The effect of triadimefon (TDM) on various biochemical parameters was studied in NaCl stressed radish (Raphanus sativus L.). Stress imposed by 80 mM NaCl decreased the protein content and proline oxidase activity, and increased the proline and glycine betaine contents, and protease, γ-glutamyl kinase and ATPase activities. The TDM treatment alleviated the stress by increasing protein, and glycine betaine contents, and by decreasing proline accumulation, and proline oxidase and ATPase activities.

A significant reduction of hop latent viroid (HLVd) content during the generative phase of hop was detected using reverse transcriptase-polymerase chain reaction (RT PCR) and molecular hybridisation methods. A low transmissibility of HLVd through seed may be a feature valuable for the selection and maintenance of viroid-free hybrid hops.

Rhododendron catawbiense cv. Album propagated in vitro were transferred ex vitro and grown in a greenhouse, under long or short days. Under long days, the rhythmic growth led to an acrotonous development. In contrast, under short days, the upper buds were unable to burst, allowing basitony. In both photoperiodic conditions, the apical buds were sampled at different stages of the experiment. Growth capacities of the isolated buds were estimated by measuring their abilities to increase and diversify their non-adenylic nucleotide pool (NTP) after supplying adenosine as a precursor. Under long days, during the growth pause, the apical buds were able to increase and diversify their NTP pool. Under short days, adenosine was used to produce important quantities of ATP, while NTP pool increase became weaker. Nevertheless, during this long growth pause, apical bud tissues retained capacities to increase their NTP pool until the basal shoots developed.

After a 6 min exposure of isolated thylakoids to 43 °C, the extent of phosphorylation of light-harvesting complex of photosystem 2 (LHC2) was higher than in control thylakoids kept at 25 °C. Similarly, the exposure of intact spinach plants to 43 °C in dark for 11 h induced higher extent of thylakoid LHC2 phosphorylation than in control plants kept at 25 °C. The induced ability of LHC2 for enhanced phosphorylation may enable better energy distribution in favour of photosystem 1.

A number of nitrogen containing compounds (NCC) accumulate in plants exposed to salinity stress. The most frequently accumulating NCC include amino acids, amids, imino acids, proteins, quarternary ammonium compounds (QAC) and polyamines. The specific NCC that accumulate in saline environment vary with the plant species. Osmotic adjustment, protection of cellular macromolecules, storage form of nitrogen, maintaining cellular pH, detoxification of the cells, and scavenging of free radicals are proposed functions for these compounds under stress conditions. NCC accumulation is usually correlated with plant salt tolerance, even though this correlation is based on untested hypotheses.

The phytopathogenic fungi Colletotrichum circinans, Fusarium solani, and Rhizoctonia solani were incubated in aerated (0, 0.5, 1 dm³ min^-1) potato dextrose broth (PDB) or Czapek-Dox broth (CDB), under 0-, 12- or 24-h photoperiods. Greater dry mass was produced in PDB. Higher air flows improved dry mass of F. solani and R. solani. The 24-h photoperiod improved F. solani dry mass. Except for F. solani, which was not affected, incubation in PDB increased protein content. The no air treatment increased protein content in F. solani, 0.5 dm³ min^-1 produced the highest protein content in R. solani, but air flow-rate did not affect C. circinans. Incubation in the dark produced the lowest protein content in C. circinans, the highest under the 24-h photoperiod for R. solani, and photoperiod did not affect protein content in F. solani. Protein content in R. solani, incubated in CDB, was lowest at the 0 dm³ min^-1 air flow at all photoperiods. Molecular masses of most proteins were under 30 kDa, and numbers of bands in SDS-PAGE gels varied with air flow. In CDB, especially under 12- or 24-h photoperiods, proteins in F. solani were between 1.6 and 310 kDa. For R. solani in PDB, at 0.5 dm³ min^-1 air flow and 12-h light, proteins were between 6 and 81 kDa.

Exposure of the freshwater green alga Scenedesmus incrassatulus Bohl, strain R-83 to salt stress (175 mM NaCl) resulted in a reduction of its growth and ¹⁴CO₂ fixation and in an increase of accumulation of free proline and malondialdehyde (MDA). The accumulation of proline in the light was higher than in dark. NaCl significantly inhibited the Fe-induced release of organic chelators from the cells. Exogenously supplied 10^-4M methyl jasmonate (JA-Me) did not considerably change the ¹⁴CO₂ fixation, but increased proline and MDA accumulation in the cells and moderately inhibited the release of chelators from cells. JA-Me supplied simultaneously with NaCl helps the algae to counteract the salt stress.

A severe drought that took place in Spain and other Mediterranean countries in 1994 produced a dieback of Quercus ilex trees on south-facing conglomerates but only minor defoliations in trees on north-facing schists. The foliar Δ¹³C of damaged trees continued to decrease in the next two wet years probably indicating increasing water use efficiency, and their δ¹⁵N continued to increase indicating progressive ecosystem N saturation and/or N losses whereas there were no significant changes in undamaged trees. Pre-drought Δ¹³C values were reached in the third year after the drought, but δ¹⁵N values did not yet recover. Another co-occurring small tree, Phyllyrea latifolia, did not show any damage and gained dominance in the most affected stands.

Sucrose, glucose, fructose, and melibiose in different concentrations and combinations in the induction media influenced the viability of the isolated maize microspores and the formation of multinuclear structures. The induction of multinuclear structures on media containing combination of sucrose, fructose and glucose was lower than on media only with sucrose. In media containing melibiose alone or in combination with sucrose, no induction of multinuclear structures was found, however, microspore viability was improved.

The effect of Zn^2- on nitrate reductase (NR, EC 1.6.6.1) activity was studied in botá wheat (Triticum aestivum cv. Oasis) leaves and in the NR enzyme partially purified from wheat leaves. Leaf segments were floated on 0 to 5 mM ZnSO₄ solutions (pH 6.0) for 24 h under continuous light. Zn^2- at 250 μM decreased NR activity and increased membrane permeability. However, parameters of cellular oxidative damage were scarcely affected by Zn^2- treatments. Accordingly, the decrease of NR activity induced by Zn^2- was not prevented by benzoate (a scavenger of oxygen radicals). The effect of Zn^2- was dependent on leaf age: it decreased NR activity in mature but not in young leaves. Zn² inhibited the partially purified NR. This inhibition was not reversed by either co- or post-incubation with cysteine, and the amount of -SH groups of the purified NR was not affected by Zn²⁺ indicating that Zn^2- inhibition does not involve key -SH groups of the enzyme. However, o-phenantroline both prevented and reversed Zn²⁺-induced NR inhibition. We concluded that the effect of Zn²⁺ on NR activity in vivo is not associated with an increase in active oxygen generation and involves a direct and reversible inhibition of the enzyme.

It is almost impossible to find a single process in plant life that is not affected by both stress and hormones directly or indirectly. This minireview is focused on the interactions between water stress and cytokinins (CKs). The attention was paid mainly to changes in endogenous CK content and composition under water stress, involvement of CK in plant responses to water stress mainly in stomatal regulation of gas exchange, water relations of transgenic plants with elevated CK content, and possibilities to ameliorate the negative effects of water stress by application of exogenous CKs.

Roots of two Zea mays L. lines (drought-resistant Polj 17, and drought-susceptible F-2) were exposed to osmotic stress induced by sorbitol (osmotic potential -1.0 MPa). The following parameters were determined in cortex cells: membrane permeability for abscisic acid (ABA), ABA fluxes across membranes, pH values and ABA content in cytoplasm and vacuole. Osmotic stress induced different distribution of ABA within cell compartments in the investigated lines. ABA transport in the F-2 line occurred according to the intracellular pH gradient and the anion trap concept. In Polj 17, however, osmotic stress did not cause any significant effect on pH gradient and compartmental ABA content, but had a stimulating effect on ABA efflux from cytoplasm to apoplast and than via xylem to the leaf. These findings indicate different mechanisms of ABA transport between the investigated lines in response to osmotic stress.

In six cultivars of rice (Oryza sativa L.), Pusa Basmati 1, Basmati 370, Type III, Pant Dhan 4, CSR 10 and Pokkali, embryogenic callus growth, plant regeneration, and proline and total protein contents were studied under salt stress (on agar solidified media containing 0, 0.5, 1.0, 1.5 and 2.0 % NaCl). Four weeks after inoculation the callus fresh mass decreased with increasing salt concentration in all the six cultivars. The regeneration frequency in salt stressed callus was also lower as compared to control. 15 d and 30 d after inoculation proline content increased several fold whereas total protein content decreased markedly with increase in salt concentration.

The substrate preference and the localization of cucumber (Cucumis sativus L.) stress-related anionic peroxidase (srPRX) were investigated in order to assess whether this activity correlates with the lignification. The results showed that none of the purified srPRX isoenzymes (PRX 1 -3) could oxidize the lignin monomer analog syringaldazine. The srPRX immunospecific signal was found to be highly abundant in both the extrafascicular and fascicular phloem regions in cucumber stem and leaf petiole. In Nicotiana, Petunia and Dahlia, the srPRX homologs were specifically deposited in both outer and inner phloem elements of stem and in both abaxial and adaxial phloem of leaf stems. The srPRX mRNA expression analysis showed similar pattern as for immunolocalization. The subcellular localization of immunospecific srPRX demonstrated that at least part of the peroxidase could be ionically-bound to phloem cell wall.

Copper tolerance in Scenedesmus biguja was studied by comparing the physiological properties and Cu uptake in wild type and copper tolerant strain. A concentration dependent reduction in growth rate, pigment, protein, sugar, and amino acid contents, oxygen evolution, and alkaline phosphatase activities was noticed in both strains at 1 and 200 μg(Cu) dm^-3. The reduction in all parameters was higher in the wild type than in the tolerant strain. The tolerant strain showed also enhanced alkaline phosphatase activity, and insignificant loss of potassium and sodium. The Cu uptake was influenced by the Cu concentrations the algae had been exposed to during their previous growth: the lower the Cu concentration in the culture medium, the higher the activity of the uptake and the capacity of the cells to accumulate Cu.

Biochemical changes associated with adventitious shoot regeneration during in vitro culture of hypocotyl explants of Jatropha integerrima were determined. Histological and biochemical studies were undertaken at 7-d intervals, up to four weeks on hypocotyl explants cultured on basal Murashige and Skoog's medium supplemented with 0.5 mg dm^-3 N⁶-benzyladenine and 1.0 mg dm^-3 indole-3-butyric acid. Initial cell proliferation occurred within one week of culture; meristemoid differentiation within two to three weeks and shoot development after four weeks. Peak activities of alkaline phosphatase, peroxidase and polyphenol oxidase was observed at day 14 indicating their involvement in the formation of meristematic centers. Protein accumulation and acid phosphatase activity were maximum at day 28.

The aim of this research was to carry out a critical study of the method of obtaining size equivalence between non-symbiotic alfalfa and alfalfa associated with Glomus and/or Rhizobium by applying fixed addition rates of nutrients to the non-symbiotic controls. The experimental design included three nutrient response curves in which the levels of added phosphorus and/or nitrogen were constant during the whole plant growth process: 1) a phosphorus response curve, in order to compare the growth of double symbiotic plants with that of only-Rhizobium inoculated ones; 2) a nitrogen response curve, that consisted of a comparison between the growth of double symbiotic alfalfa and four treatments associated only with Glomus; 3) a phosphorus and nitrogen response curve, to compare the growth of non-inoculated alfalfa with that of double symbiotic plants. Although similar size was achieved among some treatments at harvest, shoot growth over time and nutrient concentrations in tissues differed, indicating that growth equivalence did not mean functional equivalence. A second experimental design was performed taking into account the establishment of microsymbionts for determining the adequate moment to add supplemental phosphorus and/or nitrogen. It included four treatments: a) double symbiotic plants (MR); b) plants inoculated with Rhizobium only (R); c) plants inoculated with Glomus only (M), and d) non-inoculated plants (N). Great similarity in terms of plant growth and nutrient contents in tissues were obtained. Moreover, symbiotic plants were able to produce similar dry matter than non-symbiotic ones under P and N limitations.

The relation between abscisic acid (ABA) and proline accumulation was investigated in detached rice (Oryza sativa L.) leaves. In darkness, proline content increased about 2-, 2,5- and 6-fold after 24, 48 and 72 h. ABA content reached maximum after 48 h. In the light, proline content remained almost unchanged until 48 h and subsequently increased slightly. ABA content in the light was lower than in darkness, but the maximum was also after 48 h. During 12-h exposure to decreased air humidity, proline content gradually increased, but ABA content increased about 25-fold after 4 h and declined thereafter. Exogenous application of ABA resulted in an increase in proline content in detached rice leaves under both light and darkness.

An increase in exocarp peroxidase activity was observed in fruit at 5 to 30 days post pollination (DPP), and decreased at 40 and 50 DPP. Total peroxidase activity of the mesocarp was significantly lower than the exocarp in all developmental stages. Mesocarp peroxidase activity decreased consecutively from outer, to middle and, to inner tissue at every developmental stage. Total activity in the mesocarp peaked at 20 DPP. Native-PAGE of exocarp tissue showed at least two cathodic (basic) peroxidases and two anionic (acidic) peroxidases. The number of isozymes was greatest and bands most intense at 30 DPP. IEF-PAGE of the 5 to 50 DPP fruit exocarp showed at least 8 peroxidase isozymes (pI 4.6 to 9.6). Anion exchange chromatography showed only one peak of anionic peroxidase activity that was not evident until 15 DPP. This peak was greatest at 30 DPP and declined at 40 and 50 DPP. Cationic peroxidase isozymes appeared to be the predominant and most intense isoforms throughout fruit development. The changes in peroxidase activity corresponded to fruit formation and may be associated with susceptibility to fruit rot.

The influence of saline water (4, 8, 12 dS m^-1) irrigation on gas exchange and growth response of alfalfa genotypes Anand-2, T-9 and IL-112 was studied. T-9 and IL-112 showed a significant increase in net photosynthetic rate (P_N) at low salinity (4 dS m^-1) compared to the control whereas Anand-2 maintained an unaltered P_N. Reduction in P_N at higher salinities was primarily due to reduction of stomatal conductance. There was a greater reduction in transpiration rate as compared to P_N rate, which resulted in an increase in water use efficiency (WUE). High WUE may serve as one of the strategies of the plant to withstand saline environment. However, the slight increase in WUE in Anand-2 could not help in maintaining its growth. Increase in Na⁺ concentration in comparison to K⁺ concentration may also contribute to the inhibition in growth.

The alkali metals cesium, rubidium, lithium and sodium were introduced together with strontium via flaps into leaf laminas or into the stem of maturing, intact winter wheat (Triticum aestivum L. cv. Arina) grown in a field. Long-distance transport of these elements and the influence of the application date and of different application positions were investigated. The phloem-immobile Sr served as a marker for the distribution of the xylem sap in the plants. Dry matter accumulation in the grains and the transpiration per shoot were not markedly affected by the treatments as compared to control plants. The phloem mobility was rather high for Cs and Rb. Li was almost immobile in the phloem (similarly to Sr). An application into the cut stem xylem below the second leaf node contributed more to the contents in the grains than an application into the flag leaf. An earlier feeding date led to a higher accumulation in the grains. The marked losses of the elements applied during maturation (most pronounced for Li) can be explained by leakage in the rain.

The effect of calcium and zinc ions on superoxide dismutase (SOD) from four plant species (Taxus baccata, Pinus sylvestris, Medicago rigidula, and Zea mays) was followed at three temperatures: optimal (20 °C), increased (50 °C), and high, inhibiting temperature (70 - 80 °C). At 20 and 50 °C in vitro added calcium increases SOD activity, but the degree was different for the plants investigated. The effect of zinc ions at the same temperatures varied in the investigated plants from activation to inhibition. An inhibiting effect of high temperature on SOD activity was diminished in the presence of calcium or zinc ions. It was shown that calcium and zinc ions can increase activity and thermostabilize different SOD isoforms.

Incubation of 5-d-old maize seedlings in the half-strength Hoagland's nutrient solution containing 10 mM KNO₃ with FeCl₃ or FeSO₄ (0.5 or 2.0 mM) caused a significant increase in nitrate reductase (NR) activity and slightly increased total protein content in root, shoot and scutellum. In case of root, NADPH:NR activity was inhibited contrary to the NADH:NR activity. In spite of NR activity, nitrate uptake was inhibited from 13 to 37 % by the iron. The results presented demonstrate an isoform specific, organ specific, and to some extent salt specific responses of NR to iron.