title: The cyclin-dependent kinase inhibitor Orysa;KRP1 plays an important role in seed development of rice.
abstract: Kip-related proteins (KRPs) play a major role in the regulation of the plant cell cycle. We report the identification of five putative rice (Oryza sativa) proteins that share characteristic motifs with previously described plant KRPs. To investigate the function of KRPs in rice development, we generated transgenic plants overexpressing the Orysa;KRP1 gene. Phenotypic analysis revealed that overexpressed KRP1 reduced cell production during leaf development. The reduced cell production in the leaf meristem was partly compensated by an increased cell size, demonstrating the existence of a compensatory mechanism in monocot species by which growth rate is less reduced than cell production, through cell expansion. Furthermore, Orysa;KRP1 overexpression dramatically reduced seed filling. Sectioning through the overexpressed KRP1 seeds showed that KRP overproduction disturbed the production of endosperm cells. The decrease in the number of fully formed seeds was accompanied by a drop in the endoreduplication of endosperm cells, pointing toward a role of KRP1 in connecting endocycle with endosperm development. Also, spatial and temporal transcript detection in developing seeds suggests that Orysa;KRP1 plays an important role in the exit from the mitotic cell cycle during rice grain formation.
authors.affiliation: Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, B-9052 Ghent, Belgium.
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Barrôco
authors.forename: Adrian
authors.initials: A
authors.lastname: Peres
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Droual
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
authors.forename: Le Son Long
authors.initials: le SL
authors.lastname: Nguyen
authors.forename: Joris
authors.initials: J
authors.lastname: De Wolf
authors.forename: Vladimir
authors.initials: V
authors.lastname: Mironov
authors.forename: Rindert
authors.initials: R
authors.lastname: Peerbolte
authors.forename: Gerrit T S
authors.initials: GT
authors.lastname: Beemster
authors.forename: Dirk
authors.initials: D
authors.lastname: Inzé
authors.forename: Willem F
authors.initials: WF
authors.lastname: Broekaert
authors.forename: Valerie
authors.initials: V
authors.lastname: Frankard
mesh_terms: D000595:Amino Acid Sequence; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012639:Seeds / Q000254:growth & development*
chemical_list: D010940:Plant Proteins; D018844:Cyclin-Dependent Kinases