Ideotype Selection of Perennial Flax (Linum spp.) for Herbaceous Plant Habit Traits

Round 1

Reviewer 1 Report

In a generally well-written paper, the authors present the data they collected while growing accessions of different wild flax species plus cultivated flax in a common garden in 2019 in southern Minnesota. The authors sought to compare traits of interest in cut flower, oilseed and herbaceous perennial breeding populations and the wild species, to quantify effects of past selections and identify top candidate species to move forward. The covid-19 pandemic made it impossible for them to collect a second year of data as planned. It is of some concern that the data are from only one year. I would caution the authors about some of their conclusions; it is possible that a second year would have given different results.

First, it is not our experience that Linum usitatissimum is susceptible to transplant shock unless there is very hot weather after transplanting and before the seedlings are established. We grow many L. usitatissimum (and some wild species) populations by transplanting and typically see around 90% survival. I think the most the authors can say is that their L. usitatissimum did not survival well that year possibly due to methods or environmental factors (soil composition?).

Regarding L. lewisii, I was surprised that the authors found this species to be in the shorter flowering time grouping. We observe it flowering from late June/early July well into the fall even until frost or freeze and that it is very winter hardy – although one could expect there to be a weather component (snow cover, temperature and their combinations; latitude?). We do observe that hot weather can interrupt flowering until cooler temperatures return. Results suggest that such that drawing conclusions based on one year of data could be risky. 

I did enjoy reading this paper and appreciated the detail the authors provided about their materials and methods.

My comments are simply organized by order of appearance in the paper. I offer some suggestions about awkward wording/sentences and some comments about graph presentations and conclusions.

Line 24: add "of" after "and release "

Line 32: "out-of-season" seems an odd way to refer to the pollinator services provided by a long flowering flax. I could not locate reference 3 to perhaps understand how this could be better worded.

Line 37: I suggest replacing "this" with FGI because as written, "this" could be referring to the objectives and goals of the submitted paper.

In the introduction, the authors define the two flower morphs pin and strum but then do not consistently refer to the morphs by pin and/or strum, for example, lines 248 and 249.

Regarding Table 1: Is it possible to obtain more specific collection site information for the Canadian accessions and the GRIN accessions which have only CA, US or IA collection site information? Additionally, the table formatting is awkward in several places but perhaps that will be taken care of if published: for example, the Maple Grove name and its Ames number being on separate lines makes it seem like there should be two accessions there.

Lines 121-122: Why didn't the "Selections - OS" traits include oil related characteristics such as concentration and fatty acid profile?

Line 187: What is O. C."? If "off center", just say "off center". The term is not used again in the paper and two words don't take up much more space than the abbreviation.

Line 195: Do you mean "ramet" instead of "ramat"?

Regarding flower color, where on the flower petal is color measured? Color can vary from top of the petal to the center of the flower and color is also (very) dependent on the time of day the measurement is made. 

Line 270: "cut flower" should be "CF"

Line 272: How does measuring underdeveloped seeds measure seed loss? Do fewer underdeveloped seeds signify more shatter? Less shatter?

Line 318: "was significantly the widest" This is a very awkward sentence; needs to be re-worded.

Lines 324-325: Do you mean “the smallest diameter flowers (8-15 mm) occurred in L. usitatissimum and in wild accessions such as L. bienne”? As written, the sentence can mean that L. usitatissimum is a wild accession.

I like Figures 2 and 3 although it is impossible to read the text without a magnifying glass (in a printed copy).

Table 3: I do not understand what the numbers in the overlap columns signify. Number of accessions? However, Table 1 (for example) lists 18 L. austriacum accessions and the sum of the numbers in the overlap columns is 73 for that species.

The *comment at the bottom of Table 5 is cut off. What I can see ends with “…were p” Actually maybe the entire right side of the table is cut off.

The first sentence of the first paragraph in section 1.2 is very awkward. I would recommend rewriting it.

Is the " ~ " in line 529 intentional? If it is, I do not understand the meaning of the sentence.

Lines 540-543 need to be re-written. Four species are mentioned, yet the reference at the end of line 542 is to “this” species.  Which species?

In reference to Figure 6B # underdeveloped seeds, 0.5 of physical item like a seed is a calculation artifact. Seeds come in whole numbers. Please have your presentation reflect this fact.

Line 556: I would suggest substituting “except for” in place of “besides”.

Line 604: The conclusion that the plant volume for L. grandiflorum was less than expected and caused by a poor adaptation to the local environment would be bolstered by having information about what the flower volume is in the species’ native habitat. Maybe the plant volume you saw is what the species typically produces.

Lines 656-657: I do not understand the comparison between OS selections and L. hirsutum; looking at Figure 8D, it seems L. perenne is closer in value to the OS selections than is L. hirsutum.

I was surprised that L. usitatissimum was measured to be in the shortest stem group. Would you expect this, or could this result be due to poor growth as evidenced by the poor survival of the L. usitatissimum transplants?

Lines 816-817: Maybe replace "breeding goals" with "breeding priorities". The change would eliminate using "goal" twice in the same sentence.

Line 840: Eliminate the first “tested”.

Line 845-846: I would suggest re-wording to something like “We anticipate examining this diversity with molecular analyses….”

Line 869: “pollinator friendly” is a very awkward way to express the concept of providing pollinator services; I suggest re-writing this sentence.

Author Response

see attached file with responses.

Reviewer 2 Report

Dear Authors,

I would like to appreciate the team for the voluminous work put forth in bringing out this manuscript. I find the experiments designed and data collected are meticulously planned and executed.

I hope that in the continuation of this work you will include molecular as well as physiological markers to assess the traits of your interest.

Author Response

see responses in attached file

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript make a multi-trait evaluation of herbaceous perennial flax in oilseed and cut flower breeding populations to develop ideotypes and test their effectiveness. Which is a classical exemple about how to promote the use of annual flax and its wild relatives genetic resouces, and selection for target/non-target traits in wild species.
The long manuscript have a obvious issue is the lack of genetic validation, but reads very well.

Author Response

see responses in attached file

Author Response File: Author Response.pdf

Reviewer 4 Report

This study exemplified an perennial flax breeding program which promote the use of blue-flowered flax as ornamentals. They demonstrated simultaneous selection for multiple traits can be achieved  in early generations. Their results provide solid foundations to make perennial flax as an herbaceous / garden ornamental plants.

Author Response

See responses attached.

Author Response File: Author Response.pdf