The synthesis of major storage globulin polypeptides has been examined in developing seeds of sunflower(Helianthus annuus L.). Analyses of total proteins and purified globulins, also called helianthinin, by gel electrophoresis and immunoelectrophoresis have shown that a burst of protein synthesis and accumulation occurs around 10 d after flowering. There is no mature globulin before that time and only small amounts of precursor forms can be detected. Thus, 10-12 d after flowering appears to be a transition period during which genetic information for the globulin becomes actively expressed. Immunoelectrophoresis has confirmed that globulin is the main storage protein, at seed maturation, accounting up to 70 % of total proteins per kernel. Pulse chase experiments have shown that synthesis initially involves the formation of high molecular mass precursors and that storage proteins are post-translationally processed. Intermediary products, with molecular mass higher than early translational products, can be detected, together with mature globulin polypeptides.

Fruit epidermis ofMusa (AAB) cv. Poovan (S) remains single-layered throughout its development. There is no change in stomatal number but its frequency and index decrease due to slight increase in epidermal cell number and size. The external wall of the epidermal cells shows stratification of wall layers that is characteristic of normal epidermal cell with cuticle and epicuticular wax deposits. Surface wax deposits show qualitative and quantitative variations during fruit development and ripening.

The effects of chlorpromazine and calmidazolium on rapid IAA- and GA₃-induced changes in growth rate of etiolated pea stems were measured. During the initial period of up to 160 min after hormone application, the responses to both IAA and GA₃ were seen to be biphasic, showing two acceleration peaks. Chlorpromazine or calmidazolium applied simultaneously with the hormones blocked the first IAA-induced acceleration peak, but did not affect the second one. In contrast, the first GA₃-induced peak was not prevented by chlorpromazine or calmidazolium, while the second one was completely abolished. The results support the concept that the active calmodulin-calcium complex may be an essential component of hormone-controlled stem elongation. They also point to differential mechanisms of IAA and GA₃ actions.

Trans-resveratrol (4,3',5'-trishydroxystilbene) was identified in grapevine leaves with vein necrosis disease symptoms. The compound accumulates from 10 to 60 μg^-1 (fresh mass) in infected leaves.

Differentiation of Acerpseudoplatanus L. cells into tracheary elements (TE) and an increase in the number of TE inHaplopappus gracilis (Nutt.) A. Gray calli were observed after pulse-treatment of the cultures grown in glass tubes with indole-3-acetic acid (IAA) solutions. The effect was enhanced if the treatment was repeated in three subsequent days. The manner of IAA application which caused a wave-like pattern of IAA flow through the callus culture appeared to be more important than the IAA concentration. Induction of differentiation of A.pseudoplatanus cells and an increase in the number of TE inH. gracilis callus did not occur when the calli were grown on agar media supplemented with increased concentrations of IAA.

Ultrastructure of chloroplasts in leaf mesophyll cells of triazine resistant and triazine sensitiveAmaranthus retroflexus L. plants was evaluated stereologically. The most striking difference between both types of the chloroplasts was a small volume of starch inclusions in triazine resistant plants.

Agrobacterium tumefaciens binary vectors carrying kanamycin resistance gene and either C58 T-DNA gene 4 for cytokinin synthesis or genes 1 and 2 for auxin synthesis were constructed and used for transformation of a short-day tobacco Maryland Mammoth. Kanamycin resistant plants were regenerated from a small fraction of transformed tissue and the presence of T-DNA in their genome was verified by Southern blotting. The level of endogenous cytokinin in plants transgenic for gene 4 and the level of endogenous IAA in those transgenic for genes 1 and 2 increased by more than 100 %. A number of morphological characteristics distinguish them from untransformed controls.

Simultaneous uptake of NH⁺ ₄, Na⁺, Mg²⁺, Ca²⁺, NO^- ₃, SO^2- ₄, (NO^- ₂), H²PO^- ₄ and C1^- ions by N-limited winter wheat seedlings(Triticum aestivum L., cv. Regina) in a single depletion experiment was investigated. Individual ion species in uptake solution samples were determined using capillary isotachophoresis. The operating systems used are described in detail. Processing of obtained concentration data allow to construct time curves of individual ions concentration in uptake solution, time curves of accumulative uptake, and curves for uptake rate versus time and uptake rate versus external concentration. From these curves there is possible to reveal a more complex picture of behaviour of individual ions during uptake process as well as to assess interactions among them. Attention was paid to the points of intersection of time curves of NO^- ₃ and NH⁺ ₄ uptake rates. These points characterized by equal uptake rates may be considered as limits for preference of given ion species under given experimental conditions.

In this study the pattern of storage protein deposition in the developing seeds of xHaynaldoticum sardoum was examined. The accumulation of the various protein classes did not differ greatly between the two lines tested (Culmo Pieno and Culmo Vuoto). Nevertheless, some differences in the deposition pattern were revealed by polyacrylamide gel electrophoresis. In particular, the mature seeds of the two lines presented different electrophoretograms for the prolamin and glutelin proteins. These patterns reflect the differences between the two lines, which could play a role in their ability to adapt to environmental changes.

The hypocotyls, cotyledons, leaf blades, whole leaves and petioles of seedlings ofAilanthus altissima are capable of producing callus and budsin vitro. Buds and callus were also obtained from whole leaves and internodes of 2-years old plantlets grownin vitro. From the calli buds differentiated and later, both from buds developing directly without a callus phase and alsovia a callus phase, well developed shoots were formed. The cultures were mainained on MS medium in 2 combinations: A) IAA - 0.2 mg 1^-1, BAP - 1 mg 1^-1, GA₃ - 0.5 mg 1^-1, thiamine - 4 mg 1^-1 and sucrose 3 %; B) BAP - 0.5 mg 1^-1, IAA - 1 mg 1^-1, casein hydrolysate 400 mg 1^-1, thiamine 4 mg 1^-1 and sucrose 3 %. Excised shoots, which had developedde novo in culture, produced roots when incubated on the basic mineral medium of MS with the addition of IAA. The regenerative potential ofA. altissima is very high and this woody species seems to be an ideal object for various morphogenetic studies.

Growth of soybean was not altered, whatever the inorganic N-source (NO₃, NH₄ or a NO₃/NH₄ mixture); conversely, growth of Erica x darleyensis plants in vitro decreased more in. NH₄ medium than in a NO₃ medium, compared to a NO₃/NH₄ medium. The GS/GOGAT pathway (in NH₄ medium), the nitrate and nitrite reductase activities (in NO₃ medium), as the contents in free nitrogenous forms and total nitrogen (in NO₃ and NH₄ media) were not more altered in Erica than in soybean, compared to a NO₃/NH₄ medium. PEPCase activity was the highest in soybean irrespective of the N-treatments; the involvement of PEPCase in N-metabolism could be explained by its function in ionic and osmotic balances rather than its function in supplying carboxylates as acceptors for NH₄-assimilation.

The possible implication of ethylene on the growth regulation of etiolated lupin hypocotyls was investigated. Excised hypocotyl sections from actively growing seedlings produced ethylene at a rate of 3 nmol h^-1 g^-1 min^-1. The rate of ethylene production was increased about 7 times when sections were treated with 10 mM 1-aminocyclopropane-1-carboxylic acid (ACC). Measurement of endogenous ACC showed that 95 % of total ACC (64.2 nmol g^-1 min^-1) corresponded to conjugated ACC.
Treatments to intact seedlings with the ethylene precursor ACC, and the ethylene generating compound, 2-chloroethyl phosphonic acid (ethephon) during the cell elongation phase of the hypocotyl (from 7 to 21 dage), modified the cell growth of the organ. ACC (1 or 5 mM) or low concentrations of ethephon (0.66 mM) produced a transient decrease in the growth rate without modifying the final length of the hypocotyls. Higher concentrations of ethephon reduced the final length; the younger the seedlings were, the greater the reduction. Simultaneously to inhibition of cell elongation, ethephon produced stimulation of the radial expansion of cells in pith and cortex.
The growth inhibition period, which lasted for 2 days after the treatments, was followed by another period in which the growth rate of treated plants surpassed that of the control. In both cases differences were observed along the hypocotyls due to the different growth status of the cells. It is suggested that the sensitivity to ethylene and the metabolism of ethylene depend on the growth status of the cells.

A pre-treatment of 40 °Cprovided thermoprotection to wheat seedlings against 43 °C, which was otherwise a lethal temperature. Due to temperature pretreatment, the rate of protein synthesis at 45 °C increased in both plumules and radicles. The HPLC profile of plumule and radicle proteins of thermoprotection-acquired seedlings was different from the plumules and radicles of non-treated seedlings.

Primary roots ofVicia faba were grown for 24 h in the presence of tritiated thymidine (1.85-18.5 kBq ml^-1) and then irradiated with a dose of 1.5 Gy of⁶⁰Co-gamma- rays. The aim of these experiments was to determine whether low-level endogenous beta-irradiation from incorporated radioactive thymidine could influence the frequencies of sister chromatid exchanges (SCEs) and the numbers of micronuclei induced by subsequent external irradiation with high doses of gamma-rays. The results demonstrated that the pretreatment with³H-dTh had no significant effect on the frequencies of SCEs in gamma-irradiated root tip cells ofVicia faba. In contrast to SCEs, the yields of micronuclei in the³H-dTh pretreated cells were altogether less than the yield induced by gamma-rays alone (protective effects).

Spring barley seedling were grown in the dark for 21 d and respiration rates of the whole plant (including the seed), of the shoots, and of the roots were determined. A function describing the growth and maintenance components of respiration was interpolated through the experimental points and its parameters in plants under different mineral nutrition were compared. The plants grown in a complete nutrient solution showed the highest growth rate in the initial phase of development and thus reached the maximum respiration rate earlier than plants in the other variants. The highest proportion of substrate was respired in the shoot. Plants grown under deficiency of phosphorus and magnesium had a slower respiration rate than plants grown in the complete nutrient solution (NP), whereas the amount of respired substrate in plant parts was similar to that recorded in the NP plants. Plants grown in distilled water showed the lowest growth efficiency and respirated the highest proportion of substrate in the root.

A 2,4-D dependent cell line, accumulating only traces of indole alkaloids under standard conditions of subculture, was grown in two different production media. Removal 2,4-D from maintenance culture medium enhanced the production of ajmalicine and serpentine and increased the activities of the NADPH-producing enzymes: glucose 6-phosphate dehydrogenase, 6-phospho-gluconate dehydrogenase, malic enzyme and cytosolic isocitrate dehydrogenase.
Adding zeatin to a 2,4-D depleted medium further increased the alkaloid content but the activities of the NADPH-producing enzymes remained unchanged.

Two forms of α-glucan phosphorylase were isolated fromDioscorea cayenensis by ammonium sulphate gradient solubilization and further purified using starch adsorption and ion exchange chromatography on DEAE-Sephadex A-25 colunm. Fraction DC₁was purified 80 fold with specific activity of 400 umol min^-1 mg^-1 protein, while fraction DC₂showed 60 fold purification with specific activity of 300 umol min^-1 mg^-1 protein. Both enzyme forms were activated by AMP, magnesium, calcium and inhibited by ATP, ADP, ADP-glucose and sodium sulphate. They showed absolute primer requirement and obeyed Michaelis-Menten kinetics. The two forms have different Km values and different pH optima. The presence of amino acids and intermediates of glycolysis had no effect on the activities of the enzymes. There are no unusual properties of the enzymes which suggest that they function primarily in starch biosynthesis inD. cayenensis tuber.

Three isolates of strawberry mottle agent (SMA) from strawberry plants were regularly maintained and multiplied by mechanical inoculation onChenopodium quinoa plants showing mosaic and mottle symptoms. The use of 5 mM borate buffer pH 8.6 or tap water pH 6.6-7.9 with 4 % (m/v) charcoal for homogenization resulted usually in 100 % infection. The total of 2090 plants were infected from 2264 inoculated ones under the same conditions. The infectivity of SMA isolates in crude sap ofC. quinoa was retained from 48 h to 72 h at 20 °C. The dilution end points of SMA isolates were 10^-3 while the inactivation temperatures were between 50 and 55 °C. The infectivity of SMA isolates in frozen leaves ofC. quinoa was detected still after six months.
Purification procedure of SMA is based on using low molar 25 mM borate buffer pH 8.3 with cysteine hydrochloride, DIECA and Tween 20 for homogenization of infectedC. quinoa leaves, polyethyleneglycol precipitation, clarification with octanol, low and high speed centrifugation and sucrose density-gradient centrifugation. Partially purified preparations are highly infectious, causing mosaic, mottling and tip necrosis ofC. quinoa plants. The agent could not be completely separated from host proteins and it could not be concentrated to a high extent. Isometric virus-like particles 14-16 nm were observed in partially purified preparations.

The time-evolution of germination of oat seeds, suspended in the standard 5mm N. M. R. tube and supplied by water, was investigated continuouslyin vivo by the pulsed N. M. R. of water protons at the level of the seed. The results show that the spin- lattice relaxation time T1 yield the physiological information: in the germinated (living) seeds, the T¹'s are higher than in the killed seeds.

The enhancement of fruit abscission zone formation with ethephon treatment caused an increase in soluble proteins, endo-cellulase, exo-polygalacturonase and peroxidase activities. Exo-cellulase and endo-polygalacturonase did not show any relationship with apple abscission. The separation of cells initiated in the cortex region and progressed towards vascular tissue. Cell separation in the cortex appeared to be due to dissolution of middle lamella but vascular tissues ruptured mechanically.

During the growth of multiple-shoot cultures of Ruta graveolens, oxygen and carbon dioxide exchanges were continuously and simultaneously measured. The shoots subcultured on a medium containing 166 mM glucose showed a marked respiration rate. Even under light, CO₂ concentrations reached 4000 to 6000 cm³ m^-3. Photosynthesis never compensated for respiration. These cultures were photomixotrophic. A change of respiration and photosynthesis occurred between the 30th and the 32nd day of culture, with a high respiration rate. When the shoots were subcultured on a medium containing 41 mM glucose, it was possible to obtain photoautotrophy after two weeks under high irradiance (150 umol m^-2 s^-2), and after three weeks under low irradiance (60 μmol m^-2 s^-1), the CO₂ concentrations being 1100 and 600 cm³ m^-3 respectively.

An improved method for the isolation of leaf mesophyll protoplasts ofSolanum tuberosum L. cvs. Xenia and Bintje, their culture and regeneration to plants is described. The improvements involve the culture of nodal stem explants on Schenk and Hildebrandt (SH) medium supplemented with AgNO₃ (7.5 mg 1¹) and Alar 85 (5 mg 1^-1), and the pre-treatment of donor plants for 2-3 weeks at a short photoperiod (6 h), a low irradiance (17 (μmol m^-2s^-1) and a low temperature (20 °C). Regeneration of cell wals was observed within 2-3 d and cell divisions within 7-12 d after resuspending freshly isolated protoplasts in Sidorov et al. (SW) medium. The resulting microcalli were cultured on solid media containing zeatin (1-2,5 mg 1^-1) and/or NAA (0.1 and/or 0.01 mg 1^-1) and subsequently on medium with BAR (0.25 mg1^-1) and GA^-3 (0.1 mg 1¹) for shoot regeneration.