Functional and quantitative imaging study on maize kernel metabolism

玉米籽粒是最大的谷物，其胚乳在籽粒灌浆期间严重缺氧。这种缺陷（缺氧）需要在分子和生物化学水平上进行特定的适应。在之前的项目中，我们开发了一个机制框架，建立和适应玉米胚乳中的缺氧。我们发现了一个空的网络内核内，具有相关性的同化分配，并确定代谢途径（基因，代谢物），这对氧的可用性作出快速反应。基于我们的研究结果和假设，我们产生了新的基因玉米模型与调制的基因表达参与低O2信号/驯化（转录因子），线粒体代谢（2-酮戊二酸脱氢酶）和糖裂解（山梨醇脱氢酶1）。这些目标的调制预期诱导能量、氧化还原和糖代谢的变化，与籽粒生物合成性能和库强度相关。这个新项目旨在探索这些目标的功能意义。具体来说，我们在这里的目标是综合利用磁共振成像和FTIR显微光谱代谢物成像的基础上，各自的转基因和突变玉米植物的表征。此外，我们将应用代谢物和转录谱分析（通过LC/MS和RNASeq）对籽粒代谢进行全面的生化和分子表征。综合的方法将允许的相关性的生物合成能力和玉米籽粒灌浆的基因进行评估。最终目的是提高我们对主要谷类作物同化物利用和产量形成的理解。

Maize kernels are the largest cereal grains and their endosperm is severely oxygen deficient during grain fill. This deficiency (hypoxia) requires specific adaptations at the molecular and biochemical level. In the previous project, we developed a mechanistic framework for establishment of, and acclimation to hypoxia in the maize endosperm. We uncovered a void network inside the kernel, having relevance for assimilate allocation, and identified metabolic pathways (genes, metabolites) which reciprocally respond to oxygen availability. Based on our findings and hypotheses, we generated novel genetic maize models with modulated expression of genes involved in low-O2 signaling/acclimation (transcription factors), mitochondrial metabolism (2-oxoglutarate dehydrogenase) and sugar cleavage (sorbitol dehydrogenase 1). The modulation of these targets is expected to induce changes in energy, redox and sugar metabolism, with relevance for kernel biosynthetic performance and sink strength. This new project aims to explore the functional significance of these targets. Specifically, we here aim a comprehensive characterization of the respective transgenic and mutant maize plants based on the combined use of magnetic resonance imaging and FTIR microspectroscopy for metabolite imaging. In addition, we will apply metabolite and transcript profiling (via LC/MS and RNASeq) for full biochemical and molecular characterization of kernel metabolism. The integrated approach will allow an evaluation of the relevance of selected genes for biosynthetic capabilities and grain filling in maize. The ultimate aim is to enhance our understanding of assimilate usage and yield generation in major cereal crops.