title: Cellular and molecular changes associated with competence acquisition during passion fruit somatic embryogenesis: ultrastructural characterization and analysis of SERK gene expression.
abstract: The integration of cellular and molecular data is essential for understanding the mechanisms involved in the acquisition of competence by plant somatic cells and the cytological changes that underlie this process. In the present study, we investigated the dynamics and fate of Passiflora edulis Sims cotyledon explants that were committed to somatic embryogenesis by characterizing the associated ultrastructural events and analysing the expression of a putative P. edulis ortholog of the Somatic Embryogenesis Receptor-like Kinase (SERK) gene. Embryogenic calli were obtained from zygotic embryo explants cultured on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine. Callus formation was initiated by the division of cells derived from the protodermal and subprotodermal cells on the abaxial side of the cotyledons. The isodiametric protodermal cells of the cotyledon explants adopted a columnar shape and became meristematic at the onset of PeSERK expression, which was not initially detected in explant cells. Therefore, we propose that these changes represent the first observable steps towards the acquisition of a competent state within this regeneration system. PeSERK expression was limited to the early stages of somatic embryogenesis; the expression of this gene was confined to proembryogenic zones and was absent in the embryos after the globular stage. Our data also demonstrated that the dynamics of the mobilization of reserve compounds correlated with the differentiation of the embryogenic callus.
authors.affiliation: Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, Campinas, SP, 13083-862, Brazil.
authors.forename: Diego Ismael
authors.initials: DI
authors.lastname: Rocha
authors.affiliation: Institute of Life Sciences, Scuola Superiore Sant'Anna, Piazza Martiri della Libertà, Pisa, TC, 56127, Italy.
authors.forename: Daniela Lopes Paim
authors.initials: DL
authors.lastname: Pinto
authors.affiliation: Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Av. P.H. Rolfs, Viçosa, MG, 36570-900, Brazil.
authors.forename: Lorena Melo
authors.initials: LM
authors.lastname: Vieira
authors.affiliation: Departamento de Fitopatologia e Nematologia, Núcleo de Apoio à Pesquisa em Microscopia Eletrônica Aplicada à Agricultura, Universidade de São Paulo, Piracicaba, SP, 13418-900, Brazil.
authors.forename: Francisco André Ossamu
authors.initials: FA
authors.lastname: Tanaka
authors.affiliation: Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, Campinas, SP, 13083-862, Brazil.
authors.forename: Marcelo Carnier
authors.initials: MC
authors.lastname: Dornelas
authors.affiliation: Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Av. P.H. Rolfs, Viçosa, MG, 36570-900, Brazil. wotoni@ufv.br.|Departamento de Biologia Vegetal, Laboratório de Cultura de Tecidos/BIOAGRO, Campus Universitário, Universidade Federal de Viçosa, Avenida Peter Henry Rolfs s/n, 36570-900, Viçosa, MG, Brazil. wotoni@ufv.br.
authors.forename: Wagner Campos
authors.initials: WC
authors.lastname: Otoni
mesh_terms: D002454:Cell Differentiation; D015870:Gene Expression; D017343:Genes, Plant; D029598:Passiflora / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D058439:Plant Somatic Embryogenesis Techniques; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D010940:Plant Proteins; D011494:Protein Kinases
keywords: Cellular competence; In situ hybridization; Reserve mobilization; SERK gene; Somatic embryogenesis; Ultrastructure