title: Vacuolar biogenesis and aquaporin expression at early germination of broad bean seeds.
abstract: A key event in seed germination is water uptake-mediated growth initiation in embryonic axes. Vicia faba var. minor (broad bean) seeds were used for studying cell growth, vacuolar biogenesis, expression and function of tonoplast water channel proteins (aquaporins) in embryonic axes during seed imbibition, radicle emergence and growth. Hypocotyl and radicle basal cells showed vacuole restoration from protein storage vacuoles, whereas de novo vacuole formation from provacuoles was observed in cells newly produced by root meristem. cDNA fragments of seven novel aquaporin isoforms including five Tonoplast Intrinsic Proteins (TIP) from three sub-types were amplified by PCR. The expression was probed using q-RT-PCR and when possible with isoform-specific antibodies. Decreased expression of TIP3s was associated to the transformation of protein storage vacuoles to vacuoles, whereas enhanced expression of a TIP2 homologue was closely linked to the fast cell elongation. Water channel functioning checked by inhibitory test with mercuric chloride showed closed water channels prior to growth initiation and active water transport into elongating cells. The data point to a crucial role of tonoplast aquaporins during germination, especially during growth of embryonic axes, due to accelerated water uptake and vacuole enlargement resulting in rapid cell elongation.
authors.affiliation: Institute of Plant Physiology of Russian Academy of Sciences, Botanicheskaya str. 35, Moscow 127276, Russia.
authors.forename: Galina V
authors.initials: GV
authors.lastname: Novikova
authors.affiliation: INRA Montpellier SupAgro, F-34060 Montpellier, Cedex 2, France.
authors.forename: Colette
authors.initials: C
authors.lastname: Tournaire-Roux
authors.affiliation: Institute of Plant Physiology of Russian Academy of Sciences, Botanicheskaya str. 35, Moscow 127276, Russia.
authors.forename: Irina A
authors.initials: IA
authors.lastname: Sinkevich
authors.affiliation: Institute of Plant Physiology of Russian Academy of Sciences, Botanicheskaya str. 35, Moscow 127276, Russia.
authors.forename: Snejana V
authors.initials: SV
authors.lastname: Lityagina
authors.affiliation: INRA Montpellier SupAgro, F-34060 Montpellier, Cedex 2, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Maurel
authors.affiliation: Institute of Plant Physiology of Russian Academy of Sciences, Botanicheskaya str. 35, Moscow 127276, Russia. Electronic address: n.obroucheva@mail.ru.
authors.forename: Natalie
authors.initials: N
authors.lastname: Obroucheva
mesh_terms: D020346:Aquaporins / Q000378:metabolism*; D018525:Germination / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D012639:Seeds / Q000166:cytology* / Q000502:physiology*; D014617:Vacuoles / Q000378:metabolism* / Q000502:physiology*; D014867:Water / Q000378:metabolism
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D014867:Water
keywords: Cell elongation; Gene expression; Seed germination; Tonoplast aquaporins; Vacuole biogenesis; Vicia faba minor; Water transport