title: KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes.
abstract: Seed shattering is an agronomically important trait. Two major domestication factors are responsible for this: qSH1 and SH5. Whereas qSH1 functions in cell differentiation in the abscission zone (AZ), a major role of SH5 is the repression of lignin deposition. We have determined that a KNOX protein, OSH15, also controls seed shattering. Knockdown mutations ofOSH15showed reduced seed-shattering phenotypes. Coimmunoprecipitation experiments revealed that OSH15 interacts with SH5 and qSH1, two proteins in the BELL homeobox family. In transgenic plants carrying theOSH15promoter-GUSreporter construct, the reporter gene was preferentially expressed in the AZ during young spikelet development. The RNA in situ hybridization experiment also showed thatOSH15messenger RNAs were abundant in the AZ during spikelet development. Analyses ofosh15 SH5-D double mutants showed thatSH5could not increase the degree of seed shattering whenOSH15was absent, indicating that SH5 functions together with OSH15. In addition to the seed-shattering phenotype,osh15mutants displayed dwarfism and accumulated a higher amount of lignin in internodes due to increased expression of the genes involved in lignin biosynthesis. Knockout mutations ofCAD2, which encodes an enzyme for the last step in the monolignol biosynthesis pathway, caused an easy seed-shattering phenotype by reducing lignin deposition in the AZ This indicated that the lignin level is an important determinant of seed shattering in rice (Oryza sativa). Chromatin immunoprecipitation assays demonstrated that both OSH15 and SH5 interact directly withCAD2chromatin. We conclude that OSH15 and SH5 form a dimer that enhances seed shattering by directly inhibiting lignin biosynthesis genes.
authors.affiliation: Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (J.Y., L.-H.C., H.W.A., G.A.); and Department of Plant Science, Research Institute of Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea (H.-J.K.).
authors.forename: Jinmi
authors.initials: J
authors.lastname: Yoon
authors.affiliation: Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (J.Y., L.-H.C., H.W.A., G.A.); and Department of Plant Science, Research Institute of Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea (H.-J.K.).
authors.forename: Lae-Hyeon
authors.initials: LH
authors.lastname: Cho
authors.affiliation: Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (J.Y., L.-H.C., H.W.A., G.A.); and Department of Plant Science, Research Institute of Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea (H.-J.K.).
authors.forename: Htet Wai
authors.initials: HW
authors.lastname: Antt
authors.affiliation: Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (J.Y., L.-H.C., H.W.A., G.A.); and Department of Plant Science, Research Institute of Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea (H.-J.K.).
authors.forename: Hee-Jong
authors.initials: HJ
authors.lastname: Koh
authors.affiliation: Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea (J.Y., L.-H.C., H.W.A., G.A.); and Department of Plant Science, Research Institute of Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea (H.-J.K.) genean@khu.ac.kr.
authors.forename: Gynheung
authors.identifier: http://orcid.org/0000-0002-8570-7587
authors.initials: G
authors.lastname: An
mesh_terms: D002523:Edible Grain / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization / Q000379:methods; D008031:Lignin / Q000096:biosynthesis*; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D018398:Homeodomain Proteins; C116401:OSH15 protein, Oryza sativa; D010940:Plant Proteins; D008031:Lignin