Engineering high biomass plants that produce oil (triacylglycerol or TAG) in vegetative rather than seed‐related tissues could help meet our growing demand for plant oil. Several studies have already demonstrated the potential of this approach by creating transgenic crop and model plants that accumulate TAG in their leaves and stems. However, TAG synthesis may compete with other important carbon and energy reserves, including carbohydrate production, and thereby limit plant growth. The aims of this study were thus: first, to investigate the effect of TAG accumulation on growth and development of previously generated high leaf oil tobacco plants; and second, to increase plant growth and/or oil yields by further altering carbon fixation and partitioning. This study showed that TAG accumulation varied with leaf and plant developmental stage, affected leaf carbon and nitrogen partitioning and reduced the relative growth rate and final biomass of high leaf oil plants. To overcome these growth limitations, four genes related to carbon fixation (encoding CBB cycle enzymes SBPase and chloroplast‐targeted FBPase) or carbon partitioning (encoding sucrose biosynthetic enzyme cytosolic FBPase and lipid‐related transcription factor DOF4) were overexpressed in high leaf oil plants. In glasshouse conditions, all four constructs increased early growth without affecting TAG accumulation while chloroplast‐targeted FBPase and DOF4 also increased final biomass and oil yields. These results highlight the reliance of plant growth on carbon partitioning, in addition to carbon supply, and will guide future attempts to improve biomass and TAG accumulation in transgenic leaf oil crops.

中文翻译：

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通过改变转基因叶油作物的碳代谢来提高生长和产量。

设计在营养组织而不是种子相关组织中生产油（三酰甘油或TAG）的高生物量植物可以帮助满足我们对植物油日益增长的需求。一些研究已经通过创建在叶子和茎中积累 TAG 的转基因作物和模型植物证明了这种方法的潜力。然而，TAG 合成可能会与其他重要的碳和能量储备（包括碳水化合物的生产）竞争，从而限制植物生长。因此，本研究的目的是：首先，研究 TAG 积累对先前产生的高叶油烟草植物生长和发育的影响；其次，通过进一步改变碳固定和分配来增加植物生长和/或石油产量。本研究表明，TAG积累随叶片和植物发育阶段的不同而变化，影响叶片碳氮分配，降低高叶油植物的相对生长速率和最终生物量。为了克服这些生长限制，四个与碳固定（编码 CBB 循环酶 SBPase 和叶绿体靶向 FBPase）或碳分配（编码蔗糖生物合成酶胞质 FBPase 和脂质相关转录因子 DOF4）相关的基因在高叶油植物中过度表达。在温室条件下，所有四种构建体都增加了早期生长，而不影响 TAG 积累，而叶绿体靶向的 FBPase 和 DOF4 也增加了最终生物量和油产量。这些结果强调了除了碳供应之外植物生长对碳分配的依赖，并将指导未来改善转基因叶油作物生物量和TAG积累的尝试。