title: A phylogenetic analysis based on nucleotide sequence of a marker linked to the brittle rachis locus indicates a diphyletic origin of barley.
abstract: OBJECTIVE
  Barley (Hordeum vulgare ssp. vulgare) cultivation started between 9500 and 8400 years ago, and was a major part of ancient agriculture in the Near East. The brittle rachis is a critical trait in the domestication process.
  
  
  METHODS
  A DNA sequence closely linked to the brittle rachis complex was amplified and resequenced in a collection of cultivated barleys, wild barleys (H. vulgare ssp. spontaneum) and weedy brittle rachis varieties (H. vulgare ssp. vulgare var. agriocrithon). The sequence was used to construct a phylogenetic tree.
  
  
  RESULTS
  The phylogeny separated the W- (btr1-carrying) from the E- (btr2-carrying) cultivars. The wild barleys had a high sequence diversity and were distributed throughout the W- and E-clades. Some of the Tibetan var. agriocrithon lines were closely related to the E-type and others to the W-type cultivated barleys, but an Israeli var. agriocrithon line has a complex origin.
  
  
  CONCLUSIONS
  The results are consistent with a diphyletic origin of barley. The W- and E-type cultivars are assumed to have evolved from previously diverged wild barley via independent mutations at Btr1 and Btr2.
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Perumal
authors.initials: P
authors.lastname: Azhaguvel
authors.forename: Takao
authors.initials: T
authors.lastname: Komatsuda
mesh_terms: D000383:Agriculture; D018556:Crops, Agricultural / Q000235:genetics*; D035263:Flowering Tops / Q000235:genetics*; D017343:Genes, Plant; D005819:Genetic Markers; D001467:Hordeum / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D005819:Genetic Markers