title: Expression patterns of two glutamine synthetase genes in zygotic and somatic pine embryos support specific roles in nitrogen metabolism during embryogenesis.
abstract: Here, embryo-specific patterns of glutamine synthetase (GS) genes were studied for the first time using pine somatic and zygotic embryogenesis as model systems. GS1a expression was absent in zygotic embryos whereas it was detected in the cotyledons of somatic embryos at late developmental stages along with transcripts for photosynthesis genes and arginase. These findings suggest that germination was initiated in maturing somatic embryos. GS1b transcripts were found mainly in procambial cells in both zygotic and somatic embryos. Expression of the GS1b in procambial cells before the differentiation of mature vascular elements indicated that this gene could be useful as a molecular marker for early stages of vascular differentiation in pine. Accordingly, a correlation was found between the quality of somatic embryos generated from three different cell lines and the pattern and level of GS1b expression. Our data suggest that GS1a and GS1b genes play distinct functional roles in the biosynthesis and mobilization of seed nitrogen reserves. Furthermore, the results presented may have potential application for improving conifer somatic embryogenesis.
authors.affiliation: Departamento de Biología Molecular y Bioquímica. Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, ES-29071 Málaga, Spain.
authors.forename: María J Pérez
authors.initials: MJ
authors.lastname: Rodríguez
authors.forename: María Fernanda
authors.initials: MF
authors.lastname: Suárez
authors.forename: Raúl
authors.initials: R
authors.lastname: Heredia
authors.forename: Concepción
authors.initials: C
authors.lastname: Avila
authors.forename: David
authors.initials: D
authors.lastname: Breton
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Trontin
authors.forename: Lada
authors.initials: L
authors.lastname: Filonova
authors.forename: Peter
authors.initials: P
authors.lastname: Bozhkov
authors.forename: Sara
authors.initials: S
authors.lastname: von Arnold
authors.forename: Luc
authors.initials: L
authors.lastname: Harvengt
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Cánovas
mesh_terms: D002454:Cell Differentiation; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D028223:Pinus / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen