Callose deposition at plasmodesmata

Abstract

Summary. The transport of ions and metabolites through plasmodesmata has been thought to be controlled at the neck region where the cytoplasmic annulus is constricted and where callose has also been localised. In order to determine the possible structural and functional effects of callose, its deposition was inhibited through incubation of the plant tissue with 2-deoxy-D-glucose (DDG) for 1 h prior to fixation in 2.5% glutaraldehyde. The inhibition of callose formation was monitored through aniline blue-induced fluorescence of callose. The neck region of the plasmodesmata from Allium cepa L. roots treated with DDG exhibited a funnel-shaped configuration. This is in contrast to the plasmodesmata from tissue not incubated with DDG, which exhibited constricted necks similar to those previously reported. Both initial dissection and glutaraldehyde fixation induced neck constriction in plasmodesmata, however, dissection of tissue increased the frequency of constrictions. The inhibition of cap lose formation by chemical means showed that the neck constrictions and raised collars in this area are artefacts due to physical wounding and glutaraldehyde fixation. The external electron-dense material observed when tannic acid is included in the primary fixative appears to be unrelated to the deposition of callose at the neck region.

Salicylic Acid Regulates Plasmodesmata Closure during Innate Immune Responses in Arabidopsis

“…Numerous reports have presented a correlation between PD closure and callose deposition (Radford et al, 1998;Simpson et al, 2009;Vatén et al, 2011;Zavaliev et al, 2011;Koh et al, 2012), supporting the general consensus that enhanced PD callose deposition is indicative of PD closure and, thus, inhibition of cell-to-cell coupling. Our study has shown that the relative amount of PD callose deposition is inversely correlated with the extent of PD permeability but directly correlated with the level of PDLP5 expression .…”

Dysregulation of cell-to-cell connectivity and stomatal patterning by loss-of-function mutation inArabidopsis CHORUS(GLUCAN SYNTHASE-LIKE 8)

“…S3 in the supplementary material) is consistent with the recent finding that GSL8 acts as a cell-plate callose synthase (Thiele et al, 2009). In addition to its role in the cell plate, callose deposition imposes physical constraints to the symplastic channel (Levy et al, 2007b;Radford et al, 1998). To address the role of GSL8 during stomatal development, we examined callose deposition in wild-type and chor seedlings using a callose-specific dye, Aniline Blue fluorochrome (Fig.…”

Control of Arabidopsis meristem development by thioredoxin-dependent regulation of intercellular transport

“…Callose synthesis is induced by developmental and stress signals (8,9) and leads to constriction of PD during leaf senescence, abscission, or following biotic or abiotic stress (10,11). Callose is degraded by beta-1,3-glucanases; plants deficient in these enzymes show a reduced PD SEL, whereas their overexpression promotes viral movement (12,13).…”