title: Biogenesis of protein bodies during vicilin accumulation in Medicago truncatula immature seeds.
abstract: BACKGROUND
  Grain legumes play a worldwide role as a source of plant proteins for feed and food. In the model legume Medicago truncatula, the organisation of protein storage vacuoles (PSV) in maturing seeds remains unknown.
  
  
  RESULTS
  The sub-cellular events accompanying the accumulation of vicilin (globulin7S) were analysed during seed mid-maturation. Immuno-detection of vicilin in light microscopy, allowed a semi-quantitative assessment of the protein body complement. The identified populations of vicilin-containing protein bodies are distinguished by their number and size which allowed to propose a model of their biogenesis. Two distributions were detected, enabling a separation of their processing at early and mid maturation stages. The largest protein bodies, at 16 and 20  days after pollination (DAP), were formed by the fusion of small bodies. They have probably attained their final size and correspond to mature vicilin aggregations. Electron microscopic observations revealed the association of the dense protein bodies with rough endoplasmic reticulum. The presence of a ribosome layer surrounding protein bodies, would support an endoplasmic reticulum-vacuole trafficking pathway.
  
  
  CONCLUSIONS
  The stastistic analysis may be useful for screening mutations of candidate genes governing protein content. The definitive evidence for an ER-storage vacuole pathway corresponds to a challenge, for the storage of post-translationally unstable proteins. It was proposed for the accumulation of one class of storage protein, the vicilins. This alternative pathway is a matter of controversy in dicotyledonous seeds.
authors.affiliation: INRA, UMR1347 Agroécologie, BP 86510, F-21000, Dijon, France. mona.darmency@dijon.inra.fr
authors.forename: Mona
authors.initials: M
authors.lastname: Abirached-Darmency
authors.forename: Fabrice
authors.initials: F
authors.lastname: Dessaint
authors.forename: Emilie
authors.initials: E
authors.lastname: Benlicha
authors.forename: Charles
authors.initials: C
authors.lastname: Schneider
mesh_terms: D018548:Cotyledon / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D046913:Medicago truncatula / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D053141:Organelle Size; D054817:Pollination; D021381:Protein Transport; D012270:Ribosomes / Q000378:metabolism; D055314:Seed Storage Proteins / Q000378:metabolism*; D012639:Seeds / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D055314:Seed Storage Proteins; C015575:vicilin protein, plant