A phylogenetic analysis based on nucleotide sequence of a marker linked to the brittle rachis locus indicates a diphyletic origin of barley.
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.
Azhaguvel
Perumal
P
National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8642, Japan.
Komatsuda
Takao
T
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
D005819:Genetic Markers