title: An apomixis-linked ORC3-like pseudogene is associated with silencing of its functional homolog in apomictic Paspalum simplex.
abstract: Apomixis in plants consists of asexual reproduction by seeds. Here we characterized at structural and functional levels an apomixis-linked sequence of Paspalum simplex homologous to subunit 3 of the ORIGIN RECOGNITION COMPLEX (ORC3). ORC is a multiprotein complex which controls DNA replication and cell differentiation in eukaryotes. Three PsORC3 copies were identified, each one characterized by a specific expression profile. Of these, PsORC3a, specific for apomictic genotypes, is a pseudogene that was poorly and constitutively expressed in all developmental stages of apomictic flowers, whereas PsORC3b, the putative functional gene in sexual flowers, showed a precise time-related regulation. Sense transcripts of PsORC3 were expressed in the female cell lineage of both apomictic and sexual reproductive phenotypes, and in aposporous initials. Although strong expression was detected in sexual early endosperm, no expression was present in the apomictic endosperm. Antisense PsORC3 transcripts were revealed exclusively in apomictic germ cell lineages. Defective orc3 mutants of rice and Arabidopsis showed normal female gametophytes although the embryo and endosperm were arrested at early phases of development. We hypothesize that PsORC3a is associated with the down-regulation of its functional homolog and with the development of apomictic endosperm which deviates from the canonical 2(maternal):1(paternal) genome ratio.
authors: Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina.
authors: Lorena A
authors: LA
authors: Siena
authors: Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina.
authors: Juan Pablo A
authors: JP
authors: Ortiz
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy.
authors: Ornella
authors: O
authors: Calderini
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy.
authors: Francesco
authors: F
authors: Paolocci
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy.
authors: Maria E
authors: ME
authors: Cáceres
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy.
authors: Pankaj
authors: P
authors: Kaushal
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy.
authors: Simone
authors: S
authors: Grisan
authors: Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, (S2125ZAA) Zavalla, Argentina.
authors: Silvina C
authors: SC
authors: Pessino
authors: Istituto di Bioscienze e Biorisorse (IBBR-CNR), via della Madonna alta 130, I-06128 Perugia, Italy fulvio.pupilli@ibbr.cnr.it.
authors: Fulvio
authors: F
authors: Pupilli
mesh_terms: D060832:Apomixis / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017403:In Situ Hybridization; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000235:genetics; D031781:Paspalum / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011544:Pseudogenes; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger
keywords: Apomixis; Paspalum; gene silencing; origin recognition complex; seed development.