biologia plantarum

International journal on Plant Life established by Bohumil Němec in 1959

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Results 1141 to 1170 of 2232:

Enhancement of Green Gram Nodulation and Growth by Bacillus Species

S.S. Sindhu, S.K. Gupta, S. Suneja, K.R. Dadarwal

Biologia plantarum 45:117-120, 2002 | DOI: 10.1023/A:1015117027863

Rhizobacteria belonging to Bacillus sp. were isolated from the rhizosphere of green gram (Vigna radiata). Seed inoculation with the rhizobacteria showed stunting effect on root growth whereas four Bacillus strains caused stimulation of shoot growth at both 4 and 7 d of observations. Coinoculation of some Bacillus strains with effective Bradyrhizobium strain S24 resulted in enhanced nodulation and plant growth of green gram. The shoot dry mass (ratio to uninoculated control) varied from 1.32 to 6.33 at day 30 and from 1.28 to 3.55 at day 40 of plant growth. Nodule promoting effect after 40 d of plant growth was observed with majority of Bacillus strains except for MRS9 and MRS26. Maximum gains in nodulation, nitrogenase activity and plant growth were observed with Bacillus strains MRS12, MRS18, MRS22 and MRS27 after 40 d of plant growth, suggesting the usefulness of introduced rhizobacteria in improving crop productivity.

Fractionation and Electrophoretic Patterns of Storage Proteins of Ebenus cretica. A preliminary Survey as a Tool in Taxonomy

T. Syros, T. Yupsanis, A. Economou

Biologia plantarum 46:435-443, 2003 | DOI: 10.1023/A:1024350808146

Seed storage proteins of Ebenus cretica were fractionated to albumins, globulins, prolamins and glutelins according to their solubility in water, 0.5 M NaCl solution, 55 % propanol-2 and 0.125 M sodium borate (pH 9.0) containing 0.5 % SDS (sodium dodecyl sulfate) solution, respectively. Glutelins consist of the major (about 81 %) fraction of the total extracted proteins. Analysis by SDS-PAGE revealed that the total extracted protein patterns from different racemes of the same plant were similar, while those from seeds of different plants were different. In addition, distinct differences were observed within protein patterns of alkaline extractable glutelin fractions and salt soluble globulin fractions. In E. cretica four ecotypes (A - D) were distinguished by SDS-PAGE of total extracted seed proteins. The last method was more simple and rapid than others and was suggested for screening analysis.

The Activity of the Antioxidative System in Cadmium-Treated Arabidopsis thaliana

E. Skórzyńska-Polit, M. Dr±żkiewicz, Z. Krupa

Biologia plantarum 46:71-78, 2003 | DOI: 10.1023/A:1027332915500

Changes in the content of reactive oxygen species (ROS) and activity of the antioxidant system were measured in leaves of Arabidopsis thaliana (L.) Heynh exposed to Cd2+. Mature plants growing in the nutrient solution were treated with Cd2+ at different concentrations (0, 5, 25, 50, 100 μM). An increase of O2.- content in leaves was observed at 5, 25 and 50 μM Cd2+. A strong accumulation of H2O2 was found only at the lowest Cd2+ concentration. The content of OH*. was high at 50 and 100 μM Cd2+. Superoxide dismutase (SOD) activity was always higher in Cd2+-treated plants than in control. Catalase (CAT) activity decreased with increasing Cd2+ concentration in the nutrient solution. Guaiacol peroxidase (POX) activity was particularly high at the lowest and highest Cd2+ concentrations and ascorbate peroxidase (APX) activity additionally at 50 μM Cd2+. Enhanced activity of monodehydroascorbate reductase (MDHAR) and strong reduction in ascorbate (AA) content were observed at 25 μM Cd2+. Glutathione reductase (GR) activity was always higher than in control but decreased as Cd2+ concentration increased. However, it was accompanied by gradual content increase of SH-groups.

Comparison of Cadmium Effect on Willow and Poplar in Response to Different Cultivation Conditions

L. Lunáčková, A. ©ottníková, E. Masarovičová, A. Lux, V. Streąko

Biologia plantarum 46:403-411, 2003 | DOI: 10.1023/B:BIOP.0000023884.54709.09

Salix alba L. and Populus×euroamericana cv. Robusta cuttings were grown in 10 μM Cd(NO3)2 (direct treatment) or in Knop solution and afterwards in Cd(NO3)2 (indirect treatment). Cd impact on rooting of directly treated plants and its impact on normally formed roots and shoots of indirectly treated plants were studied. The cumulative length, number and biomass of willow roots, pigment and starch contents, leaf net photosynthetic rate and dry mass/leaf area ratio of willow leaves were positively influenced by indirect treatment. However, indirectly treated poplars were more sensitive to Cd than directly treated ones. Indirect treatment lowered root Cd uptake in willow, Cd accumulation in cuttings of both species and Cd accumulation in poplar shoots. Cd-caused structural changes were similar in both species and in both treatments. Root apices, rhizodermis and cortex were the most seriously damaged root parts. In directly treated willow, the structure of central cylinder (0.5 - 1 cm from apex) remained unchanged in contrast to indirectly treated plants. Formation of cambium close to the apex indicated shortening of root elongation zone of indirectly treated plants. Directly Cd-treated poplar roots exhibited unusual defence activity of root apical meristem and accumulation of darkly stained material around central cylinder.

Effects of Irradiance on Photosynthesis and Activity of Protease Inhibitors in Amaranthus hypochondriacus

Y. Nagamatsu-López, A. Blanco-Labra, J. Délano-Frier, E. Pimienta-Barrios

Biologia plantarum 46:633-634, 2003 | DOI: 10.1023/B:BIOP.0000041078.99055.93

Amaranthus hypochondriacus plants were grown under three photosynthetic photon flux densities (PPFD). Mature plants grown at full sunlight (38.8 mol m-2 d-1) had higher maximum net photosynthetic rate (PN) and significantly higher leaf trypsin inhibitor activity than plants that developed under lower PPFD (19.4 and 12.8 mol m-2 d-1). In contrast, seeds collected from plants fully exposed to sunlight showed the lowest activity of trypsin inhibitor, higher rate of germination and susceptibility to infection by Aspergillus niger.

Effects of diquat on pigment-protein complexes of thylakoid membranes in soybean and maize plants

D.B. Milivojević, B.R. Nikolić

Biologia plantarum 41:597-600, 1998 | DOI: 10.1023/A:1001804802959

Soybean (Glycine max Merrill) and maize (Zea mays L.) plants were exposed for 5 to 48 h to the herbicide diquat under "white light" (WL) or far-red radiation (FR) (photon fluence rate of 30 µmol m-2 s-1). The WL enhanced diquat effect on chlorophyll content in soybean plants, while FR had the same effects on maize plants. After 5 h, diquat increased the content of polypeptides bound to light-harvesting proteins in both plants.

Micropropagation of Crataeva nurvala

N. Walia, S. Sinha, S.B. Babbar

Biologia plantarum 46:181-185, 2003 | DOI: 10.1023/A:1022882006682

A simple protocol for mass multiplication of Crataeva nurvala, a medicinal tree, from seedling-derived explants is described. Six different types of explants (cotyledonary nodes, epicotyl nodes, hypocotyl segments, first pair of leaves, cotyledons, and root segments) developed shoots on Murashige and Skoog's (MS) basal medium or the same supplemented with different concentrations of 6-benzylaminopurine (BAP). Among the explants tested for caulogenic potential, only the epicotyl and cotyledonary nodal explants developed shoots on MS basal medium, while on BAP (0 - 2.0 mg dm-3) adjuvated media all the explants exhibited caulogenesis. The optimum concentration of BAP varied for these explants. The shoots could be rooted on half strength MS with 0.02 mg dm-3 α-naphthalene acetic acid to get plants, which have been transferred to soil. The explants from in vitro regenerated shoots also possessed a similar caulogenic potential.

Salt-Induced Changes in Two Canola Cultivars Differing in Salt Tolerance

M. Qasim, M. Ashraf, M.Y. Ashraf, S.-U. Rehman, E.S. Rha

Biologia plantarum 46:629-632, 2003 | DOI: 10.1023/A:1024844402000

Responses of 20 d-old plants of two Brassica napus L. cultivars Dunkeld and Cyclon to NaCl salinized soil [electrical conductivity 2.4 (control), 4.0, 8.0 or 12.0 dS m-1] were examined. The salt tolerant line Dunkeld had significantly higher fresh and dry masses of shoots, and seed yield than salt sensitive line Cyclon in all salinities. The effect of salt stress on reduction in total leaf soluble sugars was markedly greater in Dunkeld as compared to that in Cyclon. No effect of salt stress was observed on leaf soluble proteins but there was a slight increase in total free amino acids of both cultivars. Leaf proline content increased markedly in both cultivars and Dunkeld had greater proline content than Cyclon at all salinities. Salt stress had no significant effect on seed oil content and erucic acid content of seed oil, however, content of glucosinolates in the seed meal increased and Cyclon had greater content of glucosinolates than Dunkeld.

Production of Doubled Haploids from Androgenic Embryoids and Plantlets of Tobacco

B. Bürün, Ü. Emiroğlu

Biologia plantarum 46:293-295, 2003 | DOI: 10.1023/B:BIOP.0000022269.30902.5c

In four experiments, the chromosome doubling effect of acenaphthene vapour was tested on androgenic embryoids and/or plantlets of tobacco. The maximum rate of plants with doubled chromosome numbers (41.3 % diploids plus 2.7 % tetraploids) was recorded when approx. 100 mg acenaphthene in small and sterilized cheese-cloth bags were hanged for 72 h, into the culture jars (6.0 × 11.5 cm), containing 4 - 6 androgenic plantlets newly transferred from culture tubes. Acenaphthene treatments performed at the earlier stages of culture resulted in lower percentages (from 0.0 to 6.3 %).

Multiple Shoot Induction from Cotyledonary Node Explants of Terminalia chebula

B. Shyamkumar, C. Anjaneyulu, C.C. Giri

Biologia plantarum 46:585-588, 2003 | DOI: 10.1023/B:BIOP.0000041066.78766.34

A protocol for multiple shoot induction from cotyledonary node explants of Terminalia chebula Retz. has been developed. Germination frequency of embryos (up to 100 %) was obtained on Murashige and Skoog (MS) medium supplemented with 0.5 mg dm-3 gibberellic acid (GA3). Maximum number of shoots (6.4 shoots per cotyledonary node) was obtained on half-strength MS + 0.3 mg dm-3 GA3+ 1.0 mg dm-3 indole-3-butyric acid (IBA) + 10.0 mg dm-3 benzylaminopurine (BAP) after 4 weeks of culture. When the cotyledonary nodes along with the axillary shoot buds were allowed to grow in the same medium upto 19.2 shoots were obtained after 8 - 9 weeks. Best rooting (100 %, 5.5 roots per shoot) was observed when shoots were excised and transferred to half-strength MS medium containing 1.0 mg dm-3 IBA + 1 % mannitol and 1.5 % sucrose. Survival of rooted plants in vivo was low (35 - 40 %) when they were directly transferred to soil in glasshouse. However, transfer to soil with MS nutrients and 1.0 mg dm-3 IBA in culture room for a minimum duration of 2 weeks increased the survival percentage of plants to 100 %.

Influence of Cd2+ on growth, chlorophyll content, and water relations in young barley plants

A. Vassilev, M. Berova, Z. Zlatev

Biologia plantarum 41:601-606, 1998 | DOI: 10.1023/A:1001856819797

Barley (Hordeum vulgare L., cv. Hemus) plants were grown in nutrient solution with or without 54 µM Cd2+ for 12 d. A treatment with Cd2+ inhibited the growth of young barley plants. The main factor limiting plant growth was net assimilation rate, due to decreased photosynthetic rate and accelerated dark respiration rate. One of the reasons for the reduced photosynthetic rate was the lower chlorophyll and carotenoid content. Cd2+ decreased water potential and transpiration rate, but relative water content in leaves of the treated plants was not significantly changed.

Influence of Antiviral Factor on Tobacco Mosaic Virus RNA Biosynthesis in Tobacco

M. ©indelářová, L. ©indelář

Biologia plantarum 46:95-100, 2003 | DOI: 10.1023/A:1022370319213

An antiviral factor (AVF) was separated by removing virus particles from extracts of tobacco mosaic virus (TMV) infected leaves using calcium phosphate gel and by column chromatography on DEAE cellulose. AVF was not found in the extracts from healthy plants. The AVF restricted the virus infectivity "in vivo" and significantly decreased the activity of key enzymes of metabolic pathways tending to the purine and pyrimidine nucleotides biosynthesis of viral- RNA (glucose-6-phosphate dehydrogenase, ribonucleases, phosphomonoesterase and phosphodiesterase). No inhibition of these enzymes was observed "in vitro" when the effect of different concentrations of AVF (0.25 - 250 µg cm-3) was examined.

Plant Regeneration from Decapitated Mature Embryo Axis and Agrobacterium Mediated Genetic Transformation of Pigeonpea

M.L. Mohan, K.V. Krishnamurthy

Biologia plantarum 46:519-527, 2003 | DOI: 10.1023/A:1024803325682

A reliable method of plant regeneration has been achieved from decapitated mature embryo axes (DCMEA) explants. Shoots appear directly from explants of genotype T-15-15 when cultured on Maheswaran and Williams (EC6) basal medium supplemented with N6-benzylaminopurine (BAP) and indole-3-acetic acid (IAA) at various combinations. The shoots elongated on half strength Murashige and Skoog (MS) medium fortified with 3 μM gibberellic acid. Elongated shoots were rooted with 80 - 85 % efficiency on half strength MS medium with 0.5 μM indole-3-butyric acid. Survival of plants in the pots was 75 - 80 %. This protocol was used in Agrobacterium mediated transformation. The DCMEA explants were treated independently with two A. tumefaciens (LBA 4404) strains harbouring a binary vector carrying the green fluorescent protein (GFP) and β-glucuronidase (GUS) reporter genes, respectively. Both the strains contained neomycin phosphotransferase selectable marker gene. After co-cultivation, the explants were cultured on EC6 basal medium supplemented with 5 μM BAP and 1 μM IAA. The selection of putative transformants was on a medium containing 50 mg dm-3 kanamycin. Expression of GUS and GFP gene was confirmed by histochemical assay and fluorescence microscopy, respectively. The elongated shoots expressing GFP reporter gene were rooted and transferred to pots for hardening. The integration of GFP gene into the genome of putative transformants was confirmed by Southern blotting.

Indications of Hydraulic Lift by Pinus halepensis and Its Effects on the Water Relations of Neighbour Shrubs

I. Filella, J. Peñuelas

Biologia plantarum 46:209-214, 2003 | DOI: 10.1023/B:BIOP.0000022253.08474.fd

We measured the stable deuterium isotopic composition of xylem sap, the shoot predawn and midday water potentials, and the leaf δ13C of Mediterranean shrubs Pistacia lentiscus, Globularia alypum and Rosmarinus officinalis in a south-oriented transect from a large (12 m tall) Aleppo pine tree, Pinus halepensis. We aimed to study the possibility of hydraulic lift from the deep roots of this pine tree to the shallow soil layers and its influence on these neighbour shrubs. These same traits were also studied in several individuals of the shrub Pistacia lentiscus growing with different types of neighbours: just shrubs, a small (3 - 4 m) pine tree, and the above mentioned large pine tree. The greater the distance from P. halepensis the plants grew, the higher xylem water δD, the lower the soil water content, and, the lower the predawn and midday water potentials were found. These results suggest the existence of an hydraulic lift from deep roots to shallow soil in this big tree. Further indication of this existence is provided by the improved water status of P. lentiscus (higher water potentials and δD, and lower δ13C and, therefore, lower water use efficiencies) when growing close to the big pine in comparison with the same shrub species growing close to small pines or just surrounded by other shrubs. Moreover, all these trends occurred in the dry summer season, but disappeared in the wet spring season.

Regulation of the Activity of N-1-Naphthylphthalamic Acid Binding Protein by ATP and Phosphatase

Y.-H. Zhang, T. Xing, J.F. Hall, R.D.J. Barker, M.C. Elliott

Biologia plantarum 46:493-499, 2003 | DOI: 10.1023/B:BIOP.0000041052.31348.a0

N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, was found to bind specifically to a crude membrane preparation from sugar beet seedling leaf cell suspension cultures. The dissociation constant (Kd) and binding protein concentration were found to be 1.71 μmol dm-3 and 220 pmol g-1(membrane protein), respectively. The amount of specific 3H-NPA binding was significantly increased by adding Mg2+ATP to the binding assay solution. Treatment of membrane preparations with acid phosphatase, prior to the NPA binding assay, resulted in lower specific binding. ATP activation and phosphatase inactivation were culture stage dependent. Although a considerable effect could be detected when using cells from day 8 (representing the linear phase), the same treatment did not alter the binding if cells from day 1 (representing lag phase) or day 14 (representing the stationary phase) were used. These observations have strongly highlighted the possible involvement of a phosphorylation and dephosphorylation mechanism in vivo in the regulation of the activity of the NPA binding protein. High phosphatase activity was found in the supernatant, but not in the membrane pellet) after 50 000 g centrifugation. Our present study has indicated that receptor activity could be regulated by a phosphorylation and dephosphorylation mechanism in plants.

Rice Seedlings Release Allelopathic Substances

H. Kato-Noguchi, T. Ino

Biologia plantarum 46:157-159, 2003 | DOI: 10.1023/A:1022337706443

Rice (Oryza sativa L.) seedlings inhibited the growth of hypocotyls and roots of cress (Lepidium sativum L.) seedlings when both seedlings were grown together. Two growth inhibiting substances were found in the culture solution in which rice seedlings were hydroponically grown for 14 d. One growth inhibitor was further purified. This suggests that the rice seedlings may produce growth inhibiting substances, acting as allelochemicals to other plants, and release them from their roots into the environment.

Differential Expression of Peroxidase Isoenzymes in Soybean Roots Treated with the Benzothiadiazole

L.V. Hoffmann, M.T.V. Carvalho, E.J.B. Nogueira Cardoso

Biologia plantarum 46:451-453, 2003 | DOI: 10.1023/A:1024354909055

The protection compound benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) was applied to soybean roots or leaves in a dose of 20 cm3 of a solution containing 25 μg g-1 of the active ingredient. Electrophoretic profiles of chitinase and superoxide dismutase were not altered by the product. Increased activity of two root anionic peroxidases and three differential isoforms of these enzymes were observed in plants with roots treated by BTH, which can be used as biochemical markers of the BTH effect.

Changes in Glucose-6-Phosphate Dehydrogenase, Ribonucleases, Esterases and Contents of Viruses in Potato Virus Y Infected Tobacco Superinfected with Tobacco Mosaic Virus

M. ©indelářová, L. ©indelář

Biologia plantarum 46:99-104, 2003 | DOI: 10.1023/A:1027341217317

Effects of the superinfection with tobacco mosaic virus (TMV) on susceptible tobacco plants infected with potato virus Y (PVY) were determined. Dynamic changes in the TMV and/or PVY contents, the ribonucleases (RNases), the phosphomonoesterase (PME), the phosphodiesterase (PDE) and the glucose-6-phosphate dehydrogenase (G6P DH) activities were studied. The PVY infection caused a substantial reduction in the multiplication of TMV. The content of TMV in the PVY inoculated leaves amounts to 6 and 9 % in the PVY systemically infected leaves when compared with single TMV. Surprisingly, the challenging virus (TMV) enhanced the content of inducing virus (PVY) in the locally inoculated leaves up to 130 - 141 %. In contrast, the reduction of PVY content down to 35 - 40 % by TMV was seen in the PVY systemically infected leaves. The activities of the RNase, the PME, the PDE and the G6P DH were increased (when compared with the healthy plants) during the acute phase of single virus multiplication (PVY or TMV). The increase in the activities of the enzymes in the leaves with mixed infection was at least as high as the sum of the increases of single infections. Moreover, a higher increase than the sum was seen for G6P DH and PDE (by about 20 - 35 %).

Hexokinases of Tobacco Leaves: Changes in the Cytosolic and Non-Cytosolic Isozyme Complexes Induced by Tobacco Mosaic Virus Infection

L. ©indelář, M. ©indelářová

Biologia plantarum 46:413-419, 2003 | DOI: 10.1023/B:BIOP.0000023885.99970.30

Changes in the cytosotic (soluble) and the non-cytosolic (particulate) isozyme composition of hexokinases and in their properties were studied by ion exchange chromatography on DEAE cellulose after the subcellular fractionation both in the healthy and the tobacco mosaic virus (TMV) infected tobacco leaves. Three main isozyme complexes were obtained: one particulate fraction (the particulate hexokinase phosphorylating both glucose and fructose, EC 2.7.1.1), and two soluble fractions (the soluble hexokinase phosphorylating both the glucose and the fructose, and the soluble fructokinase, which phosphorylates primarily fructose, EC 2.7.1.4). The total fructokinase activities were nearly twice higher than the total glucokinase activities (188.6 % of glucokinase activity in healthy plants and 181.3 % in infected plants). The total particulate glucokinase activity was increased to 120.6 % and the fructokinase to 118.9 % in TMV infected tissue when compared with healthy control. The similar pattern of activity was observed for soluble hexokinase isozymes - the sum of soluble glucokinase activity was increased to 175.4 % and of fructokinase activity to 131.2 % in TMV infected tissue. The isozymes isolated both from the healthy control and TMV-infected leaves had the similar elution profiles, displayed Michaelis-Menten kinetics, showed the identical profiles of pH optima and were Mg2+ dependent with the highest enzyme activity at equimolar Mg2+ and ATP concentration.

Effect of Cytokinin 4-PU-30 on the Lipid Composition of Water Stressed Bean Plants

A.P. Ivanova, K.L. Stefanov, I.T. Yordanov

Biologia plantarum 41:155-159, 1998 | DOI: 10.1023/A:1001797407720

Fourteen days-old bean plants, grown on sand with Knop's nutrient solution were subjected to water stress (three days without irrigation). The stress led to a decrease in almost all lipid classes except phospholipids in the primary leaves. The content of palmitic acid increased, and that of the linolenic acid decreased. An increase of hexadecenoic acid in phospholipids was also observed. Rewatering for 24 h led to the recovery of the stressed plants including that of the photosynthetic apparatus, but the changes in the lipid composition were insignificant. The spraying of the plants before and after the water stress with 5 × 10-6 M solution of the phenylurea cytokinin 4-PU-30 alleviated negative effect of water stress on the lipid membrane composition permitting the plants to resist the harmful environment.

Soil Pollution Alters ATP and Chlorophyll Contents in Pisum sativum Seedlings

A.E.A. Päivöke

Biologia plantarum 46:145-148, 2003 | DOI: 10.1023/A:1022311902355

Pisum sativum L. cv. Phenomen plants were grown in pots in greenhouse and their growth, and ATP and chlorophyll (Chl) a and b contents were assessed after 9-d exposure to sodium arsenate [0.04 and 0.07 mmol kg-1(soil)], or to lead acetate [2.0 and 4.0 mmol kg-1(soil)], or zinc acetate [5.3 and 9.3 mmol kg-1(soil)]. The luciferin-luciferase method was used for ATP analyses. Soil pollution reduced significantly the growth, but the low toxicant concentrations elevated the cotyledon and shoot ATP concentrations per fresh matter content. The ATP/Chl ratio was increased in the zinc-treated seedlings as compared with the respective controls. The ATP concentration and a number of growth parameters were negatively correlated, and thus the high ATP content might contribute to the significantly reduced growth of seedlings.

Stress-Induced Proteins in Parthenium argentatum Leaves

D. Sundar, K.V. Chaitanya, A. Ramachandra Reddy

Biologia plantarum 46:313-316, 2003 | DOI: 10.1023/A:1022883501656

We have analyzed the stress-associated proteins in a high-rubber-yielding guayule (Parthenium argentatum Gray cv. 11591) leaves. Protein profiles in leaf fractions, resolved by SDS-PAGE and visualized by Coomassie Brilliant Blue staining, were different under various stresses. Changes in 25, 34 and 74 kDa polypeptides were noticed in response to low night temperature treatment while 24, 40, 47 and 81 kDa proteins responded to low irradiance. 23, 50, 75 and 82 kDa proteins were altered in response to drought stress. Certain proteins may play a significant role in the acquisition of tolerance in parenchyma cells of guayule leaves and might be useful markers to study adaptation in guayule plants.

Hop Latent Viroid (HLVd) Microevolution: An Experimental Transmission of HLVd "thermomutants" to Solanaceous Species

J. Matouąek

Biologia plantarum 46:607-610, 2003 | DOI: 10.1023/A:1024884116113

The possibility was examined whether the pool of sequence variants of HLVd which accumulated as progeny of "thermomutants" induced upon heat-treatment of hop could initiate infection of non-host solanaceous plants. It was found that HLVd microevolution led to the appearance of HLVd population in tomato. This viroid population was maintained at levels detectable by molecular hybridisation, showing the highest concentration in apical leaves. HLVd was further transferred from tomato to Nicotiana benthamiana, where distinct HLVd sequence variants appeared and were stably maintained at low levels. Our results show that replication of HLVd under heat stress resulted in the production of viroid quasispecies, potentially important for viroid evolution in so-called non host plants.

Plant Regeneration from Immature Embryo Cultures of Vigna unguiculata

P.-S. Choi, D.-Y. Cho, W.-Y. Soh

Biologia plantarum 46:305-308, 2003 | DOI: 10.1023/B:BIOP.0000022272.39625.59

Mature and immature cotyledon explants of cowpea were cultured on Murashige and Skoog's (MS) medium supplemented with 0.1 - 2.0 mg dm-3 benzyladenine (BA). Shoot organogenesis was observed from the minimal greenish calli formed at proximal cutting edges of the immature cotyledon explants after 15 - 20 d of culture. Among whole immature zygotic embryo and seven explant types we tested, single whole cotyledon was suitable for shoot organogenesis. Nearly 67.5 % of the explant types produced adventitious shoots on MS medium containing with 1 mg dm-3 BA, and the shoot number (10.1) per explant was higher than other explant types. From the histological studies, the shoot primordia originated from the procambial strands of immature cotyledon explants. When the shoots were transferred to 1/2 MS basal medium, formed roots within 20 d of culture. The rooted plants were subsequently transferred to the pots and to the field.

Thidiazuron-Induced High-Frequency Shoot Regeneration from Root Region of Robinia pseudoacacia L. Seedlings

M. Hosseini-Nasr, A. Rashid

Biologia plantarum 46:593-596, 2003 | DOI: 10.1023/B:BIOP.0000041068.19770.95

High-frequency regeneration of shoots was achieved at root region of seedlings of Robinia pseudoacacia L. cultured from seeds on medium supplemented with thidiazuron (TDZ, 1.0 μM). The roots of intact seedlings proliferated and formed a compact callus followed by differentiation of numerous shoots. Corresponding cultures on benzylaminopurine-containing medium exhibited much weaker response. Hypocotyl segments also formed shoots at a lower concentration of TDZ (0.1 μM). The shoots formed on TDZ-containing medium were well-developed and readily rooted on hormone-free medium. The obtained plants after acclimation in culture room survived after transfer to soil.

Heat shock responses of bean plants: involvement of free radicals, antioxidants and free radical/active oxygen scavenging systems

A. Edreva, I. Yordanov, R. Kardjieva, E. Gesheva

Biologia plantarum 41:185-191, 1998 | DOI: 10.1023/A:1001846009471

In non-acclimated bean plants heat shock induced oxidative damage (increase of free radical concentration and drop of bound thiols, indicating aggregation of proteins) which was regulated by the enhanced activities of peroxidase and superoxide dismutase, as well as by the accumulation of polyphenols and especially of polyamines. In the plants acclimated to high temperature no oxidative damage occurred following heat shock.

The Effect of Pseudomonas fluorescens and Fusarium oxysporum f.sp. cubense on Induction of Defense Enzymes and Phenolics in Banana

R. Thangavelu, A. Palaniswami, S. Doraiswamy, R. Velazhahan

Biologia plantarum 46:107-112, 2003 | DOI: 10.1023/A:1022374520121

The effect of Pseudomonas fluorescens treatment and Fusarium oxysporum f. sp. cubense inoculation on induction of phenylalanine ammonia-lyase (PAL), peroxidase (POX), chitinase, β-1,3-glucanase and accumulation of phenolics in banana (Musa sp.) was studied. When banana roots were treated with P. fluorescens strain Pf10, a two-fold increase in phenolic content in leaf tissues was recorded 3 - 6 d after treatment. Challenge inoculation with F. oxysporum, the wilt pathogen, steeply increased the phenolic content in P. fluorescens-treated banana plants. Significant increase in POX activity was detected 6 - 9 d after P. fluorescens treatment. PAL, chitinase and β-1,3-glucanase activities increased significantly from 3 d after P. fluorescens treatment and reached the maximum 6 d after treatment. Challenge inoculation with F. oxysporum further increased the enzyme activities. These results suggest that the enhanced activities of defense enzymes and elevated content of phenolics may contribute to bioprotection of banana plants against F. oxysporum.

Thidiazuron Induced Multiple Shoot Induction and Plant Regeneration from Cotyledonary Explants of Mulberry

T. Dennis Thomas

Biologia plantarum 46:529-533, 2003 | DOI: 10.1023/A:1024807426591

A rapid micropropagation protocol through induced multiple shoots from the cotyledonary explant of mulberry (Morus alba L) is described. The highest number of shoots (20.3) was obtained when explants from 14-d-old embryos were cultured on Murashige and Skoog (MS) medium supplemented with 7 μM thidiazuron for 45 d. Of the three cultivars used, cv. S-36 was the best followed by cv. K-2 and S-1. The shoots were transferred to MS medium supplemented with 5 μM 6-benzylaminopurine for elongation. The elongated shoots were rooted on half strength MS medium containing 1 - 7 μM indole 3-butyric acid or 1-naphthalene acetic acid. The rooted plants were transplanted to soil with 90 % success. The emerged shoot primordia probably initiated from the pre-existing meristems since the shoot bud show definite vascular connection to the major vascular tissue.

Abaxial and Adaxial Stomatal Density, Stomatal Conductances and Water Status of Bean Primary Leaves as Affected by Paclobutrazol

I. Tari

Biologia plantarum 46:215-220, 2003 | DOI: 10.1023/B:BIOP.0000022254.63487.16

The plant growth retardant, paclobutrazol at 8.5 or 17.0 μM concentrations effectively inhibited the stem elongation and primary leaf expansion of bean seedlings. Although the retardant reduced the relative water content in well-watered plants, the water and pressure potentials remained high in the primary leaves. K+, Na+, Mg2+ and Ca2+ contents in the primary leaves of the paclobutrazol-treated plants were not significantly different from those in the control. The stomatal density increased on both surfaces but the length of guard cells was not reduced significantly on the adaxial epidermes of the paclobutrazol-treated primary leaves. The inhibitory effect of paclobutrazol on the abaxial stomatal conductances became more pronounced with time during the light period but the adaxial surfaces displayed similar or slightly higher conductances than those of the control. The transpiration rate on a unit area basis did not change significantly or increased in the treated leaves thus the reduced water loss of paclobutrazol-treated plants was due to the reduced leaf area. Stomatal conductances of the adaxial surfaces responded more intensively to exogenous abscisic acid and the total leaf conductance decreased faster with increasing ABA concentration in the control than in the paclobutrazol-treated leaves. Paclobutrazol, an effective inhibitor of phytosterol biosynthesis, not only amplified the stomatal differentiation but increased the differences between the adaxial and abaxial stomatal conductances of the primary leaves.

Physiological Effects of Plant Hormones in Cotton Under Drought

D.M. Pandey, C.L. Goswami, B. Kumar

Biologia plantarum 46:535-540, 2003 | DOI: 10.1023/B:BIOP.0000041058.65442.41

Effects of plant hormones indole-3-yl-acetic acid (IAA), gibberellic acid (GA), benzylaminopurine (BAP), abscisic acid (ABA) and ethrel (ETH) in 5 μM concentration on gas exchange, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO, EC 4.1.1.39) activity, pigment content and yield in cotton (Gossypium hirsutum L. cv. H-777) under drought were studied. At reproductive stage (55 - 60 d after sowing) these hormones were sprayed on shoots one day prior to stress imposition by withholding irrigation. The soil moisture of control plants was kept at field capacity. Net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), carboxylation efficiency (CE), water use efficiency (WUE), RuBPCO activity, boll number per plant, seed number per plant and lint mass per plant significantly decreased at drought while chlorophyll (Chl) b content and flower number per plant increased. ABA and ETH significantly reduced gas exchange parameters, Chl a and Chl b content. Detrimental drought effect on PN, gs, E, CE, RuBPCO and lint mass per plant was significantly alleviated by BAP and also its effect on seed number and lint mass per plant was significantly alleviated with the ABA treatment.

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