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Genetic diversity among world hop accessions grown in the USA.

HOP is a dioecious climbing plant with bines that wine in a clockwise direction. Plants typically grow on 6-m trellises with the mature female floral structure, called hop cones (or strobiles), as the harvested portion of the plant. Lupulin glands located on the bracteoles, and to a lesser extent on the bracts, is the source of commercial value in hops. Resins within these glands give beer its bitterness while the essential oils found in the glands contribute flavoring. Hop cones were initially utilized as a preservative in beer brewing. Later, after the advent of pasteurization, hop cones were used as flavoring agents as people began to associate hop flavor with beer.

Most early hop used for beer production in the USA was imported from European countries, including Germany and England. Cultivars such as Fuggle, Saazer, Bullion, and Halletauer Mittelfruh were subsequently introduced into the USA for production as opposed to importing hop cones for brewing. Since that time, numerous foreign-developed cultivars have found their place in the USA hop brewing industry, and production of these cultivars continues in many cases. At the same time, many new domestic-developed hop cultivars have been released and collections of wild hop accessions have been pursued both within the USA and other countries. The end result of all this activity is a large holding of hop accessions with little descriptive information about their relationships.

One method of identifying similar accessions and assessing genetic and phenotypic relatedness is to perform a classification on a large collection of individuals using a statistical procedure such as cluster analysis (Anderberg, 1973). Multiple characters for each individual are used to group accessions into cluster classes. Individuals within a given cluster class are similar, while individuals from different classes are not. Similarity measurements among clusters were also determined so that relationships between groups can be established. Use of classification data can offer the hop breeder an objective judgment when determining which widely differentiated individuals to use as parents. It can also be used to classify newly introduced accessions into known population groups and determine similarity or novelty with existing collection holdings.

Several papers have discussed hop genetic variation using either biochemical or DNA descriptors. In almost all cases, cluster analysis identified two primary groups: the so-called European and American populations. SustarVozlic and Javornik (1999) analyzed 65 world hop cultivars using both random amplified polymorphic DNA (RAPDs) and dried hop cone essential oil composition. They observed the two primary groupings with further subdivision of the European group into five distinct clusters corresponding to regions of geographic adaptation. The authors stated that the RAPD data corresponded well with essential oil fingerprints groupings. Murakami (2000) also assayed 51 world cultivars using RAPD analysis and identified six clusters that were reported to agree with breeding history and country of origin, although some associations were not readily apparent. Seefelder et al. (2000) analyzed 84 world cultivars and six German experimental lines for genetic relatedness using amplified fragment length polymorphism (AFLP). Seven AFLP primer pair combinations produced a total of 130 polymorphic fragments that categorized two main clusters. These first represented European aroma-type hop accessions while the second consisted of lines developed via the incorporation of genes from wild American hop accessions into European cultivars. Further subgroups were observed in each primary cluster with the authors stating the resulting dendrogram agreed with pedigree data. Several accessions had identical fingerprints and were therefore indistinguishable from one another. Even though Seefelder et al. (2000) used German hop collection accessions, more than a third covered were not used for breeding or production in the USA, and no wild American accessions were included. Jakse et al. (2001) utilized AFLP techniques to differentiate European and American hop cultivars, but failed to do so using microsatellites. The AFLP could be used to produce several subsets clusters that agree with geographic groupings with one of these subclusters segregating out those cultivars that were aroma-type hybrids with the cultivar, Northern Brewer. Finally, Patzak (2001) compared four DNA techniques by biochemical fingerprints to estimate genetic relatedness. Three out of the four DNA techniques [RAPD, sequence tagged sites (STS), and inter-simple sequence repeat (ISSR)] failed to differentiate among three clonal selections from a Saazer population while the AFLP and biochemical data differentiated among the clonal selections. Correspondence analysis of the five techniques using cophenetic correlation coefficients demonstrated a high similarity among dendrograms estimated using DNA techniques (r [greater than or equal to] 0.86), but low correspondence between DNA techniques and biochemical characters (r [less than or equal to] 0.59).

In the aforementioned studies using DNA markers, none included wild American germplasm. With the exception of Small's work (1978, 1980) using solely morphological characteristics, only one other published study (Stevens et al., 2000) utilized wild American hop accessions. It was found that two closely related flavonoids were distributed across wild North American accessions and also in some of the hybrid cultivars that resulted from crosses between wild accessions and European hop cultivars. These same two flavonoids were not observed in nonhybridized European cultivars. However, the use of these two flavonoids as characterization variables was not sufficient to differentiate subgroups within domesticated hybrids or European accessions.

From the standpoint of germplasm collection and new accession classification, the absence of information about wild North American germplasm is a major gap. Since DNA techniques are not always readily available to all research groups, studies using commonly accessed traits of economic importance would greatly benefit a broad spectrum of researchers. Finally, phenotypic information on economic traits allows collection population structures to be defined so breeders or growers can identify specific accessions that may be of interest to them. The objective of this study was to identify distinct pools of female hop genetic diversity on the basis of yield, hop-storage-index, a acids, [beta] acids, cohumulone, myrcene, caryophyllene, and humulene contents.

MATERIALS AND METHODS

Plant Materials and Quality Evaluations

All plant materials were grown on the USDA-ARS Hop Research Facility located on the Oregon State University, Hyslop East Farm near Corvallis, OR. Data from 129 female accessions from Europe, North America, Japan, Australia, New Zealand, and South Africa were collected over a 25-yr period with replicated observations occurring over time. Two additional clones of the cultivar Early Prolific, grown on different plots, were included as controls. All data were standardized to a moisture content of 80 g [kg.sup.-1] Hop cone yield, bittering acids ([alpha]- and [beta]-acid content), Coil, and HSI were reported as published by Henning et al. (1997). Levels of M, C, and H were reported as percentages of the total essential oil extract. All data were averaged across years and only entries with at least three replicate year's data were included.

Statistical Methods

Pearson's correlation coefficient (r) was used to describe associations among the eight hop quality descriptors. Probabilities for the significance of all correlation coefficients were determined by Bonferroni inequality adjustment (Snedecor and Cochran, 1980). The 129 accessions examined were grouped into genetic diversity pools by cluster analysis based on Euclidean distance and Ward's (1963) clustering technique (Systat for the Macintosh, SPSS, Chicago, IL) with all data transformed by the standard normal deviate (Snedecor and Cochran, 1980). The designated genetic diversity pool classes were determined by the optimal number of classes ([c.sub.opt]) method (Steiner et al., 2001):

[c.sub.opt] = lim [[D.sub.n] [greater than or equal to] 0.5 * [D.sub.g]]; whenever n > 2

where [D.sub.g] was the greatest amalgamation distance between two clusters and [D.sub.n] was the least successive amalgamation distance between two clusters that was greater than or equal to one-half [D.sub.g]. The significance of each of the eight quality descriptor in developing the three genetic diversity pools and the percentage of correctly classified accession cases were tested using Wilks' Lambda statistic by step-wise discriminant analysis (SPSS, Inc., Chicago, IL). The accession genetic diversity pool membership was used as the grouping variable. The maximal number of significant canonical discriminant functions needed to describe the core subset was also determined, and percentage of accessions that were correctly classified was determined.

Each hop quality descriptor was tested for differences within each genetic diversity pool on the basis of natural geographic groupings within the pools. Subgroups within the genetic diversity pools were recognized if two or more geographic subgroups had at least one significantly different hop quality descriptor as determined by analysis of variance. Interpretive group classes for each of the eight hop quality measures were assembled using cluster analysis based on Euclidean distance and Ward's (1963) clustering technique (Systat for the Macintosh, Evanston, IL) (Steiner et al., 2001). The number of categorical classes for each hop quality descriptor interpretive group was: yield (4 classes); [alpha] acids (5 classes); [beta] acids (2 classes); HSI (4 classes); CoH (5 classes); M (4 classes); C (3 classes); and H (3 classes). The number of classes was based on a visual examination of the quality measure cluster analysis dendrograms. Class differences were verified by analysis of variance and Fisher's protected least significant difference test. Genetic diversity pools and geographic subgroups summary statistics included the mean, minimum, maximum, standard error of the mean, and mode for each interpretive group descriptor. A similarity index for interpretive group classes was calculated for each descriptor within each genetic diversity pool and significant geographic subgroups by the following equation:

I = {S - [[summation over] k[member of]n] diff([x.sub.ik], [x.sub.jk], .. [x.sub.nk])]}/S,

where the similarity index (I) for a set of observations with S possible comparisons for an interpretive group descriptor (k), for a genetic diversity pool or geographic subgroup with n accessions, and [x.sub.ik], [x.sub.jk], .. [x.sub.nk] being the k states of the descriptor in the pool or subgroup. The S possible combinations of interpretive group states for comparison in a genetic diversity pool were determined by:

S = [n!]/(n-r)!]/2,

where n is the total number of accessions in a genetic diversity pool and r = 2 (two accessions compared at a time). When all [x.sub.ik] states of k in a genetic diversity pool are the same, I = 1.0. Differences in the levels of diversity among subgroups were tested by analyzing differences in similarity index values for each subgroup. Friedman's nonparametric analysis of variance was used to test for significant differences among the eight-descriptor variables. We then tested specific comparisons among each subgroup by Wilcoxon's matched pairs test.

RESULTS AND DISCUSSION

We identified three distinct genetic diversity pools of the 129 accessions included in the study on the basis of cluster analysis with verification by discriminant analysis (Table 1). Discriminant analysis demonstrated that the greatest percentage of correctly placed accessions (96.9%) in the greatest number of groups was obtained with three genetic diversity pools. The three pools were described as European (EU), wild North American (WNA), and domesticated hybrids (HYB). Mean values for each descriptor variable differed among the three pools (Table 2). Mean values for yield, [alpha] acids, [beta] acids, and M were highest for HYB, with intermediary values for Coil and H, and lowest values for HSI and C. These values are consistent with accessions that would typically be used for extract or bittering in beer brewing. Average values for EU were lowest for [beta] acids, CoH, and M, with low but not significantly different from WNA for yield, [alpha] acids, and HSI. The EU group was highest for H and HSI, but not significantly different from WNA for this last HSI. These values are typical of accessions used primarily for aroma rather than bittering. The last group, WNA, exhibited the highest values for Coil and also exhibited high values (but not significantly different from one of the other groups) for HSI, M, and C. It had the lowest concentration of H while not differing from the EU population in yield, [alpha], and [beta] acids. No accessions from this population appear to be adequate for direct use in beer brewing since the required quality factors do not meet minimum standards.

Interpretive groups for each of the eight-descriptor characteristics were formulated and applied to the 129 accessions (Table 3). Most of the descriptive variables had enough range and distribution to include at least three and as many as five interpretive group classes for each trait. In addition, both the EU and HYB groups were split up into subgroups on the basis of geographic distribution (Table 3). The EU group was split into two subgroups: Continental Europe (CU) and United Kingdom (UK). The HYB group was divided into five subgroups: Continental Europe (CE-HYB), United Kingdom (UK-HYB), USA (USA-HYB), Asia (A-HYB), and former British Commonwealth countries (BC-HYB). We observed significant differences (P [less than or equal to] 0.05) within primary groups and subgroups for levels of diversity as measured by the similarity indices. The UK-HYB group had the lowest average similarity index indicating the greatest amount of within-group variability, while the A-HYB and CE-HYB subgroups exhibited the highest average similarity index, thus exhibiting the least amount of within-group diversity. The diversity of the remaining WNA pool and subgroups were not significantly different from one another.

Specific relationships between each subgroup within a primary genetic diversity pool were tested to determine differences. Subgroups UK and CU differed in levels of a acid and cohumulone, with UK having higher levels of both chemicals (Table 4). This is most likely due to the British consumer's apparent preference for a more bitter beer than what American and Continental European consumers prefer. The subgroups in the HYB primary pool differed only in levels of cohumulone and in yield (Table 5). Not surprisingly, yields were highest in the USA-HYB subgroup (1296 kg [ha.sup.-1]) and lowest in the CE-HYB (810 kg [ha.sup.-1]). Cohumulone levels were highest for A-HYB (40.4%) and USA-HYB (36.6%), again reflecting the primary end-use preferences for most of the hops developed in both regions. Cohumulone levels were lowest in both CU and UK (26.3 and 29.2%, respectively). Whole or pellet hops are primarily used in these two regions because of brewery preference for low cohumulone. Variability in C levels observed among several subgroups of the HYB primary group may reflect European choice of hop cultivars with low levels of C while other regions, such as USA and former British Commonwealth countries, utilize cultivars with higher levels of C. Yield differences among HYB subgroups are not representative of breeding quality as simply the difference in the environment that these cultivars were developed.

Our genetic diversity pool observations generally agree with research using DNA molecular markers. It is assumed that large numbers of categorizing variables result in a more precise classification. This assumes the descriptors used in the classification are not correlated with one another. In all cases of published work using DNA molecular markers as means of determining genetic relatedness, there was no discussion about the discriminatory value or contribution of individual molecular markers. It would be interesting to see how few molecular markers are actually required to determine the same classification as that observed with the full array of markers. We analyzed each hop quality descriptor for collinearity (Table 6). Each variable was subsequently omitted from the analysis and the resulting clusters observed for relationships to known pedigrees. Omitting one or more of the variables resulted in non-sensible classifications with unusual relationships between accessions that had little genetic relatedness based on known pedigree. Thus, all eight descriptor variables were necessary for reasonable clustering of accessions (data not shown).

Several noteworthy accession relationships were revealed by this study. Two full-sib sisters, 'Saxon' and 'Viking', were separated by 0.25 on a scale of 0 to 50.0. Three older Noble aroma cultivars, Lubelski, Spalter, and Saazer 36, were all three closely related (0.19-0.24) suggesting clonal relatedness. Using AFLP, Seefelder et al. (2000) could not identify any genetic differences between Spalter and Saazer. Similarly, four other accessions (Fuggle, 'Styrian', 'Savinja Golding' and 'USA Tettnang') all grouped together into a single cluster. The later three accessions are thought to be clonal selections from Fuggle. Both Sustar-Vozlic and Javornik (1999) and Jakse et al. (2001) could not differentiate genetic differences (on the basis of DNA) between Fuggle and Savinja Golding. Styrian is thought to be Fuggle introduced to former Yugoslavia circa 1900 (personal communication, A. Haunold, 1998). A fourth accession, 'Bramling', also grouped together with this cluster. Bramling is an old English cultivar from the 19th century and its origin is not entirely clear. Whether or not Bramling is a clonal selection from Fuggle is unknown. Finally, 'Saazer 36' and 'Tettnanger' grouped together in one cluster, which is not unexpected given the known genetic similarity of these two accessions (Seefelder et al., 2000).

Other observations merit mention. First, the two hybrid cultivars, Alliance and Progress, both developed by Wye College (United Kingdom), were placed in the UK group as opposed to EU-HYB. Obviously, these two cultivars have similar traits to those observed for older, traditional UK cultivars. Second, the cultivar Tettnanger, originally obtained by the USDA-ARS in 1961, was ranked in the heirloom EU group while Tettnanger A and Tettnanger B, later acquisitions thought to be clonal selections from a Tettnanger field, were classified with the EU-HYB group. Similarly, the original acquisitions of Saazer was placed in the EU heirloom group while a subsequent acquisition of Saazer, Saazer 36 (also thought to be a clonal selection out of a Saazer yard), was ranked with the EU-HYB group. Certainly, the fact that fewer samples have been taken off the later acquisitions than the original ones suggests the possibility that the full range of phenotypic expression for the newer acquisitions has not been observed as of yet.

Germplasm maintenance, classification, and integration of new accessions require sufficient knowledge of the relationships among current members of the collection to determine their novelty. Without such knowledge, inclusion of redundant materials increases collection maintenance costs. The information contained in this report is the first such attempt at classifying phenotypic relationships amongst members of the U.S. hop collection, with the inclusion of wild North American accessions. Current work is underway classifying this collection by DNA makers, determining relationships of markers to hop quality phenotypic descriptors, and determining genetic x environmental interactions.
Table 1. Relationship between number of cluster analysis groups,
cluster amalgamation distance between clusters, and the
percentage of correctly placed accessions by discriminant analysis
when using the number of cluster groups as the DA classification
factors.

                         Cluster analysis

                                             Discriminant analysis
Number of groups     Amalgamation distance   accessions placement

                              d                       %
2                           21.48                    93.0
3                           16.61                    96.9
4                            8.72                    89.9
5                            4.93                    89.9
6                            4.81                    90.7
7                            4.76                    90.7
8                            4.20                    90.7

Table 2. Means for three germplasm pools of hops [Domesticated
hybrids (HYB), European (EU) and wild North American
(WNA)] from a cluster analysis based on eight measures of
quality: Yield, [alpha]-acid percentage, [beta]-acid percentage,
hop storage index (HSI), cohumulone percentage (CoH), Myrcene
concentration (M), Caryophyllene concentration (C) and Humulene
concentration (H).

                              Group

Variable                   HYB               EU       WNA

Yield (kg ha-1)       1015.4a ([dagger])   408.7b   507.8b
[alpha] acid (%)         8.3a                4.6b     3.6b
[beta] acid (%)          4.7a                2.8c     3.4b
HIS                      0.26b               0.28a    0.29a
CoH (%)                 31.8b               25.3c    60.0a
M (v/v)                 56.1a               38.1b    53.5a
C (v/v)                  8.6b                9.8b    17.7a
H (v/v)                 14.7b               25.6      5.4c

([dagger]) Means within rows followed by a different letter are
significantly different at P [less than or equal to 0.05] on the
basis of Fisher's Protected Least Significant Difference test.

Table 3. Categorization of 129 USDA-ARS hop accessions into three
genetic diversity pools on the basis of cluster analysis of eight
quality descriptors. The quality descriptors are summarized as
interpretive groups. Where subpool designations are reported,
differences are based on significant differences for at least one
quality descriptor by analysis of variance using the geographic
groupings of accessions as the grouping.

Interpretative group (IG) descriptors ([dagger])

Entry                                                YLD      [alpha]
([double                                             (4)       Acids
dagger])  Cultivar           Origin     Subpool  ([section])   (5)

Genetic Diversity Pool

European

21276     Early Prolific     UK         UK       4            4
21277     Early Promise      UK         UK       2            1
21284     Bramling           UK         UK       4            4
21396     Tolhurst           UK         UK       3            1
21668     White Golding      UK         UK       3            4
21680     East Kent Golding  UK         UK       4            4
21681     Canterbury Gold    UK         UK       4            4
48209     Fuggle H           UK         UK       2            4
66050     Alliance           UK         UK       4            4
66051     Progress           UK         UK       4            5
                             Subpool IG mode:    4            4
                             Similarity index
                             ([paragraph]):      0.49         0.58
21014     Mittelfrue         CU         CU       2            4
21045     Serebrianka        CU         CU       2            2
21049     Styrian            CU         CU       3            2
21077     Saazer             CU         CU       1            3
21079     Blue North Brewer  CU         CU       1            1
21114     Nadwislanska       CU         CU       4            4
21168     Precdbourg         CU         CU       2            4
21172     Landhopfen         CU         CU       2            3
21173     Strisselspalter    CU         CU       2            2
21197     USA Tettnang       UK         CU       3            3
21213     Aromat             CU         CU       3            3
21214     Sirem              CU         CU       4            3
21217     Star               CU         CU       1            2
21673     Hersbrucker Pure   CU         CU       4            4
61020     Savinja Golding    CU         CU       4            4
61021     Tettnanger         CU         CU       4            5
                             Subpool IG mode:    2            4
                             Similarity index:   0.49         0.58

Wild North American

21115     Pocket Talisman    USA-HYB    WNA      1            2
21563     Iowa 3             WNA        WNA      1            2
21565     Iowa 5             WNA        WNA      1            2
21566     Iowa 6             WNA        WNA      3            2
21567     Iowa 7             WNA        WNA      1            4
21568     North Dakota 1     WNA        WNA      2            4
21576     Montana 4          WNA        WNA      3            4
21581     Montana 9          WNA        WNA      2            3
21585     Montana 11         WNA        WNA      2            4
21590     Montana 16         WNA        WNA      2            3
21594     Montana 20         WNA        WNA      4            4
21596     Utah 11            WNA        WNA      4            5
21599     Utah 12            WNA        WNA      2            4
21600     Utah 13            WNA        WNA      4            5
21602     Montana 24         WNA        WNA      4            4
21605     W AM Minn.         WNA        WNA      4            5
60016     New Mexico 1-3     WNA        WNA      4            5
60027     Colorado 2-2       WNA        WNA      4            5
60029     Colorado 3-1       WNA        WNA      3            5
60032     Colorado 5-1       WNA        WNA      3            5
60033     Colorado 6-1       WNA        WNA      4            5
60035     Colorado 7-2       WNA        WNA      4            4
60038     Wyoming 3-1        WNA        WNA      4            4
66052     Pride of Ringwold  BC-HYB     WNA      3            5
                             Pool IG mode:       4            4
                             Similarity index:   0.32         0.34

Hybrids

19001     Brewers Gold       UK         UK-HYB   1            2
19120     Sunshine-S         UK         UK-HYB   2            3
21043     Challenger         UK         UK-HYB   3            3
21044     Northdown          UK         UK-HYB   1            2
21112     Target             UK         UK-HYB   1            1
21278     Keyworths Early    UK         UK-HYB   3            4
21280     Pride of Kent      UK         UK-HYB   4            3
21282     Saxon              UK         UK-HYB   2            1
21283     Viking             UK         UK-HYB   4            3
21498     Yeoman             UK         UK-HYB   1            4
21667     Omega              UK         UK-HYB   3            4
64100     Bullion            UK         UK-HYB   4            5
64107     Northern Brewer    UK         UK-HYB   4            4
                             Subpool IG mode:    1            3
                             Similarity index:   0.21         0.18
21522     Saazer 36          CU         CU-HYB   2            4
21050     Ahil               CU         CU-HYB   2            2
21051     Apolon             CU         CU-HYB   2            1
21052     Atlas              CU         CU-HYB   2            3
21053     Aurora             CU         CU-HYB   1            3
21078     Record             CU         CU-HYB   2            3
21081     Dunav              CU         CU-HYB   4            4
21082     Neoplanta          CU         CU-HYB   1            4
21083     Vojvodina          CU         CU-HYB   2            4
21907     Huller Bitter      CU         CU-HYB   1            1
21169     Tardif de Bourg.   CU         CU-HYB   1            1
21170     Elsasser           CU         CU-HYB   4            3
21185     Hersbrucker        CU         CU-HYR   2            4
21186     Spalter            CU         CU-HYB   2            2
21187     Southern Brewer    BC         CU-HYB   2            2
21215     Norgard            CU         CU-HYR   1            4
21227     Perle              CU         CU-HYB   2            4
21239     Bobek              CU         CU-HYB   2            4
21496     Tettnanger A       CU         CU-HYB   2            2
21497     Tettnanger B       CU         CU-HYB   4            5
21518     Hersbrucker Alpha  CU         CU-HYB   2            4
21611     Celeia             CU         CU-HYB   4            5
21670     Magnum             CU         CU-HYB   4            5
21671     Hallertauer Gold   CU         CU-HYB   4            5
21672     Hall. Tradition    CU         CU-HYB   4            5
21674     Spalter Select     CU         CU-HYB   4            4
21675     Orion              CU         CU-HYB   4            4
21682     Wurttemberger      CU         CU-HYB   3            4
56002     Backa              CU         CU-HYB   2            4
                             Subpold IG mode:    2            4
                             Similarity index:   0.32         0.27
21040     Columbia           USA        USA-HYB  2            4
21041     Willamette         USA        USA-HYB  2            3
21055                        USA        USA-HYB  2            3
21182     Galena             USA        USA-HYB  2            1
21183     Eroica             USA        USA-HYB  3            2
21193     Nugget             USA        USA-HYB  3            3
21222     Aquila             USA        USA-HYB  1            3
21225     Olympic            USA        USA-HYB  2            2
21226     Chinook            USA        USA-HYB  2            3
21231     Pat Leavy Seed     USA        USA-HYB  4            4
21287     Banner             USA        USA-HYB  4            3
21455     Mt. Hood           USA        USA-HYB  2            4
21490     Crystal            USA        USA-HYB  4            4
21697     Sunbeam            USA        USA-HYB  3            4
21698     Bianca             USA        USA-HYB  4            4
56013     Cascade            USA        USA-HYB  3            4
60037     Wyoming 2-1        USA        USA-HYB  4            5
62013     Comet              USA        USA-HYB  2            5
65101     Talisman           USA        USA-HYB  4            5
65102     Cluster (L-1)      USA        USA-HYB  2            5
65104     Cluster (L-8)      USA        USA-HYB  2            5
                             Subpool IG mode:    2            4
                             Similarity index:   0.38         0.29
21039     Golden Star        Japan      A-HYB    1            3
21232     69K-BH66           Japan      A-HYB    4            4
21233     70K-SH6            Japan      A-HYB    3            1
21286     Kirin II           Japan      A-HYB    2            4
21676     Toyomidori         Japan      A-HYB    4            5
21677     Kitamidori         Japan      A-HYB    4            3
21678     Eastern Gold       Japan      A-HYB    4            4
60042     Shinshuwase        Japan      A-HYB    4            4
                             Subpool IG mode:    4            4
                             Similarity index:   0.5          0.42
21188     NP/55              BC         BC-HYB   2            4
21405     Super Alpha        BC         BC-HYB   1            2
21609     Pacific Gem        BC         BC-HYB   4            5
66054     Calicross          BC         BC-HYR   4            5
66050     First Choice       BC         BC-HYB   4            5
66056     Smoothcone         BC         BC-HYB   1            2
                             Subpool IG mode:    4            5
                             Similarity index:   0.39         0.39

Entry                                           [beta]
([double                                        Acids   HIS    CoH
dagger])  Cultivar           Origin              (2)    (4)    (5)

Genetic Diversity Pool

European

21276     Early Prolific     UK                 1       2      5
21277     Early Promise      UK                 1       4      3
21284     Bramling           UK                 1       4      4
21396     Tolhurst           UK                 1       4      2
21668     White Golding      UK                 2       2      4
21680     East Kent Golding  UK                 2       3      4
21681     Canterbury Gold    UK                 2       3      4
48209     Fuggle H           UK                 2       2      4
66050     Alliance           UK                 1       2      1
66051     Progress           UK                 2       2      2
                             Subpool IG mode:   1       2      4
                             Similarity index
                             ([paragraph]):     0.55    0.47   0.33
21014     Mittelfrue         CU                 1       3      2
21045     Serebrianka        CU                 2       3      5
21049     Styrian            CU                 2       2      3
21077     Saazer             CU                 1       2      4
21079     Blue North Brewer  CU                 1       3      3
21114     Nadwislanska       CU                 2       2      5
21168     Precdbourg         CU                 2       4      4
21172     Landhopfen         CU                 1       3      2
21173     Strisselspalter    CU                 1       3      3
21197     USA Tettnang       UK                 1       2      3
21213     Aromat             CU                 1       3      5
21214     Sirem              CU                 1       3      4
21217     Star               CU                 1       3      3
21673     Hersbrucker Pure   CU                 2       1      5
61020     Savinja Golding    CU                 1       2      1
61021     Tettnanger         CU                 2       2      1
                             Subpool IG mode:   1       3      3
                             Similarity index:  0.55    0.47   0.33

Wild North American

21115     Pocket Talisman    USA-HYB            2       3      3
21563     Iowa 3             WNA                1       2      3
21565     Iowa 5             WNA                2       3      3
21566     Iowa 6             WNA                1       2      4
21567     Iowa 7             WNA                2       3      2
21568     North Dakota 1     WNA                2       3      3
21576     Montana 4          WNA                2       2      3
21581     Montana 9          WNA                1       2      3
21585     Montana 11         WNA                1       3      3
21590     Montana 16         WNA                2       3      3
21594     Montana 20         WNA                1       3      5
21596     Utah 11            WNA                2       2      5
21599     Utah 12            WNA                2       1      4
21600     Utah 13            WNA                2       2      5
21602     Montana 24         WNA                2       1      4
21605     W AM Minn.         WNA                2       3      5
60016     New Mexico 1-3     WNA                2       1      1
60027     Colorado 2-2       WNA                2       3      1
60029     Colorado 3-1       WNA                2       1      1
60032     Colorado 5-1       WNA                1       1      1
60033     Colorado 6-1       WNA                1       2      1
60035     Colorado 7-2       WNA                1       3      1
60038     Wyoming 3-1        WNA                2       3      1
66052     Pride of Ringwold  BC-HYB             2       2      1
                             Pool IG mode:      2       3      3
                             Similarity index:  0.55    0.39   0.30

Hybrids

19001     Brewers Gold       UK                 1       2      3
19120     Sunshine-S         UK                 2       2      4
21043     Challenger         UK                 1       3      5
21044     Northdown          UK                 1       2      5
21112     Target             UK                 1       2      3
21278     Keyworths Early    UK                 2       4      5
21280     Pride of Kent      UK                 2       3      4
21282     Saxon              UK                 1       4      4
21283     Viking             UK                 1       4      5
21498     Yeoman             UK                 1       3      3
21667     Omega              UK                 2       2      4
64100     Bullion            UK                 2       1      1
64107     Northern Brewer    UK                 1       2      1
                             Subpool IG mode:   1       2      4
                             Similarity index:  0.49    0.27   0.21
21522     Saazer 36          CU                 1       4      2
21050     Ahil               CU                 1       3      5
21051     Apolon             CU                 1       2      2
21052     Atlas              CU                 1       3      4
21053     Aurora             CU                 2       2      4
21078     Record             CU                 1       2      4
21081     Dunav              CU                 1       2      5
21082     Neoplanta          CU                 1       4      5
21083     Vojvodina          CU                 1       3      5
21907     Huller Bitter      CU                 1       4      3
21169     Tardif de Bourg.   CU                 1       3      4
21170     Elsasser           CU                 2       2      4
21185     Hersbrucker        CU                 1       4      4
21186     Spalter            CU                 1       2      3
21187     Southern Brewer    BC                 1       3      3
21215     Norgard            CU                 1       3      2
21227     Perle              CU                 1       3      5
21239     Bobek              CU                 1       3      5
21496     Tettnanger A       CU                 1       4      4
21497     Tettnanger B       CU                 1       4      5
21518     Hersbrucker Alpha  CU                 1       3      3
21611     Celeia             CU                 2       4      5
21670     Magnum             CU                 2       1      5
21671     Hallertauer Gold   CU                 2       2      5
21672     Hall. Tradition    CU                 2       1      5
21674     Spalter Select     CU                 2       2      4
21675     Orion              CU                 2       2      4
21682     Wurttemberger      CU                 2       2      4
56002     Backa              CU                 2       3      4
                             Subpold IG mode:   1       3      4
                             Similarity index:  0.54    0.27   0.30
21040     Columbia           USA                2       2      3
21041     Willamette         USA                1       2      5
21055                        USA                2       3      3
21182     Galena             USA                1       3      3
21183     Eroica             USA                2       2      4
21193     Nugget             USA                2       2      3
21222     Aquila             USA                1       2      3
21225     Olympic            USA                1       3      3
21226     Chinook            USA                1       4      5
21231     Pat Leavy Seed     USA                1       2      5
21287     Banner             USA                1       4      3
21455     Mt. Hood           USA                2       4      4
21490     Crystal            USA                2       3      3
21697     Sunbeam            USA                2       2      4
21698     Bianca             USA                1       3      5
56013     Cascade            USA                2       2      1
60037     Wyoming 2-1        USA                2       2      1
62013     Comet              USA                2       1      1
65101     Talisman           USA                2       3      2
65102     Cluster (L-1)      USA                2       2      5
65104     Cluster (L-8)      USA                2       1      1
                             Subpool IG mode:   2       2      3
                             Similarity index:  0.55    0.37   0.29
21039     Golden Star        Japan              1       2      3
21232     69K-BH66           Japan              1       3      5
21233     70K-SH6            Japan              1       2      5
21286     Kirin II           Japan              1       4      4
21676     Toyomidori         Japan              2       4      4
21677     Kitamidori         Japan              2       4      3
21678     Eastern Gold       Japan              2       4      5
60042     Shinshuwase        Japan              2       3      1
                             Subpool IG mode:   1       4      5
                             Similarity index:  0.56    0.44   0.36
21188     NP/55              BC                 1       4      5
21405     Super Alpha        BC                 1       4      4
21609     Pacific Gem        BC                 2       4      5
66054     Calicross          BC                 1       2      2
66050     First Choice       BC                 2       2      1
66056     Smoothcone         BC                 1       3      4
                             Subpool IG mode:   1       2      4
                             Similarity index:  0.64    0.46   0.46

Entry
([double                                         M       C      H
dagger])  Cultivar           Origin             (4)     (3)    (3)

Genetic Diversity Pool

European

21276     Early Prolific     UK                 3       3      2
21277     Early Promise      UK                 1       1      2
21284     Bramling           UK                 1       3      2
21396     Tolhurst           UK                 1       2      3
21668     White Golding      UK                 2       3      1
21680     East Kent Golding  UK                 4       1      1
21681     Canterbury Gold    UK                 4       1      1
48209     Fuggle H           UK                 4       2      1
66050     Alliance           UK                 1       2      3
66051     Progress           UK                 4       2      3
                             Subpool IG mode:   1       2      1
                             Similarity index
                             ([paragraph]):     0.40    0.44   0.13
21014     Mittelfrue         CU                 2       3      2
21045     Serebrianka        CU                 2       3      2
21049     Styrian            CU                 1       3      3
21077     Saazer             CU                 1       3      3
21079     Blue North Brewer  CU                 1       3      3
21114     Nadwislanska       CU                 3       3      1
21168     Precdbourg         CU                 3       3      1
21172     Landhopfen         CU                 1       3      3
21173     Strisselspalter    CU                 1       2      3
21197     USA Tettnang       UK                 1       2      2
21213     Aromat             CU                 3       3      2
21214     Sirem              CU                 3       3      2
21217     Star               CU                 1       2      2
21673     Hersbrucker Pure   CU                 4       3      1
61020     Savinja Golding    CU                 1       2      3
61021     Tettnanger         CU                 2       3      2
                             Subpool IG mode:   1       3      2
                             Similarity index:  0.40    0.44   0.13

Wild North American

21115     Pocket Talisman    USA-HYB            2       3      2
21563     Iowa 3             WNA                1       2      3
21565     Iowa 5             WNA                1       3      2
21566     Iowa 6             WNA                2       3      1
21567     Iowa 7             WNA                1       2      3
21568     North Dakota 1     WNA                1       2      2
21576     Montana 4          WNA                2       2      2
21581     Montana 9          WNA                1       2      2
21585     Montana 11         WNA                1       3      3
21590     Montana 16         WNA                1       3      3
21594     Montana 20         WNA                4       2      1
21596     Utah 11            WNA                4       3      1
21599     Utah 12            WNA                3       3      1
21600     Utah 13            WNA                4       3      1
21602     Montana 24         WNA                4       3      1
21605     W AM Minn.         WNA                4       3      1
60016     New Mexico 1-3     WNA                4       1      3
60027     Colorado 2-2       WNA                4       1      3
60029     Colorado 3-1       WNA                3       1      3
60032     Colorado 5-1       WNA                2       3      3
60033     Colorado 6-1       WNA                4       2      2
60035     Colorado 7-2       WNA                1       1      3
60038     Wyoming 3-1        WNA                1       1      3
66052     Pride of Ringwold  BC-HYB             3       1      3
                             Pool IG mode:      1       3      3
                             Similarity index:  0.31    0.38   0.37

Hybrids

19001     Brewers Gold       UK                 1       3      2
19120     Sunshine-S         UK                 3       3      3
21043     Challenger         UK                 2       2      1
21044     Northdown          UK                 1       3      3
21112     Target             UK                 2       2      3
21278     Keyworths Early    UK                 3       3      1
21280     Pride of Kent      UK                 2       2      2
21282     Saxon              UK                 1       2      2
21283     Viking             UK                 1       3      2
21498     Yeoman             UK                 1       3      2
21667     Omega              UK                 3       2      1
64100     Bullion            UK                 3       2      3
64107     Northern Brewer    UK                 1       3      3
                             Subpool IG mode:   1       3      2
                             Similarity index:  0.31    0.46   0.29
21522     Saazer 36          CU                 2       2      2
21050     Ahil               CU                 3       3      1
21051     Apolon             CU                 2       3      3
21052     Atlas              CU                 3       3      1
21053     Aurora             CU                 2       3      1
21078     Record             CU                 2       3      3
21081     Dunav              CU                 3       3      1
21082     Neoplanta          CU                 3       3      2
21083     Vojvodina          CU                 3       3      1
21907     Huller Bitter      CU                 3       3      1
21169     Tardif de Bourg.   CU                 2       3      1
21170     Elsasser           CU                 3       2      1
21185     Hersbrucker        CU                 2       3      1
21186     Spalter            CU                 1       3      3
21187     Southern Brewer    BC                 2       3      1
21215     Norgard            CU                 3       2      2
21227     Perle              CU                 2       3      1
21239     Bobek              CU                 3       1      2
21496     Tettnanger A       CU                 4       3      1
21497     Tettnanger B       CU                 3       3      1
21518     Hersbrucker Alpha  CU                 2       2      2
21611     Celeia             CU                 4       3      1
21670     Magnum             CU                 3       3      1
21671     Hallertauer Gold   CU                 4       3      1
21672     Hall. Tradition    CU                 4       2      1
21674     Spalter Select     CU                 3       3      1
21675     Orion              CU                 3       3      1
21682     Wurttemberger      CU                 3       3      1
56002     Backa              CU                 4       2
                             Subpold IG mode:   3       3      1
                             Similarity index:  0.34    0.62   0.52
21040     Columbia           USA                3       3      1
21041     Willamette         USA                2       3      1
21055                        USA                3       3      1
21182     Galena             USA                3       2      2
21183     Eroica             USA                3       2      1
21193     Nugget             USA                3       3      1
21222     Aquila             USA                1       3      3
21225     Olympic            USA                1       1      2
21226     Chinook            USA                3       2      1
21231     Pat Leavy Seed     USA                3       3      1
21287     Banner             USA                3       1      1
21455     Mt. Hood           USA                1       3      2
21490     Crystal            USA                3       3      2
21697     Sunbeam            USA                3       3      1
21698     Bianca             USA                3       3      1
56013     Cascade            USA                1       3      3
60037     Wyoming 2-1        USA                1       3      3
62013     Comet              USA                3       2      2
65101     Talisman           USA                2       1      3
65102     Cluster (L-1)      USA                3       1      1
65104     Cluster (L-8)      USA                3       2      3
                             Subpool IG mode:   3       3      1
                             Similarity index:  0.53    0.45   0.42
21039     Golden Star        Japan              2       3      2
21232     69K-BH66           Japan              2       3      2
21233     70K-SH6            Japan              3       1      1
21286     Kirin II           Japan              1       3      3
21676     Toyomidori         Japan              3       3      1
21677     Kitamidori         Japan              3       3      1
21678     Eastern Gold       Japan              3       1      2
60042     Shinshuwase        Japan              1       2      3
                             Subpool IG mode:   3       3      2
                             Similarity index:  0.44    0.53   0.42
21188     NP/55              BC                 3       3      1
21405     Super Alpha        BC                 3       3      1
21609     Pacific Gem        BC                 3       3      1
66054     Calicross          BC                 2       2      3
66050     First Choice       BC                 1       2      3
66056     Smoothcone         BC                 3       2      3
                             Subpool IG mode:   3       3      1
                             Similarity index:  0.39    0.50   0.57

([dagger]) Descriptors: YLD, hop cone yield; HSI, hop storage index;
CoH, cohumulone; M, myrcene; C, caryophylene; H, humulene.

([double dagger]) Genetic diversity pools were determined by cluster
analysis of the normalized values for the eight hop quality
descriptors.

([section]) Numbers in parentheses indicate the number of classes for
each interpretive descriptor group.

([paragraph]) Similarity index is the percentage of possible
interpretive group class comparisons in a genetic diversity pool that
are the same.

Table 4. Relationship between England and Continental Europe
subgroups within the European-cluster for eight quality
characteristics for hops

                                 Subgroup

                                Continental
Quality                                               Significance
characteristic           England (11)   Europe (15)      level

                                                      P ([dagger])
Yield (kg [ha.sup.-1])      478.5          357.5          0.21
[alpha] Acids (%)             5.2            4.1          0.02
[beta] Acids (%)              2.6            2.9          0.27
HSI                           0.3            0.3          0.25
CoH (%)                      27.0           24.1          0.03
M (v/v)                      38.9           37.6          0.74
C (v/v)                      10.7            9.2          0.48
H (v/v)                      26.6           24.7          0.46

([dagger]) Means within rows are different at the significance level
indicated on the basis of Fisher's Protected Least Significant
Difference test.

Table 5. Relationship between five geographic subgroups within the
Hybrids-cluster for eight quality characteristics for hops.

                                      Subgroup

                        UK       CU      USA     Japan       BC
Quality
characteristic                           n

                      13        30       21        8          4
Yield                881.5bc   809c    1296.0a  1194.3ab  1120.3abc
 (kg [ha.sup.-1])  ([dagger])
[alpha] Acids (%)      9.5       7.3      9.2      8.3       9.3
[beta] Acids (%)       4.5       4.6      4.8      5.0       4.8
HSI                    0.27      0.25     0.26     0.25      0.24
CoH (%)               29.2bc    26.3c    36.6a    40.4a     35.4ab
M (v/v)               55.8      54.1     57.3     55.6      60.9
C (v/v)                8.7       7.6      9.4      8.5      14.0
H (v/v)               14.4      16.9     12.5     14.5      13.7

Quality                 Significance
characteristic             level

                             P

Yield
 (kg [ha.sup.-1])           0.01
[alpha] Acids (%)           0.10
[beta] Acids (%)            0.79
HSI                         0.07
CoH (%)                     0.01
M (v/v)                     0.57
C (v/v)                     0.07
H (v/v)                     0.25

([dagger]) Means within rows followed by a different letter are
significantly different on the basis of Fisher's Protected Least
Significant Difference test.

Table 6. Pearson correlation coefficients (r) for eight quality
descriptors for the 129 hop accessions in the USDA-ARS collection.

                           [alpha]     [beta]
Descriptor                  Acids       Acids        HSI        CoH

                                               r

Yield                      0.57 ***    0.44 ***   -0.20       -0.03
[alpha] Acids                          0.51 ***   -0.30 *     -0.26
[beta] Acids                                      -0.45 ***   -0.16
Hop storage index (HSI)                                        0.31 *
CoH
M
C

Descriptor                   M           C           H

                                         r

Yield                      0.39 ***   -0.20       -0.16
[alpha] Acids              0.40 ***   -0.21       -0.08
[beta] Acids               0.23 ***   -0.18       -0.14
Hop storage index (HSI)   -0.17        0.14       -0.06
CoH                        0.28 *      0.37 ***   -0.65
M                                     -0.19       -0.59 ***
C                                                 -0.17

* Indicates significance at P [less than or equal to] 0.05 on the
basis of the Bonferroni inequality adjustment.

*** Indicates significance at 0.001 on the basis of the Bonferroni
inequality adjustment.


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J. A. Henning, * J. J. Steiner, and K. E. Hummer

J.A. Henning and J.J. Steiner, USDA-ARS National Forage Seed Research Center, Oregon State University, Corvallis, OR 97331; K.E. Hummer USDA-ARS National Clonal Germplasm Resources, Oregon State University, Corvallis, OR 97331. Received 1 Oct. 2002. * Corresponding author (John.Henning@orst.edu).
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Title Annotation:Crop Breeding, Genetics & Cytology
Author:Henning, J.A.; Steiner, J.J.; Hummer, K.E.
Publication:Crop Science
Date:Mar 1, 2004
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