Position and extent of the elongation zone in the root tip of the broad beanVicia faba L.

It was found by measuring the length of the cortex cells of the root tips of the broad beanVicia faba L. that the beginning of the elongation zone lies at about 1–2 mm from the initials and its end at about 7–8 mm from the initials. Shrinkage of the object during microtechnical treatment was negligible. The autonomy of the individual tissues of the root tip was taken into account.     

Distribution of copper and iron in heterotrophic phase of development and growth of vicia faba L.

Distribution of Cu and Fe from the cotyledons to the root and the epicotyl of Vicia faba L. was studied during the heterotrophic phase of development and growth in dark. During this phase there was no significant difference in the distribution of the quantity of Cu in the root and in the epicotyl. When the plants had changed to the autotrophic phase, the distribution of Fe was significantly higher in the epicotyl than in the root. In roots both Cu and Fe were localized in the zone of root differentiation. The quantities of these elements in meristematic and elongation zones were about 15% and 25%, respectively. In regions of cell division and cell elongation of the root, the level of Cu was almost the same. On the contrary, the content of Fe in the zone of cell elongation was atout 3 times higher than in the meristematic zone.     

Isoenzymes of lactate dehydrogenase in the root growth zones ofVicia faba L.

The present studies of the LDH isoenzymes have been made as a part of our studies on the respiration systems of the roots ofVicia faba. All the root zones had 5 LDH isoenzymes and 2 antibands, but there were differences in their relative quantity. Cathodic isoenzymes (LDH₅, LDH₄) prevailed in the meristematic zone, whereas the anodic ones (LDH₁) prevailed in the others. The different enzyme activity in individual zones is probably connected with the transition of the anaerobic metabolism in the meristem to the aerobic one in the differentiating parts of the root.     

Contribution to the estimation of malic dehydrogenase isoenzymes in the root growth zones ofVicia faba L.

Highly active NAD-MDH (E.C.1.1.1.37) and low activity of NADP-MDH (E.C.1.1.1.40) were found inVicia faba roots. The NAD-MDH activity is associated with 6 to 12 isoenzymes. The number of isoenzymes is dependent on the extraction (use of Triton X-100etc.) and detection procudures (presence of KCN, phenazine methosulphate). The meristematic zone does not contain one isoenzyme (X) which is present in the other two zones. The meristematic zone, elongation zone and zone with the beginning differentiation differ in their activity of individual isoenzymes.     

Effects of high osmotic potential of a medium on mitotic cycle in roots ofVicia faba L

The present paper deals with the effects of osmotic potential of a medium on cell reproduction and elongation of the roots ofVicia faba L. andVicia sativa L. As the osmoticum polyethylene glycol (PEG 4000) in various concentrations ranging from 5 % to 25 % (i.e. fromca.-0.11 up to -1.27 MPa) has been used. The results show that at higher concentrations than 7.5 %, the growth of roots is slowed down and at the concentration of 25 % PEG this decrease in growth rate is as much as 6 fold compared with the control. The mitotic cycle is prolonged, however, only 1.86 times. Thus, the inhibition of root growth is caused mainly by the inhibition of cell elongation. Concerning the effect of high osmotic potential on mitotic cycle it was found that the roots after immersion into 25% PEG are able to overcome this osmotic stress and after 6 h to renew the mitotic activity. The S phase of the cycle is the most sensitive to this factor and even after mitotic activity was renewed it showed a slower rate in comparison with the control.     

Electrophoretic investigation of ribonuclease in roots and leaves ofVicia faba L.

Isozyme patterns and specific activity of ribonuclease (ribonucleate pyridinenucleotido-2′-transferase, E. C. 2.7.7.16) were followed in the extracts of segments from three growth zones of the root and in extracts of young and senescent leaves ofVicia faba L. Electrophoreograms of extracts from all three investigated root zones were identical, in the electrophoreograms of extracts from senescent leaves however one new ribonuclease occurred which could not be detected in the electrophoreograms of extracts from young leaves. Extracts from senescent leaves had higher specific activity of ribonuclease than extracts from young leaves. Extracts from the enlargement zone of the root and those from the maturation zone had a three times higher specific activity of RNase than extracts from the division zone.     

The effect of high concentrations of growth substances on water uptake

Changes in water uptake immediately following the application of high concentrations of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into the root medium of whole plants ofPisum sativum andVicia faba were investigated potometrically under controlled conditions. It was found that concentrations between 10^?2 and 10^?5 m bring about a sudden, pronounced and lasting inhibition of water uptake. Its rate depends directly on MCPA concentration. At 10^?2 m, sudden inhibition of water uptake becomes apparent as early as 10 min after application. With decreasing concentrations the appearance of inhibition is retarded but the inhibition is still sudden and well-pronounced. The inhibition of water uptake observed after MCPA application to the root medium of whole plants agrees with the sudden striking reduction in transpiration intensity observed byAllerup (1964) after the application of similar concentrations of 2,4-dichlorophenoxyacetic acid. The presence of MCPA in the nutrient medium causes inhibition of water uptake even in cut plants. Its rate again depends on the concentration of the growth substance. The inhibition does not appear here as quickly and is not as sudden and pronounced. High concentrations of MCPA during application to over-ground plant organs do not bring about immediate inhibition of water uptake by the root.     

Cytogenetic effect of radiation products of cytosine: Parabanic and oxaluric acids

The two final products of radiolytic degradation of cytosinei.e. parabanic and oxaluric acids were investigated as regards their cytogenetic effects. Broad bean (Vicia faba L.) root meristem was used as experimental material. While the oxaluric acid was not able to induce chromosomal aberrations to a greater extent, the parabanic acid acts as a clastogenic compound. When applied on a resting broad bean root meristem at concentration from 10^-3 to 10^-2 M it induces chromosome and chromatid aberrations, especially breakages. Their frequency reaches 9–12% at the highest tested concentration. The same concentrations of the parabanic acid increases mitotic index of the first cell generation of primary root.     

Biochemical Changes Associated with the Growth of Root Tips of Vicia faba in vitro, and the Effect of 2,4-Dichlorophenoxyacetic Acid

Root tips of Vicia faba were cultured for 3 weeks on a semi-solidmedium containing 40 g/l sucrose ±10^–5 M 2:4-dichlorophenoxyaceticacid (2,4-D). Inhibition of root elongation and the stimulationof an actively dividing meristematic zone in the pericycle regionwere observed in the 2,4-D-treated tissues. Biochemical dataon the DNA content and respiration of these root tips correlatewell with the morphological observations. 2,4-D also induceda marked decrease in the -cellulose content of the cell wallsand analyses of the carbohydrate content of the ethanol-solublepool and starch content of the cultured root tips have providedtentative evidence for some of the controlling factors exertedin the presence and absence of 2,4-D.     

Comparison of the effects of radiation and deoxyribonucleic acids on the mitosis in roots ofVicia faba

Differences as well as similarities in the action of ionizing radiation and deoxyribonucleic acids from various sources on mitosis in root cells ofVicia faba were established. The time course of occurrence of aberrations were examined. Whereas in irradiated broad beant the maximum percentage of aberrations was observed immediately after irradiation, the aps plication of non-isologous DNA was followed by maximum aberrations after 8–16 hours. As all the time-intervals studied, an incraasad number of aberrations was found during metaphase-as compared with anaphases, both after irradiation and after application of DNA. A comparison of isologous, homologous and heterologous DNA as inductors of chromosomal aberrations supported our previous findings and showed that the efficiency of DNA depends on the genetic difference between donor and acceptor. During a study of distribution of aberrations between large and small chromosomes of meristematic cells ofVicia faba, at various time-intervals it was obsarved that after irradiation the distribution of aberrations between individual chromosomes is proportional to their total length, whereas the effect of heterologous DNA is mostly in the damage to small chromosomes. It was also found that aftar irradiation mostly chromatid aberrations are formed at shorter time-intervals and only later chromosomal aberrations will appear. On the other hand, heterologous DNA brings about in all time-intervals a predominance of chromatid aberrations.     

The influence of exogenous DNA of different origin on the mitosis and chromosomes of irradiated meristematic cells ofVicia faba

In this paper we compare the influence of heterologous and isologous DNA on the radiation damage repair of primary root meristematic cells ofVicia faba. Roots, irradiated by exposure of 150 r were cultivated at different time intervals either in tap water, or in a solution of heterologous or isologous DNA. In comparing mitotic activity of meristematic cells it was found that both types of DNA studied enhance the recovery of irradiated cells. The frequency of postmetaphase chromosomal aberrations of irradiated cells was influenced also by post-irradiation action of exogenous DNA. While heterologous DNA exhibited synergical effect with radiation in the sense that it increased the post-irradiation incidence of aberrations in all time intervals studied, isologous DNA had a strong repair effect—the application caused a significant decrease of the percentage of post-metaphase aberrations. Both kinds of DNA caused changes in the relation of chromosome to chromatid aberrations; a higher percentage of chromatid aberrations was registered. The study of the distribution of aberrations between large and small chromosomes ofVicia faba showed that the post-irradiation application of heterologous DNA increases damage of small chromosomes while isologous DNA caused an increased repair ability in this chromosomal group.     

Histogenesis and localization of non-specific esterase in root tip

A procedure was developed for satisfactory freeze-sectioning of root tips. The use of Ca formol-fixed material kept and frozen in Holt's syrup is recommended. The existence and different localization of 2 fractions of non—specific esterase was verified in root tips ofVicia faba. The same results were revealed in fixed and unfixed material. The dynamics ofin situ reaction was followed with respect to optimal incubation time. The results with substrates of different chain length support the existence of 2 fraction of the studied enzyme, none of which, concerning substrate specificity, is a lipase. It follows from the present studies inVicia faba and other species (Cucurbita pepo, Lupinus albus, Pisum sativum Zea mays), that non-specific esterase localization is not directly given by histogenesis.     

Chromosome aberrations caused by the effect of ultrasound in the meristematic cells ofvicia faba

In our present work the formation of chromosome aberrations has been studied in dependence on the tima interval between sonication and fixation of the primary root tips of Vicia faba. Maximum occurrence of aberrations was recorded immediately after sonication. The results of our experiments pointed to the fact that the frequency of the induced changes was independent on the sonic waves intensity within the range of 0-2—3-0 W/cm² and on ultrasond treatment duration within the range of 1—20 min. Studies of the distribution of chromosome abnormalities caused by ultrasound between the large and small chromosomes of theVicia faba meristematic cells in various time intervals showed that the frequency of the aberrations in both chromosome groups was proportional to its total metaphase lengths. Analysis of the type of aberrations observed in various time intervals after sonication indicated the simultaneous formation of chromosome and chromatide abnormalities.     

Contribution to the study on the reparative effect of exogenous DNA in the irradiated meristem ofVicia faba

The present report is focused on the study of participation of exogenous DNA in the process of postirradiation reparation of meristematic cells ofVicia faba primary roots. It is aimed at comparison of the positive reparative effect of isologous DNA with postirradiation action of heterologous DNA in its native, thermally denatured and DNAase-degraded forms, or DNA degraded by ultrasound, and with the effect of other biologically important macromolecules (RNA, histone, heparin, and dextran sulphate). For this purpose, the roots ofVicia faba irradiated by 150 r exposure were cultivated in solutions containing the above substances for an appropriate time interval. In squash slides both mitotic activity of the investigated cell population and frequency of postmetaphase chromosomal aberrations induced by radiation were evaluated. It was shown that a stimulation of cell division and reparation of chromosome damages were supported exclusively by isologous DNA. On the contrary, exogenously applied heterologous DNA increased postirradiation frequency of aberrations; maintenance of native structure of applied DNA was an essential condition for the above effect. Other macromolecules investigated on the course of postirradiation reparation ofVicia faba meristematic cells were without effect.     

The effect of maleic hydrazide and exogenous DNA on chromosomes ofVicia faba

The mitotic activity of merstematic cells ofVicia faba, the frequency of chromosomal abnormalities and their interchromosomal distribution are evaluated in dependence on the concentration of maleic hydrazide (MH) and on the recovery period. The influence of exogenous DNA of different genetic origin on the course of repair of primary root cells damaged by MH was also studied. Isologous DNA which exhibited a strong repair effect in authors' previous experiments was quite ineffective in the case of maleic hydrazide. Heterologous DNA, on the other hand, had to some extent a parallel effect with MH in breaking down the structural integrity of chromosomes and increased the frequency of aberrations induced by maleic hydrazide in meristematic cells ofVicia faba.     

Participation of exogenous DNA in the repair processes of meristematicVicia faba cells injured by monofunctional alkylating agens ethylmethane sulphonate

The effect of exogenous DNA of syngeneic origin on the course of reparation of meristematic cells ofVicia faba primary roots followed after treatment with monofunctional alkylating agent, ethyl methanesulphonate (EMS), was tested. Time course of alternations in mitotic activity of investigated cellular population and the dynamics of formation of postmetaphase chromosomal aberrations was evaluated. A reparation of damaged cells was significantly supported by syngeneic DNA; its application induced an increased incidence of cellular division already in the early intervals of the repair which was accompanied by concomitant decrease of microscopically detectable rupture in the chromosomes. The study performed on the localization of induced damages occurring in metaphase chromosomes pointed out an increased sensitivity of small chromosomes ofVicia faba to EMS. Similarly, a reparative action of syngeneic DNA was exhibited by significant decrease of aberrations frequency, predominantly in the same chromosomal group. Per cent representation of individual types, not affected by the action of syngeneic DNA, was established by detailed classification of induced aberrations. In both cases, isochromatide breaks were found of greatest predominance.     

The differentiation of α- and β -glucosidase and α- and β-galactosidase isoenzymes from maize and broad bean root tips using disc electrophoresis in polyacrylamide gels

For the separation of α- and β-glucosidase and α- and β-galactosidase isoenzymes fromZea mays L. andVicia fabaL. root tips the system of disc electrophoresis in polyacrylamide gel developed for basic protein separation proved most suitable. The detection was carried out by a simultaneous azocoupling reaction. In maize α-glucosidase was not detected, β-glucosidase gave 3, α-galactosidase 4, and β-galactosidase 3 zones. In broad bean a- and β-glucosidases were absent, α-galactosidase gave 2 and β-galactosidase 3 zones, α- and β-galactosidase activity zones correspond principially to each other in their position. In maize one zone gives a positive reaction for both β-glucosidase and α- and β-galactosidaso.     

Nitrate reductase of Dunaliella parva

Nitrate reductase of the salt tolerant alga Dunaliella parva, in contrast to that of most green algae, can use NADPH as well as NADH as electron donor. Extracts of cells contained various amounts of latent nitrate reductase. The latent enzyme could be activated at 45°C but only in the presence of flavine adenine dinucleotide. The heat activated enzyme did not require flavine adenine dinucleotide for activity and was fully active with NADH, NADPH or reduced flavine mononucleotide as electron donors.     

Cytoplasmic Components of the Broad Bean Root Tip Cells

The cytoplasmic components of broad bean (Vicia faba L.) root tip cells were studied light- and electronmicroscopically. Using a light microscope, differences were revealed between cells from the cortex and from the central cylinder. For electron microscope studies the cells near the boundary between the mentioned parts of the root tip were selected at a distance of about 2 mm from the initials. The orientation of objects during embedding made possible fairly accurate localization. No peculiar, strikingly osmiophillic bodies were seen, which could be identified without doubt as osmiophillic platelets. It follows that some of the current cytoplasmic components, perhaps more or less altered were described as osmiophillic platelets. After fixation with KMnO₄, in which case the electronmicrographs are most instructive, the leucoplasts show several inclusions, mostly only partially limited against the matrix; it is not clear whether the true membrane is concerned here. The origin of intravacuolar membraneous formations is discussed.     

Formation of ascochitine by plant pathogens of the genus Ascochyta

Strains of fungi isolated from pulse crops: pea (Pisum sativum) and faba beans (Vicia faba) plants with symptoms of Ascochyta blight, footrot and stems lesions have been examined under laboratory conditions for their ability to produce ascochitine and metabolites toxic toArtemia salina. BothAscochyta pisi Lib and Ascochyta fabae LK Jones isolates formed ascochitine in yields of 20–480mg/kg. The highest yield of ascochitine was produced on rice and the lowest on maize grain. Ascochyta pinodes andPhoma medicaginis varpinodella (LK Jones) Boerema (formerlyAscochyta pinodella LK Jones) did not produce ascochitine. Crystalline ascochitine was found to be of moderate toxicity toArtemia salina larvae (LC₅₀ = 85μg/cm³BSM*). Extracts ofPhoma medicaginis var,pinodella cultures were found to be highly toxic toArtemia salina.