Reorganization of growth in the shoot apex ofChenopodium rubrum during transition to flowering is described. Growth and morphogenic changes - a rise in cell division rate, changes in leaf and bud formation and changes in directions of cellular growth - are viewed from the aspect of a possible role of growth hormones in controlling these changes. Growth and morphogenic effects of exogenous growth regulators in the shoot apex ofChenopodium are summarized and their floral effects explained in terms of changing apical growth correlations. New evidence concerning the timing of increased cell division rate and showing the limited requirement of axillary cell division and a shift to more vertical direction of growth in the apex in the floral developmental pathway was obtained in experiments with kinetin application and by surgical treatments.

Some general data on the genetic control and the possibilities of regulation of developmental paths inDrosophila are furnished. The insights to be gained from this insect will surely have implications that extend far beyond the fruit-fly. For example, in plants, developmental programs for floral organs, implying specific proteins are known. Developmental mutants in which mutate alleles control developmental programs for flowering were also selected in several species (Zea, Pisum, Sorghum, Cucumis, Mercurialis). Chemicals, especially phytohormones interfering with these programs are discussed. The case of sexual differentiation ofMercurialis is discussed in more detail. In this species, sex organs are controlled by sex determination genes and by auxins (male) and cytokinins (female). Flowers of each sex can be characterized by specific mRNA populations. They were evidenced by translationin vitro in a cell-free system of the various kinds of mRNAs [poly(A), non poly(A), polysomes]. The feminisation of genetic males by cytokinins induces the mRNA population of female type. Evidence concerning the implications of cytokinins in protein synthesis before translation level is presented. This is also probably true for auxins, although direct evidence is lacking.

The phenotype appearance ofArabidopsis thaliana hairy roots and crown galls their teratomas and regenerated plants were compared. Several differences were found, which correlate with T-DNA differences between Ti and Ri plasmids.

CAM-like photosynthesis was found in the isoetid aquatic plantsLittorella uniflora andIsoetes lacustris, but not in the isoetid speciesLobelia dortmanna or in the elodeidElodea canadensis. Of the taxa studied, the first three are known to utilize sediment-borne CO₂, whereasElodea is dependent on bicarbonate.

The analysis of the kinetic behaviour of pea L-tryptophan aminotransferase isolated from mitochondrial and cytosolic fraction unambiguously showed the preference of some of its keto acid substrates demonstrated by statistical criteria (R2, SSQ, AIC). An attempt is made to evaluate this result in connection with the availability of the keto acid substrates in different cell compartments.

Acid phosphatase isolated from low altitude grown plants of two high altitude plant species,Selinum vaginatum Clarke andAcer caesium Wall, displayed higher thermostability than that from plants of the same species grown at high altitude. The isozyme composition, however, remained unchanged inSelinum vaginatum. InA. caesium, one of four isozymes, was thermolabile in the samples from high altitude and was lost after 10 min heating of the extracts at 60 °c. In the samples from low altitude, this isozyme was not detected and a band with slightly lower Rf value was present which was thermostable. The described changes in the thermal properties of acid phosphatase reflect an adaptive step towards high temperature acclimation at low altitude.

Current knowledge about effects of exogenous PGR on cone initiation in coniferous trees is briefly reviewed. Long life-cycles, large tree size and great irregularity in coning have imposed severe restraints, but experimental study of reproduction can now be achieved in small plants of some species. In adult, clonal cuttings ofThuja plicata, standard injections of 50-250 (μg GA₃ induce substantial male and female coning, and have been used to test effects of other PGR on cone initiation and development. In thePinaceae, propagation of naturally heavily-coning genotypes has facilitated research on the effects of PGR.

N-malonyl-D-tryptophan (MT) and D-tryptophan added to the medium instead of auxin stimulated growth of soybean and tomato cell and tissue cultures. Effects of 50-100 μmol 1^-1 MT and 100 -300 μmol 1^-1 D-tryptophan were equal to the effect of 3-10 μmol 1^-1 IAA. Soybean cells grown in the presence of 100 μmol 1^-1 MT contained 125-170 ng IAA per 1 g fresh mass (as determined by spectrofluorimetric indole-α-pyrone method), whereas the cells grown in the presence of NAA 10. 7 μmol 1^-1 contained 50 -60 ng IAA and the cells grown in the absence of auxin failed to show endogenous IAA. MT as proposed can be hydrolyzed by plant cells with liberation of D-tryptophan, which in turn can be used in IAA synthesis. It is proposed that MT is a possible source of endogenous auxin in plants.

The effect of anaerobiosis of wheat seedling roots during 6 consecutive days on contents of ethanol, lactate and glucose in roots and shoots and on the exudation of ethanol from roots to the medium was examined. Activities of alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH) were determined. After 36 h of anaerobiosis the concentration of ethanol in roots increased temporarily about 6 times and after 6 days it decreased to the level of control plants. The exudation of ethanol from roots to the medium showed similar pattern. The content of lactate was unaffected by anaerobiosis. In contrast, the content of glucose in roots of seedlings increased already after 1 day of anaerobiosis about 2 times and this higher level of glucose was noticed during consecutive 5 days. Anaerobiosis of roots caused an increase in the activity of ADH in both roots and shoots but the increase was not related to the content of ethanol in tissues, or exudated to the medium. The activity of LDH was unaffected by this factor. The results are discussed in relation to the limitation of energy supply of plants grown under root anaerobiosis.

The salt tolerance was studied according to both fresh and dry matter increases of callus cultivated on the media supplemented with various sodium chloride concentrations as well as a high amount of K⁺, Na⁺, Ca²⁺, and Mg²⁺ ions as found in the East Slovakia salt soil lowland. The cells tolerate salinity at least up to 85 mM. According to statistical evaluation the salt concentrations used did not inhibit growth rate and development of tissue cultures.

Seven day- and six week-old alfalfa (Medicago sativa L.) plants, susceptible and resistant to bacterial wilt, were inoculated withCorynebacterium michiganense pv.insidiosum (McCulloch) Dye & Kemp. Leakage of solutes absorbing UV light from leaf discs into distilled water was investigated. The bacterial infection did not affect solute leakage rate from unifoliate and trifoliate leaves of either susceptible or resistant plants at an early stage of the disease. This may indicate that cell membrane integrity in alfalfa leaf tissues was not impaired.

A study was made on the effect of increasing photon fluence rate (I) at a unilateral irradiation of adaxial (normal leaf position) and abaxial (inverse leaf position) blade surface of maize leaves of various insertion levels on net photosynthetic CO₂ uptake (P _n ) by the leaves, as well as the contribution of individual surfaces toP _n of the leaves, and the significance of, or relationship between the stomatal (g _s ) and intracellular (gm) conductances at the CO₂ transport.P _n of leaves of various age according to their insertion level was unaffected by the direction of incident irradiation. Upon irradiation of the leaves in normal and inverse position the contribution of the adaxial and abaxial surfaces toP _n ,g _s and g_m was different. On irradiating the leaves in normal position, the contribution of the irradiated adaxial surface to the characteristics mentioned made on the average 55% of total values, the contribution of the abaxial surface irradiated in inverse position made on the average 70% inP _n andg _m , and 80% ing _s . At lowerI's g _m was higher thang _s both in irradiated and non-irradiated surfaces. The ratio ofg _s to g_m gradually got square with increasingI. In the irradiated adaxial surface the equilibrium (g _s /g _m = 1.0) took place at the highestI's, in the irradiated abaxial surface between 500 to 1000 μmol m^-2 s^-1. The significance of the ratiog _m in the CO₂ transport through the individual surfaces is discussed.

The effects of vanadium and tungsten on growth of the heterocystous cyanobacteriumNostoc linckia (Roth.) Born. and the activity of its nitrogenase and nitrate reductase were studied. While vanadate stimulated the growth of molybdate-limited cells and also their acetylene-reducing ability, it did not stimulate nitrate reductase activity. Tungstate inhibited growth in molybdate-limited cells and also their acetylene reducing and nitrate reductase activities. Acetylene reduction response of cells grown in a tungstate-containing medium indicated certain difference between the modes of action of vanadium and molybdenum. Tungstate caused a slight increase in heterocyst frequency both in nitrogen-fixing and nitrate-grown material. Cyanophycin granules and polyhedral bodies disappeared in molybdate-deficient cells in which thick deposition of polyglucan-like granules occurred throughout the breakdown of cytoplasm and the thylakoids.

Chlorides, nitrates, and sulfates of alkali metals, ammonium, calcium, and magnesium inhibit P_i uptake into maize root cortex segments. The concentration 100 mM brought about 50-100% inhibition, whereas 10 mM concentration (with the exception of salts of NH₄+, Ca²⁺, Mg²⁺) about 15-55%. Also potassium benzenesulfonate (100 mM) dramatically decreases P_i uptake.
Osmotic shock also inhibits P_i uptake. Marked decrease of P_i uptake ability proceeds in concentration range 0.12-0.13 M NaCl. Concomitantly, proteins are released into rehydration medium and their amount is proportional to the degree of P_i uptake inhibition.
The effect of 0.13 M NaCl on P_i uptake and protein release is about the same in roots of intact plants, excised roots, root segments and segments of isolated cortex and stele. Roots of intact plants and excised roots are more responsive to osmotic shock than studied segments.
The degree of salt tolerance of glycophytes is in correlation with NaCl concentration, which brings about 50% inhibition of P_i uptake.

There are several differences between monocotyledonous and dicotyledonous plants. The sensitivity towards added galactose which inhibits auxin-induced coleoptile elongation but not stem elongation is one of the conspicuous differences between the two types of plants. InAvena coleoptile segments, galactose, probably as galactose-1-phosphate, inhibits the formation of UDP-glucose from glucose-l-phosphate. The inhibition of UDP-glucose formation due to galactose is not found inPisum epicotyl segments. InAvena UTP: α-D-glucose-1-phosphate uridyltransferase (EC 2.7.7.9) which catalyzes the reaction from glucose-1-phosphate to UDP-glucose seems to be inhibited by galactose-1-phosphate.

The present paper deals with the hormonal regulation of reproductive development,i.e. flowering and sex manifestation. Representation of hormonal regulation of flowering is based on the concept of florigen as a two-component, complementary system of flowering hormones, which consists of gibberellins and anthesins. Data are presented on the effect of extracts of gibberellin- and anthesin-type substances from the leaves of flowering and vegetatively growing plants under non-inductive conditions of day length. Experiments with flowering of plants under the influence of graftings serve as a basis for considering the question about the common nature of one of the florigen components - anthesins, for various plant species.
The mechanism controlling tuberization in both intact and grafted plants is based on the participation of all the components of the hormonal system and constitutes one of the most vivid manifestations of integration of all the organs in the whole organism.

Pharbitis nil, strain Kidachi and Violet, were grown at 20° C under continuous light in various cases of different sizes, containing the nutrient solution or tap water. Kidachi initiated flowers when seedlings were cultured in small cases containing nutrient solution but did not flower in large cases. The application of NAA, kinetin, ABA or 5-chlorobenzoiec acidvia roots in large cases caused flowering, Floral initiation was always accompanied by the suppression of root elongation. The promotion of root elongation by aeration inhibited flowering. Root cutting inhibited flowering. On the other hand, Kidachi did not flower in tap water irrespective of vessel size. Violet did not flower in the nutrient solution even in small vessels, but initiated floral buds in tap water irrespective of vessel size, though the plants grown in large cases developed very long roots. In both types of flowering, cotyledons are necessary to induce flowering and the removal of cotyledons before the 16th day after the start of culture in Kidachi and before the 12th day in Violet completely inhibited flowering. GA₃ promoted stem elongation without preventing flowering of Kidachi.

Black currant reversion disease causes serious problems in some cultivars of black and red currant. Investigating ultrathin sections prepared from overground parts of diseased red currant plants cv. Heinemann's rote spätlesse, we observed consistently local cell wall disintegration of tracheids in vascular bundles. We have observed these changes in red currant plants showing reversion symptoms during the vegetation period from March to June. The observed phenomenoni.e. cell wall disintegration of tracheids might be utilized as an auxiliary diagnostic criterion m ident ification of red currant reversion disease in the cultivar Heinemann.

Crown galls induced onArabidopsis thaliana plants by octopine or nopaline strains ofAgrobacterium tumefaciens were grownin vitro on different media. Dark growth of all tumor tissues was strictly hormone-dependent. In contrast, hormonal autonomy was observed in the light where crown gall calli readily differentiated into teratomas and (sometimes fertile) plants. Differentiating tissues always grew more vigorously than subtended calli. The growth of transformed calli was stimulated by vitamins and partly inhibited by growth regulators in concentrations used for the maintenance of untransformed calli. Crown gall calli, teratomas and sometimes regenerated plants were shown to express lysopine or nopaline dehydrogenase activities.

The metabolism of exogenously supplied abscisic acid (ABA) during translocation attracted under the influence of indolyl-3-acetic acid (IAA) was studied in etiolated segments of pea (Pisum sativum L.). After 8 and 24 h 90% and 60% of the ABA, respectively, were found in the segments in unchanged form. Phaseic acid, dihydrophaseic acid and the glucose ester of ABA were found as ABA metabolites. Results indicated that the growth processes initiated by the application of IAA were associated neither with an increased immobilization nor increased metabolization of this growth regulator.

A low frequency androgenesis was inducedin vitro in all experimental variants ofCapsicum anthers cultured in standard and minimalized media. The embryogenic frequency was stimulated by the presence of activated charcoal which also prolonged the vitality of the culture. The percentage of embryoids growing to complete plants increased, if the embryoids were removed from the anthers and cultured separately. The morphogenic initiation of globular embryoids was conditioned by the presence of FeEDTA in the culture medium. The stimulation of androgenesis initiation can be explained by the same change in the decisive factor caused by various effects. In long-term embryoid cultures, which stagnated in growing and seemingly necrotized, a second somatic embryogenesis occurred. About 10% of obtained androgenic plants were fertile and even gave progenies. The process can be recommended for breeding.

Evidence is presented to support the generalization that gibberellin A₁ is the main 'gibberellin hormone' that is activeper se in the control of elongation growth in higher plants. The evidence is based on a combination of chemical and genetic studies using single gene mutants of maize, pea and rice.

Seed protein patterns were compared in 10 species of the genusVigna, and in the generaMacroptilium, Strophostyles, Macrotyloma, Psophocarpus andPhaseolus. ThreeVigna groups could be clearly separated using immunochemical methods:Vigna hosei andVigna luteola;Vigna mungo, Vigna angularis, Vigna umbellata, Vigna trilobata andVigna radiata;Vigna sinensis,Vigna unquiculata andVigna aconitifolia.
Among the other investigated generaPsophocarpus appears to be very distant, the others showing partial similarity in seed protein patterns.

IAA synthesis proceeding by indol-3-ylpyruvate (IPyA) pathway seems to be regulated in two steps. In the first the L-trp conversion into IPyA is reduced by a low affinity of L-trp to the unspecific aminotransferase, by competition of L-trp with some aminoacids (e.g. L-asp) and indoles (e.g. indol-3-ylacetylaspartate). Simultaneously, a specific L-trp-dehydrogenase in dependence on the NAD(P)/NAD(P)H ratio regulates by its reversible effect the level of IPyA, connecting photosynthesis with growth. A second more "delicate" regulation of IAA level is carried out by the indol-3-ylacetaldehyde system. In pea plants two indol-3-ylacetaldehyde oxidases with pH optima 4.5 and 7.0 were found. The oxidases are differentially inhibited by an excess of IAA, different indoles as indol-3-ylacetylaspartate and aminoacids as L-asp. GA₃ and kinetin stimulate the conversion of indol-3-ylacetaldehyde to IAA.