RNA synthesis as measured by the incorporation of tritiated uridine into trichloroacetic acid insoluble material was studied in the leaf protoplasts of cv. Kennebec and its parthenogenically derived dihaploid. Protoplasts of cv. Kennebec incorporated tritiated uridine at a greater rate and accumulated more than twice the amount of radioactive materials than did the dihaploid over a 6-h incubation period. Poly(A)⁺RNA, isolated from the total RNA of the tetraploid and of the dihaploid, by oligo(dT)-cellulose column chromatography, was present in amounts of 11.3 and 5.2 % respectively. The tetraploid synthesized 4.8 times the amount of poly(A)⁺RNA that was synthesized by the dihaploid.

Plants of peanut (Arachis hypogaea L.) were subjected to 7-d and 14-d waterlogging and sprayed with 10 and 100 mg 1^-1 of gibberellic acid (GA₃). Waterlogging decreased the leaf area (A), net photosynthetic rate (P_n), chlorophyll content (Chi) and temporarily the leaf water potential (Ψ_w) and increased stomatal diffusive resistance (r_s) of both leaf surfaces. Application of GA₃ increased A and P_n and significantly decreased the r_s of both leaf surfaces but did not affect Ψ_w or Chl. Thus GA₃ partially alleviated the effects of waterlogging on A, r_s and P_n.

Salinity inhibited growth, and affected the contents of chlorophylls, carotenoids, saccharides, amino acids, proteins, DNA and RNA in broad bean plants. Foliar application of NaH₂PO₄ and NaNO₃ greatly ameliorated the adverse effects of NaCI. This counteraction was associated with an increase in contents of saccharides, proteins, DNA and RNA.

Changes in the phenylalanine ammonia-lyase (PAL) activity, accumulation of phenolic acids and ionically-bound peroxidase activity in thein vitro selected embryogenic and nonembryogenicMedicago sativa callus cultures resistant to the filtrate ofFusarium spp. were found. The PAL activity in bothin vitro selected cultures during a 4-week cultivation on a medium with phytotoxins was higher than in the control calli grown on a medium without toxin. The filtrate fromFusarium spp. evoked an increase in the contents of all determined phenolic acids in the selected calli. They occurred predominantly bound as esters. The most pronounced portions in the elevated acids level were of ester-bound p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids. The ionic cell wall-bound peroxidase activity in both selected calli cultivated on a medium with a filtrate was twice as high as the activity determined in the control cultures. The activity of soluble peroxidase was not influenced by challenge with a filtrate. No significant differences were found between thein vitro selected embryogenic and nonembryogenic alfalfa callus cultures in the response to the phytotoxic filtrate.

Thidiazuron incorporated into MS medium stimulated rosettes formation only in some treatments. This effect was more pronounced in cultures ofMorus alba thanPrunus sp. Mulberry cultures responded to the optimal concentration of thidiazuron (0.2 mg I^-1) not only with shoot formation but also, with growth of large leaves and poor development of callus tissue. In cultures of both investigated genera the shoot elongation was inhibited. Shoots of mulberry cultures growing on proliferation medium supplemented with thidiazuron formed roots, in many cases.

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.

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.

The effects of different nitrogen salts on nitrate reductase activity and protein contents were investigated in three Yugoslav cultivars of wheat. The nitrate salts appeared to be a better form of nitrogen than ammonium in respect of the increase of the nitrate reductase activity and root total protein contents, whereas the treatment with ammonium salt resulted in a comparably higher shoot total protein contents. KNO₃ was the best in respect of the level of nitrate reductase activity. Different concentrations of nitrate and ammonium ions in nutrient solution, showed very similar effects on investigated parameters. NS Rana 2 cultivar had the highest values of nitrate reductase activity and protein contents.

The efficiency ofAgrobacterium-based transformation technique in oilseed rape and cauliflower was influenced by cultivar specificity, donor plant age and explant type. Marked differences in demands for plant hormone contents in the regeneration medium were recorded already among different types of nontransformed explants. The highest regeneration capacity was recorded with stem and leaf segments isolated from one-month-old aseptically grown plants. The regeneration was markedly species-dependent. Regeneration of transformed plants from stem segments and thin layers isolated from field-grown oilseed rape plants (at the most 2% of regenerating explants) and from oilseed rape hypocotyls (0.8% of regenerating explants) and cauliflower (1.2% of explant regenerated transformed shoots) was achieved after disarmedAgrobacterium treatment. Hypersensitive reaction of explants could be prevented by using prolongedin vitro precultivation and delayed application of the selective agent.

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.

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.

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.

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.