トウモロコシ根の重力応答に伴うCa イオン動態の解析

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■原著■ 2008 年度神奈川大学総合理学研究所共同研究助成論文To provide information about the role of Ca and other ions in the regulation of gravitropic response, conventional electron microscopic observation of bulk and ultrathin sections and quantitative X-ray microanalysis of cryosections, obtained from the statenchyma of corn roots grown under gravity or simulated microgravity, were carried out. In columella cells of the statenchyma, amyloplasts were exclusively localized at the bottom of cells grown undernormal gravity. In those cells of corn roots grown under simulated microgravity, amyloplasts were diffusely distributed in the columella cells, indicating that amyloplasts function as a statolith. In the quantitative X-ray microanalysis of cryosections, small amount of Ca was detectedin the cytoplasmic matrix of columella cells in corn roots grown under simulated microgravity. However the concentration of K was significantly decreased in cytoplasmic matrix and vacuole of columella cells, although it could not change in cell walls surrounding these cells. This finding may indicate that, during gravitational disturbance, K ions move entirely towardthe extracellular space. Further experiments are now needed to clarify the possibility that Ca ions play a role in regulating K ion movement during gravitropic response.
2009-06-30