Aerenchyma Formation in Adventitious Roots of Tall Fescue and Cocksfoot under Waterlogged Conditions

Round 1

Reviewer 1 Report

Overall, I felt that the manuscript ‘Aerenchyma Formation in Adventitious Roots of Tall Fescue and Cocksfoot Under Waterlogged Conditions’ was a clearly articulated presentation of a robust experiment. The authors presented the different responses in the two forage grass species to waterlogging and how these differences may be related to the greater waterlogging tolerance of tall fescue. Although they showed that there were little differences between the responses of the two cultivars within each species, and suggested that an extended screening program would be required to understand more, I felt that the claim of species differences based on two cultivars of each, especially when one TF cultivar contained a fungal endophyte which are known to impact plant performance waterlogged conditions, was a little ambitious and I would have preferred the authors to be more forthright in acknowledging this limitation to the study. Apart from that I only have a few minor comments on the manuscript:

Line 80: were placed under glasshouse conditions and

Line 87-88: sub-plots and cultivars (2 cultivars

Line 89: conducted in 4 four main plot tanks considered as 4 four blocks. Each tank was divided into 2 two

Line 102: measured from soil the surface to a depth

Line 107: to destructive measurements by using a portable

Line 132: The slice option in statements lsmeans were was used to specify

Line 173: with TF showing a greater reduction

Line 175: beyond 14-days of waterlogging

Lines 176 to 178: Suggest deleting the sentence which states that SPAD readings were significantly lower in waterlogged CF plants compared to waterlogged TF plants because, in table 2, the figures show that at day-21 SPAD readings were significantly lower in waterlogged TF compared to waterlogged CF plants....

Line 186: After 14 days of waterlogging, root dry

Line 197: between two species, root RGR of CF was

Figure 5: please include day 0 in the charts

Line 212: a higher proportion in waterlogged TF plants

Line 243: both TF and CF plants, with being although greater

Line 254: species had the ability to maintain their

Author Response

Dear Reviewer 1, Thank you for your constructive critique of our paper. Your suggestions make it a stronger paper. Specific replies to your comments can be found attached. 

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Reviewer report

 

The authors present a compelling work covering the characterization of the mechanisms used by two pasture grasses to cope with waterlogging stress. The authors focused on mechanisms related to the morphological changes of the root, identifying root morphogenesis traits related to enhanced waterlogging tolerance. These traits represent a solid starting point for future strategies aimed at the identification of the gene variables after waterlogging tolerance. Moreover, the importance of pastures and the potential application of the insights from this work to important monocotyledonous crops extend the interest of this work to a wide audience.

 

Introduction:

 

The authors start with a very well-structured introduction which clearly address the importance of waterlogging as a productivity constraint, how waterlogging reduces plant productivity, and the common strategies to cope with this problem. Finally, authors introduce us to the changes in the root morphology (formation of adventitious roots, aerenchyma development) under waterlogging stress and how they contribute to enhance the plant tolerance. This presents the main objective of the manuscript, the characterization of these root morphological changes which besides their relevance have been less studied than other waterlogging tolerance mechanisms.

 

Despite how efficiently the authors convey the reader to the main objective I have a question regarding the chosen species. What is the relevance of focusing this work on cocksfoot and tall fescue?  The authors place many examples of the effect of waterlogging stress over crop species, mostly of monocotyledonous ones, but they do not explain the relevance of waterlogging in pastures. Authors may have selected these different species due to their described differences in waterlogging tolerance and their ability to generate adventitious roots even under control conditions. If this is the case authors must explain the described differences along the relevance of these species.

 

Material and methods, results:

 

Lines 101-102. “The number of adventitious roots were counted, and root length was measured from soil surface to a depth where the majority of root tips had reached”. Do the authors measure the length of all roots or those of adventitious roots alone?

 

Figure 1. Size of figure lettering should be increased.

 

Figure 1, 3, 5, 6. Homogenize figure lettering format (size/color).

 

Figure 5, 6. Authors should homogenize graph style.

 

Figure 6. Authors should include information about cultivar and species below each figure panel. Moreover, the figure is distorted, authors must correct this.

 

Discussion:

 

Besides the insights about waterlogging tolerance generated in this work, the authors do not correctly separate these insights from previous evidence. One of the most problematic examples is in lines 242-244 “In this study, aerenchyma formation was observed in control conditions of both TF and CF plants, with being greater in TF plants, which has also been reported by Liu et al.”. Does the work of Liu et al. characterize the differences in aerenchyma formation between TF and CF?

Author Response

Dear Reviewer 2, Thank you for your comments to our manuscript. We hope we have answered and attended you your comments in the attached to your satisfaction. 

Author Response File: Author Response.pdf