Wang Dayong, Xu Yunjian, Li Qing, Hao Xuemei, Cui Keming, Sun Fangzhen, Zhu Yuxian
The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
Plant J. 2003 Jan;33(2):285-92. doi: 10.1046/j.1365-313x.2003.01627.x.
PPF1 is a gibberellin-induced, vegetative growth-specific gene, first isolated from short-day (SD)-grown G2 pea plants. In the current work, we found that transgenic Arabidopsis plants overexpressing the PPF1 gene (PPF1 (+)) flowered much later and had a significantly longer lifespan compared to control plants, whereas suppression of this gene (PPF1 (-)) resulted in a very rapid reproductive cycle. Western blotting analyses of PPF1 (+) and (-) plant lines revealed a positive correlation between the amount of antibody-reactive protein and the time of flowering. Green fluorescent protein (GFP) co-expression assays showed that the PPF1 protein is likely localized in chloroplast membranes. Transgenic expression of PPF1 affected the calcium storage capacities since chloroplasts isolated from PPF1 (+) plants contained high Ca2+ levels while chloroplasts of PPF1 (-) plants contained very low amounts of calcium ion. Using Novikoff human hepatoma cells, we demonstrated that expression of PPF1 leads to a significant inward calcium ion current that was absent in untransformed cells. We conclude that, as a putative calcium ion carrier, PPF1 affects the flowering time of higher plants by modulating Ca2+ storage capacity within chloroplasts.
PPF1是一种赤霉素诱导的、营养生长特异性基因，最初从短日照（SD）生长的G2豌豆植株中分离得到。在当前研究中，我们发现与对照植株相比，过表达PPF1基因的转基因拟南芥植株（PPF1(+)）开花晚得多且寿命显著更长，而该基因的抑制（PPF1(-)）导致生殖周期非常迅速。对PPF1(+)和(-)植株系的蛋白质免疫印迹分析揭示了抗体反应性蛋白量与开花时间之间呈正相关。绿色荧光蛋白（GFP）共表达分析表明PPF1蛋白可能定位于叶绿体膜。PPF1的转基因表达影响了钙储存能力，因为从PPF1(+)植株分离的叶绿体含有高钙水平，而PPF1(-)植株的叶绿体含有非常少量的钙离子。使用诺维科夫人类肝癌细胞，我们证明PPF1的表达导致未转化细胞中不存在的显著内向钙离子电流。我们得出结论，作为一种假定的钙离子载体，PPF1通过调节叶绿体内的钙储存能力来影响高等植物的开花时间。
