In this study, the effects of benomyl, a systemic fungicide were investigated in the mitotic cell division in onion (Allium cepa) root tip cells during germination. For this aim, different concentrations (1, 2, 5, 10 and 20 mM) of benomyl solutions were used. All the concentrations used caused several abnormalities in mitotic cell divisions and the mitotic frequency in the onion root tip cells decreased as the concentration of benomyl solution increased. Based on our findings, it is reported that benomyl has some negative effects on mitotic divisions in onion root tip cells.
Seed germination response of black nightshade to hormones, osmotic potential, salt stress, pH and burial depth was investigated in laboratory and green house. Adding the concentration of GA3 increased seed germination to 99% at the treatments of 25, 200 and 400 ppm. Seed germination decreased as concentration of cytokinin increased from 0.1–5 mM. Wet and dry prechilling duration increased seed germination of black nightshade. Germination of black nightshade seeds decreased as ethanol concentrations increased from 0.3 to 30%. A significant decline in germination was observed by increasing in NaCl concentration. Germination of black nightshade seed significantly decreased as the osmotic potential declined. Seed germination was observed over a broad range of pH. Seedling emergence was the greatest for seeds scattered on the soil surface and decreased by increasing in planting depth.
In the present study, the cytogenetic effects of the herbicide Logran on root tip cells of Triticum aestivumL. and Hordeum vulgareL. and changes of total protein content in root tip meristems were studied. The seeds of plants were treated with various concentrations of Logran (125, 250, 500 µg/ml) for 3 and 6 h. The percentages of abnormal cells were seen to increase with increasing treatment period and concentrations. The most dominant types of observed abnormalities were C-mitosis, distributed metaphase and anaphase, stickiness. All the used concentrations of Logran significantly induced a number of chromosomal aberrations in root tip cells of HordeumvulgareL. and TriticumaestivumL. Logran also decreased mitotic index. The decrease of protein content in root tips of TriticumaestivumL. is significant at all the treated concentrations and treatment periods when compared with control.
Authors:Z. A. M. Baka, F. F. Migahed, and A. M. Nofel
Ultrastructural investigations of the effect of lithium chloride on Botrytis fabae and its host, Vicia faba are described. Five concentrations (1, 3, 5, 7, 9 mM) of lithium chloride are chosen in the study. The results indicate that the chlorophyll content of host leaves is not affected at lower concentration (3 mM), whereas the higher concentration (9 mM) decreased the chlorophyll content. These two concentrations caused a pronounced cellular disorganization of B. fabae that ranged from disruption of the wall to marked cytoplasmic degeneration. Inoculated host leaves with B. fabae led to the appearance of more vacuolated cytoplasm, a disorganized membrane system of chloroplast and an increase in number of plastoglobuli. These observations are similar to those of host cells treated with 9 mM of lithium chloride. Host cells are not affected by the concentration of 3 mM. Ultarstructural studies indicate that the lower concentration of lithium chloride can be used as a safe fungicide to control B. fabae without a harmful effect on the host (V. faba).
Authors:C. Vieira da Silva, I. Bianchini Jr., J. F. Gonçalves Jr., R. A. Oliveira, and R. Henry
Pagioro , T.A. and S.M. Thomaz . 1998 . Loss of weight and concentration of carbon, nitrogen, and phosphorus during decomposition of Eichhornia azurea in the floodplain of the upper Paraná river, Brazil . Revista Brasileira de Biologia 58 ( 4
A pot experiment was conducted to evaluate the beneficial effect of glycine betaine application on salinity tolerance of sorghum plants subjected to two salinity levels (125 and 250 mM) for 18 days. Salinity greatly reduced sorghum growth and this effect was more pronounced at 250 mM than at 125 mM NaCl. Foliar application of glycine betaine at 75 mM mitigated to some extent the adverse effects of salinity on sorghum growth. The measured osmotic pressure and solutes concentration (Na, K, Ca, Mg, QACs, total soluble sugar and betaine) increased while K/Na ratio decreased in sorghum sap with increasing salinity level. The major contributors to the measured osmotic pressure were found to be soluble sugars and K, however, this effect decreased with increasing salinity level while that of Na, proline and betaine increased. The obtained results clearly showed that betaine application reduced proline accumulation in sorghum sap under salinity treatments. It was appeared that the expanding leaf had more osmolality, K, sugars, proline and betaine concentrations than the fully expanded leaf. Conversely, Na, Ca and Mg concentrations were higher in the fully expanded leaf than the expanding leaf. Total N concentration increased, while that of C decreased with increasing salinity level. Hydrogen concentration slightly affected by salinity treatments. Stomatal conductance was markedly reduced with increasing salinity level; the main effect of foliar application of glycine betaine was not significant for this criterion.
Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced. The fresh weight remained lower in NaCl treated seedlings compared to control. NaCl at 100 and 150 mM concentrations had significant effect on the dry matter contents of the treated seedlings. The chloroplast pigments in the treated seedlings were affected, suggesting that the NaCl had a significant effect on the chlorophyll and carotenoid biosynthesis. The results showed that the salt treatments induced an increase in proline concentration of the seedlings. The osmotic potential (ψs) of NaCl treated seedlings decreased with increasing NaCl concentrations. Salt treatments resulted in dramatic quantitative reduction in the total sterol percent compared with control ones. Salt stress resulted in increase and decrease of Na+ and K+ ions, respectively. NaCl salinity increased lipid peroxidation. SDS-PAGE was used to evaluate protein pattern after applying salt stress. High molecular weight proteins were intensified, while low molecular weight proteins were faint. NaCl at 100 and 150 mM concentration distinguished with new protein bands. Salt stress induced a new peroxidase bands and increased the band intensity, indicating the protective role of peroxidase enzyme.
Among the different concentrations of Thidiazuron (TDZ) and between the two media Gamborg (B5) and Murashige and Skoog (MS), the highest frequency of shoot formation could be seen in the MS medium with TDZ concentration of 4.54 μM. Among the different concentrations of Naphtalene acetic acid (NAA) and Benzyl adenine (BA) in the two aforementioned media, the maximum proliferation and rooting of saffron shoots were obtained in a B5 medium containing 2.22 μM NAA and 2.68 μM BA. Peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), esterase (EST) and polyphenoloxidase (PPO) measurements proved that all the enzymes had a similar pattern of changes, according to which their concentrations increased in the first stages of development and then decreased. The same pattern was observed for polyphenoloxidase in a B5 medium while in the MS medium a reverse pattern was observed. The enzyme concentration decreased and then increased during shoot formation. The results show the principal role of antioxidant enzymes in the complicated process of organogenesis.
Authors:C. Máthé, G. Vasas, G. Borbély, F. Erdődi, D. Beyer, Andrea Kiss, G. Surányi, S. Gonda, Katalin Jámbrik, and Márta M-Hamvas
This study compares the histological, cytological and biochemical effects of the cyanobacterial toxins microcystin-LR (MCY-LR) and cylindrospermopsin (CYN) in white mustard (Sinapis alba L.) seedlings, with special regard to the developing root system. Cyanotoxins induced different alterations, indicating their different specific biochemical activities. MCY-LR stimulated mitosis of root tip meristematic cells at lower concentrations (1 μg ml−1) and inhibited it at higher concentrations, while CYN had only inhibitory effects. Low CYN concentrations (0.01 μg ml−1) stimulated lateral root formation, whereas low MCY-LR concentrations increased only the number of lateral root primordia. Both inhibited lateral root development at higher concentrations. They induced lignifications, abnormal cell swelling and inhibited xylem differentiation in roots and shoots. MCY-LR and CYN induced the disruption of metaphase and anaphase spindles, causing altered cell divisions. Similar alterations could be related to decreased protein phosphatase (PP1 and PP2A) activities in shoots and roots. However, in vitro phosphatase assay with purified PP1 catalytic subunit proved that CYN in contrast to MCY-LR, decreased phosphatase activities of mustard in a non-specific way. This study intends to contribute to the understanding of the mechanisms of toxic effects of a protein phosphatase (MCY-LR) and a protein synthesis (CYN) inhibitory cyanotoxin in vascular plants.
Treatment of rat cortical synaptosomes with micromolar concentrations of L-glutamate stimulated the release of the secreted form of amyloid precursor protein in a concentration-dependent, however biphasic manner as assayed by semiquantitative Western blot analysis. The secreted amyloid precursor protein released from synaptosomes into the incubation medium was highest in the presence of 500 µM L-glutamate (about 64% over the level assayed in the incubation medium in the absence of any drug). In contrast, direct stimulation of protein kinase C by phorbol-12-myristate-13-acetate resulted in a concentration-independent increase in secretory amyloid precursor protein release by about 100% already detectable at a concentration of 0.1 µM but with no significant change at higher concentrations up to 10 µM. The presented data show that there is a constitutive release of secretory amyloid precursor protein from synaptosomes and suggest that (i) processing of amyloid precursor protein at the synaptic level is controlled by L-glutamate presumably via activation of protein kinase C, and (ii) isolated cortical synaptosomes represent a useful experimental approach to selectively study amyloid precursor protein metabolism at the synaptic level.