The First Record of a North American Poplar Leaf Rust Fungus, Melampsora medusae, in China
Junli Zhang
Round 1
Reviewer 1 Report
The major discovery of a North American poplar leaf rust fungus, Melampsora medusa in China from this manuscript is informative to the forestry of China. Some details are need to be added into the manuscript before the acceptance of this paper.
1. Page 3, Line 112-113, “Additional samples of M. medusae were collected in Shaanxi in 2017 and 2018, and from Henan in 2015 through 2018”. Data such as a table like Table 2 is needed to support this statement. Additionally, other than morphology identification, I think PCR confirmation using primers from Table 1 is also necessary to support this. It is important for supporting your conclusion of “this introduced pathogen is widespread and persistent from year to year in China.”
2. For the morphology of the fungus, more pictures should be provided.
1) Images for Line 124-125 “Uredinia of M. medusae were mainly hypophyllous; a few uredinia were epiphyllous with small or more scattered pustules. Uredinia were roundish, golden orange to orange.”
2) Image for line 130, “golden yellow cytoplasm”
3) Images for line 135-137, “Telia were mainly hypophyllous. Their initial color was pale amber brown but that eventually became deep reddish brown or almost black. Telia were raised slightly above the leaf surface, roughly circular to irregular in outline.”
4) For Figure 2 and Figure 3, in the legends, please indicate which strain you used for each image.
3. Please add references for the following two statements.
1) Line 221 “The aecial host of M. medusae in North America is Larix laricina”.
2) Line 222-223 “The most likely hosts in China would be species of Larix, Pseudotsuga and Cathaya. These three genera belong to subfamily Laricoideae of Pinaceae”
4. Typos: Line 53 “from early July until fall”, should change “until” to “to”.
Check the scientific nomenclature, if some need to be italicized, please make the change.
Author Response
Comments of Reviewer 1:
The major discovery of a North American poplar leaf rust fungus, Melampsora medusa in China from this manuscript is informative to the forestry of China. Some details are need to be added into the manuscript before the acceptance of this paper.
1. Page 3, Line 112-113, “Additional samples of M. medusae were collected in Shaanxi in 2017 and 2018, and from Henan in 2015 through 2018”. Data such as a table like Table 2 is needed to support this statement. Additionally, other than morphology identification, I think PCR confirmation using primers from Table 1 is also necessary to support this. It is important for supporting your conclusion of “this introduced pathogen is widespread and persistent from year to year in China.”
Response: given findings contained in Tables 2 and 3 we knew that M. medusae was the only rust on Populus in China with urediniospores with smooth equatorial areas. Thus, all additional identification of M. medusae became routine and morphology-based and is reported as ‘additional sampling’.
2. For the morphology of the fungus, more pictures should be provided.
1) Images for Line 124-125 “Uredinia of M. medusae were mainly hypophyllous; a few uredinia were epiphyllous with small or more scattered pustules. Uredinia were roundish, golden orange to orange.”
2) Image for line 130, “golden yellow cytoplasm”
3) Images for line 135-137, “Telia were mainly hypophyllous. Their initial color was pale amber brown but that eventually became deep reddish brown or almost black. Telia were raised slightly above the leaf surface, roughly circular to irregular in outline.”
4) For Figure 2 and Figure 3, in the legends, please indicate which strain you used for each image.
Response: Images are not needed as we are just confirming the existing description of M. medusae. In this context we have removed Figs. 2 and 4 as they are unnecessary. The caption for Fig. 3 has been revised so that we explain why we focused on two taxa that are the only two to affect sections Tacamahaca and Aigeiros of Populus: M. medusae and M. larici-populina.
3. Please add references for the following two statements.
1) Line 221 “The aecial host of M. medusae in North America is Larix laricina”.
2) Line 222-223 “The most likely hosts in China would be species of Larix, Pseudotsuga and Cathaya. These three genera belong to subfamily Laricoideae of Pinaceae”
Response: References have been added.
4. Typos: Line 53 “from early July until fall”, should change “until” to “to”.
Check the scientific nomenclature, if some need to be italicized, please make the change.
Response: These edits have been made.
We are grateful for your knidness and comments
Reviewer 2 Report
This paper reports species diversification of poplar leaf rust fungi in China. In this study, the authors found an introduced causal agent of poplar leaf rust disease, Melampsora medusae. This finding is important also in epidemiology. The reviewer thinks that this research was well organized and required results were obtained. That is, the information of this study is required to be opened to the public.
However, there are some weak points that should be corrected for acceptance in this journal. Weak points of this paper are 1) unclear description of the research purpose and 2) the composition of the Results section. According to the research purpose, the authors may correct the title of this paper. The reviewer’s questions are: Is the research purpose to identify the pathogen causing rust disease on P. deltoids?, or again, Is the research purpose to clarify the pathogens causing rust disease on Populus?, then, in course of this survey, the authors found M. medusa?
Concerning this matter of unclear purpose, the reviewer is wondering the reason why the authors examined the fifteen fully characterized samples and other ADDITIONAL samples? If the authors aimed to identify a rust fungus on P. deltoids, the latter additional samples might not need to be examined.
The reviewer would like to ask the authors to define the research purpose, and then, to logically rearrange the composition of this article, Results section in particular.
In addition to the above-mentioned points, please consider and then, correct the followings:
Line 19-20: ITS1, ITS2 and D1/D2, not make those digits subscript.
Line 53: “fall” is obscure to show the term in this case. The authors may indicate the Month instead.
Line 57-61: This sentences are not suitable to mention in Introduction section. Instead, the authors need to define the purpose of this study.
Line 63: Figure 1. Sampling sites...for rust fungi of… , or Figure 1. Sites…for rust sampling..
In addition, The authors may enlarge the map and indicate the names of landmarks on the map.
Line 80: Why did the authors conduct the germination test of urediniospores, and two species only?
Line 88: ITS1F and ITS4, not make those numbers subscript.
Line 96: ‘..balsted in GneBank.’, ‘..were blasted..’ , is it OK to use ‘blast’ as a verb?
Line 101: Correct 2.4 to 2.5.
Line 108: This paragraph in section 3.1 is like a conclusion of this study. This composition is strange in Results.
from Line 109 onward: Please make Scientific Names ITALIC.
Lines 142 & 153: In Figures 2 and 3, why did the authors compared M. medusae with M. larici-populina. How about the others?
Line 197: If the authors conducted this examination to confirm forma speciales of M. medusa, the authors should mention the reason and the function of primers used in Mate & Meth section.
Line 208: Please give suitable discussion for the results obtained under the research purpose(s) clearly defined, and then, describe the conclusions of this study.
Thank you for your consideration.
Author Response
This paper reports species diversification of poplar leaf rust fungi in China. In this study, the authors found an introduced causal agent of poplar leaf rust disease, Melampsora medusae. This finding is important also in epidemiology. The reviewer thinks that this research was well organized and required results were obtained. That is, the information of this study is required to be opened to the public.
However, there are some weak points that should be corrected for acceptance in this journal. Weak points of this paper are 1) unclear description of the research purpose and 2) the composition of the Results section. According to the research purpose, the authors may correct the title of this paper. The reviewer’s questions are: Is the research purpose to identify the pathogen causing rust disease on P. deltoids?, or again, Is the research purpose to clarify the pathogens causing rust disease on Populus?, then, in course of this survey, the authors found M. medusa?
Response: The following statement of purpose was added to the Abstract: “This study was prompted by the new susceptibility of a previously resistant cultivar: cv. ‘Zhonghua hongye’ of Populus deltoides (section Aigeiros) as well as by the need to know more about the broader context of poplar leaf rust in China.” The title does not need to be amended, since the discovery of M. medusae was the central finding.
Concerning this matter of unclear purpose, the reviewer is wondering the reason why the authors examined the fifteen fully characterized samples and other ADDITIONAL samples? If the authors aimed to identify a rust fungus on P. deltoids, the latter additional samples might not need to be examined.
Response: once we knew that M. medusae was in China and that it could be routinely identified on the basis of morphology alone, we then considered additional samples to flesh out the distribution and persistence of this introduced species.
The reviewer would like to ask the authors to define the research purpose, and then, to logically rearrange the composition of this article, Results section in particular.
Response: Purpose is now defined in Abstract as stated above.
In addition to the above-mentioned points, please consider and then, correct the followings:
Line 19-20: ITS1, ITS2 and D1/D2, not make those digits subscript.
Line 53: “fall” is obscure to show the term in this case. The authors may indicate the Month instead.
Line 57-61: This sentences are not suitable to mention in Introduction section. Instead, the authors need to define the purpose of this study.
Line 63: Figure 1. Sampling sites...for rust fungi of… , or Figure 1. Sites…for rust sampling..
In addition, The authors may enlarge the map and indicate the names of landmarks on the map.
Line 80: Why did the authors conduct the germination test of urediniospores, and two species only?
Response: These edits have been made, and all mention of germination of urediniospores has been deleted as non-essential.
Line 88: ITS1F and ITS4, not make those numbers subscript.
Line 96: ‘..balsted in GneBank.’, ‘..were blasted..’ , is it OK to use ‘blast’ as a verb?
Line 101: Correct 2.4 to 2.5.
Response: These edits have been made
Line 108: This paragraph in section 3.1 is like a conclusion of this study. This composition is strange in Results.
from Line 109 onward: Please make Scientific Names ITALIC.Lines 142 & 153: In Figures 2 and 3, why did the authors compared M. medusae with M. larici-populina. How about the others?
Line 197: If the authors conducted this examination to confirm forma speciales of M. medusa, the authors should mention the reason and the function of primers used in Mate & Meth section.
Response: The formae speciales of M. medusae are controversial and unnecessary given that our samples were from P. deltoides and other expected host species for f.sp. deltoidae. Still we confirmed the latter and included it here as a minor result. We revised the scientific names form.
Line 208: Please give suitable discussion for the results obtained under the research purpose(s) clearly defined, and then, describe the conclusions of this study.
Response: Now the conclusions are in line with the research purpose included in the Abstract.
We are thankful for your kindness and comments.Thank you very much.
Round 2
Reviewer 1 Report
Thank you for the patient reply. However, two questions need to be answered before the acceptance.
Your response: given findings contained in Tables 2 and 3 we knew that M. medusae was the only rust on Populus in China with urediniospores with smooth equatorial areas. Thus, all additional identification of M. medusae became routine and morphology-based and is reported as ‘additional sampling’.
My response: the problem that your current data cannot support the conclusion "“this introduced pathogen is widespread and persistent from year to year in China.” is yet to be solved, especially for "persistent from year to year". The current data can only support that "this introduced pathogen exists in China". Therefore, please provide more data to support it or modify your current data to support your conclusion.
Your response: Images are not needed as we are just confirming the existing description of M. medusae. In this context we have removed Figs. 2 and 4 as they are unnecessary. The caption for Fig. 3 has been revised so that we explain why we focused on two taxa that are the only two to affect sections Tacamahaca and Aigeiros of Populus: M. medusae and M. larici-populina.
My response: Since the description of M. medusae is "existing", please provide the reference. If not, it will be considered your data, and the original figures are necessary.
Thank you!
Author Response
Your response: given findings contained in Tables 2 and 3 we knew that M. medusae was the only rust on Populus in China with urediniospores with smooth equatorial areas. Thus, all additional identification of M. medusae became routine and morphology-based and is reported as ‘additional sampling’.
My response: the problem that your current data cannot support the conclusion "“this introduced pathogen is widespread and persistent from year to year in China.” is yet to be solved, especially for "persistent from year to year". The current data can only support that "this introduced pathogen exists in China". Therefore, please provide more data to support it or modify your current data to support your conclusion.
Response：We sample this rust fungi at same place from 2017-2018 in Shaanxi, and 2015-2018 in Henan, 2016-2017 in Sichuan consecutively. And we now mark the sample years in Tab.1 and Tab.2, you can find this fungi expand without stop at different years
Your response: Images are not needed as we are just confirming the existing description of M. medusae. In this context we have removed Figs. 2 and 4 as they are unnecessary. The caption for Fig. 3 has been revised so that we explain why we focused on two taxa that are the only two to affect sections Tacamahaca and Aigeiros of Populus: M. medusae and M. larici-populina.
My response: Since the description of M. medusae is "existing", please provide the reference. If not, it will be considered your data, and the original figures are necessary.
Response: M. medusae was firstly described by Thuem in 1885;Newcombe et al. (1994) first reported M. medusae in the Pacific Northwest for the first time; Gadgil (2005) from New Zealand; Spiers & Hopcroft from Australia(1994); Fresa (1936) from Argentina; Galović et al.(2010) from Australia and South Africa; Dupias (1943) from France; Hiratsuka (1939) from Japan; Hennebert (1964) from Spain; Pinon(1986) from Portugal.
Please refer to literatures 4,7,10,11-17 in MS, and line41-42.
Thank you very much for your kindness and comments.
Reviewer 2 Report
As far as I see, an available revised manuscript seems not to be corrected fully yet, for example, as follows:
1) Line 19-20: ITS1, ITS2 and D1/D2, not make those digits subscript.
2) Line 80: Why did the authors conduct the germination test of urediniospores, and two species only?
Response: ...and all mention of germination of urediniospores has been deleted as non-essential.
3) Line 88: ITS1F and ITS4, not make those numbers subscript.
4) Line 96: ‘..balsted in GneBank.’, ‘..were blasted..’ , is it OK to use ‘blast’ as a verb?
5) from Line 109 onward: Please make Scientific Names ITALIC.
and so on.
Author Response
As far as I see, an available revised manuscript seems not to be corrected fully yet, for example, as follows:
1) Line 19-20: ITS1, ITS2 and D1/D2, not make those digits subscript.
Response: These edits have been made. Due to the version of Microsoft, you may can't find the corrected subscript when the ms was downloaded.
2) Line 80: Why did the authors conduct the germination test of urediniospores, and two species only?
Response: ...and all mention of germination of urediniospores has been deleted as non-essential.
Response: M. medusae and M. larici-populina are the only two to affect sections Tacamahaca and Aigeiros of Populus, and occurred approximately in the field, their morphologies under light microscope are similar and often caused confused, therefore, in this study, we only compared this two taxa. Spires has already described their morphological difference and found their tube morphology was one of important difference [9], so we conducted urediopsore germination, and found the results were almost same as Spires (1994),please refer to reference 9 in MS. However, the nuclei in the tubes of M. medusae were different that of M. larici-populina , so we accepted your kind suggestion and reserved the previous Figure in this version .
3) Line 88: ITS1F and ITS4, not make those numbers subscript.
Response: We have corrected them.
4) Line 96: ‘..balsted in GneBank.’, ‘..were blasted..’ , is it OK to use ‘blast’ as a verb?
Response: We changed these words into "searched".
5) from Line 109 onward: Please make Scientific Names ITALIC.
and so on.
Response: We have corrected all scientific name into italic.
Thanks so much for your kindness and suggestion
