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Wyświetlanie 1-8 z 8
Tytuł:
Dynamics of the ray pattern in cambium of Diospyros lotus
Autorzy:
Myskow, E.
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/41766.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Opis:
Cambial rays, give rise to phloem and xylem rays. This way they affect the efficiency of a radial conducting system in a tree. Both, frequency of rays and their arrangement on the expanding cambial surface must be precisely controlled during tree ontogeny. The main aim of this research was to analyse the changes in the ray arrangement of Diospyros lotus L. cambium during transition from its nonstoried to double–storied structure. In order to trace the history of cambial ray dynamics, the behaviour of wood rays was followed in successive annual rings. Special attention was paid to developmental events, such as initiation and elimination of rays as well as their splitting and uniting. Moreover, the additions and eliminations of ray cell initials at the both opposite ray margins were followed. The most evident was the initial split of high primary rays into the smaller parts and their subsequent separation concurrent with the increase in cambial girth during the first years of a tree ontogeny. Between the existing rays new secondary rays were initiated by segmentation of fusiform initials. These all developmental events led to the formation of a double-storied pattern. In addition, the recurrent uniting and splitting of rays indicated their permanent rearrangement and the dynamic maintenance of a general pattern. The presented data are discussed in light of the processes occurring in cambial rays that lead to the storied pattern formation, which in turn may affect the mechanical properties of the wood.
Źródło:
Dendrobiology; 2013, 69
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The significance of gamma-and lambda-dislocations in transient states of phyllotaxis: how to get more from less - sometimes
Autorzy:
Zagorska-Marek, B.
Szpak, M.
Powiązania:
https://bibliotekanauki.pl/articles/59112.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
In some plants, developmental changes of phyllotaxis are so frequent that the whole spectrum of phyllotactic patterns becomes available for investigation and thus many unknown subtleties of phyllotaxis come to light. Among these, Magnolia acuminata is the most prominent. In a series of experiments performed in silico with application of a simple geometric model of phyllotaxis, we were able to confront the empirical data on phyllotactic transitions occurring in magnolia flowers with the results of computer simulations. They revealed that in addition to the ratio between the sizes of plant organs, the history of developing pattern was also important, especially for the direction of ontogenetic changes. The parameters of size tolerance and vertical tolerance in positioning a new element in the first available space, brought the effects of simulations closer to the real patterns. They helped especially to resolve the enigma of multiplication of parastichies (γ-dislocations) observed sometimes during determined growth of magnolia floral axes. We conclude that ontogenetic changes in phyllotaxis result mainly from changing sizes of organs in the course of development and that the changes do not always occur with mathematical accuracy.
Źródło:
Acta Societatis Botanicorum Poloniae; 2016, 85, 4
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ontogenetic development of storied ray pattern in cambium of Hippophae rhamnoides L.
Autorzy:
Myskow, E
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/58338.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
storied ray
cambium
plant development
storied pattern
Hippophae rhamnoides
morphology
ray
Opis:
Storied pattern, in the arrangement of both fusiform initials and the rays in cambium of Hippophae rhamnoides, develops in ontogeny relatively quickly and becomes clearly visible in terminal parenchyma of third and fourth annual ring. At first, anticlinal longitudinal divisions and restricted intrusive growth of fusiform initials lead to the formation of their characteristic horizontal tiers. Then, initiation of secondary rays, taking place rather within such tiers, not between them, makes possible the formation of storied ray pattern. New secondary rays originate most frequently from fusiform initials by their segmentation. This makes the appearance of ray tiers rather quick. However, the high order in the structure of cambium of Hippophae rhamnoides is also due to another, very curious and not known until now mechanism. It operates through limited in its range, thus highly controlled, vertical migration of rays on the cambial surface. This applies to asymmetrically positioned rays either primary, which are often originally sited "out of order" or secondary, initiated off-centre within the existing tiers. Excessively asymmetric rays, lying accidentally on the border between two neighbouring storeys, often undergo splitting and then the derivative rays move toward the centres of the storeys. Ray displacement is due to elimination of one or two of ray initial cells on one edge of the ray and simultaneous, multiple divisions adding new ray cells on the opposite edge.
Źródło:
Acta Societatis Botanicorum Poloniae; 2004, 73, 2
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geometric parameters of the apical meristem and the quality of phyllotactic patterns in Magnolia flowers
Autorzy:
Wiss, D.
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/56546.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
geometrical parameter
apical meristem
quality
phyllotactic pattern
Magnolia
flower
phyllotaxis
plant development
primordium
meristem
Opis:
The ratio of primordium size to the meristem size (P/M ratio) is regarded by some geometrical models of phyllotaxis as the parameter, which determines the quality of spiral and whorled patterns of lateral organ arrangement. This assumption was tested on floral meristems in four genets representing four Magnolia taxa: M. × salicifolia, M. stellata, M. denudata and M. acuminata. In successive zones of Magnolia flower, lateral organs are initiated in specific phyllotactic patterns and at specific values of the meristem and primordia sizes. The elements of perianth, usually positioned in three trimerous whorls, are initiated as large primordia on relatively small meristem. The switch in the identity of primordia, from tepals to stamens is accompanied by an abrupt increase in the size of the meristem and decrease in the primordia size. Small values of P/M ratio and frequent occurrence of qualitative transformations of phyllotaxis contribute to the exceptionally rich spectrum of spiral patterns in androecium zone. New spiral patterns emerge when bigger primordia of carpels are initiated on the meristem, which at the same time starts diminishing in size either abruptly (M. × salicifolia, M. stellata, M. acuminata) or slowly (M. denudata). Spiral patterns identified in gynoecia have lower numbers of parastichies than the patterns of androecia and occur in frequencies specific for the genet. Although noted ranges of the meristem and primordia sizes, justify the occurrence of phyllotactic patterns observed in successive zones of Magnolia flower, they do not explain genet-specific frequencies of the patterns observed in gynoecium zone. The lack of straightforward relationship between frequency of the patterns and P/M ratio in gynoecium suggests that more complex geometrical factors or factors of non-geometrical nature are engaged in determination of Magnolia floral phyllotaxis.
Źródło:
Acta Societatis Botanicorum Poloniae; 2012, 81, 3
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phyllotaxis instability - exploring the depths of first available space
Autorzy:
Szpak, M.
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/56528.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
phyllotaxis
instability
depth
available space
phyllotactic transition
shoot apical meristem
plant
ontogenesis
Opis:
The theoretical analysis of the consequences of the phyllotactic pattern being propagated according to the first available space rule has revealed that all monojugate patterns, with the exception of the main Fibonacci pattern, should become developmentally unstable in their low expressions. This fact explains why the main Fibonacci pattern plays the dominant role among other patterns of spiral phyllotaxis. The probability that the pattern becomes unstable varies for different patterns, which likely makes them more or less frequent, and thus easier or more difficult to encounter in nature. The unstable pattern inevitably transforms into another, as the computer simulations show. Theoretically predicted instability of low order phyllotaxis may be treated as one of the causes of natural ontogenetic transitions, occurring in plants. This, however, still does not explain why in nature some patterns with high order of phyllotaxis also change, quite readily one into the other, in shoot apical meristem’s ontogeny.
Źródło:
Acta Societatis Botanicorum Poloniae; 2011, 80, 4
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signals flowing from mature tissues to shoot apical meristem affect phyllotaxis in coniferous shoot
Autorzy:
Banasiak, A
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/57096.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
mature tissue
shoot
apical meristem
phyllotaxis
coniferous plant
auxin
vascular system
leaf
primordium
Opis:
Axial homodromy in growing shoots of perennial plants with spiral phyllotaxis is the case when the chirality of phyllotactic pattern does not change in consecutive growth increments of the same axis. In conifers such as Picea or Abies this rule is strictly observed, except for the rare cases of discontinuous phyllotactic transitions. In Torreya, however, the chirality changes, at random, every year. The pattern of primordia packing, executed by vegetative shoot apical meristem (SAM), depends in Torreya on their identity. The primordia of bud scales are initiated in the decussate and those of needles in bijugate spiral pattern. The decussate, achiral i.e. neutral pattern always precedes the formation of new spiral pattern and thus facilitates random selection of its chiral configuration. Periodic change in organ identity cannot itself be responsible for the special behavior of Torreya, because in other conifers it also exists. There is, however, one important difference: in Torreya, when the initiation of bud scales begins at SAM, the distance between differentiated protoxylem and the initiation site gradually increases, while in other conifers it remains constant and small. In Torreya, at this phase of development, the rate of xylem differentiation and the rate of organogenesis become uncoupled. Closer anatomical examination shows that the decussate pattern in a bud scale zone develops slowly suggesting gradual decrease of the putative signal flowing acropetally from differentiated protoxylem, responsible for positioning of primordia. We hypothesize that in the absence of this signal SAM starts acting autonomously, distributing primordia according to their identity only. A constant presence of the signal in other conifers assures the continuation of the same phyllotactic pattern throughout the period of bud scale formation, despite the change in organ identity.
Źródło:
Acta Societatis Botanicorum Poloniae; 2006, 75, 2; 113-121
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seasonal changes in the degree of symplasmic continuity between the cells of cambial region of Acer pseudoplatanus and Ulmus minor
Autorzy:
Sokolowska, K
Zagorska-Marek, B.
Powiązania:
https://bibliotekanauki.pl/articles/59005.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
seasonal change
symplasmic continuity
symplasmic isolation
cell
cambium
Acer pseudoplatanus
Ulmus minor
plasmodesma
Opis:
The presence of symplasmic isolation and symplasmic continuity which are functional aspects of cell-to-cell communication, had been studied in cambium of Acer pseudoplatanus and Ulmus minor, with hope that uniqueness of this meristem, exemplified by its morphology and seasonal variations in its activity is also manifested in differences in the efficiency of communication between cambial cells during the year. The degree of symplasmic continuity was estimated by loading the fluorescent symplasmic tracer to the stem and following its distribution in a population of cambial cells observed on tangential, transverse and radial sections. In active cambium the tracer did not enter the rays. This suggested that the ray and fusiform cells, growing and dividing intensively at different rates were specifically isolated from each other. In the state of dormancy the tracer was present also in the rays implying continuity between the two types of cambial cells. Temporal restriction in tracer spreading from secondary xylem to cambial region was observed on transverse sections in both physiological states of the meristem. Higher degree of symplasmic isolation in active cambium is, most probably, associated with functional distinctiveness of ray and fusiform cells. We hypothesize further that the symplasmic continuity in dormant cambium results from the open conformation states of plasmodesmata, because the energy costs of these states are low. It is reasonable strategy when cambial cells do not divide and maintenance of their functional individuality is not necessary.
Źródło:
Acta Societatis Botanicorum Poloniae; 2007, 76, 4; 277-286
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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