Molecular phylogeny of wild Hops, Humulus lupulus L.

Abstract

We have analysed wild hops collected widely from the Northern Hemisphere, assessing the genetic diversity and the geographical distribution of haplotypes, to investigate the evolution and phylogeny of hops, Humulus lupulus. The haplotypes were characterized by the nuclear ribosomal DNA spacer region (length and DNA sequence) and chloroplast DNA noncoding regions (DNA sequences). The results indicated that primary divergence into European (including Caucasus and Altai hops), and Asian-North American types, was 1.0570.28 to 1.2770.30 million years ago. Although an Eastern boundary for European nuclear haplotype distribution was unclear due to the ambiguous origin of Northern Chinese samples, the European hop group showed a wide geographical distribution across Eurasia from the Altai region to Portugal. The low genetic variation in this group suggested rapid and recent expansion. The North American hop group showed high diversity, and is considered to include hops that have migrated from Asia. Japanese and Chinese hops were identified as genetically distinct. This study has shown that wild hops in each growing region are genetically differentiated with considerable genetic diversity. It gives insights into the evolution and domestication of hops that are discussed.

Genetic structure and differentiation in hop (Humulus lupulus L.) as inferred from microsatellites

“…Germplasm group F, depicted on the Fitch-Margoliash tree, is similar to groups of native NA hops, for which high differentiation from wild European hops and from cultivated hops containing either EU or NA germplasm, has been shown (Stevens et al 2000;Henning et al 2004;Jakše et al 2004;Murakami et al 2006aMurakami et al , 2006b. Cultivated NA germplasm has also been defined in other studies as a group containing a high number of accessions with predominant NA germplasm in their pedigree (Sustar-Vozlic and Javornik 1999;Seefelder et al 2000;Jakse et al 2001).…”

“…The pedigree of the other two cultivars with more than 90% E ancestry was unknown, or too complex for interpretation, but the assumption of a high proportion of native NA germplasm is supported by previous molecular and quality data. Only the proportion of native NA germplasm in the wild Japanese accession in germplasm group E could not be well explained, because of its wild origin and the unresolved overall relationship of Japanese wild hops to NA and EU wild hops (Murakami et al 2006a(Murakami et al , 2006b. However, we assumed that E ancestry or germplasm group E represents a specific hop germplasm which has been created by introgression of native NA germplasm into EU hops through hybridization and artificial selection.…”

“…This is in contrast with earlier evaluations of 60 wild hop accessions from 9 European countries by 11 SSR markers (Murakami et al 2006a), which revealed some differentiation among accessions but overall suggested close genetic relationships among EU wild accessions. Similarly, a hop phylogenetic study (Murakami et al 2006b) identified Eurasian wild hops (Western Europe, Georgia/Caucasus, Altai), as one group with a wide geographic distribution.…”

Genic SSRs for European and North American hop (Humulus lupulus L.)

“…These SSRs were used for cultivar identification (Brady et al 1996;Cerenak et al 2004), genetic diversity evaluation among wild and cultivated hop Murakami et al 2006b), and for genetic mapping (Č erenak et al 2006). Sixty primer pairs were recently developed from six hop genomic-enriched libraries (Stajner et al 2005).…”

Phenotypic and alpha-acid content diversity of wild hop populations in Croatia

“…Studying of hop wild gene pool is of essential need for sustainability of hop production (Nesvadba 2007). Cytogenetic and molecular studies of wild hops have brighten up the phylogeny of hops (Ono 1961, Henning et al 1997, Hampton et al 2001, Hampton et al 2002, Jakše et al 2004, Murakami et al 2006, Lutz et al 2007, Nesvadba 2007, Probasco et al 2007, but a few authors reported on phenotypic variability of wild hop populations (Wormald 1915, Schmidt 1917, Salmon and Wormald 1921, Blattny 1950, Davis 1957, Ono 1961, Wagner 1974and 1975, Nesvadba 2007. However, phenotypic characterization of hop plants is the very first step that precedes the mentioned molecular analyses.…”