Stevia rebaudiana under a CO2 Enrichment Atmosphere: Can CO2 Enrichment Overcome Stomatic, Mesophilic and Biochemical Barriers That Limit Photosynthesis?
, Carlos A. Espitia-Romero 2,†, Juán de Diós Jaraba-Navas 1,†, Luis Alfonso Rodriguez-Paez 1,† and Alfredo Jarma-Orozco 1,†
Round 1
Reviewer 1 Report
The performance of S. rebaudiana under a CO2 enrichment atmosphere has only been the subject of a small amount of research, and the authors claim that no studies have attempted to identify variation in the Stevia genotype under this circumstance. So, their study's primary goal was to assess the impact of elevated and superelevated CO2-enriched atmospheres, and show whether S. rebaudiana can overcome stomatic, mesophilic, and biochemical barriers that restrict photosynthesis when growing in CO2-enriched environments. Overall, the work is interesting and well-compiled with recent information and many results. The theme is a timely effort from the authors. The data is well supported with nice Figures and a Table. Further, this manuscript can be accepted for publication after some following minor revisions:
1. Reduce the number of keywords;
2. Show the main quantitative results that support your conclusions in the abstract section;
3. Do not combine references. Instead, include a brief summary of each paper's primary contribution in a separate sentence. Please read the entire manuscript attentively;
4. In addition to the improvements indicated above, I would like to advise the authors to read some recent articles and include their findings in a logical position while maintaining more updated content from more recent literature;
5. Check the resolution of some figures, since some of them have different qualities.
Author Response
The authors are grateful for your valuable contributions to improving this manuscript
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors made a substantial effort to understand the response of Stevia towards elevated Co2 in terms of photosynthesis efficiency and stevioside content. The authors have used standard methods and procedures while conducting the experiment and need encouragement in terms of publication. However, the authors have completely forgotten to mention the statistical analysis done and the software used for analysis. This needs to be mentioned before accepting the paper for publication.
Author Response
The authors apologize for this lapse. A new section (2.7 Experimental design and statistical analyses) was added with all statistical details and used software. Please verify it on lines 305-315 or below and the attached files.
2.7 Experimental design and statistical analyses
The experiments were conducted in a completely randomized block design in a four-way ANOVA composed of 2 genotypes (G4 and G16), 3 concentrations of CO2-inside the chambers (400, 800, and 1200 μmol mol-1), 2 times of exposed enriched- CO2-atmosphere (1 and 2 hours), and 3 timelines (0, 45 and 90-days plants). All treatments were composed of 5 repetitions. All the data were analyzed by tri-way ANOVA (comparing CO2 concentrations inside the chamber, time of exposure in enriched- CO2-atmosphere, and timeline). The t-test was used to compare all media between both genotypes). The 3-way ANOVA was performed to compare medians using an SNK test (P < 0.05) by SigmaPlot for Windows v. 14.0 (Systat Software, Inc., San Jose, CA, USA) and R v. 2022.07.2 [60] was used to make a t-test.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper of Pompelli et al. entitled “Stevia rebaudiana under a CO2 enrichment atmosphere: Can CO2 enrichment overcome stomatic, mesophilic and biochemical barriers that limit photosynthesis?” represents a solid contribution towards the characterization of the performance of plants that are important economically in conditions of elevated concentrations of CO2. The topic might look as very important because of climate change and increased concentrations of CO2; however, it is well known that elevated concentrations of CO2 (600-800 ppm) have beneficial effects on a variety of crops. Actually, in advanced greenhouses production, for increased productivity of crops like tomatoes, pepper and cucumbers, raising CO2 concentration is a common practice. We also know that in geologic times plants use to grow in much higher concentrations of CO2 which might explain why RUBISCO functions the way it does.
Taking into account this, it is not unexpected that this study showed that both genotypes analyzed performed quite well even at levels that are generally not used in production, that is, 1200 ppm (or umol CO2 mol-1). The authors performed a very large number of analyses to support something that is, more or less, known. Overall, because of the large number of analyses, the paper is very difficult to be read. The results section is more than 15 pages long! Discussion another 6 pages! This MS is more like a condensed form of a thesis rather than a research paper! It is rather odd is that authors are referring to findings in tropical trees and so on, when there is such an extensive literature on crops grown in greenhouses under increased concentrations of CO2.
Otherwise, though very dense, the paper is generally well written is spite of the fact that there are still a few places in which it could be done better.
For example, it is not OK to write “To ribulose-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activity” (line 251) or “To glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) activity” (line 256). One can say: “To measure (or determine) the activity of RUBISCO or GADPH”.
Such small things can be found throughout the MS but have no important effects on the readability of the MS.
Major questions:
1. Why the authors decided to expose the plants only for 1 h and 2 h to elevated conc. of CO2? Why not for a longer period of time? The authors might explain their choice in the MS as well.
2. The authors mention that there were 3 timeline, 0, 45 days and 90 days. Can they make clear, in the materials and methods section, that analyses presented in Table 3, enzymatic assays (section 2.5.2, and 3.4), steviosides and biomass were done only after 90 days?
Author Response
The authors are grateful for your valuable contributions to improve this manuscript
Author Response File: Author Response.pdf
