Resin Canal Traits Variation in Pinus spp. with Different Susceptibility to the Pine Wood Nematode

Round 1

Reviewer 1 Report

Resin is synthetized and stored in cellular structures called resin canals，which constitute the primary defense mechanism of pine. However, the resin canal plays an important role in the migration of pine wood nematode through resin canal, but the relationship between anatomical traits of their constitutive resin canals, nematode infection and host resistance is unclear. In this paper, the changes of resin channels in 7 pine species inoculated with pine wood nematode were analyzed, and the relationship between resin channel characteristics and host resistance was partially explained. The following problems exist in the paper.

1. When inoculation experiment was conducted under greenhouse conditions, the size of pine trees.

2. Picture of changes of resin tract before and after infection of pine wood nematode. Resin canal is a hole surrounded by a layer of elastic lipid cells with strong ability to secrete resin. After the infection of pine wood nematode, whether the change of lipid cells leads to the change of resin canal.

3. The role of cortical resin and xylem resin tract in the infection and migration of pine wood nematodes, and which cortical resin tract or xylem resin tract can better reflect the relationship with nematode invasion.

4. The susceptible and high-susceptible pine species do not have significant changes in common resin channels. But，anatomical traits of constitutive resin canals were significantly different among different pines.

5. Traumatic resin canals induced by non-pine wood nematode are different from normal resin canals. After inoculation with water or pine wood nematode, there was no significant difference in the changes of resin channels in some pine trees, so it is necessary to further analyze the changes in different sampling sites and sampling time.

6. The corresponding relationship between resin channel characteristics and host resistance to pine wood nematodes should be further analyzed.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This study evaluated differences in resin canal traits among seven Pinus species with different susceptibility to the PWN, including the low-susceptible group's P. canariensis, P. halepensis, P. pinea, and P. taeda, and the high-susceptible group's P. pinaster, P. radiata, and P. sylvestris. They found that some anatomical and growth traits were related to PWN susceptibility. The high-susceptible group showed wider constitutive canals in the cortex. The inoculation of the PWN increased the frequency and diminished the size of canals in the xylem, and the high-susceptible group showed more frequency of induced xylem canals than the low-susceptible group. Besides, the high-susceptible group showed larger radial growths in the xylem than the low-susceptible group. These results suggest a role of resin canal traits on Pinus spp. susceptibility to the PWN. Nevertheless, the high interspecific variability found in these traits within each susceptibility group evidences the importance of other factors in the susceptibility to the PWN.

This study just evaluated differences in resin canal traits among seven Pinus species during their seedling stage; how about the tree stage? Whether they follow the same pattern? In the natural environment, the pine wilt disease infected pine trees most at the tree stage rather than one-year-old seedlings. Therefore, to clarify the relationship between the constitutive axial resin canals and PWN infection, the pine tree trunk's resin canal traits should also be evaluated.

1.     Line 22, "In turn" is the inappropriate phrase here; please change it.

2.     Line 96, please check the format of "℃". 

3.     Line 102, "… was previously published by [8], …" should be "… was previously published by Menéndez-Gutiérrez et al. [8],…"? 

4.     Line 107, please cite a reference that details the Baermann funnel technique. 

5.     Line 138, "ii)" should be "(ii)"? 

Results section

6.     In Section 3.1, the result description is too simple to difficult to understand. The differences in tree species between the two sensitive groups in each indicator are not explained in detail based on the statistical results of Table 1.

7.     The data in Table 1 is difficult to follow, suggesting part of the data can be shown graphically to make it more intuitive.  

8.     In Table 1, what is the meaning of the lowercase behand the value of LSMeans analyses? Please note that behind the table.  

9.     You can add the figures of the transverse section of each species as the supplement file to support your results in Table 1. 

10. In Table 2, "023" should be "0.23".

Discussion section

11. Line 303-317, there are many "this" in this paragraph, resulting in confusion; please rewrite this paragraph.

12. Line 314 and 315, please check the sites of references [36] and [38]; they should be cited at the end of the sentence.

13. Line 320-321, please add the reference.

14. Line 322, "organ" should be "tissues"?

15. In line 342, the period is missing at the end of the sentence.

16. Please check the format of the references carefully; some are absent in the number of pages.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The research done has some novelty, but it is difficult to explain the specific reasons for susceptibility due to insufficient data. Further testing is needed. In addition, existing experiments need to be supplemented with relevant images and data

1 Supplement photos of pine wilt disease symptoms change at different time points after inoculation of different susceptible pine trees;

2 Supplement photos of the transverse section before and after the inoculation of PWN of different susceptible pine trees;

3 Supplementary data on the number of isolated nematodes after supplementary vaccination. The susceptibility of pine trees to PWN is related not only to the strength of symptoms but also to the Population reproduction quantity of nematodes;

4. Confused causal relationships. The full text must further clarify various causal relationships. Such as, Is xylem canal size a cause or a result of susceptibility?

5 This article only describes the phenomenon, and further design experiments are needed to prove the cause of susceptibility;

6 Although there are many reasons for susceptibility, at least a quantitative explanation should be given of the specific role of the xylem canal size;

7 The correlation between nematode body width and xylem canal size needs to be calculated;

8 Figure 2. Should display multi - points in time data.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

The manuscript entitled “Variation of resin canal traits between pine species of different susceptibility to the pinewood nematode” presents scientific information on the role of resin canal traits on Pinus spp. susceptibility to the pinewood nematode, Bursaphelenchus xylophilus. This manuscript is well written with clear and concise results and present new information about pine constitutive and anatomical features related with pine resistance/susceptibility to PWN infection. Thus, this manuscript is in the scope of Forests journal and my opinions are indicated in the pdf file attached.

 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf