Immunohistochemical localisation of ubiquitin and the proteasome in sunflower ( Helianthus annuus cv. Giganteus)

Abstract

This study provides an immunohistochemical demonstration of the involvement of the ubiquitin- and proteasome-dependent pathway during differentiation and organogenesis in plants. The localisation of ubiquitin and the proteasome was studied in meristems, leaves, stems and roots of sunflower (Helianthus annuus L. cv. Giganteus). By using a new technique that enhances very low antigen signals, we obtained information on the structural distribution of the ubiquitin- and proteasome-dependent pathway, and of the importance of this pathway during organogenesis and plant development. Ubiquitin and the proteasome showed overall similarities in their cellular localisation. The highest antigenic signal was observed in the root and shoot apical meristems, in leaf primordia and vascular tissue. The cambium showed less expression than the apical meristems. During adventitious root formation in cuttings, no sign of increased expression was observed within dedifferentiating tissue, but as organogenesis progressed, the antigenic signal of ubiquitin and the proteasome gradually increased in the developing roots. Comparison of immunochemical results and Western blots demonstrated that important changes in the cellular antigen signal could only be detected by immunochemistry.

Laser-Capture Microdissection, a Tool for the Global Analysis of Gene Expression in Specific Plant Cell Types: Identification of Genes Expressed Differentially in Epidermal Cells or Vascular Tissues of Maize[W]

“…UBC and UBP12 are involved in the ubiquitinproteasome system (reviewed by Vierstra, 1996). It has been reported that ubiquitin and the proteasome accumulate in the vascular tissues as well as in the shoot or root apical meristem of sunflower (Ingvardsen et al, 2001). Similarly, UBCs are highly expressed in vascular tissues of Arabidopsis (Thoma et al, 1996).…”

Immunofluorescent localization of ubiquitin and proteasomes in nucleolar vacuoles of soybean root meristematic cells

“…However, the highest amount was observed in the root and shoot apical meristems, in leaf primordia and vascular tissue of young sunflower 21 and rice plants 28 suggesting that proteolysis mediated by the 26S proteasomes may be involved in organ formation. Hence, an enhanced level of ubiquitin and proteasomes can be observed at the onset of organogenesis.…”

“…20 Transcription factors are regulated via the UPS during organogenesis and vascular differentiation. 21 The UPS is involved in the replacement of histones with protamine-like proteins during spermatogenesis in algae. 22 Ubiquitin-mediated proteolysis regulates hormone biosynthesis, transport, perception and signaling.…”

“…Hence, an enhanced level of ubiquitin and proteasomes can be observed at the onset of organogenesis. 21 …”

Overexpression of monoubiquitin improves photosynthesis in transgenic tobacco plants following high temperature stress

“…As the name implies, ubiquitin (Ub) is nearly ubiquitous, being present in all eukaryotic species examined and all tissues of plants [7,16]. In Ub/26S pathway, Ub is a small (76 amino acids) multifunctional protein [17], and one of its primary functions is to tag proteins for selective degradation by the 26S proteasome [18,19].…”