19. タバコ培養細胞 BY-2 のアミロプラスト分化誘導系におけるブラシノライドの効果

概要

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Brassinosteroids (BRs) are steroidal phytohormones that are essential for many processes in plant growth and development, such as cell expansion, vascular differentiation, and responses to stress. The effects of BRs on cell division are unclear, as attested by contradictory published results. To determine the effect of BRs on cell division, we used the tobacco BY-2 cell line, which is a widely-used model system in plant cell biology. We found that brassinolide (BL) promoted cell division only during the early phase of the culture and in the absence of auxin (2,4-D). This promotion of cell division was confirmed by RNA gel blot analyses using cell-cycle-related gene probes. At later stages in the culturing periods of BL-supplied and 2,4-D-supplied BY-2 cells, differences in cell multiplication and cell-cycle-related gene expression were observed. To determine whether suppressed organellar DNA replication limited this promotion of cell division during the early culture phase, we examined this replication and found that BL treatment had no effect on activating organellar (plastid-and mitochondrial-) DNA synthesis. As preferential organellar DNA synthesis, which is activated by 2,4-D, is necessary during successive cell divisions in BY-2 cells, our data suggest that the mechanism of the promotion of cell division by BL treatment is distinct from that regulated by the balance of auxin and cytokinin.
植物化学調節学会の論文
2003-10-10