Crab Apple (Malus spp.) Seed Tocopherol Profile: Impact of Genotype, Species, Purpose and Rootstock

Round 1

Reviewer 1 Report

In the article, the seeds of 30 crab apple genotypes (edible and ornamental) were assessed for the contents of tocopherols (α, β, γ and δ). Principal Component Analysis (PCA) revealed that analysed apple genotypes could be divided into six groups differing in the representation of individual homologues of tocopherols and cultivar type (ornamental and edible). Positive correlations were found between α-tocopherol vs. β-tocopherol and γ-tocopherol vs. δ-tocopherol, while negative correlations between α-T vs. δ-T, α-T vs. γ-T, γ-T vs. β-T, 249 and β-T vs. δ-T. Purpose of the crab apples (ornamental and edible) were partly associated with tocopherol profile. These relationships can be explained by the underlying pathways of compound biosynthesis.

To the article, I have next comments and recommendations:

·         In the explanatory notes of Table 1 delete: “Different letters in the same column indicate statistically significant difference at p < 0.05. T, tocopherol; dw, dry weight basis; (±), standard deviations (n = 3).” This explanation note belongs to Table 2, where it is already listed.

·         I recommend possible insertion of two publications into the cited literature and then after their inclusion renumbering the following citations:

…disease resistant trees. By-products of apple-trees and apples can become an important source for obtaining some constituents with healthy properties, like phloridzin and flavonoids. Their levels are affected by many factors, such as genotypes, localities of cultivation, times of harvesting or treatments [3].

3. Táborský, J.; Sus, J.; Lachman, J.; Šebková, B.; Adamcová, A.; Šatínský, D., Dynamics of phloridzin and related compounds in four cultivars of apple trees during the vegetation period. Molecules, 2021, 26, (13), 3816.

…and other prenyllipids [7]. Also, tocochromanols (tocols) are affected by many factors (genotypes, time of harvest, climatic conditions, way of cultivation) as was demonstrated in colored-grain wheat, tritordeum and barley [7].

7. Lachman, J.; Hejtmánková, A.; Orsák, M.; Popov, M.; Martinek, P., Tocotrienols and tocopherols in colored-grain wheat, tritordeum and barley. Food Chem. 2018, 240, 725-735.

·         In the reference 11 should be corrected:…of tocopherol (α, β,γ and δ).

Author Response

In the article, the seeds of 30 crab apple genotypes (edible and ornamental) were assessed for the contents of tocopherols (α, β, γ and δ). Principal Component Analysis (PCA) revealed that analysed apple genotypes could be divided into six groups differing in the representation of individual homologues of tocopherols and cultivar type (ornamental and edible). Positive correlations were found between α-tocopherol vs. β-tocopherol and γ-tocopherol vs. δ-tocopherol, while negative correlations between α-T vs. δ-T, α-T vs. γ-T, γ-T vs. β-T, 249 and β-T vs. δ-T. Purpose of the crab apples (ornamental and edible) were partly associated with tocopherol profile. These relationships can be explained by the underlying pathways of compound biosynthesis.

To the article, I have next comments and recommendations:

• In the explanatory notes of Table 1 delete: “Different letters in the same column indicate statistically significant difference at p < 0.05. T, tocopherol; dw, dry weight basis; (±), standard deviations (n = 3).” This explanation note belongs to Table 2, where it is already listed.

Thank you for the notification. The notes have been removed.

• I recommend possible insertion of two publications into the cited literature and then after their inclusion renumbering the following citations:

…disease resistant trees. By-products of apple-trees and apples can become an important source for obtaining some constituents with healthy properties, like phloridzin and flavonoids. Their levels are affected by many factors, such as genotypes, localities of cultivation, times of harvesting or treatments [3].

3. Táborský, J.; Sus, J.; Lachman, J.; Šebková, B.; Adamcová, A.; Šatínský, D., Dynamics of phloridzin and related compounds in four cultivars of apple trees during the vegetation period. Molecules, 2021, 26, (13), 3816.

…and other prenyllipids [7]. Also, tocochromanols (tocols) are affected by many factors (genotypes, time of harvest, climatic conditions, way of cultivation) as was demonstrated in colored-grain wheat, tritordeum and barley [7].

7. Lachman, J.; Hejtmánková, A.; Orsák, M.; Popov, M.; Martinek, P., Tocotrienols and tocopherols in colored-grain wheat, tritordeum and barley. Food Chem. 2018, 240, 725-735.

Thank you for the suggestion. The references have been added and discussed.

 

• In the reference 11 should be corrected:…of tocopherol (α, β,γ and δ).

Thank you for the notification. The correction has been done.

The references list and numbering them have been updated by the software, therefore the "track changes" are not visible.

Reviewer 2 Report

Abstract

The abstract should be started with a general introduction sentence. For example, a sentence can be given about apples.

Too many symbols are used in the abstract section, making it difficult to understand the study.

Introduction

In the introduction, “Edible crab apples are mainly processed for preserves, juices and cider,  while ornamental apples may have fruits too small, too astringent and not as juicy. Mallus domestica Borkh. The sentence includes dessert and cider apples, while crab apples belong to several species and often are interspecific crosses”. Please add citation.

The introductionsections of the articles are among the richest sections in the literature. In the current study, only 11 literature was used in this section and the number should be increased.

Material and Method

Please write the plant material section in the first line.

Soil analysis values ​​are missing,

Climatic data is missing

These values ​​are important in the study.

Conclusion

More literature on the effect of rootstock should be added.

Author Response

Abstract

The abstract should be started with a general introduction sentence. For example, a sentence can be given about apples.

Too many symbols are used in the abstract section, making it difficult to understand the study.

Thank you for the comment. The abstract has been improved. Presently, excluding the Greek letters, only one abbreviation is used (tocopherol “T”).

Introduction

In the introduction, “Edible crab apples are mainly processed for preserves, juices and cider,  while ornamental apples may have fruits too small, too astringent and not as juicy. Mallus domestica Borkh. The sentence includes dessert and cider apples, while crab apples belong to several species and often are interspecific crosses”. Please add citation.

Thank you for the notification. The citation has been added.

The introduction sections of the articles are among the richest sections in the literature. In the current study, only 11 literature was used in this section and the number should be increased.

Thank you for the comment. The introduction part has been supplemented by additional sentences and literature positions. Presently the literature number in the introduction part is 22.

Material and Method

Please write the plant material section in the first line.

Thank you for the notification. The correction has been done.

Soil analysis values are missing,

Climatic data is missing

These values are important in the study.

Thank you for the notification. The missing information has been added.

Conclusion

More literature on the effect of rootstock should be added.

Thank you for the comment. The conclusion part is not the best place for discussion and references. However, we feel that some information about the impact of rootstock on phytochemicals in apples should be added and we did this in the introduction part.

Round 2

Reviewer 2 Report

Dear editor and author. I re-evaluated the article. The article is suitable for publication.