维管植物中的质体有各种分化形式,其中淀粉体对于淀粉储存和植物生产力至关重要。尽管对叶绿体分裂的二元裂变模式有广泛的了解,我们对非光合质体复制的理解,包括淀粉体,仍然有限。最近的研究表明,当分裂器出现故障时,基质(基质填充的小管)参与质体复制。然而,潜在机制的细节及其与正常过程的相关性尚未阐明。这里,我们开发了一种实时分析系统,用于使用拟南芥(拟南芥)胚珠整合研究淀粉体复制。我们显示了淀粉体发育的完整序列,并证明了野生型淀粉体采用三种复制模式,二元裂变,多重裂变,和流弹介导的裂变,通过FtsZ环的多路放置。MinE突变体,叶绿体分裂受到严重抑制,显示出淀粉体大小的明显异质性,由质体裂变的大小依赖性但野生型模式引起。基质的动态特性区分野生型和minE表型。在minE细胞中,从巨大的淀粉体获得的延长基质稳定性,允许FtsZ环组装和收缩,以及其中淀粉颗粒的生长。尽管形成了超滑鼠,在ftsZ空突变体中,淀粉体没有增殖。这些数据阐明了淀粉体和叶绿体复制之间的差异,并证明了淀粉体的结构可塑性是其复制过程多样性的基础。此外,这项研究表明,基质可以通过FtsZ环的组装产生子质体。
Plastids in vascular plants have various differentiated forms, among which amyloplasts are crucial for starch storage and plant productivity. Despite the vast knowledge of the binary-fission mode of chloroplast division, our understanding of the replication of non-photosynthetic
plastids, including amyloplasts, remains limited. Recent studies have suggested the involvement of stromules (stroma-filled tubules) in plastid replication when the division apparatus is faulty. However, details of the underlying mechanism(s) and their relevance to normal processes have yet to be elucidated. Here, we developed a live analysis system for studying amyloplast replication using Arabidopsis (Arabidopsis thaliana) ovule integuments. We showed the full sequence of amyloplast development and demonstrated that wild-type amyloplasts adopt three modes of replication, binary fission, multiple fission, and stromule-mediated fission, via multi-way placement of the FtsZ ring. The minE mutant, with severely inhibited chloroplast division, showed marked heterogeneity in amyloplast size, caused by size-dependent but wild-type modes of plastid fission. The dynamic properties of stromules distinguish the wild-type and minE phenotypes. In minE cells, extended stromules from giant amyloplasts acquired stability, allowing FtsZ ring assembly and constriction, as well as the growth of starch grains therein. Despite hyper-stromule formation, amyloplasts did not proliferate in the ftsZ null mutant. These data clarify the differences between amyloplast and chloroplast replication and demonstrate that the structural plasticity of amyloplasts underlies the multiplicity of their replication processes. Furthermore, this study shows that stromules can generate daughter
plastids via the assembly of the FtsZ ring.