title: Mitogen-Activated Protein Kinase Kinase 3 Regulates Seed Dormancy in Barley.
abstract: Seed dormancy has fundamental importance in plant survival and crop production; however, the mechanisms regulating dormancy remain unclear [1-3]. Seed dormancy levels generally decrease during domestication to ensure that crops successfully germinate in the field. However, reduction of seed dormancy can cause devastating losses in cereals like wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) due to pre-harvest sprouting, the germination of mature seed (grain) on the mother plant when rain occurs before harvest. Understanding the mechanisms of dormancy can facilitate breeding of crop varieties with the appropriate levels of seed dormancy [4-8]. Barley is a model crop [9, 10] and has two major seed dormancy quantitative trait loci (QTLs), SD1 and SD2, on chromosome 5H [11-19]. We detected a QTL designated Qsd2-AK at SD2 as the single major determinant explaining the difference in seed dormancy between the dormant cultivar "Azumamugi" (Az) and the non-dormant cultivar "Kanto Nakate Gold" (KNG). Using map-based cloning, we identified the causal gene for Qsd2-AK as Mitogen-activated Protein Kinase Kinase 3 (MKK3). The dormant Az allele of MKK3 is recessive; the N260T substitution in this allele decreases MKK3 kinase activity and appears to be causal for Qsd2-AK. The N260T substitution occurred in the immediate ancestor allele of the dormant allele, and the established dormant allele became prevalent in barley cultivars grown in East Asia, where the rainy season and harvest season often overlap. Our findings show fine-tuning of seed dormancy during domestication and provide key information for improving pre-harvest sprouting tolerance in barley and wheat.
authors.affiliation: NARO Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan. Electronic address: shingo@affrc.go.jp.
authors.forename: Shingo
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: NARO Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Pourkheirandish
authors.affiliation: NARO Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Morishige
authors.affiliation: Faculty of Agriculture, Kagawa University, Kitagun, Kagawa 761-0795, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Kubo
authors.affiliation: Faculty of Agriculture, Kagawa University, Kitagun, Kagawa 761-0795, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Faculty of Agriculture, Kagawa University, Kitagun, Kagawa 761-0795, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ichimura
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Shigemi
authors.initials: S
authors.lastname: Seo
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanamori
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Wu
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Tsuyu
authors.initials: T
authors.lastname: Ando
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research, Stadt Seeland/OT Gatersleben 06466, Germany.
authors.forename: Goetz
authors.initials: G
authors.lastname: Hensel
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Sameri
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research, Stadt Seeland/OT Gatersleben 06466, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Stein
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sato
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: NARO Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yano
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Komatsuda
mesh_terms: D019943:Amino Acid Substitution; D001210:Asia, Southeastern; D005075:Biological Evolution; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics / Q000502:physiology*; D048371:MAP Kinase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D057445:Plant Dormancy / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D040641:Quantitative Trait Loci
chemical_list: D010940:Plant Proteins; D048371:MAP Kinase Kinase 3