Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript “Anthocyanin biosynthesis of white asparagus spears in relation to the preharvest exposure to infrared and sunlight radiation” is conducted well and have scientific worth. This study highlights the importance of sunlight exposure in promoting anthocyanin biosynthesis in white asparagus spears, particularly in the upper portions. The findings suggest that managing light exposure can enhance the nutritional quality and color of asparagus, providing valuable insights for agricultural practices aimed at improving crop quality.

Summary of this Manuscript:

The findings revealed that infrared radiation trapped beneath the tunnel during the initial 7-day growth period induced anthocyanin biosynthesis only in the lower part (base) of the spears. Notably, exposure to sunlight for at least 3 hours was essential for significant anthocyanin biosynthesis in the epidermal cells of the top 7 cm of the spears. The amount of anthocyanins measured 24 hours later was directly proportional to the duration of sunlight exposure, with higher levels found in spears that were harvested and kept in the dark compared to those that continued to grow in dark conditions.

• Key Findings:
• White asparagus spears were grown in the dark for 7 days before sunlight exposure.
• Sunlight exposure for at least 3 hours was critical for significant anthocyanin biosynthesis in the top 7 cm of the spears.
• Infrared radiation trapped under the tunnel induced anthocyanin production only in the lower part of the spears.
• The amount of anthocyanins increased proportionally with sunlight exposure time.
• Spears harvested and kept in the dark had greater anthocyanin levels than those that continued to grow in dark conditions.

 

Comments for Authors (Areas needs Improvements):

• In the abstract: the authors need to writ background/introduction lines and raise a scientific question or gap that need to be studied etc… than results and conclusion.
• Line 15-16: “Exposure to sunlight for at least 3 h was critical for significant anthocyanin biosynthesis in the epidermal cells of the top 7 cm part”. Write the concentration/levels of anthocyanins here. The results mentioned in the figures 4-7 should be added in the abstract.
• Why are there no statistics applied on the figures 4, 5, 6, and 7?
• For determination of anthocyanins and phenols what was control/blank was used?
• Line 132: the temperature degree symbol is wrong
• If authors applied LSD they must mentioned the statistically separation of different treatments with letters such as a, b, c, etc…

Author Response

Comment 1:

In the abstract: the authors need to writ background/introduction lines and raise a scientific question or gap that need to be studied etc… than results and conclusion.

Response 1:

The following was added (L 8-14): ‘Although the presence of anthocyanins in white asparagus is undesirable because it degrades its commercial quality, very little is known about their biosynthesis and regulation. The biosynthesis of anthocyanins in most plants is light dependent, but in white asparagus spears only a few studies have evaluated the effects of light and all of them focus mainly on the post-harvest period. There are no relevant reports on the effects of exposure of spears to solar and infrared radiation during their growth and development. For this purpose’

 

Comment 2:

Line 15-16: “Exposure to sunlight for at least 3 h was critical for significant anthocyanin biosynthesis in the epidermal cells of the top 7 cm part”. Write the concentration/levels of anthocyanins here. The results mentioned in the figures 4-7 should be added in the abstract.

Response 2:

Τhe concentration/levels of anthocyanins were written (L 23-26).

 

Comment 3:

Why are there no statistics applied on the figures 4, 5, 6, and 7?

Response 3:

There are statistics on the figures (the vertical bars in the graphs represent the 5% LSD value) and in addition, the letters have now been added.

 

Comment 4:

For determination of anthocyanins and phenols what was control/blank was used?

Response 4:

The corresponding extractant was used, i.e.: acidified ethanol (85:15 v/v EtOH:0.1N HCl) and 95% ethanol, respectively.

 

Comment 5:

Line 132: the temperature degree symbol is wrong

Response 5:

It was corrected (L 139).

 

Comment 6:

If authors applied LSD they must mentioned the statistically separation of different treatments with letters such as a, b, c, etc…

Response 6:

The letters have now been added.

Reviewer 2 Report

Comments and Suggestions for Authors

1. The authors claim that the radiation close to the soil is infrared radiation. Is it  possible to confirm it by instrument? the anthocyanin content induced by such radiation at the bottom is similar to content in the top part by the 7 h-sunlight exposure. How to explain this result?
2. how to explain the accumulation of anthocyanins after 0 h-sunlight exposure then dark storage of the harvested or continuine growth in darkness.
3. Based on the present study, can the authors suggest a handling method to avoid anthocyanin accumulation or coloring?
4. minor: the x-axil title in figure 4 and 7 may be "time after sunlight exposure in darkness"

Author Response

Comment 1:

The authors claim that the radiation close to the soil is infrared radiation. Is it  possible to confirm it by instrument? the anthocyanin content induced by such radiation at the bottom is similar to content in the top part by the 7 h-sunlight exposure. How to explain this result?

Response 1:

This radiation (Figure 1) is known to be infrared (López-Martínez et al., 2021) and this has been confirmed by other authors (Jishi et al., 2008). In our Lab we do not have any other equipment to measure this radiation other than the Lufft Opus II (Lufft Mess-und Regeltechnik GMBH, Stuttgart, Germany) with an external solar radiation sensor (pyranometer) and therefore it is not possible to confirm it further. Indeed, the anthocyanin content induced by such radiation in the lower part of the spears (0.82±0.04 μg g⁻¹ FW) is quite similar to the content in the upper part after exposure to sunlight for 7 h (0.95±0.09 μg g⁻¹ FW). We assume that due to the low intensity of infrared radiation (total 61 W m^-2) a longer exposure period (7 days) is required, in contrast to sunlight, the exposure to which is required to be much shorter (7 h), due to the very high intensity (total 3,807 W m^-2). These results suggest that both types of radiation (infrared and solar) induce anthocyanin biosynthesis in white asparagus spears.

 

Comment 2:

how to explain the accumulation of anthocyanins after 0 h-sunlight exposure then dark storage of the harvested or continuine growth in darkness.

Response 2:

The accumulation of anthocyanins after exposure to sunlight for 0 h and subsequent storage of the harvest in the dark or continuous growth in the dark is negligible and without any impact on the quality of the spears. Apparently, this insignificant amount is a result of the fact that it is practically impossible to ensure absolute darkness throughout the manipulations during the application of the treatments.

 

Comment 3:

Based on the present study, can the authors suggest a handling method to avoid anthocyanin accumulation or coloring?

Response 3:

The comment is very important and is what is required in practice. To avoid the accumulation of anthocyanins that will result in the appearance of undesirable coloration in the spears, it is recommended to minimize the exposure of white asparagus spears both pre-harvest and during post-harvest handling, and in any case, this exposure should not exceed 3 h.

 

Comment 4:

minor: the x-axil title in figure 4 and 7 may be "time after sunlight exposure in darkness"

Response 4:

It was corrected.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript shows a well designed and conducted study. However, it is necessary to fit the title and the conclusions to the materials, methods and results shown. Even though radiation was measured, no data are shown about anthocyanin concentration related to infrared radiation.
Some additional comments are included in the pdf file.

Comments for author File: Comments.pdf

Author Response

Comment 1:

The manuscript shows a well designed and conducted study. However, it is necessary to fit the title and the conclusions to the materials, methods and results shown.

Response 1:

We particularly appreciate the positive comments but do not agree with the reviewer's suggestion, as we believe that the title and conclusions are fully consistent with the materials, methods, and results presented, based on the responses to the reviewer's comments, as well as the clarifications in the comments of the other reviewers.

 

Comment 2:

Some additional comments are included in the pdf file.

Even though radiation was measured, no data are shown about anthocyanin concentration related to infrared radiation.

Response 2:

Data on the concentration of anthocyanins related to the exposure to infrared radiation are shown (L 161-163), which escaped the reviewer's attention.

 

Comment 3:

Values of solar radiation (L174-175) are not coincident  with those shown on Figure 3.

Response 3:

Values of solar radiation coincide with those shown on Figure 3, since the mentioned values of solar radiation (L 174-175) are the sum of the solar radiation intensity for the corresponding periods of 1, 3, 4, 5 and 7 h.

 

Comment 4:

There are not data supporting this statement (L 269-271) and this conclusion (L 330-332) is not supported by data shown in the results section

Response 4:

In L 161-163 there are data supporting the statement of L 269-271 as well as the conclusion in L 330-332. Data on the concentration of anthocyanins related to the exposure to infrared radiation are shown (L 162-163), which escaped the reviewer's attention.