Cadmium Tolerance in Tea Plants (Camellia sinensis): Physiological, Biochemical, and Molecular Insights

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript titled “Cadmium Tolerance in Tea Plants (Camellia sinensis): Physiological, Biochemical, and Molecular Insights” attempts to provide a holistic review of Cd toxicity, uptake, and tolerance mechanisms in Camellia sinensis. Although the topic is timely and relevant, the scientific rigor, organization, figure/table quality, and interpretive synthesis are considerably weak. The review lacks cohesion between sections, relies heavily on generic plant Cd literature, and provides limited tea-specific critical insights.

Comment 1: The manuscript requires extensive English editing to correct grammatical errors, redundancies, and awkward phrasing. Examples:

“ACadmium (Cd)” → “Cadmium (Cd)”

“effect the immune, nervous, genital system” → “affect the immune, nervous, and reproductive systems”

“Material stress will damage the cell membrane” → “Metal stress can disrupt membrane integrity.”
Many sections read as translated or paraphrased text rather than scientifically articulated prose. A thorough professional editing is essential.

Comment 2: The authors did not adequately emphasize the importance of this review on Cd toxicity and its specific relevance to Camellia sinensis. The introduction mainly discusses the general importance of tea, the environmental impact of Cd, and its effects on plants overall, with little focus on tea-specific aspects. As a reader, I would expect the authors to present a clear rationale for why a Cd-focused review in C. sinensis is warranted. Although the manuscript summarizes the broader literature on Cd stress, its novelty within the tea context remains unclear. Much of the discussion reiterates general plant Cd-toxicity mechanisms rather than highlighting Camellia-specific insights. The authors should better define how this review extends prior works—for instance, by emphasizing unique transcriptomic, proteomic, or metabolomic evidence specific to tea.

Comment 3: The manuscript lacks a coherent logical flow, with considerable overlap among several sections, particularly “ROS-mediated Cd toxicity,” “Cd-induced signaling pathways,” and “Methylation-mediated adaptation.” These sections repeat similar concepts without a clear hierarchical organization. I suggest reorganizing the content into broader thematic sections to improve readability and conceptual continuity, such as: 1) Cd sources and uptake in tea ecosystems, 2) Physiological and biochemical responses, 3) Molecular and transcriptional regulation, 4) Epigenetic, proteomic, and metabolomic perspectives, and 5) Breeding and mitigation strategies.

Comment 4: The review should incorporate recent advancements on tea plant Cd responses, omics datasets, and functional gene validations (e.g., CsHMA3, CsPCS1, CsWRKY53).

Comment 5: The review primarily summarizes findings without critical evaluation or comparison. For example, how do Cd tolerance mechanisms in tea differ from those in model plants such as tomato, rice, or Arabidopsis? Which transporter gene families show lineage-specific expansions in tea? The author should utilize the background of Table 3 and revise the entire manuscript to highlight the tissue-specific route of Cd in the tea plant and its differentiation mechanisms by comparing with other model plants.

Comment 6: The term “tea tree” is occasionally used instead of “tea plant”; please standardize terminology.

Comment 7: There is a conflict between the title of Table 1 and the context discussed in Table 1. There is no connection to discuss “Cadmium (Cd) Contamination: Sources & Risks” and “Cd Uptake, Mobility & Management” in Table 1. What does 98 mean? Try to strengthen the view of “Global Tea Production & Consumption” or else focus on Cd and its significance.

Comment 8: Figure 1 is poorly designed and presented, lacking quantitative detail and subcellular labelling; only arrows and acronyms are shown without defining the direction of flow or energy dependency. A clear schematic diagram with detailed soil to root, root to shoot, and the fate of accumulation with proper membrane transporters and genes marking is required.

Comment 9: Figure 2: The schematic duplicates much of Figure 1 and adds little new information; both can be merged into a single integrated conceptual diagram.

Comment 10: Figure 3 must be redrawn entirely to integrate ROS generation, scavenging systems, and cross-talk with signaling pathways.

Comment 11: Re-organize Table 2 for clarity and data integrity; improve citation precision and column consistency.

Comment 12: The authors should include a future perspective section outlining genomic-assisted breeding or CRISPR-based approaches for Cd detoxification in tea.

Comment 13: The Conclusion section should be more concise, focusing on knowledge gaps and future directions (e.g., multi-omics integration, breeding for Cd-safe cultivars).

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This review paper provides a comprehensive overview of cadmium (Cd) uptake, transport, detoxification, and molecular responses in Camellia sinensis, integrating physiological, biochemical, and genetic aspects. It successfully compiles existing findings and offers a valuable reference for researchers in the fields of tea physiology and heavy-metal stress biology. However, several revisions are recommended to improve clarity, scientific precision, and structure.

Major comments

The review summarizes known mechanisms but does not clearly highlight what new perspectives or conceptual frameworks it contributes. The authors could strengthen the “novel contribution”, for example, by including a comparative analysis of Camellia sinensis versus other perennial crops or by discussing knowledge gaps that should guide future research.

Some sections overlap (e.g., “ROS-mediated Cd toxicity” and “Cadmium-induced signaling pathways”). Consider merging or better differentiating them to avoid redundancy.

Figures (e.g., Figures 1–3) are informative, but legends should be more self-contained and schematic clarity improved (especially Figure 2). Ensure all abbreviations (e.g., ZIP, HMA, JA) are defined at first use in both text and figures.

The paper cites numerous relevant studies but should update citations with the most recent tea-related research (2022–2024), especially on transcriptomics, methylation, and proteomics in Cd-stressed Camellia sinensis. Some older references (pre-2010) could be replaced with newer, higher-impact sources.

The review would benefit from a concluding conceptual model or summary figure integrating soil–plant Cd dynamics, key transporters, and regulatory genes. This would help readers grasp how physiological and molecular mechanisms interconnect.

Minor formatting issues:

• • Correct typographical inconsistencies (e.g., “Gwoth” → “Growth”).
  • Maintain a consistent italic font for scientific names.
  • Ensure uniform citation style (e.g., [1–3] instead of [1], [2], [3]).

Comments on the Quality of English Language

While understandable, the English requires editing to improve fluency and eliminate minor grammatical errors (e.g., “effect the immune system” → “affect the immune system”). Professional English editing is recommended.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf