Leaf Epidermis: The Ambiguous Symplastic Domain

Frontiers in Plant Science

Olga V. Voitsekhovskaja¹  Anastasiia I. Maksimova²  Elena V. Tyutereva²  Valeria A. Dmitrieva²  Kirill N. Demchenko²  Gertrud Lohaus³  Alexandra N. Ivanova⁴  Anna N. Melnikova⁴  Olga A. Koroleva⁵  A. Deri Tomos⁵ 

[1]Department of Plant Biochemistry, Albrecht von Haller Institute for Plant Sciences, Göttingen, Germany

[2]Komarov Botanical Institute, Russian Academy of Sciences, Saint Petersburg, Russia

[3]Molecular Plant Research/Plant Biochemistry, School of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal, Germany

[4]Saint Petersburg State University, Saint Petersburg, Russia

[5]School of Biological Sciences, Bangor University, Bangor, United Kingdom

关键词: Alonsoa meridionalis;    Asarina barclaiana;    Hordeum vulgare;    Solanum tuberosum;    leaf epidermis;    phloem loading mode;   

DOI  :  10.3389/fpls.2021.695415

来源: DOAJ

【 摘 要 】

The ability to develop secondary (post-cytokinetic) plasmodesmata (PD) is an important evolutionary advantage that helps in creating symplastic domains within the plant body. Developmental regulation of secondary PD formation is not completely understood. In flowering plants, secondary PD occur exclusively between cells from different lineages, e.g., at the L1/L2 interface within shoot apices, or between leaf epidermis (L1-derivative), and mesophyll (L2-derivative). However, the highest numbers of secondary PD occur in the minor veins of leaf between bundle sheath cells and phloem companion cells in a group of plant species designated “symplastic” phloem loaders, as opposed to “apoplastic” loaders. This poses a question of whether secondary PD formation is upregulated in general in symplastic loaders. Distribution of PD in leaves and in shoot apices of two symplastic phloem loaders, Alonsoa meridionalis and Asarina barclaiana, was compared with that in two apoplastic loaders, Solanum tuberosum (potato) and Hordeum vulgare (barley), using immunolabeling of the PD-specific proteins and transmission electron microscopy (TEM), respectively. Single-cell sampling was performed to correlate sugar allocation between leaf epidermis and mesophyll to PD abundance. Although the distribution of PD in the leaf lamina (except within the vascular tissues) and in the meristem layers was similar in all species examined, far fewer PD were found at the epidermis/epidermis and mesophyll/epidermis boundaries in apoplastic loaders compared to symplastic loaders. In the latter, the leaf epidermis accumulated sugar, suggesting sugar import from the mesophyll via PD. Thus, leaf epidermis and mesophyll might represent a single symplastic domain in Alonsoa meridionalis and Asarina barclaiana.

【 授权许可】

Unknown