植物种子的老化劣变是自然界的普遍现象，也是种质资源保存面临的严重问题。北京林业大学教授汪晓峰课题组研究发现，家榆种子老化过程存在典型的细胞程序性死亡特征。该研究为进一步探究延缓种子老化的方法提供了重要线索。相关成果已在线发表于《植物学报》。

虽然前人在种子老化方面做了大量工作，但仍有很多问题尚不清楚。该项研究首次阐述了ROS引发的依赖于线粒体的PCD在种子老化过程中的作用，为进一步从细胞及分子水平上阐明种子老化机理奠定了重要的理论基础。研究还证明了线粒体动力学改变是种子老化的一个先兆，为进一步探究延缓种子老化的方法提供了重要线索。

汪晓峰说，该项研究利用激光共聚焦显微镜、透射电镜检测了种子老化过程中线粒体在胞内的分布和聚集情况，证实老化过程中ROS产生与线粒体的形态改变具有时空一致性。通过生理生化检测，结果表明在种子老化初期ROS积累可能是以“报警信号”的角色存在，而非氧化胁迫，但随着其在老化过程的逐渐积累最终造成氧化损伤。

研究还发现线粒体通透性转换孔（MPTP）相关基因在老化初期明显上调，在时间上响应于活性氧的产生并与线粒体形态改变密切相关，阐明了种子细胞MPTP开放与跨膜电势的内在联系。（来源：中国科学报 郑金武 铁铮 李香云）

Reactive oxygen species (ROS)-provoked mitochondria-dependent cell death during ageing of elm (Ulmus pumila L.) seeds

Abstract  Previous studies have shown that controlled deterioration treatment (CDT) induces programmed cell death (PCD) in elm (Ulmus pumila L.) seeds, which undergo certain fundamental processes that are comparable to apoptosis in animals. In this study, the essential characteristics of mitochondrial physiology in elm seeds during CDT were identified by cellular ultrastructural analysis, whole-body optical imaging, western blotting, and semi-quantitative RT-PCR. The alteration of mitochondrial morphology was an early event during CDT, as indicated by progressive dynamic mitochondrial changes and rupture of the mitochondrial outer membrane; mitochondrial transmembrane potential (Δψm) loss ensued, and mitochondrial adenosine triphosphate (ATP) levels became depleted. The mitochondrial permeability transition pore (MPTP) inhibitor cyclosporine A (CsA) effectively suppressed these changes during ageing. The in situ localisation of reactive oxygen species (ROS) production and the evaluation of voltage-dependent anion-selective channel (VDAC) and cyclophilin D (cyp D) expression indicated that the levels of MPTP components were positively correlated to ROS production, leading to an imbalance of the cellular redox potential and ultimately to PCD. Pre-incubation with ascorbic acid (AsA) retarded mitochondrial Δψm loss and diminished the effect of CDT on seed viability. However, there were no significant changes in multiple antioxidant elements or chaperones in the mitochondria during early stages of ageing. Our results indicate that CDT can induce dynamic changes in mitochondrial physiology via increased ROS production, ultimately resulting in an irreversible loss of seed viability.

原文链接：http://onlinelibrary.wiley.com/doi/10.1111/tpj.12737/pdf