26 research outputs found
Is callose a barrier for lead ions entering Lemna minor L. root cells?
Plants have developed a range of strategies for resisting environmental stresses. One of the most common is the synthesis and deposition of callose, which functions as a barrier against stress factor penetration. The aim of our study was to examine whether callose forms an efficient barrier against Pb penetration in the roots of Lemna minor L. exposed to this metal. The obtained results showed that Pb induced callose synthesis in L. minor roots, but it was not deposited regularly in all tissues and cells. Callose occurred mainly in the protoderm and in the centre of the root tip (procambial central cylinder). Moreover, continuous callose bands, which could form an efficient barrier for Pb penetration, were formed only in the newly formed and anticlinal cell walls (CWs); while in other CWs, callose formed only small clusters or incomplete bands. Such an arrangement of callose within root CWs inefficiently protected the protoplast from Pb penetration. As a result, Pb was commonly present inside the root cells. In the light of the results, the barrier role of callose against metal ion penetration appears to be less obvious than previously believed. It was indicated that induction of callose synthesis is not enough for a successful blockade of the stress factor penetration. Furthermore, it would appear that the pattern of callose distribution has an important role in this defence strategy
The effect of pre-incubation of Allium cepa L. roots in the ATH-rich extract on Pb uptake and localization
The positive influence of anthocyanin (ATH) on toxic metal-treated plant material is well documented; however, it is still not explained if it is caused by changes in element absorption and distribution. Therefore, detailed analysis of the effect of the ATH-rich extract from red cabbage leaves on Pb uptake and localization at morphological, anatomical and ultrastructural level was the goal of this study. Two-day-old adventitious roots of Allium cepa L. (cv. Polanowska) were treated for 2 h with the aqueous solution of Pb(NO3)2 at the concentration of 100 μM with or without preliminary incubation in the anthocyanin-rich extract from Brassica oleracea L. var. capitata rubra leaves (250 μM, 3 h). The red cabbage extract did not change the total Pb uptake but it enhanced the translocation of accumulated metal from roots to shoots. Within the pretreated roots, more Pb was deposited in their basal part and definitely smaller amount of the metal was bound in the apoplast of the outer layers of cortex cells. The ultrastructural analysis (transmission electron microscopy and X-ray microanalysis) revealed that the ATH-rich extract lowered the number of Pb deposits in intracellular spaces, cell wall and cytoplasm of root meristematic cells as well as in such organelles important to cell metabolism as mitochondria, plastids and nucleus. The Pb deposits were preferably localised in those vacuoles where ATH also occurred. This sequestration of Pb in vacuoles is probably responsible for reduction of metal cytotoxicity and consequently could lead to better plant growth.This work was supported by the grant of the
University of Lodz, no. 505/04038
Influence of lead (Pb2plus) on chloroplast distribution patterns in Lemna trisulca L. mesophyll cells in darkness
Wpływ dewernalizacji na przejście merystemu pędu brokuła Brassica oleracea var. italica cv. 'Fiesta' z fazy wegetatywnej w fazę początku kwitnienia
The morphological and histological changes which
occur in the cold-induced apical meristem of broccoli (B. oleracea
var. italica cv. ‘Fiesta’) during transition from the vegetative
to the generative phase have been demonstrated in
our previous investigations. Now, a light microscopic study
on the micromorphological parameters of the tunica and corpus
of the meristem was undertaken to ascertain their association
with devernalisation. Changes in the apex of broccoli
seedlings grown for 26 days at 24oC, succeeded by 35 days
of cold treatment (16oC - vernalization) followed by 14 days
of warm treatment (24oC - devernalization), were studied and
described. Microscopic analysis according to the new method
of slide preparation showed cytohistological zonation and the
spatial distribution of cells in the central and peripheral zones
of the broccoli shoot meristem more precisely than possible
hitherto. Comparison between subsequent stages of meristem
reorganization after devernalization revealed variation in the
structure of the apex during its transition to the evocation phase
of flowering. The results of measurements show that the tunica
width changes irregularly, increasing from its minimum value
(112.39±5.78 μm) through the medium one to the maximum
values (260.32±2.50), to decrease again, while its height increased
and decreased sinusoidally from its minimum value
(21.52±4.30μm) to the maximum one (76.98±7.44μm) and
then decreasing again to the minimum value (21.52±4.30). The
stratification of the tunica as well as its width and height revealed
relatively low variation within the analyzed time. These
structural traits correlated with cold/warm treatments may be
further utilized in the broccoli breeding programme against developmental
disturbances.Aby zbadać skutki dewernalizacji (skokowego
podwyższenia temperatury po indukcji chłodem) wykonano
analizę morfometryczną wierzchołków wzrostu
pędu brokuła (B. oleracea var. italica cv. ‘Fiesta’).
Sadzonki brokuła otrzymane z wysiewu 23 marca
2006 r., po sześciu dniach przepikowano do paletodoniczek
wypełnionych substratem torfowym. Do fazy
5 liści sadzonki rosły w fitotronie (temp. 24oC), po
czym były wernalizowane (temp. 16oC, 35 dni) i dewernalizowane
(temp. 24oC, 14 dni). Od 27 maja do
10 czerwca w odstępach 2 dniowych pobierano wierzchołki
wzrostu brokuła do analiz. Pomiary morfometryczne
wykazały, że dewernalizacja spowodowała
zaburzenia w przejściu z fazy wegetatywnej do fazy
ewokacji kwitnienia, co przejawiało się w opóźnieniu
i rozchwianiu poszerzania i spłaszczania się wierzchołka.
Natomiast tendencja do stopniowego redukowania
warstw tuniki (w miarę spłaszczania się wierzchołka)
nie uległa zmianie.
Rośliny poddane dewernalizacji, chciaż z opóźnieniem,
zawiązały pąki kwiatostanowe. Zastosowanie
devernalizacji u żadnej rośliny nie spowodowało całkowitego
zahamowania rozwoju ‘róży’ brokuła
Effects of endogenous signals and F. oxysporum on the mechanism regulating genistein synthesis and accumulation in yellow lupine and their impact on plant cell cytoskeleton
Pb induces plant cell wall modifications - in particular - the increase of pectins able to bind metal ions level
Low - methylesterified pectin fraction, able to bind metal ions, is the cell wall compound which participates in land and water plant cell response to toxic metals. Protonemata of Funaria hygrometrica (Hedw.), root tips of Populus tremula x P.tremuloides and Lemna trisulca fronds, were used for studying the effects of Pb on plants cell walls (CW). The study were focused on the low- methylesterified pectins level and distribution. It was carried out by immunocytochemical methods, using JIM5 antibody which recognized lowmethylesterified pectins fraction - up 40%. Pb exposure resulted in the cell wall modifications in all investigated objects. The most striking result was the marked increase of the low-methylesterified pectins level. Moreover, cell walls thickenings were formed both in the moss protonemata and the poplar roots. The cell wall thickenings in both objects contained especially high level of low-methylesterified pectins. Simultaneously, cell wall thickenings accumulated extremely large and numerous Pb deposits. In many regions of the cell wall and cell wall thickenings the colocalization of low- methylesterified pectins and Pb deposits occurred. Low - methylesterified pectins level increased also in the cell walls of Lemna trisulca fronds and some of Pb deposits were colocalized with this pectin fraction in the CW. In fronds several Pb deposits occurred between plasma membrane and cell wall and only occasionally they were colocalized with lowmethylesterified pectins. However, in L. trisulca - cell wall was generally thicker in response to Pb. We did not observed almost any local cell wall thickenings as in Funaria and Populus. Taken these facts together we can conclude that plant cell walls were actively and intensively modified in response to Pb. In particular, the amount of low - methylesterified pectins, able to bind toxic Pb ions, markedly increased. Simultaneously, both cell wall and cell wall thickenings were the compartments which accumulate large amount of Pb. Hence, modified cell walls appear to be a very important repository for Pb2+ in different types of plant cells and different species. Detection of such a reaction in three different plant species and three different types of plant cells indicates that it may be more common plant tolerance strategy to Pb