Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article takes wheat under nickel stress as the object to verify the growth-promoting, detoxification and nutritional regulation effects of Bacillus megaterium AFI1 and Bacillus thuringiensis AFI2. The core conclusion is clear and has application potential. However, there are still some problems to be solved.

1. The preface is quite lengthy but mostly consists of conventional descriptions, lacking novel knowledge. Notably, it fails to clearly state the problem this article aims to solve. What scientific issues remain in the plant-metal-microbe interaction? The introduction merely briefly mentions "insufficient research on PGPB regulation of nickel-stressed wheat nutrition", without clearly highlighting the core differences between this study and existing ones, such as strain specificity, nickel concentration gradients, and organ nutrient distribution mechanisms, thus providing insufficient support for the study's innovation.
2. When PGPB appears for the first time, its full name should be written.
3. Some key mechanisms are insufficiently referenced (such as PGPB immobilization of heavy metals, ACC deaminase regulation of stress), and the citation format is inconsistent. It is necessary to supplement high-score literature from the past five years and unify the format.
4. In the Materials and Methods section, many paragraphs can be merged.
5. Only the strain numbers and functions are mentioned, without providing the 16S rRNA gene sequence or strain preservation number, making it impossible to verify the taxonomic status of the strains.
6. The pot experiment does not specify the full data of soil physical and chemical properties, wheat planting density, or water and fertilizer management plans.
7. The inoculation method is only described as "inoculated three times", without specifying the bacterial liquid concentration, inoculation time points, or precise inoculation methods, resulting in poor experimental reproducibility.
8. No sterilized or inactivated bacterial liquid control was set up, making it impossible to rule out the non-specific effects of bacterial debris or the medium, thus the experimental logic is not rigorous.
9. Only a simple list of "PGPB production of ACC deaminase, iron carriers, and phosphorus and nitrogen fixation" is provided, without explaining how AFI1/AFI2 reverse nickel toxicity through specific functions in combination with the data of this study, and lacking molecular/physiological level mechanism correlations.
10. No comparison with similar studies is made to illustrate the advantages and specificity of the strains in this study. The discussion merely repeats the results without academic elevation.
11. There are conflicts in the data and expressions in the abstract and conclusion sections, which need to be uniformly checked and corrected.
12. There are too many figures and tables in the main text. It is suggested that the number of figures and tables in the main text does not exceed 10, and the rest should be placed in the supporting materials.

Author Response

See attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a detailed study on the stimulating effect of plant growth promotion bacteria on wheat plants grown in Ni-polluted soil. The experimental design and the obtained results are scientifically sound, but the quality of the presentation should be improved. 

The main points which the authors should address (besides the quality of English) are these:

1) Why the authors chose to test metabolic activity of the studied strains at 100mg/L Ni, which is an almost lethal concentration for them in liquid medium (according to fig. 3)? And how do they explain that on solid medium (figs. 1 and 2) the colonies still had a substantial size?

2) Table 2: what are the units for H2O2 content?

3) Table 3: the content of photosynthetic pigments should be expressed per unit of plant weight.

4) Some subsections in Materials & Methods should be more concise; the text in the section needs careful revision.

 

Comments on the Quality of English Language

The manuscript would benefit from English proofreading, especially the Materials & Methods section. There are also numerous inconsistences (e.g., line 44: "It has" should be replaced with "They have"; line 113: some words are missing from the sentence; numerous typos throughout the text; line 418: "the cations exchanged capacity" should be replaced by "element content"; line 475: missing reference).

Author Response

1) Why the authors chose to test metabolic activity of the studied strains at 100mg/L Ni, which is an almost lethal concentration for them in liquid medium (according to fig. 3)? And how do they explain that on solid medium (figs. 1 and 2) the colonies still had a substantial size?

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, Veronika N. Pishchik and colleagues investigated the effect of PGPB (plant growth promotion bacteria) in wheat plants to cope with nickel (Ni) stress. I have following comments:

1, For the Title, full names for the abbreviations AF1, AF2, and Ni should be spelt out.

2, For the Abstract, practical interests of this study should be stated. In addition, full names for the abbreviations Fe, B, N and P should be spelt out.

3, For the introduction, all references should be cited. For instance, reference 2 is not cited. In addition, paragraph 1 and 6 comprise only one sentence, please optimize.

4, For the materials and methods, technique replicates and biological replication should be clearly described. Randomization in the samplings should be clearly described. In addition, please review and update the Methods section to ensure good reproducibility of the experiments. For instance, providing details on “Nitrogen Fixing Ability”. The update should be made to other relevant sections as well.

5, For Figures 1 and 2, scale bars should be displayed.

6, For Figure 3, data for the control group should be included.

7, For Tables 2 and 3, error values 3.7, 2.8, 0.37, 1.8, and 0.18 were surprisingly repeated many times, please the raw data.

8, For the discussion section, the unanswered questions and future perspectives should be discussed.

9, Reference should be standardized according to the MDPI template. For instance, the journal name “Russ J Plant Physiol” (Line 1008) is not in italics.

Author Response

1, For the Title, full names for the abbreviations AF1, AF2, and Ni should be spelt out.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Authors have addressed my concerns in the revision.