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

通过磷酸丝氨酸(PS)途径合成丝氨酸(Ser)是植物胚胎和胚后发育所必需的。然而，观察到的PS途径缺陷植物发育和代谢缺陷的确切原因仍然是未知的。PS途径的基因在分生组织和发育中高度表达，PS途径活性降低的植物生长受阻，细胞扩张和下胚轴伸长受到抑制。除了这些发育缺陷外，PS途径缺陷植物还表现出过氧化氢、淀粉和包括丝氨酸在内的大多数氨基酸的异常积累。观察到的发育和代谢表型类似于已知的在氧化还原动态平衡、代谢产物和激素信号方面缺乏的植物的表型。在拟议的研究计划中，我们的目标是解开这些通路之间的未知相互作用。此外，我们的目标是阐明未知的上游成分，因为我们之前的研究和电子分析表明，PS途径受到非生物和生物因素的强烈调控。茎中PS途径的活性似乎仅限于异养/发育中的细胞，但对这些细胞的新陈代谢知之甚少。因此，我们将对含有PS途径的细胞的翻译组进行分析，并将其与地上部自养/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.