15 research outputs found
The simulation model of growth and cell divisions for the root apex with an apical cell in application to Azolla pinnata
In contrast to seed plants, the roots of most ferns have a single apical cell which is the ultimate source of all cells in the root. The apical cell has a tetrahedral shape and divides asymmetrically. The root cap derives from the distal division face, while merophytes derived from three proximal division faces contribute to the root proper. The merophytes are produced sequentially forming three sectors along a helix around the root axis. During development, they divide and differentiate in a predictable pattern. Such growth causes cell pattern of the root apex to be remarkably regular and self-perpetuating. The nature of this regularity remains unknown. This paper shows the 2D simulation model for growth of the root apex with the apical cell in application to Azolla pinnata. The field of growth rates of the organ, prescribed by the model, is of a tensor type (symplastic growth) and cells divide taking principal growth directions into account. The simulations show how the cell pattern in a longitudinal section of the apex develops in time. The virtual root apex grows realistically and its cell pattern is similar to that observed in anatomical sections. The simulations indicate that the cell pattern regularity results from cell divisions which are oriented with respect to principal growth directions. Such divisions are essential for maintenance of peri-anticlinal arrangement of cell walls and coordinated growth of merophytes during the development. The highly specific division program that takes place in merophytes prior to differentiation seems to be regulated at the cellular level
Cytogenetic characterization of the Arabidopsis thaliana natural tetraploid ecotype Warschau stability during in vitro regeneration
The morphological and cytogenetic features of the natural autotetraploid Arabidopsis thaliana ecotype Warschau (Wa-1) were investigated. Most of the Warschau plant organs that were analyzed showed higher size values in comparison with diploid Columbia plants. The tetraploid chromosome number was confirmed by analysis of mitotic metaphase cells and rDNA loci were localized. 35S rDNA loci were present on chromosomes 2 and 4, while 5S rDNA, which is polymorphic among A. thaliana ecotypes, were present on chromosomes 4 and 5. Well-characterized autotetraploid plant material was used for in vitro culture to investigate somaclonal variation. Efficient regeneration through organogenesis was achieved. Most of the plants obtained in vitro exhibited an unchanged ploidy level. Detailed cytogenetic analysis that included chromosome, chromocenters and rDNA signals numbers, revealed the stability of regenerants. Based on these data we recommend the ecotype Warschau as a well-characterized plant material for future investigations on the consequences of polyploidy for the genome
Topological traits of a cellular pattern versus growth rate anisotropy in radish roots
The topology of a cellular pattern, which means the spatial arrangement of cells, directly corresponds with cell packing, which is
crucial for tissue and organ functioning. The topological features of cells that are typically analyzed are the number of their neighbors
and the cell area. To date, the objects of most topological studies have been the growing cells of the surface tissues of plant and animal
organs. Some of these researches also provide verification of Lewisâs Law concerning the linear correlation between the number of
neighboring cells and the cell area. Our aim was to analyze the cellular topology and applicability of Lewisâs Lawto an anisotropically
growing plant organ. The object of our study was the root apex of radish. Based on the tensor description of plant organ growth, we
specified the level of anisotropy in specific zones (the root proper, the columella of the cap and the lateral parts of the cap) and in
specific types of both external (epidermis) and internal tissues (stele and ground tissue) of the apex. The strongest anisotropy occurred
in the root proper, while both zones of the cap showed an intermediate level of anisotropy of growth. Some differences in the topology
of the cellular pattern in the zones were also detected; in the root proper, six-sided cells predominated, while in the root cap columella
and in the lateral parts of the cap, most cells had five neighbors. The correlation coefficient rL between the number of neighboring
cells and the cell area was high in the apex as a whole as well as in all of the zones except the root proper and in all of the tissue types
except the ground tissue. In general, Lewisâs Law was fulfilled in the anisotropically growing radish root apex. However, the level of
the applicability (rL value) of Lewisâs Lawwas negatively correlated with the level of the anisotropy of growth, which may suggest
that in plant organs in the regions of anisotropic growth, the number of neighboring cells is less dependent on the cell size
An application of the plant functional group concept to restoration practice on coal mine spoil heaps
The history of coal mining in South Poland has left a legacy of many spoil heaps across the landscape. These have presented the opportunity to study their colonisation and spontaneous successional sequences over a long time period. We use the plant functional group (PFG) approach to characterize and compare species diversity on spoil heaps of different ages by utilising the ecological characteristics (PFG categories) of the species recorded during the course of spontaneous vegetation development. By changing species frequency into functional group frequency it was possible to find the significant differences in the functional composition of the studied vegetation and to analyze the dataset using nonâparametric statistics. There was a small increase in the number of species over time, while the frequency of geophytes, nanophanerophytes and megaphanerophytes increased significantly. A significant increase was also recorded for the frequency of competitors, stressâtolerators and stressâtolerant competitors and for native species. We found that the significant differences in species composition measured as PFG diversity occurred between the youngest and the oldest age classes. The PFG approach provided valuable insights into the nature of the species composition of the developing vegetation on hardâcoal mine spoil heaps. We suggest that it could be usefully applied in restoration practice in the future by facilitating the natural colonization of native species adapted to local conditions and thus retaining the local gene pool in these areas
Evaluation of Fungistatic Activity of Eight Selected Essential Oils on Four Heterogeneous Fusarium Isolates Obtained from Cereal Grains in Southern Poland
The aim of the study was to determine the relationship between the chemical composition
of eight commercial essential oils (EsO) (garlic, grapefruit, lemon grass, tea tree, thyme, verbena,
cajeput, and Litsea cubeba) and their fungistatic activity in relation to four species of Fusarium:
F. avenaceum, F. culmorum, F. graminearum, and F. oxysporum. The species identification of Fusarium
isolates was confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)
mass spectrometer. The determination of qualitative and quantitative chemical composition of the EsO
was carried out using the gas chromatographyâmass spectrometry (GCâMS) method. The fungistatic
activity of EsO was assessed by using the method of poisoned substrates. The data were compiled in
the STATISTICA 13.0 program. The chemical composition of the tested oils varied; the dominant
fraction, except for grapefruit and garlic oils, were monoterpenoids. The greatest similarity to the
action of the synthetic pesticide Funaben T was found in four oils, i.e., thyme, lemongrass, verbena,
and Litsea cubeba. The studies showed that F. oxysporum and F. avenaceum were characterized by
a higher resistance to low oil concentrations, and F. culmorum and F. graminearum by sensitivity.
The fungicidal activity of two EsO-dominant monoterpenoids-thymol and citralâhas been confirmed
Effectiveness of the influence of selected essential oils on the growth of parasitic fusarium isolated from wheat kernels from central Europe
The aim of the study was to determine the effectiveness of selected seven commercial
essential oils (EsO) (grapefruit, lemongrass, tea tree (TTO), thyme, verbena, cajeput, and Litsea cubeba)
on isolates of common Central European parasitic fungal species of Fusarium obtained from infected
wheat kernels, and to evaluate the oils as potential natural fungicides. The study was conducted in
2 stages. At each stage, the fungicidal activity of EsO (with concentrations of 0.025; 0.05; 0.125; 0.25;
0.50; 1.0, and 2.0%) against Fusarium spp. was evaluated using the disc plate method and zones of
growth inhibition were measured. At the first stage, the fungistatic activity of EsO was evaluated
against four species of Fusarium from the Polish population (F. avenaceum FAPL, F. culmorum FCPL,
F. graminearum FGPL and F. oxysporum FOPL). The correlation coefficient between the mycelial growth
rate index (T) and the fungistatic activity (FA) was calculated. At the second stage, on the basis of the
mycelium growth rate index, the effectiveness of the EsO in limiting the development of Fusarium
isolates from the German population (F. culmorum FC1D, F. culmorum FC2D, F. graminearum FG1D,
F. graminearum FG2D and F. poae FP0D) was assessed. The first and second stage results presented
as a growth rate index were then used to indicate essential oils (as potential natural fungicides)
effectively limiting the development of various common Central European parasitic species Fusarium
spp. Finally, the sensitivity of four Fusarium isolates from the Polish population and five Fusarium
isolates from the German population was compared. The data were compiled in STATISTICA
13.0 (StatSoft, Inc, CA, USA) at the significance level of 0.05. Fusarium isolates from the German
population were generally more sensitive than those from the Polish population. The sensitivity of
individual Fusarium species varied. Their vulnerability, regardless of the isolate origin, in order from
the most to the least sensitive, is as follows: F. culmorum, F. graminearum, F. poae, F. avenaceum and
F. oxysporum. The strongest fungicidal activity, similar to Funaben T, showed thyme oil (regardless
of the concentration). Performance of citral oils (lemongrass and Litsea cubeba) was similar but at a
concentration above 0.025%
Cytogenetic characterization of the Arabidopsis thaliana natural tetraploid ecotype Warschau stability during in vitro regeneration
The tensor-based model of plant growth applied to leaves of <i>Arabidopsis thaliana</i>: A two-dimensional computer model
Larcher. Renaissance. Cocard et Bicoquet : [photographie, tirage de démonstration] / [Atelier Nadar]
Background: The development of cell pattern in the surface cell layer of the shoot apex can be investigated in vivo
by use of a time-lapse confocal images, showing naked meristem in 3D in successive times. However, how this layer is
originated from apical initials and develops as a result of growth and divisions of their descendants, remains unknown.
This is an open area for computer modelling. A method to generate the surface cell layer is presented on the example
of the 3D paraboloidal shoot apical dome. In the used model the layer originates from three apical initials that meet
at the dome summit and develops through growth and cell divisions under the isotropic surface growth, defined by
the growth tensor. The cells, which are described by polyhedrons, divide anticlinally with the smallest division plane
that passes depending on the used mode through the cell center, or the point found randomly near this center. The
formation of the surface cell pattern is described with the attention being paid to activity of the apical initials and
fates of their descendants.
Results: The computer generated surface layer that included about 350 cells required about 1200 divisions of the
apical initials and their derivatives. The derivatives were arranged into three more or less equal clonal sectors composed
of cellular clones at different age. Each apical initial renewed itself 7â8 times to produce the sector. In the
shape and location and the cellular clones the following divisions of the initial were manifested. The application of the
random factor resulted in more realistic cell pattern in comparison to the pure mode. The cell divisions were analyzed
statistically on the top view. When all of the division walls were considered, their angular distribution was uniform,
whereas in the distribution that was limited to apical initials only, some preferences related to their arrangement at
the dome summit were observed.
Conclusions: The realistic surface cell pattern was obtained. The present method is a useful tool to generate surface
cell layer, study activity of initial cells and their derivatives, and how cell expansion and division are coordinated
during growth. We expect its further application to clarify the question of a number and permanence or impermanence
of initial cells, and possible relationship between their shape and oriented divisions, both on the ground of the
growth tensor approach