Microtubule Associated Filaments Observed by Electron Microscopy

Electron micrographs of plant cells demonstrate that 7-nm-wide filaments often run along microtubules (Fig. 1A). Even from their earliest observation in Lilium pollen tubes, it was suggested that (based on their diameter) these filaments were composed of actin (Franke et al. 1972). This was later confirmed in Lilium pollen tubes with actin antibodies (Lancelle and Hepler 1991 Fig. 1B), and in Hydrocharis root hairs with heavy meromyosin labelling (Tominaga et al. 1997). These...

Cellular Mechanisms of Wood Formation

Although wood is of great economical importance, the precise process of its formation (xylogenesis) is not yet fully understood (see Higuchi 1997 Lachaud et al. 1999 Sundberg et al. 2000 Mellerowicz et al. 2001 Plomion et al. 2001 Chaffey 2002a Samuels et al. 2006). Therefore, in order to create new woods with more desirable qualities by biotechnological manipulation, more detailed information is needed on the cellular and molecular aspects of wood formation. Increases in the diameter of tree...

References

Ackmann M, Wiech H, Mandelkow E (2000) Nonsaturable binding indicates clustering of tau on the microtubule surface in a paired helical filament-like conformation. J Biol Chem 275 30335-30343 Aguilar I, Sanchez F, Martin A, Martinez-Herrera D, Ponz F (1996) Nucleotide sequence of Chinese rape mosaic virus (oilseed rape mosaic virus), a crucifer tobamovirus infecting Arabidopsis thaliana. Plant Mol Biol 30 191-197 Ainger K, Avossa D, Morgan F, Hill SJ, Barry C, Barbarese E, Carson JH (1993)...

Cell Axis and Plant Development

During the growth of any organism, volume increases with the third power of the radius. Surface extension, however, increases only with the second power and thus progressively lags behind. In order to balance these two processes, the surface has to be enlarged substantially, either by internal or external exten sions. Due to their photosynthetic lifestyle, plants must increase their surface in an outward direction. As a consequence, plant architecture must be able to cope with a considerable...

Role of the Cytoskeleton in Penetration Resistance to Fungal Pathogens

A number of pathogenic fungi form infection structures, such as germ tubes and appressoria, when they attack and then directly penetrate into plant cells. When plant cells sense fungal penetration attempts, they express various morphological and physiological responses contributing to penetration resistance. Penetration resistance is the first line of defence against pathogenic fungi, because direst penetration is essential for, at least some, fungal pathogens (Tsuji et al. 2003 Xu et al....

The Influence of Cortical Microtubules on Heterogeneous Cell Wall Structure

Heterogeneous thickenings of the secondary wall are observed in many plant cells. These secondary thickenings are visible as annular, spiral, reticulate, scalariform, or pitted patterns. They are due to the localized deposition of components of the cell wall, in particular cellulose microfibrils. The localized deposition of cellulose microfibrils might be related to a heterogenous distribution of cellulose-synthase complexes (Herth 1985 Schneider and Herth 1986). Groups of cortical microtubules...

Microtubules as Thermometers

In temperate regions, temperature poses major constraints to crop yield. Attempts to increase photosynthetic rates by conventional breeding programs, although pursued over a long period, were not very successful, which indicates that evolution has already reached the optimum (Evans 1975). However, optimal photosynthetic rates can be reached only, when the leaves are fully expanded. The cold sensitivity of growth is much more pronounced than that of photosynthesis. This means that, in temperate...

Plant Microtubules as Mechanosensors

Plant growth and development responds very sensitively to mechanical stimulation, a phenomenon that has been termed thigmomorphogenesis (Jaffe 1973). For instance, cell expansion is redistributed from elongation towards lateral thickening, when a shoot is repeatedly touched or bent. Later, it was possible to demonstrate thigmomorphogenesis on the cellular level as well. For instance, when a protonema of the fern Adiantum was squeezed by a needle, chloroplasts fled from the contact site (Sato et...

Rops in Epidermal Cells

Arabidopsis Epidermal Cell Cytoskeleton

Cross-talk between microtubules and microfilaments has been explored in detail for the development of the interdigitated epidermal or pavement cells of Arabidopsis and other plants. During leaf development, epidermal cells with simple shapes undergo co-ordinated and selective, localized expansion to form highly complex and interlocking patterns (Fig. 5A). Outgrowths (lobes) of one cell must be matched with reduced or inhibited growth (necks) of the adjoining cell. This requires both...