Background and Aim: The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. Methods: In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. Key Results: ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. Conclusions: The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport.
- MeSH
- Arabidopsis genetika metabolismus MeSH
- buněčná stěna metabolismus MeSH
- komplex proteinů 2-3 souvisejících s aktinem genetika metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The plant-specific DREPP protein family comprises proteins that were shown to regulate the actin and microtubular cytoskeleton in a calcium-dependent manner. Our phylogenetic analysis showed that DREPPs first appeared in ferns and that DREPPs have a rapid and plastic evolutionary history in plants. Arabidopsis DREPP paralogues called AtMDP25/PCaP1 and AtMAP18/PCaP2 are N-myristoylated, which has been reported as a key factor in plasma membrane localization. Here we show that N-myristoylation is neither conserved nor ancestral for the DREPP family. Instead, by using confocal microscopy and a new method for quantitative evaluation of protein membrane localization, we show that DREPPs rely on two mechanisms ensuring their plasma membrane localization. These include N-myristoylation and electrostatic interaction of a polybasic amino acid cluster. We propose that various plasma membrane association mechanisms resulting from the evolutionary plasticity of DREPPs are important for refining plasma membrane interaction of these signalling proteins under various conditions and in various cells.
Microtubules (MTs) are essential for many processes in plant cells. MT-associated proteins (MAPs) influence MT polymerization dynamics and enable them to perform their functions. The molecular chaperone Hsp90 has been shown to associate with MTs in animal and plant cells. However, the role of Hsp90-MT binding in plants has not yet been investigated. Here, we show that Hsp90 associates with cortical MTs in tobacco cells and decorates MTs in the phragmoplast. Further, we show that tobacco Hsp90_MT binds directly to polymerized MTs in vitro. The inhibition of Hsp90 by geldanamycin (GDA) severely impairs MT re-assembly after cold-induced de-polymerization. Our results indicate that the plant Hsp90 interaction with MTs plays a key role in cellular events, where MT re-organization is needed.
- MeSH
- benzochinony farmakologie MeSH
- fylogeneze MeSH
- makrocyklické laktamy farmakologie MeSH
- mikrotubuly účinky léků metabolismus MeSH
- molekulární sekvence - údaje MeSH
- polymerizace účinky léků MeSH
- proteiny tepelného šoku HSP90 chemie izolace a purifikace metabolismus MeSH
- rekombinantní proteiny izolace a purifikace metabolismus MeSH
- repetitivní sekvence aminokyselin MeSH
- rostlinné proteiny metabolismus MeSH
- rýže (rod) účinky léků metabolismus MeSH
- sekvence aminokyselin MeSH
- tabák cytologie účinky léků metabolismus MeSH
- transport proteinů účinky léků MeSH
- tubulin metabolismus MeSH
- vazba proteinů účinky léků MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Somatic embryogenesis in spruce is a process of high importance for biotechnology, yet it comprises of orchestrated series of events whose cellular and molecular details are not well understood. In this study, we examined the role of actin cytoskeleton during somatic embryogenesis in Norway spruce line AFO 541 by means of anti-actin drugs. RESULTS: Application of low doses (50-100 nM) of latrunculin B (Lat B) during the maturation of somatic embryos predominantly killed suspensor cells while leaving the cells in meristematic centres alive, indicating differential sensitivity of actin in the two cell types. The treatment resulted in faster development of more advanced embryos into mature somatic embryos and elimination of insufficiently developed ones. In searching for the cause of the differential actin sensitivity of the two cell types, we analysed the composition of actin isoforms in the culture and isolated four spruce actin genes. Analysis of their expression during embryo maturation revealed that one actin isoform was expressed constitutively in both cell types, whereas three actin isoforms were expressed predominantly in suspensor cells and their expression declined during the maturation. The expression decline was greatly enhanced by Lat B treatment. Sequence analysis revealed amino-acid substitutions in the Lat B-binding site in one of the suspensor-specific actin isoforms, which may result in a different binding affinity for Lat B. CONCLUSIONS: We show that manipulating actin in specific cell types in somatic embryos using Lat B treatment accelerated and even synchronized the development of somatic embryos and may be of practical use in biotechnology.
- MeSH
- aktiny antagonisté a inhibitory metabolismus MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- cytoskelet účinky léků MeSH
- embryonální vývoj MeSH
- fylogeneze MeSH
- protein - isoformy metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- RNA rostlin genetika MeSH
- rostlinné geny MeSH
- sekvenční seřazení MeSH
- smrk embryologie růst a vývoj MeSH
- substituce aminokyselin MeSH
- techniky tkáňových kultur MeSH
- thiazolidiny farmakologie MeSH
- vazebná místa MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
