Matsuno Koya, Fujimura Tatsuhito
Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan,
Mol Genet Genomics. 2015 Aug;290(4):1551-62. doi: 10.1007/s00438-015-1018-6. Epub 2015 Mar 3.
Starch synthesis is activated in the endosperm during seed development and also in rice suspension cells cultured with abscisic acid. In the anticipation that the mechanisms of starch synthesis are similar between the endosperm and the suspension cells cultured with abscisic acid, expression of genes involved in starch synthesis was evaluated in the suspension cells after abscisic acid treatment. However, it was found that the regulatory mechanism of starch synthesis in the suspension cells cultured with abscisic acid was different from that in developing seeds. Expression analyses of genes involved in oil bodies, which accumulate in the embryo and aleurone layer, and seed storage proteins, which accumulate mainly in the endosperm, showed that the former were activated in the suspension cells cultured with abscisic acid, but the latter were not. Master regulators for embryogenesis, OsVP1 (homologue of AtABI3) and OsLFL1 (homologue of AtFUS3 or AtLFL2), were expressed in the suspension cells at levels comparable to those in the embryo. From these results, it is suggested that interactions between regulators and abscisic acid control the synthesis of phytic acid and oil bodies in the cultured cells and embryo. We suggest that the system of suspension cells cultured with abscisic acid helps to reveal the mechanisms of phytic acid and oil body synthesis in embryo.
在种子发育过程中，胚乳中的淀粉合成被激活，在用脱落酸培养的水稻悬浮细胞中也是如此。鉴于胚乳和用脱落酸培养的悬浮细胞中淀粉合成机制相似，在用脱落酸处理后的悬浮细胞中评估了参与淀粉合成的基因表达。然而，发现用脱落酸培养的悬浮细胞中淀粉合成的调控机制与发育中的种子不同。对在胚和糊粉层中积累的油体以及主要在胚乳中积累的种子贮藏蛋白相关基因的表达分析表明，前者在用脱落酸培养的悬浮细胞中被激活，而后者未被激活。胚胎发育的主要调控因子，OsVP1（AtABI3的同源物）和OsLFL1（AtFUS3或AtLFL2的同源物），在用脱落酸培养的悬浮细胞中的表达水平与在胚中的表达水平相当。从这些结果表明，调控因子与脱落酸之间的相互作用控制着培养细胞和胚中植酸和油体的合成。我们认为，用脱落酸培养的悬浮细胞体系有助于揭示胚中植酸和油体合成的机制。
