Symplasmic Isolation Contributes to Somatic Embryo Induction and Development in the Tree Fern Cyathea delgadii Sternb

Abstract

In this report, we describe studies on symplasmic communication and cellular rearrangement during direct somatic embryogenesis (SE) in the tree fern Cyathea delgadii. We analyzed changes in the symplasmic transport of low-molecular weight fluorochromes, such as 8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt (HPTS) and fluorescein (delivered to cells as fluorescein diacetate – FDA), within stipe explants and somatic embryos originating from single epidermal cells and developing during 16 days long culture. Induction of SE is preceded by a restriction in fluorochrome distribution between certain explant cells. Microscopic analysis showed a series of cellular changes like decrease of vacuole size, increase of vacuoles numbers, increased density of cytoplasm and deposition of electron-dense material in cell walls which may be related with embryogenic transition. In somatic embryo, the limited symplasmic communication between its cells was observed first in linear tri-cellular embryo. Further development of the fern embryo was associated with the formation of symplasmic domains corresponding to the four segments of the plant body. Using symplasmic tracers, we provided evidence that the changes in plasmodesmata permeability are corelated with somatic-to-embryogenic transition and somatic embryo development.

Polish Contribution to Global Research on Somatic Embryogenesis

“…is system can easily track it from the induction phase through the first embryogenic division to the formation of embryo segments from which organs differentiate. Current research has shown that the course of SE in C. delgadii depends on cytoplasmic connectivity between the cells of the initial explant and the cells of the somatic embryo (Grzyb et al, 2020). ese studies also confirmed the occurrence of isolation during the induction of embryogenesis and differentiation of the embryo body.…”

Apoplastic and Symplasmic Markers of Somatic Embryogenesis

“…Symplasmic domains were determined for embryogenesis [ 66 , 81 , 82 , 83 , 84 ], androgenesis [ 85 ], and somatic embryogenesis [ 67 , 86 , 87 , 88 , 89 , 90 ].…”

“…Studies on symplasmic communication during SE were performed using the example of direct somatic embryogenesis in the tree fern Cyathea delgadii [ 87 ]. An analysis using low-molecular-weight fluorochromes showed that the restriction in symplasmic communication preceded the induction of SE.…”

Komunikacja symplastowa – nadkomórkowy system regulacji różnicowania komórek

“…Badania komunikacji symplastowej w trakcie somatycznej embriogenezy na przykładzie Arabidopsis wykazały, ze izolacja symplastowa jest niezbędnym czynnikiem dla przejścia komórek ze stanu somatycznego w embriogenny [41,50]. Podobną zasadę wykazano w trakcie somatycznej embriogenezy paproci drzewiastej Cyathea delgadii Sternb [51].…”