Tobacco cv. White Burley was transformed with disarmed expression vector pCB1314 containing dimeric cDNA of potato spindle tuber viroid (PSTV, severe strain) in plus orientation regulated from the mannopine promoter. Amount of PSTV specific (-) and (+) sequences and PSTV circular forms was measured in transformed tobacco stock and compared with PSTV content in untransformed tomato and tobacco grafts. It follows from the results that lower rate of accumulation of PSTV in tobacco as compared with tomato is due to less intensive viroid transportation through the cytoplasm and/or cell to cell moverment, whereas both, viroid replication and processing showed comparable characteristics in tomato and tobacco with respect to accumulation of minus and plus strands and circular forms in infected tissues. Despite of accumulation of viroid in comparable amount in both transformed tobacco and infected tomato, no expression of any morphological symptom of disease was observed in transgenic tobacco.

Thein vivo ¹⁴CO₂ fixation assay and xylem sap analysis showed that inSesbania rostrata the transport of fixed nitrogen from stem nodules was in the amide form. The majority of nitrogen was transported as asparagine. The close relationship between nodule phosphoenolpyruvate carboxylase and nitrogenase activities suggested that nodule CO₂ fixation contributed directly to nitrogen assimilation in stem nodules ofS. rostrata.

Monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and sulfoquinovosyl diacylglycerol (SQDG) are the most abundant lipid classes present in both the autotrophically and heterotrophically grownChlamydomonas reinhardtii. However, phosphatidylcholine (PC) and diacylglycerol (N,N,N-trimethyl)-homoserine (DGTS) were absent in both alga types. The polyne index B was higher in heterotrophic than photoautotrophic algae, but the unsaturation index was higher in photoautotrophic algae PI, PE and DGDG. The proportion of linolenic acid decreased under heterotrophy with compensatory increases in hexadecadienoic (16 : 3), oleic (18 : 1) and linoleic (18 : 3) acids.

The current-response method was used to characterize effect of oxygen deficiency on functional state of membranes along the roots of wheat seedlings. The results show apical parts of older roots being most affected by hypoxia, while the youngest roots behaved as effectively adapted.

Decrease in soil water potential during vegetative and flowering stages of two cultivars of pipeon pea (Cajanus cajari) caused higher decrease in relative water content in cv. ICPL-151 than in cv. H-77-216. Both cultivars showed partial recovery during rehydration. Cv. H-77-216 also accumulated more proline and carbohydrates during stress and showed better drought tolerance than cv. ICPL-151.

Total nonstructural saccharides (TNS) content in young plant ofAlopecurus pratensis was always above 4% of dry matter even at several types of stress treatment (nitrogen deficiency, low irradiance). TNS content was in negative correlation with concentration of total nitrogen in all cases. Positive correlation was found between the TNS content in plants and relative increase in their root growth rate.

Restriction fragment analysis of the chloroplast gene psbA was carried out in twelveAbies species native to Asia, Europe and North America using the four restriction enzymes. The pair of Asiatic representatives ofA. koreana andA. veitchii differed profoundly not only from each other but also with respect to the European and Northamerican species. The variation observed within the last mentioned groups of firs was mainly due to the different restriction profiles of the gene inA. alba andA. nordmanniana species of the former region as well as owing to its heterogenous nature in all the four species from North America. The RFLP data presented to far only partially correlate with the taxonomic status and hybridological relationships of the species concerned.

Introduction of the gene for cytokinin synthesis into potato genome lead to a manifold increase in the level of cytokinins (zeatin, zeatin riboside, isbpentenyl-adenine, isopentenyladenosine) in plantlets grownin vitro.The increasing cytokinin level was associated with increasing tendency to teratoma formation, to decreasing leaf net photosynthetic rate and to increasing dark and light respiration rates and CO₂ compensation concentration. During plantlet (or teratoma) ontogeny, net photosynthetic rate increased simultaneously with the decrease in cytokinin level. High level of endogenous cytokinins was associated also with lower photochemical activities of both photosystems in isolated chloroplasts.

Growthof Atriplex amnicola P.G. Wilson was not affected by different levels (10, 100, and 200 mM) of NaCI. Na concentrations in roots and shoots increased significantly at higher levels of NaCI. K/Na ratios in plant parts were higher compared to those in the external solutions, indicating selectivity for K over Na. P uptake, as determined using³²P, was not affected by increasing NaCl in the root medium.

Somatic embryos were induced from immature cotyledons and immature embryonal axis ofArachis hypogaea L. on L-6 basal medium supplemented with NAA, picloram or 2,4-D at 5-50 mg 1^-1. Immature embryonal axis produced a higher number of somatic embryos in comparison with immature cotyledons. The highest number of responding cultures was produced on medium supplemented with NAA (50 mg 1^-1), while the highest average number of somatic embryos per culture was produced on medium with 2,4-D (10 or 20 mg 1^-1) and picloram (30 mg 1^-1) from cotyledons. The somatic embryos developed into plants on basal medium supplemented with activated charcoal and about 100 plants were successfully transferred to the field.

Eight major pathogenesis related (PR) proteins were found in a soluble extract of cucumber mosaic virus (CMV) infectedCapsicum annuum leaves. None of them was present in the soluble extract of sham-inoculated controls. The proteins were detected by two-dimensional polyacrylamide gel electrophoresis using (2D-PAGE)PhastSystem, native-PAGE in the first dimension and SDS-PAGE in the second. Two major acidic PR-proteins were identified on the basis of their relative molecular mass (M_r), PR1 of 15.3 kD and PR2 of 29 kD. Six proteins were basic and were identified as PRla of 15.9 kD, PRlb of 15.0 kD, PRlc of 15.9 kD, PR2 of 27.0 kD, PR3 of 36.3 kD and PR4 of 48.8 kD.

A culture system was developed which allows continuous production of adventitious buds. Segments of seedlings germinated on media supplemented with different growth regulator combinations were used as explants. Cultivation was carried out in two phases, which alternate permanently: (I) without and (II) with growth regulators. Thus it was possible to establish meristematic tissue cultures from 5-10% of the seedlings tested. They have produced buds now for over 3 years with multiplication rates of about 1.5 within 5-6 weeks.

In barley genotype susceptible toErysiphe graminis f. sp.hordei 1,3-β-glucan synthase activity in whole leaf extracts was higher in comparison with healthy plants. A positive correlation was found between the activity of 1,3-β-glucan synthase and the degree of barley resistance. On the contrary, the 1,3-β-D-glucanase activity in whole leaves was negatively correlated to host plant resistance. This phenomen is evident only in the early phase of plant pathogen interaction. However, in epidermal cells the 1,3-glucanase activity was not significantly changed after attack and the 1,3-glucan synthase activity was practically zero. Chitinase activity in inoculated leaves and epidermis was higher than in healthy ones, but no unambigous correlation was found between the enzyme activity and host resistance.

Structural adaptations to increased transport activities were investigated in the cells of vascular parenchyma at the site of the lateral root junction, in non-stressed plant roots. Typical transfer cells were differentiated in dicotyledonousHelianthus tuberosus and in two different genotypes ofH. annuus, the cv. IBH166 and a decorative form. In the representatives of monocotyledonous, no structural adaptations occurred in the roots ofHordeum vulgare but small and rare cell wall protuberances were found in xylem and phloem ofZea mays inbred line VIR17. Some degree of cell wall labyrinth differentiation was seen in xylem and typical transfer cells were found in phloem of the roots of the maize hybrid CE380. The capability of vascular parenchyma to differentiate transfer cells did not depend on species, genotype, or on the growing conditions withHelianthus. On the other hand, the development of the structural adaptations in monocotyledonous representatives depended on both the species and the genotype. This capability may be linked with the taxonomic and evolutionary position of plant species.

Investigation on karyotype, 4C nuclear DNA amount and interphase nuclear volume (INV) of different HimalayanBupleurum species belonging toUmbelliferae revealed genetic differentiation. Numerical and structural alternation of chromosomes in interspecific level were manifested in their statistically significant altered species specific 4C nuclear DNA content. Somatic chromosome number ranged between 2n = 14 and 2n = 16.B. himalayense was reported for the first time having 2n = 16 chromosomes. Correlation coefficient among the various chromosomal and nuclear parameters showed no significant progressive or regressive interdependence except in between INV and nuclear DNA amount. Critical differences between 4C DNA content showed interspecific variation.

The relative efficiency of incorporation of the exogenously supplied primary precursors [2-¹⁴C]acetate, [U-¹⁴C]glucose and [U-¹⁴C]sucrose into essential oil was determined in the immature leaves of threeCymbopogon species(C. martinii,C. winterianus andC. flexuosus). Acetate was most efficiently incorporated into essential oil inC. winterianus andC. flexuosus, whereas glucose was the best precursor inC. martinii. The observations are consistent when expressed as radioactivity [Bq] of essential oil per leaf, as percent incorporation or moles of precursors utilized for essential oil synthesis. Thus, there is selectivity in the efficiency of precursor utilization for the oil synthesis inCymbopogon species.

Parthenin - a sesquiterpene lactone fromParthenium hysterophorus L. is an allelochemical that prevents the germination ofPhaseolus aureus Roxb. cv. ML-5 seeds. The response of the seed has been attributed to the inhibition of the respiratory electron transport ability of its embryo. It has been shown to depend directly not only upon concentration of parthenin, but simultaneously on the duration of exposure of the seeds to the chemical as well. A strong correlation exists between the quantum of the response and the product of the period of exposure and the concentration of parthenin. In order to predict the maximum possible germination ability of the seed exposed for a given period to a given concentration of parthenin, an expression X = 10000 Y³ / [e^Y/0.31-1] was formulated from the equation X = AY³/[e^Y/Y0-1], where X represents values of maximum respiratory activity, Y represents the product of concentration and time in units mg cn^-3 h, A represents a dimensional constant. The trend and nature of response that is calculated on the basis of formulation coincides with that of measured response through spectrophotometry.

The counteraction of exogenous L-proline at different concentrations with salinity (100 mM NaCl at sublethal concentration) were observed on germinating rice. Supplemented 30 mM L-proline was shown to be the most effective; at higher concentration it reduced seedling growth and K⁺/Na⁺ ratio. Thus 30 mM L-proline can alleviate the salinity stress in rice seedlings.

Methylmethanesulfonate induced chromosomal aberrations in callus culture ofCrepis capillaris. The clastogenic effect was markedly decreased when calli were pretreated with dimethylsulfoxide.

Coleoptile removal-induced ethylene production was investigated in light-grown winter rye seedlings. Removal of the coleoptile induced 1-aminocyclopropane-l-carboxylic acid (ACC) synthesis and ethylene production by primary leaves and caused an inhibition of elongation growth of the leaves. The activity of ethylene-forming enzyme (EFE) was associated with the increase in ethylene evolution. Both rise in ethylene and ACC production, as well as EFE activity were inhibited by cycloheximide. Wounding the tissue 40 min after the initial treatment resulted in the second increase in ethylene evolution. Derooting of the seedlings without coleoptile removal did not induce ethylene production. It is suggested that the coleoptile represents a barrier for wound-induced ethylene production from actively growing leaf tissue.

The effect of chloramphenicol (CP) on the differentiation of callus cells ofHaplopappus gracilis into tracheary elements (TE) was studied. CP (1 mg l^-1) added to the medium stimulating the differentiation was shown to have an inhibitory effect. This observation points to the importance of the impaired functions of mitochondria in the processes leading to the differentiation of callus cells into TE.

Phenylalanine labelled by¹⁴C was administered to the cultured cells and the intact flowers ofCarthamus tinctorius, and the biosynthetic activity of carthamin in these two materials was compared. The cultured cells took up positively the fed substrate, but they could not incorporate the label into carthamin, while incorporation of the radioactivity from phenylalanine into the red pigment occurred in the intact flowers. The activities of polyphenol-oxidizing enzymes were screened in the cell cultures and the intact tissues from the herbal plant. Polyphenol-oxidizing enzymes were operative normally in the mother explant, whereas their activity patterns changed altogether in the cultured cells, where kurenamin, a new reddish pigment, is produced actively. The data are discussed in terms of the phenotypic changes in the polyphenol metabolism of the cultured cells propagated under restricted culture conditions.

Haploid and dihaploid female and rare dihaploid male plants were produced inMelandrium album throughin vitro induced androgenesis. In the seed progeny obtained from cross-hybridization between dihaploid androgenic males (supermales) and standard females only male plants were observed. The microspores containing Y chromosome gave rise to supermales.

During 195-min light exposure following 5 d in dark, nitrate content was studied in different organs of lucerne plants in early bud stage. Nitrate content varied considerably especially in stems. Rapid diurnal variations in nitrate content were found in lower and upper halves of stems, in petioles and in leaf blades. The results reflected discontinuous nitrate movement in lucerne shoots. The positive correlation between the diurnal course of the nitrate and potassium contents in different plant organs showed that the K⁺ transport followed the NO₃ ^- transport. Similar diurnal changes were found also in Na⁺ and Ca²⁺ contents. Discontinuous salt movements occurring in xylem sap flow were in contrary to continuous transpiration stream and could be a consequence of temporary adsorption or binding of salts in xylem vessels.

The effect of growth in saline medium on the activity of two ATP utilizing enzymes was studied. Hexokinase in carrot (Daucus carota L.) cells grown in suspension culture either in the absence or presence of 150 ml NaCl, and tonoplast H⁺-ATPase in tobacco (Nicotiana tabacum L. cv. Wisconsin 38) cells grown in suspension culture either in the absence of presence of 428 mM NaCl. There was no difference in the pH profiles, NaCl sensitivity and kinetic parameters towards glucose of hexokinase activities from carrot cells grown in the presence or the absence of NaCl, but the activity from cells grown in the presence of NaCl was more resistant to inhibition by N-ethylmaleimide and to inactivation by heat. Two separate apparent Km values toward ATP were delineated in the extract from cells grown in presence of NaCl while extracts from cells grown in the absence of NaCl had only one apparent Km value. The tonoplast H⁺-ATPase from NaCl grown tobacco cells showed changed kinetic compared to this activity from cells grown in the absence of NaCl. These data may indicate that growth in NaCl results in the appearance of isozymic activity that enhances the ability of plant cells to utilize metabolic energy more efficiently.

Four-year-old seedlings ofQuercus petraea (Matt.) Liebl. andNothofagus procera (Poepp. et Endl.) Querst were grown outdoors in pots while subjected to full, medium and low irradiances. Shading and decrease in height of leaf attachment generally increased specific leaf area, the diameters of chloroplasts and of palisade and spongy mesophyll cells, but decreased leaf thickness, number of palisade cell layers, length of palisade and spongy mesophyll cells, number of chloroplasts per mesophyll cell and epidermal cell and cuticle thickness, stomata and hair densities per unit leaf area, hair length, maximum hair breath and cell wall thickness in the two species. However, inN. procera grown under full irradiance, leaves at the upper and middle positions had hairs on both upper and lower epidermes, whereas those in other treatments and all leaves in all treatments inQ. petraea, had theirs only on the upper epidermis.