this reflected in a marked increase in potato yield (kg/ha) compared to the negative control? This isn't discussed.
Our response: Thank you for your valuable suggestion. We have revised the discussion in Lines 402-403 of the revised manuscript as follows: “Based on its significant disease prevention effect, it ensures the normal growth of potatoes, thereby increasing the yield and commercial rate of potatoes.”
3. What differences exist between the tested potato varieties? This discussion is not addressed. This is because Longshu 7 had a superior kg/ha yield,
Our response: Thank you for your valuable suggestion. We selected two potato cultivars to verify the stability of Bacillus velezensis HZ33 efficacy against potato black scurf. We have revised the discussion in Lines 403-405 of the revised manuscript as follows: “Importantly, our experiments on two potato varieties confirm the stability and reliability of its control effect on potato black scurf.”
4. Briefly mention the culture conditions for B. velezensis: were spores added along with the culture medium, or were they used alone?
Our response: Thank you for your valuable suggestion. We have added the culture conditions for B. velezensis in Lines 89-92 and 104 of the revised manuscript as follows: “The HZ33 was cultured in an optimized medium (maltose 24.15, yeast extract 13.14, beef extract 8.0, NaCl 5.0 g/L) with a 4.5% inoculum at 40°C and 180 rpm for 48 h, followed by centrifugation, washing, and dilution to 1×10⁸ CFU/mL as a spore suspension.” and “potato seeds coated with HZ33 spore suspension at 1 × 10⁸ CFU mL⁻¹.”
5. Is common that lipopeptides produced by Bacillus genera in particular some of them as B. velezensis are used for biocontrol Fungi diseases, but why is so selective? This is mentiones by the discussion in line 411.
Our response: Thank you for your valuable suggestion. This paper is part of a doctoral dissertation. Bacillus velezensis HZ33 was identified as the biocontrol strain through extensive screening trials (briefly described in Lines 78-79), where it exhibited the strongest antagonistic activity against the potato black scurf pathogen (Rhizoctonia solani). Consequently, the lipopeptides it produces may demonstrate selectivity toward R. solani. Further supporting this selectivity, we isolated the cyclic lipopeptide marihysin B from its fermentation broth, confirming this targeted activity.
6. In the figure S2, regarding Venn diagrams in Xindaping variety, the fungal community structure according to the OTUs is superior in the experiment with the chemical control azoxystrobin. Please discuss.
Our response: Thank you for your valuable suggestion. Upon careful examination, we found that the number of fungal community OTUs in the two potato cultivars, Xin Daping and Longshu 7, treated with azoxystrobin was higher than those treated with HZ33. And we have added to the discussion in Lines 446-448 of the revised manuscript as follows: “We also observed that HZ33 uniquely decreased the relative abundances of Alternaria solani (causing potato early blight) and Fusarium (causing potato root rot). This broad-spectrum activity likely reflects multiple disease-suppression mechanisms of B. velezensis HZ33, including production of diverse antibacterial compounds, competition for ecological niches and induction of plant systemic resistance, and these mechanisms may represent key contributing factors to the reduced number of OTUs observed in the HZ33 treatment compared with the azoxystrobin treatment in the Venn diagram.”
7. Some writing considerations
- Define OTUs in text
- sp. must not be writing in italics
- Define that X was used for Xindaping variety and L was for Longshu 7
- Put space before each section.
Our response: Thank you for your valuable suggestion. We have defined OTUs in Lines 159-160 of the revised manuscript as follows: “OTUs were clustered with 98.65% similarity cutoff using UPARSE (v10)”. And we have clarified that X was used for the Xindaping variety and L was for Longshu 7 in Lines 101-102 of the revised manuscript as follows: “The susceptible potato cultivars Xindaping （abbreviated as X）and Longshu 7 (abbreviated as L) were planted in the experimental field”.
Additionally, we sincerely appreciate your thorough review, which has significantly contributed to enhancing the accuracy of our manuscript. We have revised all instances of "sp" and the formatting throughout the text to comply with the journal's requirements.
Reviewer 2 Report
Comments and Suggestions for Authors"Bacillus velezensis HZ33 controls Potato Black Scurf and improves the potato rhizosphere microbiome, growth and yield" is and interesting manuscript quite well written and organized with data which look properly reported and analyzed. few notes are reported on the attached document
Comments for author File: 
Comments.pdf
The English could be improved to more clearly express the research.
Author Response
Reviewer 2: "Bacillus velezensis HZ33 controls Potato Black Scurf and improves the potato rhizosphere microbiome, growth and yield" is and interesting manuscript quite well written and organized with data which look properly reported and analyzed.
1. few notes are reported on the attached document
Our response: Thank you for your valuable suggestion. We have carefully revised the attached supplementary materials by adding detailed notes for all figures and tables. All revisions are marked in yellow in the revised supplementary materials (Notes in Supplementary Tables and Figures).
2. The English could be improved to more clearly express the research.
Our response: Thank you for your valuable feedback regarding the English clarity of our manuscript. We fully agree that clear language is essential for effectively conveying our research. We have utilized the journal’s official language-editing service to refine grammar, coherence, and technical precision. This will enhance the manuscript's readability and ensure that it meets the journal’s standards.
We sincerely appreciate your guidance and are committed to improving the manuscript through this professional editing process.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors and Editors
Review of the paper:
Bacillus velezensis HZ33 controls Potato Black Scurf and improves the potato rhizosphere microbiome, growth and yield.
The manuscript is well-written by authors. The authors have done a great deal of in-depth analytical and microbiological research. The results presented in the paper are very interesting, they are promising and could be implemented into practice.
I suggest that authors change the Key words. In the presented version they are the same as in the title.
The Methodology is written precisely and presented with details.
I have only one question :
Was the field experiment repeated in the following year ?
Why did authors choose the cultivars Xindaping and Longshu ?
The Results are presented very well and clearly in the Tables and in the Figures. Some of them, especially in Figures are very complicated, contain a lot data and sometimes they are difficult to interpret.
The authors have interpreted the results correctly. There are a lot of results, especially microbiological results and their bioinformatic analysis. Some results are presented in the Supplementary Section. I wonder if it would be were to divide the paper into two papers. I think it would be easier to read and interpret all complicated results. But of course this decision should be taken by Editors and others reviewers.
The Discussion is well-written, however it is very long. Please try to shorten it. Please mainly concentrate on the issues which have positive results.
The References contain the newest papers, there are a lot of positions – 80. So, some of them authors could not cite.
Author Response
Reviewer 3: The manuscript is well-written by authors. The authors have done a great deal of in-depth analytical and microbiological research. The results presented in the paper are very interesting, they are promising and could be implemented into practice.
1. I suggest that authors change the Key words. In the presented version they are the same as in the title.
Our response: Thank you for your valuable suggestion. We have revised the keywords in Lines 28-29 of the revised manuscript as follows: “Potato black scurf; Rhizoctonia; Microbial community; Bacillus velezensis; Abundance”.
2. The Methodology is written precisely and presented with details. I have only one question: Was the field experiment repeated in the following year?
Our response: Thank you for your valuable suggestion. In this study, although field experiments were conducted within a single growing season, we tested two potato varieties to ensure the reliability of the experimental results. Specifically, (1) two locally representative potato varieties (Xindaping and Longshu 7), which are widely cultivated in the study region and susceptible to potato black scurf disease, allowed us to fully verify the control efficacy of B. velezensis HZ33 against potato black scurf disease; (2) comprehensive data analysis (e.g., growth parameters, yield, control efficacy, soil nutrients, and rhizosphere microbial community structure) were performed. These analyses consistently demonstrated that HZ33 promotes plant growth, increases yield, controls potato black scurf, and alters the rhizosphere microbial community structure in both cultivars. Collectively, these data support the stability of the biocontrol and the growth‑promoting effects of HZ33 under the environmental conditions of the experimental year.
Additionally, we greatly value your comment and fully agree that multi‑year field validation is crucial to confirm the long‑term performance of HZ33 across different climatic and soil conditions. As part of our ongoing research, based on the current experimental results, we are developing HZ33 microbial agent products and further expanding the scope of field trials. These findings will be incorporated into subsequent research papers to further verify the reliability of our results.
3. Why did authors choose the cultivars Xindaping and Longshu?
Our response: Thank you for your valuable suggestion. Xindaping and Longshu 7 are main cultivated varieties in major potato-producing regions of Gansu Province, China, and are susceptible to potato black scurf disease. Thus, we selected these two varieties for field experiments to better reflect the control efficacy of Bacillus velezensis HZ33 against potato black scurf disease. Additionally, field experiments were conducted with the two varieties to fully verify the stability of the growth-promoting and black scurf disease control effects of Bacillus velezensis HZ33 on potatoes.
4. The Results are presented very well and clearly in the Tables and in the Figures. Some of them, especially in Figures are very complicated, contain a lot data and sometimes they are difficult to interpret.
Our response: Thank you for your valuable suggestion. To improve the clarity and interpretability of the complicated figures, we have optimized them as follows:
- Figures 4 and 7 have been modified with clear labels added, as detailed in the revised manuscript.
- Detailed annotations have been added to the figures to help readers quickly and clearly understand the data presented.
5. The authors have interpreted the results correctly. There are a lot of results, especially microbiological results and their bioinformatic analysis. Some results are presented in the Supplementary Section. I wonder if it would be were to divide the paper into two papers. I think it would be easier to read and interpret all complicated results. But of course this decision should be taken by Editors and others reviewers.
Our response: Thank you for your valuable suggestion. We appreciate your thoughtful comment on the manuscript structure. After careful consideration, we prefer to keep the manuscript as a single paper to maintain the integrity and coherence of our research, which we believe is essential for readers to fully understand the context and findings. However, we will further streamline the presentation of results and optimize the supplementary materials to enhance readability, ensuring complex data are clearly communicated without compromising content completeness. We respect the final decision of the editors and reviewers regarding this matter.
6. The Discussion is well-written, however it is very long. Please try to shorten it. Please mainly concentrate on the issues which have positive results.
Our response: Thank you for your valuable suggestion. We sincerely appreciate your constructive comment on the Discussion section. We have thoroughly revised this section by
- Shortening preliminary exploratory analyses that are not directly related to our core findings;
- Removing discussions of less critical conclusions.
The revised Discussion section has been condensed significantly, and all modifications are marked in yellow in the revised manuscript.
7. The References contain the newest papers, there are a lot of positions – 80. So, some of them authors could not cite.
Our response: Thank you for your valuable suggestion. We have carefully evaluated all 80 references and removed redundant and marginally relevant citations that were not directly referenced in the main text. Meanwhile, we have retained all the latest and core literature essential to supporting the novelty and scientific rationale of this study. All adjustments to the reference list are clearly marked in the revised manuscript.
