title: Micro-CT observations of the 3D distribution of calcium oxalate crystals in cotyledons during maturation and germination in Lotus miyakojimae seeds.
abstract: The cotyledon of legume seeds is a storage organ that provides nutrients for seed germination and seedling growth. The spatial and temporal control of the degradation processes within cotyledons has not been elucidated. Calcium oxalate (CaOx) crystals, a common calcium deposit in plants, have often been reported to be present in legume seeds. In this study, micro-computed tomography (micro-CT) was employed at the SPring-8 facility to examine the three-dimensional distribution of crystals inside cotyledons during seed maturation and germination of Lotus miyakojimae (previously Lotus japonicus accession Miyakojima MG-20). Using this technique, we could detect the outline of the embryo, void spaces in seeds and the cotyledon venation pattern. We found several sites that strongly inhibited X-ray transmission within the cotyledons. Light and polarizing microscopy confirmed that these areas corresponded to CaOx crystals. Three-dimensional observations of dry seeds indicated that the CaOx crystals in the L. miyakojimae cotyledons were distributed along lateral veins; however, their distribution was limited to the abaxial side of the procambium. The CaOx crystals appeared at stage II (seed-filling stage) of seed development, and their number increased in dry seeds. The number of crystals in cotyledons was high during germination, suggesting that CaOx crystals are not degraded for their calcium supply. Evidence for the conservation of CaOx crystals in cotyledons during the L. miyakojimae germination process was also supported by the biochemical measurement of oxalic acid levels.
authors.affiliation: Graduate School of Life Science, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan. dyamauch@sci.u-hyogo.ac.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamauchi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tamaoki
authors.forename: Masato
authors.initials: M
authors.lastname: Hayami
authors.forename: Miyuki
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Ichirou
authors.initials: I
authors.lastname: Karahara
authors.forename: Mayuko
authors.initials: M
authors.lastname: Sato
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishioka
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Terada
authors.forename: Kentaro
authors.initials: K
authors.lastname: Uesugi
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takano
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kagoshima
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Mineyuki
mesh_terms: D002129:Calcium Oxalate / Q000032:analysis* / Q000737:chemistry; D018548:Cotyledon / Q000166:cytology / Q000378:metabolism*; D018525:Germination / Q000502:physiology; D000070116:Lotus / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D055114:X-Ray Microtomography
chemical_list: D002129:Calcium Oxalate