title: Natural variation in Early flowering1 contributes to early flowering in japonica rice under long days.
abstract: Natural variation in heading-date genes enables rice, a short-day (SD) plant, to flower early under long-day (LD) conditions at high latitudes. Through analysis of heading-date quantitative trait loci (QTL) with F7 recombinant inbred lines from the cross of early heading 'H143' and late heading 'Milyang23 (M23)', we found a minor-effect Early Heading3 (EH3) QTL in the Hd16 region on chromosome 3. We found that Early flowering1 (EL1), encoding casein kinase I (CKI), is likely to be responsible for the EH3/Hd16 QTL, because a missense mutation occurred in the highly conserved serine/threonine kinase domain of EL1 in H143. A different missense mutation was found in the EL1 kinase domain in Koshihikari. In vitro kinase assays revealed that EL1/CKI in H143 and Koshihikari are non-functional. In F7:9 heterogeneous inbred family-near isogenic lines (HNILs), HNIL(H143) flowered 13 days earlier than HNIL(M23) in LD, but not in SD, in which EL1 mainly acts as a LD-dependent flowering repressor, down-regulating Ehd1 expression. In the world rice collection, two types of non-functional EL1 variants were found in japonica rice generally cultivated at high latitudes. These results indicate that natural variation in EL1 contributes to early heading for rice adaptation to LD in temperate and cooler regions.
authors.affiliation: Department of Plant Science, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
authors.forename: Choon-Tak
authors.initials: CT
authors.lastname: Kwon
authors.forename: Soo-Cheul
authors.initials: SC
authors.lastname: Yoo
authors.forename: Bon-Hyuk
authors.initials: BH
authors.lastname: Koo
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Cho
authors.forename: Joon-Woo
authors.initials: JW
authors.lastname: Park
authors.forename: Zhanying
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jinjie
authors.initials: J
authors.lastname: Li
authors.forename: Zichao
authors.initials: Z
authors.lastname: Li
authors.forename: Nam-Chon
authors.initials: NC
authors.lastname: Paek
mesh_terms: D000483:Alleles; D047389:Casein Kinase I / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D015536:Down-Regulation; D035264:Flowers / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D014644:Genetic Variation; D005843:Geography; D007178:Inbreeding; D020125:Mutation, Missense; D012275:Oryza / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D010766:Phosphorylation; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci / Q000235:genetics*; D013696:Temperature
chemical_list: D010940:Plant Proteins; D047389:Casein Kinase I
keywords: Early Heading3; Hd16; casein kinase I; heading-date QTL