Oil-Body-Membrane Proteins and Their Physiological Functions in Plants
Oil-Body-Membrane Proteins and Their Physiological Functions in Plants
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DOI：
10.1248/bpb.33.360
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发表时间：
2010-03-01
影响因子：
2
通讯作者：
Hara-Nishimura, Ikuko
中科院分区：
文献类型：
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作者：
Shimada, Takashi L.;Hara-Nishimura, Ikuko
油料种子积累了大量的储藏脂，作为种子萌发和幼苗生长的碳源和能源。在种子成熟过程中，油体中积累了大量的储脂。种子中的油体被油球蛋白、蜡质球蛋白和甾体球蛋白三个油体膜蛋白家族所包围。这些蛋白质是植物特有的，在种子中含量很高。在这里，我们展示了油球蛋白在防止油体融合和保持种子萌发方面的独特功能。利用油球蛋白缺失突变体进行的反向遗传分析表明，油体大小与总油球蛋白含量成反比。油球蛋白含量最低的双突变体Ole1-Ole2种子细胞油体不规则增大，几乎不发芽。发芽率与油球蛋白含量呈正相关，表明种子萌发缺陷与油球蛋白缺乏导致油体膨胀有关。有趣的是，冷冻处理后在4摄氏度的吸胀抑制了单个突变体(OLE1和OLE2)的种子萌发，这些突变体在没有冷冻处理的情况下正常萌发。冷冻处理加速了油体的融合，并在油1种子中产生偏心核，从而导致种子死亡。综上所述，我们的发现表明，油球蛋白通过防止越冬时油体的异常融合来提高油籽的生存能力。对油球蛋白的了解不仅有助于深入了解油料种子的耐寒性，还有助于创造转基因植物以开发生物能源和生物质资源。
Oilseeds accumulate a large amount of storage lipids, which are used as sources of carbon and energy for seed germination and seedling growth. The storage lipids are accumulated in Oil bodies during seed maturation. Oil bodies in seeds are surrounded with three oil-body-membrane protein families, oleosins, caleosins and steroleosins. These proteins are plant-specific and much abundant in seeds. Here we show a unique function of oleosins in preventing fusion of oil bodies and Maintaining seed germination. Reverse genetic analysis using oleosin-deficient mutants shows the inverse proportion of oil-body sizes to total oleosin contents. The double mutant ole1 ole2 with file lowest levels of oleosins has irregularly-enlarged oil bodies throughout the seed cells, and hardly germinates. Germination rates are positively associated with oleosin contents, suggesting that the defects of germination are related to the expansion of oil bodies due to oleosin deficiency. Interestingly freezing treatment followed by imbibition at 4 degrees C inhibits seed germination Of Single mutants (ole1 and ole2), which germinate normally without freezing treatment. The freezing treatment accelerates the fusion of oil bodies and generates eccentric nuclei in ole1 seeds, which caused seed mortality. Taken together, our findings suggest that oleosins increase the viability of oilseeds by preventing, abnormal fusion of oil bodies for overwintering. Knowledge of oleosin contributes a great deal to not only all insight into freezing tolerance of oilseeds, but also creating genetically modified plants for developing a bioenergy and biomass resource.