Plastids and stromules interact with the nucleus and cell membrane in vascular plants

Abstract

The various metabolic activities of plastids require continuous exchange of reactants and products with other organelles of the plant cell. Physical interactions between plastids and other organelles might therefore enhance the efficiency of plant metabolism. We have observed a close apposition of plastids and nuclei in various organs of Nicotiana tabacum and Arabidopsis thaliana. In hypocotyl epidermal cells, plastids and stromules, stroma-filled tubular extensions of the plastid envelope membrane, were observed to reside in grooves and infoldings of the nuclear envelope, indicating a high level of contact between the two organelle membranes. In a number of non-green tissues, including suspension-cultured cells, perinuclear plastids were frequently associated with long stromules that extended from the cell center to the cell membrane. In cotyledon petioles, cells lying adjacent to one another frequently contained stromules that met on either side of the shared cell wall, suggesting a means of intercellular communication. Our results therefore suggest that stromules have diverse roles within plant cells, perhaps serving as pathways between nuclei and more distant regions of the cell and possibly even other cells.

Do plastids inDendrobiumcv. Lucky Duan petals function similar to autophagosomes and autolysosomes?

“…36,37 Furthermore, stromules have been shown to extend into the cytoplasm, generally, in a rather straight line. 34,35 This was not found in the present material. The data suggest, therefore, that the plastids did not form protrusions of any type, including stromules.…”

“…They can extend far into the cytoplasm, are able to interconnect plastids and allow the transfer of protein complexes as large as 550 kDa. 33 Using light microscopy the stromule diameter varied between 0.3 and 0.8 μm 34,35 whilst TEM showed stromules of about 0.4 μm diameter. 37 The means and standard deviation of the diameter of the thin plastid strands …”

Glycerolipid transfer for the building of membranes in plant cells

“…In different tissues of tobacco and Arabidopsis, stromules interact with the nucleus, the plasma membrane and mitochondria. They possibly support transfers such as DAG, PC or DGDG transfers, although this role of stromules has never been demonstrated [89,90]. Other plastid envelope structures have been visualised to resemble myelin.…”

Low-Phosphate Induction of Plastidal Stromules Is Dependent on Strigolactones But Not on the Canonical Strigolactone Signaling Component MAX2

“…SFs were similar to those previously reported for Arabidopsis (Holzinger et al, 2008;Newell et al, 2012). Because hypocotyl epidermal cells were used to study stromules in numerous previous publications (Hanson and Sattarzadeh, 2013;Kwok and Hanson, 2004;Holzinger, Kwok et al, 2008;Newell et al, 2012), we selected these cells to evaluate the effect of different treatments involving low phosphate, sugars, or strigolactones.…”

“…Thus, stromules give a large increase in the potential contact between plastid and other cell compartments. Indeed, stromules seem to be intercalated between ER membranes (Schattat et al, 2011a(Schattat et al, , 2011b, but stromules have also been observed in infoldings of the nuclear envelope (Kwok and Hanson, 2004). In a high-throughput screen of cDNA-GFP fusions, many proteins were found to be localized to the stroma of chloroplasts, but not all of them were also localized to stromules (Escobar et al, 2003).…”