Amino Acid Transporters on Amino Acid Absorption, Transport and Distribution in Crops
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript reviews amino acid transporters in plants and could be of interest to Horticulturae readers. It is well-organized and written, but it does not focus on vegetables. The authors mentioned that little research has been done on these types of crops but they neither discussed about the importance thant they could have in tubers, flowers, leaves, fruits, etc. The word “review” should be removed from the title and since the manuscript does not cover them, the word vegetables as well. Most of the reported findings are in Arabidopsis (a plant model, but not a vegetable) and model crops such as rice, soybean, and pea.
Figure 1 is not self-explanatory; each gene in it must be described in detail. Figure 2 is also irrelevant as presented. The main text needs to include a paragraph explaining this figure.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript summarized the recent studies on plant amino acid transporters, their classification, expression in different tissues, physiological function and impact on plant yield and quality. Overall the manuscript is well written and the references are appropriate.
There are a few minor issues that the authors need to address.
1. Line 42-48, the authors first introduced that AtAAP1, AtAAP2 expression is higher in flowers. But the authors later mentioned that AtAAP1 is located in root and AtAAP2 in the phloem. Please clarify this part.
2. Figure 1 presents a nice overview of the amino acid transporters in plants and their location. However, the introduction session did not cover all the contents shown in Figure 1. The reviewer recommends reorganizing the introduction section based on Figure 1.
3. Some of the acronyms in the text are not explained well so some readers may not know what they stand for. For example, Line 70-71, Cs; Line 124, GUS; Line 125, PUT; Line 173, UMAMIT.
Comments on the Quality of English LanguageThe reviewer notices sporadic grammatical errors in the manuscript.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThey review the published works on some amino acid transporters in plants considering that these transporters are key elements for plant growth and development. They analyze the expression of these transporters under different conditions or availability of C and N and their response to different environmental conditions.
They study the different types of amino acid transporters, the affinity for their specific substrates, their cellular location and their location in different tissues and organs. This allows a broader view of the different functions of transporters.
They point out that mutants in transporters generate different phenotypes related to the affinity of the substrate and the absorption of different amino acids.
They report the function of transporters in the distribution of amino acids from the root to the leaves and from the leaves to the root, emphasizing the distribution of nitrogen compounds between the phloem and the xylem and its relationship with yield or production. In particular, they refer to the phenotype of the rice mutant OsLHT1 which is a transporter that is located in the root and its mutation reduces the absorption and distribution of N resulting in a decrease in yield.
Regarding the role of amino acids in N and C metabolism, I consider that they write a very limited version given the deep knowledge that exist of the interaction and regulation between the two most important metabolic processes in biology.
It should be noted that they do not mention at any time sensor elements of the nutritional condition such as the TOR complex. TOR is expressed under abundant N conditions and is associated with plant growth by promoting an increase in the plant's anabolic processes. The role of this element would explain why a higher concentration of amino acids is related to a higher yield and quality of crops.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsI consider that the work has been substantially improved by introducing more information on the amino acid transporters already studied. The new information related to the distribution of amino acids from different source tissues to sink tissues, the integration that describes nitrogen assimilation with amino acid synthesis and its distribution, and finally the integration of the function of amino acid transporters with the regulation of TOR, give greater academic value to this review. For these reasons, I consider that in its new version, the work should be published.
