Analysis of the function and regulation of the plastidial serine biosynthesis in Arabidopsis thaliana

丝氨酸（Ser）的生物合成是植物胚胎发育和胚后发育所必需的。然而，所观察到的PS途径缺陷的植物的发育和代谢缺陷的确切原因仍然难以捉摸。PS途径的基因在分生组织和发育组织中高度表达，PS途径活性降低的植物生长迟缓，细胞扩增和下胚轴伸长受到抑制。除了这些发育缺陷，PS途径缺陷的植物表现出异常积累的过氧化氢，淀粉和大多数氨基酸，包括Ser。所观察到的发育和代谢表型类似于已知的表型的植物缺乏氧化还原稳态，代谢产物和激素信号。在拟议的研究计划中，我们的目标是解开这些途径之间未知的相互作用。此外，我们的目标是阐明未知的上游组件，因为我们以前的研究和计算机分析表明，非生物和生物因素的PS途径的密集调节。PS途径在芽中的活性似乎仅限于异养/发育细胞，但对这些细胞的代谢知之甚少。因此，将分析含PS通路的细胞的翻译组，并与芽的自养/光呼吸细胞的翻译组进行比较。

Serine (Ser) biosynthesis by the phosphoserine (PS) pathway has been shown to be essential for embryonic and postembryonic plant development. However, the exact cause for the observed developmental and metabolic defects of plants deficient in the PS pathway is still elusive. The genes of the PS pathway are highly expressed in meristematic and developing tissues and plants with reduced PS pathway activity are retarded in growth and inhibited in cell expansion and hypocotyl elongation. Beside these developmental defects, PS pathway-deficient plants show an abnormal accumulation of hydrogen peroxide, starch and most amino acids including Ser. The observed developmental and metabolic phenotypes resemble known phenotypes of plants deficient in redox homeostasis, metabolite and hormone signaling. In the proposed research program we aim to unravel the unknown interaction between these pathways. In addition we aim to elucidate unknown upstream components since our previous studies and in silico analysis indicated an intensive regulation of the PS pathway by abiotic and biotic factors. The activity of the PS pathway in the shoot seems to be restricted to heterotrophic/developing cells but only little is known about these cells in terms of metabolism. Therefore, the translatome of PS pathway-containing cells will be analyzed and compared with the translatome of autotrophic/photorespiratory cells of the shoot.