Abstract
Zeins are the main storage proteins in maize seed endosperm, and the onset of zein synthesis in young seeds challenges the endomembrane system and results in the formation of storage organelles. Even though zeins lack a conventional endoplasmic reticulum (ER) retention signal, they accumulate within the ER and assemble in conspicuous ER-derived protein bodies (PBs) stabilized by disulfide bridge formation and hydrophobic interaction between zein chains. Zein body formation during seed development has been extensively studied, as well as the mechanisms that lead to the initiation of PBs. However, the exact course of the PB formation process and the spatial relationship with the ER remain unclear. The development of serial block face scanning electron microscopy (SBF-SEM) techniques that allow three-dimensional imaging combined with the high resolution of electron microscopy provides new perspectives on the study of the plant endomembrane system. Here, we demonstrate that (i) the ER of maize seeds is mainly formed by massive sheets and (ii) PBs are not budding from tubules or the edge of sheets, but protrude from the entire surface of the ER sheet.
Highlights
Cereal seeds are characterized by a high degree of functional specialization for the storage of proteins and energy
On the other hand, offers a high resolution and early studies on protein bodies (PBs) biogenesis and distribution of zeins within the PBs were mostly based on transmission electron microscopy (TEM) pictures providing detailed, but only two-dimensional information, at the ultrastructural level (Lending and Larkins, 1989)
The cereal endosperm consists of four different cell types, including the embryo-surrounding region, transfer cells, the starchy endosperm and the aleurone layer
Summary
Cereal seeds are characterized by a high degree of functional specialization for the storage of proteins and energy. On the other hand, offers a high resolution and early studies on PB biogenesis and distribution of zeins within the PBs were mostly based on TEM pictures providing detailed, but only two-dimensional information, at the ultrastructural level (Lending and Larkins, 1989). Modern 3D imaging techniques with nanoscale resolution include serial section TEM or electron tomography Both techniques offer the possibility to image volumes at ultrastructural level, but the former is technically challenging and the latter is restricted to small volumes (Kittelmann, 2018). In order to investigate the ultrastructure of the ER and its spatial relationship with nascent PBs and oil bodies in a highly specialized storage tissue, we have generated 3D models based on SBF-SEM of maize endosperm cells at two stages of seed development
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
