Variation and Genetic Parameters of Leaf Morphological Traits of Eight Families from Populus simonii × P. nigra
Round 1
Reviewer 1 Report
General remarks:
The introduction should mention why male clones of one tree species and female clones of others were chosen. With a constant emphasis on male and female differences in the text, the comparison of species, which is essential, is remembered only occasionally.
Remarks:
37 line
"compatibility" should not be included in the keywords, as the paper does not deal with the results of crossings between species, such as seed yield, percentage of empty seeds, etc.
169-172 line
It should be justified, why two statistical models were used to calculate the variance components. Some reference would be useful.
180 line
Check formula description “σ2f was the full-sib family variance”
222 line
It is stated “The approximate standard errors for the genetic parameters are given in parentheses” which is not the case.
248 line
Fisher’s Least Significant Difference test should be mentioned in M&M.
277 line.
What is marked in bold in Table 5 must be indicated. The same for Table 6.
Author Response
General remarks: Q1: The introduction should mention why male clones of one tree species and female clones of others were chosen. With a constant emphasis on male and female differences in the text, the comparison of species, which is essential, is remembered only occasionally. RE: In the introduction, I added these information of two prantal species as these as follow: P. nigra (section Aigeiros) is extremely well suited to biomass production because of its rapid juvenile growth, high photosynthetic capacity. It also has strong plasticity, which make it grow well easily in different environments. P. simonii (section Tacamahaca) has cold and drought resistant but limited growth under acidic soil conditions. These two sections comprise most of the species of economic importance. Species of these sections are sexually compatible and natural interspecific hybridization occurs. Because of the huge interspecific differences, we can probably gain greater genetic diversity, heterosis and specific adaptation to specific conditions. While intraspecific hybridization obtained relatively simple and small genetic gain for the purpose breeding. In addition, the genotypes behave variable in different environments as the consequence of the poplar plantation widely planted with the soil and climate conditions complexity and changeable. Therefore, it is expected to obtain the hybrid genotypes with rapid growth, high resistance and strong adaptability by using the hybridization of the two, so as to provide clone materials for the extensive plantation of the plantation. Remarks: ① 37 line "compatibility" should not be included in the keywords, as the paper does not deal with the results of crossings between species, such as seed yield, percentage of empty seeds, etc. RE: ‘compatibility’ was deleted and replaced with ‘crossing combination’ in the keywords. ② 169-172 line It should be justified, why two statistical models were used to calculate the variance components. Some reference would be useful. RE: There were two different models for the parental clones and the progenies with variance components at different level. Because the parent has only one ‘Clone’ factor as a random term, therefore following a random model. While there are many variation levels of hybrid progeny, including fixed term and random term, which following a mixed linear model. Therefore, the variance components need to be calculated separately. ③ 180 line Check formula description “σ2f was the full-sib family variance” RE: In the fomula description, “σ2f was the full-sib family variance” was a mistake and has been deleted. ④ 222 line It is stated “The approximate standard errors for the genetic parameters are given in parentheses” which is not the case. RE: It was mistake and has been revised in the article as follows: “The approximate standard errors (SE) for the genetic parameters are indicated for each clone/genotype.” ⑤ 248 line Fisher’s Least Significant Difference test should be mentioned in M&M. RE: It has been added in MM “Considering that leaf shapes of these plants exhibited a large difference, Fisher’s LSD (Least Significant Difference) test was used to carry out multiple comparisons of 5 leaf morphology traits among the parental clones and the 8 families.” ⑥ 277 line. What is marked in bold in Table 5 must be indicated. The same for Table 6. RE: It has been revised and added the information as that as follows: “Note: The values in bold indicate the maximum GCA or SCA in the corresponding traits.” And “b) The items in bold represent the genotypes existed in five leaf traits simultaneously.”
Reviewer 2 Report
The manuscript provides interesting information and data on leaf morphology in Populus.
I have the following comments for the improvement of this manuscript.
Please revise the title to reflect the results of your study.
In the Abstract, please state the objective of your research, the reasons that you undertook this study and the innovations. I am not clear on the innovative ideas in your paper.
In the Introduction, please create more paragraphs to make it less tiring to the reader.
Material and Methods are well organized.
Line 146. One plot per block with spacing at 30 cm x 50 cm….
I assume that the spacing of 30 cm x 50 cm in populus includes competition which may bias your genotypic and phenotypic correlations as well as heritability estimates. Please elaborate.
It will be constructive if the authors read and reference the review article below.
Competitive ability and plant breeding. 1997. Plant Breeding Reviews. Vol 14, pages 89-138. John Wiley & Sons.
Please separate Discussion and Conclusions and add a separate paragraph in the end in order to discuss the most important conclusions of your study and the significance of your results to the other researchers.
Author Response
Q1: Please revise the title to reflect the results of your study. RE: The title has been revised “Variation and Genetic Parameter of Leaf Morphology in Eight Populus simonii × P. nigra Families”. Q2: In the Abstract, please state the objective of your research, the reasons that you undertook this study and the innovations. I am not clear on the innovative ideas in your paper. RE: It has been revised and added the words: “P. nigra (section Aigeiros) with large and triangular leaves is a commercial forest tree of economic importance for fast growth and high yield in Europe. P. simonii (section Tacamahaca) with small land rhomboid ovate leaves performs cold and dry resistance/tolerance in semi-arid region of Northern China. Leaf morphological traits could be used as early indicator to improve the efficiency of selection. In order to investigate genetic variation pattern of on leaf morphology traits, estimate breeding values (combining ability), as well as evaluate crossing combinations of parents, 1872 intersectional progenies from 8 families (P. simonii × P. nigra) and their parents were planted with cuttings for the clonal replicate field trial in Northern China. As for the innovations, intensive research on physiological processes has contributed immensely to our understanding of the function of leaves. However, comparatively little is known about how leaf size and shape is determined. And the aim of my paper is to assay leaf shape variation among individuals of P. simonii and P. nigra, as well as eight families resulting from these two parents (multiple-level variations) to characterize the genetic architecture underlying variation. Q3: In the Introduction, please create more paragraphs to make it less tiring to the reader. RE: It has been revised and rearranged the paragraphs for less tiring to the reader. Q4: Material and Methods are well organized. Line 146. One plot per block with spacing at 30 cm x 50 cm…. I assume that the spacing of 30 cm x 50 cm in populus includes competition which may bias your genotypic and phenotypic correlations as well as heritability estimates. Please elaborate. It will be constructive if the authors read and reference the review article below. Competitive ability and plant breeding. 1997. Plant Breeding Reviews. Vol 14, pages 89-138. John Wiley & Sons. RE: P. nigra performs with fast growth, straight stem and few branches. P. simonii performs with slow growth, narrow shape and weak branches. The progenies of these species showed the characters of their parents, straight stem, narrow shape and weak branches. The spacing of 30 cm × 50 cm is enough for plant growing and arisen less competition for the one and half year old plants . And Tsarev et al (2018) also used the seedling and the distance between seedlings was about 20 × 10 cm with good performance. Tsarev A, Tsareva R, Tsarev V, et al. Aspen hybridization: Parents' compatibility and seedlings' growth[J]. Silvae Genetica, 2018, 67(1): 12-19. Q5: Please separate Discussion and Conclusions and add a separate paragraph in the end in order to discuss the most important conclusions of your study and the significance of your results to the other researchers. RE: It has been revised and Discussion and Conclusions were separated and the paragraph of Conclusion were added in the end.
