ABI4介导油脂和糖代谢进而调控种子寿命的分子机制

种子贮藏期间寿命与活力逐渐下降，直接影响到种子萌发及萌发后生长；因此，延长其寿命、维持高水平种子活力对于植物生命周期至关重要。种子贮藏期间油脂和糖代谢与种子寿命密切相关，但确切的调控机制尚未明晰。我们前期研究发现，拟南芥转录因子ABI4具有维持种子活力的功能。abi4种子油脂含量与野生型无明显差异，对人工老化处理敏感；长期贮藏的突变体种子萌发后生长受到抑制，外施蔗糖则可回复其表型；进一步发现其三酰甘油代谢关键基因SDP1转录显著下调，由此推测ABI4可能介导油脂向糖的转化进而调控种子寿命，但具体机理有待深入研究。本项目将利用ABI4已有的相关遗传材料，分析种子贮藏过程中油脂和糖等能量代谢变化，检测这些代谢通路上关键基因表达情况，通过染色质免疫共沉淀、凝胶阻滞、酵母单杂交等方法筛选ABI4直接调控的靶标基因，在ABI4与油脂和糖代谢通路之间建立直接分子联系，最终揭示其调控种子寿命的分子机理。

The seed longevity and vitality decreased gradually during storage, which directly influence seed germination and post-germination growth. Consequently, prolongation of seed longevity and maintenance of seed vitality are important for plant life cycle. Numerous studies demonstrated that the strengthen of triacylglycerol, fatty acid and sugar metabolism during seed storage is closely related to seed longevity, while the regulatory mechanisms are large unknown so far. In the previous investigation, we found that Arabidopsis transcription factor ABI4 is involved in the maintenance of seed vitality. No difference was detected in regard to the content of several types of fatty acids between abi4 and Wild Type seeds. The abi4 mutant seeds are sensitive to controlled deterioration treatment. The post-germination growth of long-term storage abi4 seeds are impaired significantly, while exogenous application of sucrose fully rescue its phenotype. Further qPCR assay revealed that the transcription level of SDP1 (Sugar Dependent 1) in abi4 seeds is down-regulated, and the latter encodes a triacylglycerol lipase that initiates hydrolysis of oil in seed. Altogether, these evidences strongly suggested that the transition from oil to sucrose is impaired in abi4 mutant background during storage, but the detailed mechanisms are needed further dissection. This project will employ the available genetic materials of ABI4, and further investigate the changes of energy substances including soluble sugar and oil during seed storage, and analyses the expression pattern of the key genes involved in those metabolic pathways. Subsequently, we will employ several assays including chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay (EMSA), yeast one hybrid and transient expression system in tobacco to identify the direct target genes of ABI4. Finally, we hope construct the direct relationship between ABI4 and the oil and sugar metabolic pathways, and present the molecular mechanisms through which ABI4 precisely regulates seed longevity.