油菜核苷酸三磷酸转运蛋白调控种子油脂合成的生化与分子机制

Seed oil biosynthesis is a complicated process regulated by key enzymes in biosynthesis pathway, transcriptional factors, oil binding proteins and metabolite transporters. Nucleotide triphosphate transporter (NTT) is responsible for transferring cytoplasmic ATP into plastid, to satisfy the needs of fatty acid biosynthesis and other metabolism activities. However, there is no evidence that whether NTT could bind to and transfer ATP into plastid, and also whether NTT participates in regulation of seed oil biosynthesis in plant. In this project, we intend to study whether NTT transfers ATP and regulates seed oil biosynthesis, and had identified that overexpression of BnNTTC6-2 and BnNTTC8 significantly increased seed oil content in rapeseed. Still, this study will further analyze whether BnNTT binds to and transfers cytoplasmic ATP into plastid, and clarifiy the significance of BnNTT in seed oil biosynthesis through oil content, fatty acid and lipidome analysis. Last, we will preliminarily elucidate the biochemical and molecular mechanism of BnNTT in regulation of seed oil content of Brassica napus.

植物种子油脂合成是一个复杂的过程，受到合成途径关键酶、转录因子、油脂体结合蛋白和代谢物转运蛋白等调控。核苷酸三磷酸转运蛋白（NTT）负责将胞质ATP转运至质体，满足脂肪酸合成和其他代谢活动需要。植物中NTT是否结合并转运ATP还没有实验证据，NTT是否参与调控种子油脂合成也尚未报道。本项目拟开展油菜NTT转运ATP并调控种子油脂合成的相关研究，已经分析鉴定BnNTTC6-2与BnNTTC8显著提高种子含油率。本项目将进一步分析BnNTT是否结合并转运胞质ATP进入质体，通过含油量、脂肪酸和脂质组分析，明确BnNTT对油菜种子油脂合成的影响。初步阐明BnNTT参与调控油菜种子油脂合成的生化与分子机制。

质体定位的核苷酸三磷酸转运蛋白（NTT）将胞质三磷酸腺苷（ATP）转运到质体中，以满足质体中生物化学活性的需求。本项目研究了油菜中两个保守的BnaNTT1基因，BnaC06.NTT1b和BnaA07.NTT1a以及一个保守的BnaNTT2基因，BnaC08.NTT2的关键功能。结合测定和代谢分析表明，BnaNTT1和BnaNTT2结合ATP/二磷酸腺苷（ADP），转运胞质ATP进入叶绿体，并将ADP交换到细胞质。油菜NTT1与NTT2的CRISPR突变体叶绿体结构异常、且植株生长受到抑制。BnaC06.NTT1b和BnaA07.NTT1a或BnaC08.NTT2在质体中ATP/ADP稳态的调节中起重要作用。BnaC06.NTT1b和BnaA07.NTT1a或BnaC08.NTT2和BnaA08.NTT2的变化导致糖酵解和膜脂质组成的显著变化，表明质体中ATP的增加会促进更多的种子油脂积累。总之，这项研究揭示了BnaC06.NTT1b和BnaA07.NTT1a或BnaC08.NTT2在油菜植物代谢和生长中的重要作用。