Morphological and Biochemical Characterization of Wild Hop (Humulus lupulus L.) Populations from Banja Luka Area (Bosnia and Herzegovina)

Round 1

Reviewer 1 Report

Manuscript ID: agronomy-1052649

Submitted to section:  Crop Breeding and Genetics

 

Title: Morphological and Biochemical Characterization of Wild  Hop (Humulus lupulus L.) Populations from Banja Luka Area (Bosnia and  Herzegovina)

Authors: Danijela Kondić *, Andreja Čerenak, Iztok Jože  Košir, Miha Ocvirk, Tanja Krmpot, Gordana Đurić

 

The manuscript presents the results of morphological and biochemical characterization of seven wild hop populations originating from Bosnia and Herzegovina. Although the number of analysed accessions is not that high, the majority of collected wild hop germplasm in the country was included. Morphological characterization was carried out for all the most important agronomic characters and the biochemical analysis was performed for parameters that are important for brewing industry, i.e. components of essential oil and hop resins. The results indicate that one of the analysed accessions has a potential to be used for further selection and breeding. This could be important for a country where brewing industry has a long tradition, but up to now no breeding programme has been in place.

 

In general, the manuscript is well written. In the introduction part a review of the most important hop parameters that are important from agronomic and brewing point of view is presented. I only miss a sentence or two at the end of the introduction part presenting the aims of the study. Material and methods are well defined; the results are clearly presented and discussed. 

I only suggest a few minor corrections that are specified bellow. I assume that the Latin names will be written in italics in the final version. I would also suggest a final revision of English language by a native speaker.

 

Abstract:

Line 17: write ‘inflorescences’ instead of ’inflorescence’

Lines 20-21: instead of ' Morphological parameters were carried out for: cone,..' write ‘Morphological characterization was carried out for the following parameters: cone, ‘

 

Introduction

Line 47: Rewrite the sentence, e.g.: Hop essential oils are mostly used in beer brewing, and more recently also in biological and pharmacological products.

Line 62: As already written above, add a sentence or two to present the aims of the study.

 

Materials and methods

Line 103: ‘were’ instead of ‘weere’

Line 132-133:  correct the font

 

Results

Line 167: ‘were not statistically significant’ instead of ‘was not statistically significant’

Line 202-203: ‘In the examined year 2018’ instead of ‘In the examined 2018’

 

Discussion

L 280: ‘precedes chemical as well as’ instead of ‘precedes chemistry’

Line 288: ‘In our study’ instead of ‘In our conducted study’

Line 331: Better: However, also in this case there was a grouping…

Author Response

Dear reviewer, we are sending a corrected manuscript and cover letter. We apologize for the slight delay. Thank you for the suggestions. Best regards, Autors

Author Response File: Author Response.docx

Reviewer 2 Report

The article presents the results of the morphological and biochemical characteristics of seven wild hop populations from the Banja Luka region. Until now, wild hops from this region have not been investigated, so it is a new element of this work. The study of morphological traits was conducted in 2018-2019, while the biochemical properties were studied for only one year (2019), so the obtained results should be treated as preliminary.The research was properly planned and performed, but the article requires some additional information and corrections to all chapters. The introduction should contain more information about the presence of hops in the area of ​​research, as well as the importance of individual studied groups of metabolites in beer production. It should also be emphasized what is a new aspect of this research. The research material and the method of sampling should be described in more detail. The discussion should refer to numerous studies on wild hops from other regions of the world and compare the obtained results with the results of other researchers.Details are given below.

I suggest the following changes in the article:  

Chapter 1. Introduction  

Line 38: it should be added that hops grow spontaneously in the temperate climate zone between 35 and 55 latitudes (add appropriate reference, e.g. Barth H.J., Klinke Ch., Schmidt C. Der Grosse Hopfenatlas Geschichte und Geographie Einer Kulturpflanze. Nurnberg: Carl, Getranke-Fachverl., 1994 ISBN 3-418-00744-9) 

Line 39: the term “mature” should be clarified - hop cones are harvested in the technological maturity stage 

Lines 40-42 make the following change to the sentence: …… where grandular trichomes termed lupulin glands are developed , which are the most important source of secondary metabolites (resins, essential oils and prenylflavonoids)(add appropriate reference, e.g.: EST Analysis of Hop Glandular Trichomes Identifies an O-Methyltransferase That Catalyzes the Biosynthesis of Xanthohumol Jana Nagel, Lana K. Culley, Yuping Lu, Enwu Liu, Paul D. Matthews, Jan F. Stevens and Jonathan E. Plant Cell,2008, 20;186-200 

Lines 45-46: I suggest to add more informations about the composition of hop bitter acids and the role of particular hop bitter acids compounds in beer. 

Lines 58-59: Please complete the information about the presence of hops in the study area, is it a common species or rather rare? 

Lines 60-62: In the description of the goals, please specify what is new and original in the conducted research. 

Chapter 2. Materials and Methods 

Lines 65-66: What was the approximate acreage of ​​the research area? At what distance were the tested hop populations from each other?

The studied wild hop populations should be described in more detail (estimated number of plants in each populations, ratio of female to male plants, plant density, i.e. number of plants per square meter)

 Lines 67-68: Please complete the information on the number of plants from which cones were sampled 

Table 1. should be transferred to the chapter “Results” 

Lines 98-100: use superscript, e.g. mL min^-1, ^oC min^-1 

Line 103: correct “weere” to “were” 

Line 105: correct “acetat” to “acetate” 

Line 107: correct “humulene epoxide-2” to “humulene epoxide-1” 

Line 108: add “Delta-cadinene” T

ables 2 and 3 with appropriate comments (lines 116-118 and lines 122-126 respectively) should be removed to the “Results” chapter

Change the title of Table 3: The chemical analysis of soil samples from permanent localities of hop populations (2019).

Complex units write as: mg 100g^-1

 Chapter 3. Results 

Add subchapter “ Meteorological and soil conditions of the research area” and insert tables 2 and 3. 

Add subchapter “Cone shape of hop populations” and insert table 1 with appropriate comments. 

Line 173: change the title: Difference in the number of nodes per cone spindle 

Lines 177-178: Figure 2 shows that the DKH3 population is a separate group with the largest number of nodes per cone spindle. The remaining populations can be grouped into two subgroups.

Figure 3.: please check the correctness of the data in Figure 3. It seems more likely that the population DKH3 will be in one group with the population DKH5 and not with the population DKH9

Line 258: remove “and d”

Chapter 4. Discussion

The obtained results should be compared in more detail with the results of other studies on wild hops from other regions of Europe or the world (e.g.

Patzak et al. Evaluation of genetic variability of wild hops (Humulus lupulus L.) in Canada and the Caucasus region by chemical and molecular methods. Genome, 53 (2010), pp. 545-557

Patzak J. et al. Assessment of the genetic diversity of wild hops (Humulus lupulus L.) in Europe using chemical and molecular analyses. Biochem. Syst. Ecol., 38 (2010), pp. 136-145)

It would also be interesting to compare some traits of examined hop populations to selected commercial hop cultivars (e.g.: Krofta K. Comparison of quality parameters of Czech and foreign hop varieties. Plant Soil Environ., 49 (2003), pp. 261-268)

Lines 289-291: compare your results with other authors (e.g. Solberg et al.Genetic variation in Danish and Norwegian germplasm collections of hops. Biochemical Systematics and Ecology 52 (2014)53-59)

Line 301: correct „most used” to „most useful”

Line 280: correct “chemistry” to “chemical”

 Lines 309-313: The authors compare the number of seeds in the cones of cultivars with that obtained in the cones of the wild hop populations studied. It should be added that the number of seeds in the cones of commercial cultivars is smaller because they are protected against open pollination by removing male plants from the plantation and its surroundings. 

Lines 314-317: The number of seeds depends not only on the biological predisposition of the female inflorescences, but also on the presence of males blooming at the same time as the female plants. The obtained results should be commented based on the information about the presence of male plants in the individual hop populations studied. 

Line 329: Based on the information from the literature, it should be added what is the significance of the individual examined parameters, i.e. ratios cohumulone/alpha acids, colupulone/beta acids and alpha/beta acids. 

Lines 335-337: the results obtained for alpha acids should be discussed with other authors who have studied wild hops

Line 337: correct “quit” to “quite” 

Lines 343, 346, 347, 356: correct “varieties” to “cultivars” 

The authors do not refer to the meteorological and soil data in tables 2 and 3. However, it is known that environmental conditions have a significant influence, especially on the chemical composition of hops, which should be discussed. The most important biochemical properties of cones was tested only in 2019. Therefore, it should be stated that these are preliminary results that require confirmation in the following years.

There is no reference to Fig. 7 in the article. This figure does not add any new information and can be removed without reducing the quality of the presented results.

 Chapter 5. Conclusions  

 Lines 365-366: Seeds formation in cones is not desirable trait but only in case of commercial cultivars.  In breeding work that involves crossing, the formation of large numbers of seeds is a very desirable feature. The authors predict that the studied populations may be used as breeding materials, so a more favorable feature in this case will be the higher number of seeds observed in the DKH8 and DKH9 populations. I suggest to change this conclusion.

Author Response

Dear reviewer,

we are sending a corrected manuscript and cover letter. We apologize for the slight delay. Thank you for your suggestions. Best regards, Autors

Author Response File: Author Response.docx