Cellular plasticity in response to suppression of storage proteins in the Brassica napus embryo

The trade-off between protein and oil storage in oilseed crops has been tested here in oilseed rape (Brassica napus) by analyzing the effect of suppressing key genes encoding protein storage products (napin, cruciferin). The phenotypic outcomes were assessed using nuclear magnetic resonance and mass spectrometry imaging, microscopy, transcriptomics, proteomics, metabolomics, lipidomics, immunological assays as well as by flux balance analysis. Surprisingly, the profile of storage products was only moderately changed in RNAi transgenics. However, embryonic cells had undergone remarkable architectural rearrangements. The suppression of storage proteins led to the elaboration of membrane stacks enriched with oleosin (6-fold higher protein abundance) and novel ER morphology. Protein rebalancing, and amino acid metabolism were focal points of the metabolic adjustments to maintain embryonic carbon/nitrogen homeostasis. Flux balance analysis indicated a rather minor additional demand for cofac...

本研究以甘蓝型油菜（Brassica napus）为材料，通过分析抑制编码蛋白质储存产物（napin蛋白、十字花科蛋白）关键基因的效应，验证了油料作物中蛋白质与油脂储存之间的权衡关系。研究采用核磁共振（nuclear magnetic resonance）、质谱成像（mass spectrometry imaging）、显微镜技术、转录组学、蛋白质组学、代谢组学、脂质组学、免疫学检测以及通量平衡分析（flux balance analysis）等方法评估表型结果。令人惊讶的是，RNAi转基因植株中储存产物的谱图仅发生中度改变；然而，胚胎细胞却经历了显著的结构重排。储存蛋白的抑制导致富含油体蛋白（oleosin）的膜堆叠结构细化（蛋白丰度提高6倍），并形成了新的内质网（Endoplasmic Reticulum, ER）形态。为维持胚胎碳氮稳态，蛋白质重平衡与氨基酸代谢成为代谢调整的核心焦点。通量平衡分析显示，辅因子的额外需求相当微小……