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首页> 美国卫生研究院文献>Proceedings of the National Academy of Sciences of the United States of America >PNAS Plus: The plastidial pentose phosphate pathway is essential for postglobular embryo development in Arabidopsis
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PNAS Plus: The plastidial pentose phosphate pathway is essential for postglobular embryo development in Arabidopsis

机译：PNAS Plus：质朴戊糖磷酸途径对于拟南芥球状胚发育至关重要

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摘要

Large numbers of genes essential for embryogenesis in Arabidopsis encode enzymes of plastidial metabolism. Disruption of many of these genes results in embryo arrest at the globular stage of development. However, the cause of lethality is obscure. We examined the role of the plastidial oxidative pentose phosphate pathway (OPPP) in embryo development. In nonphotosynthetic plastids the OPPP produces reductant and metabolic intermediates for central biosynthetic processes. Embryos with defects in various steps in the oxidative part of the OPPP had cell division defects and arrested at the globular stage, revealing an absolute requirement for the production via these steps of ribulose-5-phosphate. In the nonoxidative part of the OPPP, ribulose-5-phosphate is converted to ribose-5-phosphate (R5P)—required for purine nucleotide and histidine synthesis—and subsequently to erythrose-4-phosphate, which is required for synthesis of aromatic amino acids. We show that embryo development through the globular stage specifically requires synthesis of R5P rather than erythrose-4-phosphate. Either a failure to convert ribulose-5-phosphate to R5P or a block in purine nucleotide biosynthesis beyond R5P perturbs normal patterning of the embryo, disrupts endosperm development, and causes early developmental arrest. We suggest that seed abortion in mutants unable to synthesize R5P via the oxidative part of the OPPP stems from a lack of substrate for synthesis of purine nucleotides, and hence nucleic acids. Our results show that the plastidial OPPP is essential for normal developmental progression as well as for growth in the embryo.
机译：拟南芥中胚发生所必需的大量基因编码质体代谢的酶。许多这些基因的破坏导致胚胎在球形发育阶段停滞。但是，致死性的原因尚不清楚。我们检查了质体氧化戊糖磷酸途径（OPPP）在胚胎发育中的作用。在非光合作用的质体中，OPPP产生用于中央生物合成过程的还原剂和代谢中间体。在OPPP氧化部分的各个步骤中具有缺陷的胚胎具有细胞分裂缺陷，并在球状阶段停滞，这显示了通过这些步骤生成5磷酸核糖的绝对要求。在OPPP的非氧化部分中，将核糖5磷酸转化为核糖5磷酸（R5P）（嘌呤核苷酸和组氨酸合成所需），然后转化为赤藓糖4磷酸，这是芳香氨基合成所必需的。酸。我们表明，通过球状阶段的胚胎发育特别需要合成R5P而不是4磷酸赤藓糖。无法将5磷酸核糖转化为R5P或嘌呤核苷酸生物合成中的R5P以外的阻滞干扰了胚胎的正常构图，破坏了胚乳的发育，并导致了早期发育停滞。我们建议无法通过OPPP的氧化部分合成R5P的突变体中的种子流产是由于缺乏嘌呤核苷酸和核酸合成的底物。我们的结果表明，质体OPPP对于正常的发育进程以及胚胎的生长至关重要。

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