Several tomato cultivars were infected with a severe strain of PSTV and a pathophysiological reaction was characterized by means of enzyme-linked immunosorbent assay with serum containing IgGs to disease-associated host-specific leaf proteins. A strong expression of disease-associated symptoms (stunting, epinasty, leaf blade malformation and rugosity) and strong immunochemical reaction was found for cultivars Bizon, Linia, Revermun and Rutgers. The immunochemical assay revealed appearence of a major antigenic protein having a molecular mass of about 70 kD in these cultivars. The immunochemical reaction with disease-associated proteins reached a maximum four weeks after inoculation of PSTV. A weak immunochemical reaction was observed, if proteins from cvs. Sonato, Harzfeuer and Karlik were analyzed. Cvs. Sonato and Harzfeuer did not show characteristic symptoms such as stunting, leaf blade malformation and rugosity. Except for stunting, the same was true for cv. Karlik. On the other hand, no significant difference in PSTV accumulation was observed among the cultivars analyzed.
Reciprocal hybrids obtained by crossing cvs. Revermun and Karlik showed strong symptoms of the disease (Revermun-type) and increased activity of nuclease due to PSTV infection. On the contrary, an immunochemical analysis revealed a low level of the disease-associated antigens in these hybrid tomatoes, suggesting rather recessive genetic background determining their expression during PSTV-caused pathogenesis.

Twenty one winter wheat(Triticum aestivum L.) genotypes classified as (1) short, (2) medium or (3) tall were grown in field trials. The following parameters have been measured on the main stem: stem length, peduncle length, dry mass and conducting system parameters including number of vascular bundles and their total and phloem area on peduncle cross section, ear yield and its components. Regardless of differences in peduncle length among the genotypes groups differing in stem length, the peduncle relative length varied only between 36 and 38 % of the total stem length. Nearly identical was also the peduncle specific dry mass reaching 7.4 to 7.6 mg (dry mass) per cm (peduncle length).
The highest number of vascular bundles as well as the largest bundle and phloem area per peduncle cross section were found in the group of short cultivars. There was a positive correlation between the anatomical parameters and kernel number or dry mass per spike. The relationships need not be valid with each genotype because the final ear productivity is subjected to climatic variation well after anthesis when the formation of the stem anatomy has been by far accomplished.

Lead chloride (10^-5 M) inhibited the growth of the main root, the duration of development, the number and growth of lateral roots, primary and trifoliate leaves, and also the mitotic index in root apical meristems. Lead strongly inhibited root growth rate, mainly by reducing the number of dividing cells. Other mechanisms of this inhibition are discussed.

Vegetation experiments were conducted under greenhouse conditions in which long-term effects of simulated acid rain on the shoots, and short-term effects of acidified root medium on the roots of two maple species (Acer pseudoplatanus L. andAcer negundo L.) were studied. Both alternatives of the acidification stress were studied with respect to exogenous applications of auxins and gibberellins. Changes in seedling growth caused by acid rain were not marked, but changes in the levels of endogenous growth regulators were detected, both the long-term exposure ofAcer pseudoplatanus L. seedling shoots to acid rain and the short-term acidification of root environment resulted in enhanced cytokinin activity and in decreased gibberellin activity. But when A.pseudoplatanus L. seedlings were pretreated with gibberellins, their activity was further increased by increased acidity.Acer negundo L. seedlings responded to the acidification of their root environment with enhanced cytokinin activity only when pretreated with exogenous auxins. The differences in the responses ofA. pseudoplatanus L. and A.negundo L. to the acidification can be explained in terms of their distinct physiological properties, including changes recorded in chlorophyll content. The results obtained show that a pretreatment of maple seedlings with exogenous growth regulators can modify the effects of increased acidity in the environment on their physiological status as characterized by the level of endogenous cytokinins and gibberellins.

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.

Previous results with potato leaf tissues revealed that a treatment with ABA (10^-4 M) induced an increase of K⁺ uptake (Suleimanet al., 1990a).
In this study, we investigate the relationship between increased K⁺ uptake, Ca²⁺ fluxes and calmodulin by treating potato leaf discs with Ca²⁺ channel blockers (La³⁺, verapamil and nifedipine) and with calmodulin inhibitors (chlorpromazine, W₇: N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide, and compound 4880).
We found : a) all these inhibitors decreased K⁺ uptake in the same ratio in tissues treated or not with ABA; b) a synergistic effect between ABA and the Ca²⁺ ionophore A 23187 on K⁺ uptake.
The results suggest that the hormone may act on K⁺ uptake like a Ca²⁺ agonist, in accord with HUDDART's hypothesis.

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.

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.

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.

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.