title: One tissue, two fates: different roles of megagametophyte cells during Scots pine embryogenesis.
abstract: In the Scots pine (Pinus sylvestris L.) seed, embryos grow and develop within the corrosion cavity of the megagametophyte, a maternally derived haploid tissue, which houses the majority of the storage reserves of the seed. In the present study, histochemical methods and quantification of the expression levels of the programmed cell death (PCD) and DNA repair processes related genes (MCA, TAT-D, RAD51, KU80, and LIG) were used to investigate the physiological events occurring in the megagametophyte tissue during embryo development. It was found that the megagametophyte was viable from the early phases of embryo development until the early germination of mature seeds. However, the megagametophyte cells in the narrow embryo surrounding region (ESR) were destroyed by cell death with morphologically necrotic features. Their cell wall, plasma membrane, and nuclear envelope broke down with the release of cell debris and nucleic acids into the corrosion cavity. The occurrence of necrotic-like cell death in gymnosperm embryogenesis provides a favourable model for the study of developmental cell death with necrotic-like morphology and suggests that the mechanism underlying necrotic cell death is evolutionary conserved.
authors.affiliation: Department of Biology, University of Oulu, PO Box 3000, 90014 Oulu, Finland. jaana.vuosku@oulu.fi
authors.forename: Jaana
authors.initials: J
authors.lastname: Vuosku
authors.forename: Tytti
authors.initials: T
authors.lastname: Sarjala
authors.forename: Anne
authors.initials: A
authors.lastname: Jokela
authors.forename: Suvi
authors.initials: S
authors.lastname: Sutela
authors.forename: Mira
authors.initials: M
authors.lastname: Sääskilahti
authors.forename: Marja
authors.initials: M
authors.lastname: Suorsa
authors.forename: Esa
authors.initials: E
authors.lastname: Läärä
authors.forename: Hely
authors.initials: H
authors.lastname: Häggman
mesh_terms: D000165:Acridine Orange; D017209:Apoptosis / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D053938:DNA Fragmentation; D004260:DNA Repair; D018744:DNA, Plant / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D009336:Necrosis; D041605:Pinus sylvestris / Q000166:cytology* / Q000196:embryology* / Q000235:genetics; D012639:Seeds / Q000166:cytology / Q000196:embryology; D013194:Staining and Labeling; D015053:Zygote / Q000166:cytology / Q000378:metabolism
chemical_list: D018744:DNA, Plant; D000165:Acridine Orange