Molecular Physiology of Endosperm-limited Seed Germination - Gene Function and Regulation in the Endosperm of Brassicaceae Species

大多数被子植物的成熟种子是胚乳的，在许多情况下，覆盖胚根的珠孔胚乳是胚扩展和种子萌发的机械约束。我们对大麦和拟南芥的跨种研究表明，胚乳弱化是这些十字花科植物的一个重要特征。我们利用种子组织特异性转录组分析、遗传转化、qRT-PCR、萌发生理学、细胞壁生物化学、反向遗传学和生物力学等方法，建立了独行草作为跨学科种子研究的模式系统。我们的新工作计划包括识别和分析反向遗传学的组织特异性启动子和利用我们的种子组织特异性转录组进行种子研究的qRT-PCR优越的管家基因。我们希望进一步优化我们的独生子种子反向遗传技术。两种组织特异性反向遗传学方法以GA受体GID1(上游，信号)和果胶修饰酶为下游机制，以麻疯树胚乳弱化为靶点。果胶介导的机理(S)属于后期弱化机理。胚乳特异的cDNA文库和早期时间点的组织特异性跨物种转录组分析将被用于识别早期胚乳弱化靶标。该项目旨在提供改变胚乳弱化上下游机制的转基因种子，以进行功能和生物力学分析，并将为研究种子萌发过程中胚乳功能提供新的视角。

The mature seeds of most angiosperm species are endospermic and in many cases the micropylar endosperm that covers the radicle is a mechanical constraint to embryo expansion and seed germination. We have shown by cross-species work with Lepidium sativum (Lepidium, big seeds) and Arabidopsis that endosperm weakening is an important trait of these Brassicaceae species. We have used seed-tissue-specific transcriptome analysis, genetic transformation, qRT-PCR, germination physiology, cell-wall biochemistry, reverse-genetics, and biomechanics to establish Lepidium as a model system for interdisciplinary seed research. Our new work plan includes as goals to identify and analyse tissue-specific promoters for reverse-genetics and superior housekeeping genes for qRT-PCR for seed research by utilizing our seed-tissue-specific transcriptome. We want to further optimize our reverse-genetics techniques for Lepidium seeds. Two tissue specific reverse-genetics approaches have the GA receptor GID1 (upstream, signaling) and pectin modifying enzymes as downstream mechanism for Lepidium endosperm weakening as targets. Pectin-mediated mechanism(s) belong to the late weakening mechanisms. Endosperm-specific cDNA libraries and tissue-specific cross-species transcriptome analysis at early time points will be used to identify early endosperm weakening targets. This project aims to deliver transgenic seeds altered in upstream and downstream mechanisms of endosperm weakening for functional and biomechanical analysis and will provide novel insight into endosperm function during seed germination.