Effects of Source Strength and Sink Size on Starch Metabolism, Starch Properties and Grain Quality of Rice (Oryza sativa L.)

Round 1

Reviewer 1 Report

The authors have clarified the mechanism how source/sink strengths affect grain quality characteristics by investigating transcript levels of the genes, amylose content, amylopectin chains, starch morphology, etc. The results in the manuscript should be of significant interest to researchers in the field of rice breeding, cultivation, grain metabolism, or quality.
I have some comments that the authors might consider.

Comment 1
In line 22 and 31, the phrase “cooking and tasting qualities” is used. However, cooking test and tasting test were not conducted in the study. I recommend adding detailed description about how the data in the study are related to cooking or tasting quality.

Comment 2
There is no mention about year of cultivation in Figures and Tables except Table 5. If the values presented in Figures 1-4 and Tables 2-4 are the results obtained from the samples which was grown only in 2019 or 2020, please add description about it.

Author Response

Response to Reviewer 1 Comments

Dear Reviewer:

Thank you very much for your inputs during the reviewing of our manuscript entitled “Effects of source strength and sink size on starch metabolism, starch properties and grain quality of rice (Oryza sativa L.)” (agronomy-2356508). We very appreciate the reviewers for the constructive comments. We have studied these comments carefully and made the corrections. I now submit the revised manuscript. In Response parts, we explain, point by point, how we have dealt with the comments during the revision. Now the revised manuscript should be more convinced, and we hope you will be satisfied. For your convenience, comments are repeated here and our responses follow. The changes in revised manuscript are marked up using the “Track changes”, so that you can easily assess where the changes have been made. Thanks very much!

 

Comment 1: In line 22 and 31, the phrase “cooking and tasting qualities” is used. However, cooking test and tasting test were not conducted in the study. I recommend adding detailed description about how the data in the study are related to cooking or tasting quality.

Response: Thank you for your valuable comments on our manuscript. Besides pasting properties and gelatinization consistency, which contribute to grain cooking and tasting qualities, we have also added data about cooking and tasting qualities (hardness, stickiness and taste value) according to your request. Please check Table 5 in the revised manuscript.

Comment 2: There is no mention about year of cultivation in Figures and Tables except Table 5. If the values presented in Figures 1-4 and Tables 2-4 are the results obtained from the samples which was grown only in 2019 or 2020, please add description about it.

Response: Thank you for your valuable comments on our manuscript. Figures 1-4 and Tables 2-4 were the results obtained from the samples which was grown only in 2020. We have explained this in line 134-135 in the revised manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

This work focuses on the effect of source limitation (by cutting flag leaves) and less sink capacity (by cutting some spikelets) on rice starch profile (structure/functionality) and gene expression. The research topic although is not a novel idea, however it is important for sustainable agriculture.

Authors performed testing in two years (2019 and 2020), however the only results were presented for both years are those in the Table 5. Why then experiments done in two years and only one year results presented (not clear which one).

Many acronyms used in the manuscript which is hard to follow when there is not a table to introduce them at the beginning.

Cooking and eating quality have not been examined, so authors can not claim that these parameters improved (in the Abstract).

Authors tried to show both varieties performed the same, while there is obvious different performance for some tested traits. 

Authors should revise the results section thoroughly to reflect the facts found in Graphs/Tables; see my comments on the attached pdf.

In its current format, I found this manuscript not meeting the requirement to be published in Agronomy. It needs a major revision of Results, and then revisit the Discussion based on the results.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

Dear Reviewer:

Thank you very much for your inputs during the reviewing of our manuscript entitled “Effects of source strength and sink size on starch metabolism, starch properties and grain quality of rice (Oryza sativa L.)” (agronomy-2356508). We very appreciate the reviewers for the constructive comments. We have studied these comments carefully and made the corrections. I now submit the revised manuscript. In Response parts, we explain, point by point, how we have dealt with the comments during the revision. Now the revised manuscript should be more convinced, and we hope you will be satisfied. For your convenience, comments are repeated here and our responses follow. The changes in revised manuscript are marked up using the “Track changes”, so that you can easily assess where the changes have been made. Thanks very much!

Here are the specific comments raised by the reviewers.

Comment 1: Authors performed testing in two years (2019 and 2020), however the only results were presented for both years are those in the Table 5. Why then experiments done in two years and only one year results presented (not clear which one).

Response: Thank you for your valuable comments on our manuscript. Rice qualities were measured both in 2019 and 2020. We found that there was a consistent trendy for both varieties in 2019 and 2020 on cooking and eating qualities, and the interaction effect during the years with no significant effect. Therefore, we presented transcript levels of starch metabolic genes during grain filling stage of year 2020 to explore the mechanism.

Comment 2: Many acronyms used in the manuscript which is hard to follow when there is not a table to introduce them at the beginning.

Response: Thank you for your valuable comments on our manuscript. We have added the list of abbreviations before introduction section. Please check line 40-45 in the revised manuscript.

Comment 3: Cooking and eating quality have not been examined, so authors can not claim that these parameters improved (in the Abstract).

Response: Thank you for your valuable comments on our manuscript. We have added data about cooking and tasting qualities (hardness, stickiness and taste value) in 2019 and 2020 according to your request. Please check Table 5 in the revised manuscript.

Comment 4: Authors tried to show both varieties performed the same, while there is obvious different performance for some tested traits.

Response: Thank you for your valuable comments on our manuscript. YD 6 has a larger sink size (larger panicle size). In our study we found the effects of LC on cooking and eating qualities were bigger in YD 6 than in JXY 1. We have discussed the differences between both varieties under LC treatment as “There were some minor differences in the responses of the gelatinization consistency and amylose content to leaf cutting between YD 6 and JXY 1. YD 6 is a variety with larger panicle sizes, so a higher extent of response to leaf cutting is observed in YD 6 than in JXY 1 (Table 5).” (P15L706-P15L709).

Comment 5: Authors should revise the results section thoroughly to reflect the facts found in Graphs/Tables; see my comments on the attached pdf.

Response: Thank you for your valuable comments on our manuscript. We have revised the description of results section thoroughly to reflect the facts found in Graphs/Tables. Most your comments were list below and our responses follow.

1.Line 30: Cooking and eating quality have not been examined, so authors cannot claim that these parameters improved.

Response: We have added data about cooking and tasting qualities (hardness, stickiness and taste value) according to your request. Please check Table 5 in the revised manuscript.

2.Line 51: Confusing sentence, please revise it.

Response: Thanks for the comments, we revised this sentence to “For example, low light environment would limit the supply of photosynthetic assimilates for grain filling, and resulted in lower yield [11,12]”. (P2L60-P2L62).

3.Lines 71-72: The enzyme has already been introduced, just use the acronym.

Response: Thanks for the suggestion. We have deleted the full name of AGPase.

4.Lines 79-80, 85, 446-448: This work was done in potato not rice which has different starch structure/composite; revise sentence. This work is also done on maize not rice, and authors did not mention it in the text. The cited reference has not mentioned the ISA1 gene; not even once in the entire paper. How authors made this claim?

Response: Thank you for your finding these mistakes with wrong cited reference on our manuscript. We have rechecked these cited references and revised them.

5.Line 90: I believe this should be α-1,6-glucosidic linkage!

Response: Thank you for your finding the mistake on our manuscript. We have revised to a-1,6-glucosidic linkage.

6.Line 121: confusing!! In the result section, there is no explanation of how these two years data have been combined, or just one year data has been picked!!

Response: Thank you for your valuable comments on our manuscript. Rice eating and cooking qualities were measured both in 2019 and 2020. There no significant differences between two years for cooking and eating qualities, so we used the data in 2020. We have added illustration about data of years according to your suggestions. Please check line 146-147 in the revised manuscript.

7.Lines 122-123: How were these measurements done?

Response: We have added the methods of measurements of the soil nutrient contents (organic matter, alkaline nitrogen, available phosphorus and available potassium). Please check line 186-188 in the revised manuscript.

8.Line 141: Have this testing done only on mature grains (25 DAF)? In the results section e.g. Figure 6, only one image is shown for each treatment. Please make it clear. The same comments for all the testing introduced in the section 2.2.

Response: Thank you for your valuable comments on our manuscript. The filling grains at 1, 2, 3, 5, 10, 15, 20, 25 DAF were measured for genes transcriptions. The filling grains at 10, 15, 20, 25 DAF were measured for chain length distribution (CLD) and mature grains were measured for grain qualities and other starch physicochemical properties. We have added the illustration of testing samples. Please check line 164-169 in the revised manuscript.

9.Lines 184-187: move this paragraph up before section 3.1.

Response: Thank you for your valuable comments on our manuscript. We have moved this paragraph up before section 3.1. Please check line 236-238 in the revised manuscript.

10.Lines 306-309: It is hard to draw these conclusions from Figure 6. for instant in YD 6 variety, the cavity in LC treatment is less than CK treatment, but authors concluded the opposite.

Response: We thank the reviewer for the comments. Despite the numbers of the cavities of a specific starch granule were less in LC treatment than in CK treatment, but the total numbers of the cavities of starch granules in LC treatment were larger than in CK treatment.

11.Lines 319-321: This is not valid for all DAFs, and two varieties behave differently.

Response: Thanks for the comments, we revised the sentence to “Compared with CK, the contents of A and B1 chains decreased and the contents of B2 and B3 chains increased under LC treatment in variety YD 6. The opposite results were valid when compared ST with CK treatment in variety YD 6. But for variety JXY 1, the effects of ST or LC on CLD were not obvious, especially for the contents of B1 chain and B2 chain.” (P10L454-P10L457).

12.Lines 397-399: This has been already mentioned in the previous sentence; delete it.

Response: Thank you for your comments. We have deleted this sentence.

13.Lines 425-426: In the previous paragraph, authors claimed that "the contents of A and B1 chains increased after 10DAF", and now they say B1 chain was relatively stable!?

Response: We have revised this sentence to “the contents of B1 chain slightly increased in the middle and late stages of grain filling”.

Comment 6: In its current format, I found this manuscript not meeting the requirement to be published in Agronomy. It needs a major revision of Results, and then revisit the Discussion based on the results.

Response: Thank you for your valuable comments on our manuscript. We carefully revised the manuscript according to the reviewer’s comments. I believe the quality of the revised manuscript is significantly improved. We hope that we have resolved all the concerns raised by the reviewer.