Changes of Fruit Abscission and Carbohydrates, Hormones, Related Gene Expression in the Fruit and Pedicel of Macadamia under Starvation Stress

Round 1

Reviewer 1 Report

The article describes results of a multidisciplinal study of the changes leading to fruit abscission and ripening in macadamia (Macadamia integrifolia) evoked by a starvation  stress. The starvation was induced by interrupting of the carbon supply to the fruit by girdling and defoliation. Significant changes in carbohydrate and endogenous hormone levels as well as in the expression of the selected genes were observed in different parts of the plant. The data were analysed statistically and thoroughly discussed. They indicated a complex interplay between individual elements of plant metabolism and constitute a basis for further elucidation of regulatory mechanisms connected with fruit abscission and ripening.

I have no particular remarks to the work. The paper is well written containing  only minor typing errors, as for example:

Line 112: the cuts were 0.8 mm apart (it seems too close, shouldn´t it be 8 mm?)

Line 148: analysis

Figure 2: part G of the graph is not mentioned in the caption, while the part "J" of the graph is missing.

Line 264: like sucrose

Line 495: Giberellic acid

 

 

Author Response

Point 1:

Line 112: the cuts were 0.8 mm apart (it seems too close, shouldn´t it be 8 mm?)

Response 1: Ok, the cut should be 0.8 cm apart.

Point 2:

Line 148: analysis

Response 2: Ok, we have revised ‘annlysis’ in the caption with ‘analysis’.

Point 3:

Figure 2: part G of the graph is not mentioned in the caption, while the part "J" of the graph is missing.

Response 3: Ok, we have revised ‘pedicel (H-J)’ in the caption with ‘pedicel (G-I)’.

Point 4:

Line 264: like sucrose

Response 4: Ok, we have revised the ‘liking’ with the ‘like’.

Point 5:

Line 495: Giberellic acid

Response 5: Ok, we have revised the ‘Gibberellin acid’ with the ‘Gibberellic acid’.

Reviewer 2 Report

Comments for author File: Comments.docx

Author Response

Point 1：The language or sentence formations need to be addressed carefully for better understanding.

Response 1: Ok, we have revised carefully the language and sentence.

Point 2：Line 149 (the word primer is repeated twice).

Response 2: Ok, we have deleted the repeat word ‘primer’.

Point 3：Discussion section needs more explanation.

Response 3: Ok, we have revised the discussion section.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper examined the abscission of Macadamia fruit under starvation stress. The topic is relevant to the scope of Horticulturae. Results are interesting for me. I am surprised that the girdling and defoliation significantly decreased the sucrose content in husk at day 1 and day 3 after treatment, especially within 1 day after treatment the decrease was about 50.0%.There are, however, some issues that needed to be resolved prior to publication.

1. Line 106: I ask you about sample collection. The girdling and defoliation accelerated fruit drop, and cumulative fruit drop rate increased rapidly to about 90%. Which did you analyze carbohydrates and hormones in attached or detached fruit especially in 5 days after treatment? If you used attached fruit. you have to discuss it. Because physiological conditions significantly differ in attached or detached fruit.

2. Line 109: You should refer to the reason why you select 32 days after anthesis for the treatment.

3. Line 141: not ‘liguid’ but ‘liquid’

4. Line 148: You should refer to the reason why you select 15 genes. For example, ACS and ACO are well-known to be multi-gene family.

5. Line 224: You wrote that NI was significant during 4 to 5 days after treatment in the husk. Sucrose rapidly decreased next day after treatment. You have to discuss this discrepancy.

Author Response

Point 1：
1. Line 106: I ask you about sample collection. The girdling and defoliation accelerated fruit drop, and cumulative fruit drop rate increased rapidly to about 90%. Which did you analyze carbohydrates and hormones in attached or detached fruit especially in 5 days after treatment? If you used attached fruit, you have to discuss it. Because physiological conditions significantly differ in attached or detached fruit.
Response 1: After girdling and defoliation treatment, the fruits are destined to abscise, but these fruits are different in the duration of abscission process, which renders the difficulty in distinguishing the fate of these fruits. However, in the late stage of treatment, all the fruits are about to abscise. Thus, these abscising fruits were used as our samples at late period of treatment.

Point 2：Line 109: You should refer to the reason why you select 32 days after anthesis for the treatment.
Response 2: Ok. In macadamia, most of the flowers have abscised in the first 2 weeks after anthesis due to the pollination and fertilization failure, and the abscission of immature fruit occurs mainly at 6-7, and 10 weeks post-anthesis. Thus, we selected the 32 days after anthesis for the treatment in case of avoiding the peak of natural fruit drop.

 

Point 3：Line 141: not ‘liguid’ but ‘liquid’
Response 3: Ok, we have revised this word.

Point 4：Line 148: You should refer to the reason why you select 15 genes. For example, ACS and ACO are well-known to be multi-gene family.
Response 4: Ok, we have added the reason for the selection of 15 genes, that is ‘To explore the crosstalk mechanism between sugar and hormone signaling during macadamia young fruit shedding induced by carbohydrate stress, 15 genes associated with the sugar and hormone metabolism and its signaling were subjected to qRT-PCR analysis . ’ 

 

Point 5：Line 224: You wrote that NI was significant during 4 to 5 days after treatment in the husk. Sucrose rapidly decreased next day after treatment. You have to discuss this discrepancy.

Response 5: Ok, the sentence ‘Consistent with the report in longan [12], the up-regulation of NI expression was significantly later than the decrease of sucrose content after the girdling and defoliation treatment, which might be a stress response of fruit to the rapid sucrose deficiency in order to increase the sink power of fruit’ was added in the discussion section.

Reviewer 4 Report

The author must follow the following comments:

Title:  delete (and) as follows:

Changes of Fruit Abscission and Carbohydrates, Hormones, Related Gene Expression in the Fruit and Pedicel of Macadamia Under Starvation Stress

Introduction:

• Line 49, reference needed
• Line 67, Hunag et al. [22].
• Line 69, delete [22].
• Line 69, Guo et al. [23].
• Line 79, delete 2000 and add [17]
• Line 125, Zeng et al. [20] delete 2016
• Line 192, check Figure No
• Line 264, photosynthesis
• Lines 266-268 spaces needed
• Line 275, Stopar et al. [14]
• Lines 276-277 spaces needed
• Lines 298-302,303,306 spaces needed
• Line 316, Zhu et al. [16]
• Line 318, delete 2013 O Hara et al. [7]
• Line 343, delete 2021 and add [19]
• Line 360, delete 2015 and add [46]
• Line 385, Abebie et al. 2008 missed in the ref.
• Line 387, delete 2006 and add [54]
• Line 393, delete 2015a
• Line 416 delete 2002
• Line 419 delete 2010
• Line 435 delete 2015a  Li et al. [26]
• Line 441, delete 2014
• Line 452 delete 2019

References:

• Check all the ref (the year and volume No) (bold and italic)

 

Best regards

 

Comments for author File: Comments.pdf

Author Response

Point 1:

Title:  delete (and) as follows:

Changes of Fruit Abscission and Carbohydrates, Hormones, Related Gene Expression in the Fruit and Pedicel of Macadamia Under Starvation Stress

Response 1: Ok.

 

Introduction:

Point 2: Line 49, reference needed

Response 2: Ok, we have added a reference to this sentence.

 

Point 3: Line 67, Hunag et al. [22].

Response 3: Ok.

 

Point 4: Line 69, delete [22].

Response 4: Ok.

 

Point 5: Line 69, Guo et al. [23].

Response 5: Ok.

 

Point 6: Line 79, delete 2000 and add [17]

Response 6: Ok.

 

Point 7: Line 125, Zeng et al. [20] delete 2016

Response 7: Ok.

 

Point 8: Line 192, check Figure No

Response 8: Ok, we have checked the Figure NO is Figure2H, I.

 

Point 9: Line 264, photosynthesis

Response 9: Ok.

 

Point 10: Lines 266-268 spaces needed

Response 10: Ok.

 

Point 11: Line 275, Stopar et al. [14]

Response 11: Ok.

 

Point 12: Lines 276-277 spaces needed

Response 12: Ok.

 

Point 13: Lines 298-302,303,306 spaces needed

Response 13: Ok.

 

Point 14: Line 316, Zhu et al. [16]

Response 14: Ok.

 

Point 15: Line 318, delete 2013 O Hara et al. [7]

Response 15: Ok.

 

Point 16: Line 343, delete 2021 and add [19]

Response 16: Ok.

 

Point 17: Line 360, delete 2015 and add [46]

Response 17: Ok.

 

Point 18: Line 385, Abebie et al. 2008 missed in the ref.

Response 18: Ok, Abebie et al. 2008 was added in the references.

 

Point 19: Line 387, delete 2006 and add [54]

Response 19: Ok.

 

Point 20: Line 393, delete 2015a

Response 20: Ok.

 

Point 21: Line 416 delete 2002

Response 21: Ok.

 

Point 22: Line 419 delete 2010

Response 22: Ok.

 

Point 23: Line 435 delete 2015a,  Li et al. [26]

Response 23: Ok.

 

Point 24: Line 441, delete 2014

Response 24: Ok.

 

Point 25: Line 452 delete 2019

Response 25: Ok.

 

Point 26: Check all the ref (the year and volume No) (bold and italic)

 Response 26: Ok, we have checked all the references and revise the formats of the year (bold) and the volume No (italic).

Reviewer 5 Report

I read with interest the study ‘Changes of fruit abscission and carbohydrates, hormones and related gene expression in the fruit and pedicel of Macadamia under starvation stress’. The manuscript is well written and the results are interesting from an applicative viewpoint as well as scientific soundness. I recommend the acceptance of the manuscript with minor revision.

• Keywords missing, please add
• Provide more information about when girdling was done
• In all figures since the statistical analysis is for each day separately and many comparisons are without a difference, please delete all letters and just add an asterisk, it will be easier for the reader to observe the statistical differences

Author Response

Point 1：Keywords missing, please add

Response 1: Ok, we have added the Keywords: Macadamia; fruit abscission; starvation stress; carbohydrate; hormone.

 

Point 2：Provide more information about when girdling was done

Response 2: Ok, girdling was done at day 32 after anthesis.

 

Point 3：In all figures since the statistical analysis is for each day separately and many comparisons are without a difference, please delete all letters and just add an asterisk, it will be easier for the reader to observe the statistical differences

Response 3: Ok, we have deleted all letters and added the asterisks.

Author Response File: Author Response.docx