Expression of beta-tubulin during dormancy induction and release in apical and axillary buds of five woody species (original) (raw)

Cell Cycle Activity and β-Tubulin Accumulation During Dormancy Breaking of Acer platanoides L. seeds

Biologia Plantarum, 2004

Cell cycle events in embryo axes of Norway maple (Acer platanoides L.) seeds were studied during dormancy breaking by flow cytometric analyses of the nuclear DNA content and by immunodetection of β-tubulin. Most embryonic nuclei of dry, fully matured seeds were arrested in the G 2 phase of the cell cycle. In addition, the lowest content of β-tubulin was detected in dry, mature seeds. Imbibition in water and cold stratification resulted in a decrease in the number of nuclei in G 2 , and a simultaneous increase in β-tubulin content. In germinated seeds the content of β-tubulin was the highest and the number of cells in G 2 was the lowest. Both cell cycle events preceded cell expansion and division and subsequent growth of the radicle through the seed coat. The anatomical investigation has proved that the main reason for decrease in the number of nuclei in G 2 is mitosis, started with seeds germination (radicle protrusion). The activation of the cell cycle and the β-tubulin accumulation were associated with embryo dormancy breaking.

Cell Cycle Activity and -Tubulin Accumulation During Dormancy Breaking of Acer platanoides L. seeds

Biologia Plantarum, 2000

Changes in the accumulation of α- and β-tubulin during bud development in Vitis vinifera L

Planta, 2010

Microtubules play important roles during growth and morphogenesis of plant cells. Multiple isoforms of -and -tubulin accumulate in higher plant cells and originate either by transcription of diVerent genes or by post-translational modiWcations. The use of diVerent tubulin isoforms involves the binding of microtubules to diVerent associated proteins and therefore generates microtubules with diVerent organizations and functions. Tubulin isoforms are diVerentially expressed in vegetative and reproductive structures according to the developmental program of plants. In grapevine (Vitis vinifera L.), vegetative and reproductive structures appear on the same stem, making this plant species an excellent model to study the accumulation of tubulin isoforms. Proteins were extracted from grapevine samples (buds, leaves, Xowers and tendrils) using an optimized extraction protocol, separated by twodimensional electrophoresis and analyzed by immunoblot with anti-tubulin antibodies. We identiWed eight -tubulin and seven -tubulin isoforms with pI around 4.8-5 that group into separate clusters. More acidic -tubulin isoforms were detected in buds, while more basic -isoforms were prevalently found in tendrils and Xowers. Similarly, more acidic -tubulin isoforms were used in the bud stage while a basic -tubulin isoform was essentially used in leaves and two central -tubulin isoforms were characteristically used in tendrils and Xowers. Acetylated -tubulin was not detected in any sample while tyrosinated -tubulin was essentially found in large latent buds and in bursting buds in association with a distinct subset of tubulin isoforms.

Differential Expansion and Expression of α- and β-Tubulin Gene Families in Populus

Plant Physiology, 2007

Microtubule organization is intimately associated with cellulose microfibril deposition, central to plant secondary cell wall development. We have determined that a relatively large suite of eight a-TUBULIN (TUA) and 20 b-TUBULIN (TUB) genes is expressed in the woody perennial Populus. A number of features, including gene number, a:b gene representation, amino acid changes at the C terminus, and transcript abundance in wood-forming tissue, distinguish the Populus tubulin suite from that of Arabidopsis thaliana. Five of the eight Populus TUAs are unusual in that they contain a C-terminal methionine, glutamic acid, or glutamine, instead of the more typical, and potentially regulatory, C-terminal tyrosine. Both C-terminal Y-type (TUA1) and M-type (TUA5) TUAs were highly expressed in wood-forming tissues and pollen, while the Y-type TUA6 and TUA8 were abundant only in pollen. Transcripts of the disproportionately expanded TUB family were present at comparatively low levels, with phylogenetically distinct classes predominating in xylem and pollen. When tension wood induction was used as a model system to examine changes in tubulin gene expression under conditions of augmented cellulose deposition, xylem-abundant TUA and TUB genes were up-regulated. Immunolocalization of TUA and TUB in xylem and phloem fibers of stems further supported the notion of heavy microtubule involvement during cellulose microfibril deposition in secondary walls. The high degree of sequence diversity, differential expansion, and differential regulation of Populus TUA and TUB families may confer flexibility in cell wall formation that is of adaptive significance to the woody perennial growth habit. 2003-35103-12906 to C.-J.T. and S.A.H., and 2005-35103-15251 to C.-J.T.). Fukazawa K (1995) Changes in the arrangement of microtubules and microfibrils in differentiating conifer tracheids during the expansion of cells. Ann Bot (Lond) 75: 305-310 Abe T, Thitamadee S, Hashimoto T (2004) Microtubule defects and cell morphogenesis in the lefty1lefty2 tubulin mutant of Arabidopsis thaliana.

Review: A current review on the regulation of dormancy in vegetative buds

Weed Science, 2001

In this review, we examine current techniques and recent advances directed toward understanding cellular mechanisms involved in controlling dormancy in vegetative propagules. Vegetative propagules (including stems, rhizomes, tubers, bulbs, stolons, creeping roots, etc.) contain axillary and adventitious buds capable of producing new stems/branches under permissive environments. Axillary and adventitious buds are distinct in that axillary buds are formed in the axil of leaves and are responsible for production of lateral shoots (branches). Adventitious buds refer to buds that arise on the plant at places (stems, roots, or leaves) other than leaf axils. Both axillary and adventitious buds generally undergo periods of dormancy. Dormancy has been described as a temporary suspension of visible growth of any plant structure containing a meristem . Dormancy can be subdivided into three categories: (1) ecodormancy-arrest is under the control of external environmental factors; (2) paradormancy-arrest is under the control of external physiological factors within the plant; and (3) endodormancy-arrest is under the control of internal physiological factors. One common feature in all of these processes is prevention of growth under conditions where growth should otherwise continue. There is growing evidence that lack of growth is due to blockage of cell division resulting from interactions between the signaling pathways controlling dormancy and those controlling the cell cycle.

Tyrosinated, but not detyrosinated, ?-tubulin is present in root tip cells

Protoplasma, 1999

The distribution of tyrosinated and detyrosinated tubulin in microtubuIe arrays of pine and onion ceils was investigated by immunoftuorescence techniques. Staining of isolated ceils and methacrylate sections of Pinus radiata and Allium cepa root tips indicated that all microtubule structures contained tyrosinated tubulin but not the posttranslationally modified detyrosinated tubulin. The detyrosinated tubulin epitope was, however, created in vitro by treating both sections and fixed whole ceils with carboxypeptidase A.

Intranuclear accumulation of plant tubulin in response to low temperature

Protoplasma, 2006

Concurrently with cold-induced disintegration of microtubular structures in the cytoplasm, gradual tubulin accumulation was observed in a progressively growing proportion of interphase nuclei in tobacco BY-2 cells. This intranuclear tubulin disappeared upon rewarming. Simultaneously, new microtubules rapidly emerged from the nuclear periphery and reconstituted new cortical arrays, as was shown by immunofluorescence. A rapid exclusion of tubulin from the nucleus during rewarming was also observed in vivo in cells expressing GFP-tubulin. Nuclei were purified from cells that expressed GFP fused to an endoplasmic-reticulum retention signal (BY-2-mGFP5-ER), and green-fluorescent protein was used as a diagnostic marker to confirm that the nuclear fraction was not contaminated by nuclear-envelope proteins. These purified, GFP-free nuclei contained tubulin when isolated from cold-treated cells, whereas control nuclei were void of tubulin. Furthermore, highly conserved putative nuclear-export sequences were identified in tubulin sequences. These results led us to interpret the accumulation of tubulin in interphasic nuclei, as well as its rapid nuclear export, in the context of ancient intranuclear tubulin function during the cell cycle progression.

Differential Expansion and Expression of a -a nd b-Tubulin Gene Families in Populus1(W)(OA

Molecular and physiological mechanisms of dormancy regulation

Acta horticulturae

Dormancy can be defined as a developmental process involving a temporary suspension of visible growth of any plant structure containing a meristem. Dormancy is a survival mechanism assuring a seasonal synchronization of growth, but is also contributing to the control of plant architecture. Dormancy of seeds, bulbs and buds may certainly involve common metabolic processes, but there might also be fundamental differences due to the different roles of these organs. Knowledge of the molecular basis of dormancy is still scarce, but since it is associated with reduced rates of cell division, control of dormancy must at some level interact with the mechanisms of cell cycle regulation, which also involve hormonal signals. Several dormancy-associated genes have been identified, and some of them are involved in the regulation of cell division, some are hormone related, and others are involved in phytochrome responsiveness. In particular, the roles of hormones in different aspects of dormancy have been widely studied. Auxin and cytokinin are well known to be involved in the regulation of dormancy of axillary and adventitious buds that is due to an inhibitory control by the shoot apex, but also other signals and factors apparently have important roles. In the seasonal cycles of growth and winter dormancy in perennial woody plants the light climate, particularly the daylength, is a primary determinant acting through the phytochrome system. This is in turn interacting with gibberellin metabolism, but also abscisic acid is considered an important factor. Under conditions inducing winter dormancy communication between cells of the apical meristem ceases as a consequence of a breakdown of symplastic fields, and is re-established upon breakage of dormancy. The nature of the signals involved is unknown, but a role of hormones can be hypothesized. An overview of possible physiological and molecular mechanisms of dormancy regulation will be presented, emphasizing bud dormancy.

Expression of beta-tubulin during dormancy induction and release in apical and axillary buds of five woody species (original) (raw)

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