Micro-CT observations of the 3D distribution of calcium oxalate crystals in cotyledons during maturation and germination in Lotus miyakojimae seeds

Daisuke Yamauchi, Daisuke Tamaoki, Masato Hayami, Miyuki Takeuchi, Ichirou Karahara, Mayuko Sato, Kiminori Toyooka, Hiroshi Nishioka, Yasuko Terada, Kentaro Uesugi, Hidekazu Takano, Yasushi Kagoshima, Yoshinobu Mineyuki

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)353-361
Number of pages9
JournalJournal of Electron Microscopy
Volume62
Issue number3
DOIs
Publication statusPublished - 2013 Jun
Externally publishedYes

Keywords

  • Lotus seed
  • SPring-8
  • calcium oxalate crystals
  • micro-CT
  • synchrotron radiation

ASJC Scopus subject areas

  • Instrumentation

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