W077 Identification of grain dormancy Qsd1 from wild barley

Date: Saturday, January 14, 2012
Time: 3:10 PM
Room: San Diego
Kazuhiro Sato , Okayama University, Okayama, Japan
Kazuyoshi Takeda , Okayama University, Japan
Hiroyuki Kanamori , National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
Takashi Matsumoto , National Institute of Agribiological Sciences, Tsukuba, Ibaraki, Japan
Takao Komatsuda , National Institute of Agrobiological Sciences, Ibaraki, Japan
Seed dormancy in wild barley is an adaptation trait to prevent germination and escape from summer heat in arid environments. Cloning dormancy genes in barley will contribute to understand the domestication process, and it will facilitate optimizing the trait in cultivated barley for pre-harvest sprouting and malting. Genetic factors controlling seed dormancy have been reported as quantitative trait loci (QTLs). Of these QTLs, Qsd1 at the centrometic region of chromosome 5H has been most frequently identified and showed the largest effect across mapping populations including Haruna Nijo (HN) (H. vulgare ssp. vulgare) x wild barley H602 (H. vulgare ssp. spontaneum). A series of recombinant chromosome substitution lines with segments of H602 in a HN genetic background was developed and the line with only Qsd1 among seed dormancy QTLs was selected. Seed dormancy was scored, and Qsd1 mapped with the derived 910 BC3F2 plants and further mapped with 4,792 BC3F3 plants. Two gene candidates were estimated both directing 3’ ends toward the 345bp sequences between genes. The alignment of H602 and HN genomic sequences showed SNPs and limited the mutation region within 9,467bp by the crossing-overs within two genes. Mapping of Haruna Nijo full length cDNAs on genomic sequences indicated only one non-synonymous substitution on a gene. The results of QTL analysis among nine mapping populations, on which Qsd1 was detected, agreed to have this substitution with the same dormancy effect of QTL allele. The association analysis of cultivars with known seed dormancy also supported the substitution as a cause of reduced seed dormancy in cultivated barley.