Foliar application of gibberellin (GA₃) to patchouli (Pogostemon cablin Benth.) increased the plant height, number of nodes per plant, leaf fresh mass and photosynthetic pigment contents. The content of chlorophyll (Chl)b increased faster than that of carotenoids (Car), Chl (a+b) and Chla. This was reflected in a decline in Chla/b and Chl (a+b)/Car ratios. There was a GA₃ concentration dependent variation in the number of branches, leaves, total leaf area, and leaf area index. These growth parameters decreased over control values up to 250 g(GA₃) m^-3 and increased at 500 g(GA₃) m^-3 concentration. The patchouli oil yield varied from 2.4 to 2.6% of the leaf dry mass.

In pea, maize and tomato plants a hitherto undescribed L-tryptophan dehydrogenase activity (TDH) has been detected. This enzyme catalyzes the reversible formation of indolepyruvic acid (IPyA) from L-tryptophan (L-trp). TDH and L-glutamate dehydrogenase (GDH), related enzymes in their mode of action, could be separated by gel chromatography. Enzymatic activity of TDH was sustained by both pyridine coenzymes NAD/NADP. With pea TDH the coenzyme NAD displays, at optimum pH 8.5 and at room temperature, only about 40-70 % of the activity of NADP. The amination of IPyA is catalysed more actively than the deamination of L-trp. L-trp/IPyA, L-glu/ketoglutarate, L-ala/pyruvate reacted as dehydrogenase substrates; L-phe/ phenylpyruvate, D-trp and D-phe did not react with pea enzyme extracts. A considerable similarity between the active centres of TDH and GDH has been found using inhibitors: absence of heavy metals, presence of a carbonyl group, indispensibility of bivalent ions for the enzyme activity. Pea TDH and GDH were distinctly inhibited by sodium azide. For the activity of TDH the presence of SH groups is less important than for GDH. The TDH activity in the investigated plants was lower than the GDH activity. The possible role of TDH in the regulation of the IPyA pool is discussed.Doc. RNDr. PhMr. M. Kutáček died on 28 November, 1989. The final form for print was prepared by dr. Ivana Machdckovd of the same Institute, who will also answer the reprint requests. Received June 6, 1990; accepted October 10, 1990

Drought created by withholding the irrigation at 30 and 45 d after sowing significantly decreased relative water content (RWC) and osmotic potential (ψ_s) ofVigna radiata (L.) Wilczek cv. MH-83-30 nodules. Potassium fed plants showed higher RWC, whereas ψ_s was further declined irrespective of soil moisture levels. The nitrogenase activity and leghemoglobin content of nodules markedly decreased under drought and nodules of potassium fed plants showed better recovery after rehydration. The proline content significantly increased under drought but declined upon reirrigation. Also, the C, N and K contents of nodules significantly declined under drought.

Sampling of natural cocksfoot (Dactylis glomerata L.) populations was carried out on the O Morrazo peninsula in NW Spain, characterized by a strong moisture gradient. The plants were kept in greenhouse under standard conditions. Nevertheless, they differ in height of plants, length and width of flag leaves, panicle size, stomatal density and size as well as in flowering period. The effects of two levels of soil water deficit and two levels of salinity on photosynthetic rate were tested. One population was exceptionally well adapted to its original environment with great tolerance to water deficit and salinity

The effect of crude volatile oils from the leaves ofEucalyptus globulus andE. citriodora and the pure terpenes - cineole and limonene from these oils, (in vapour form) was studied onPhaseolus aureus, Lens esculentum, Hordeum vulgare and Avena sativa. The parameters like germination of seeds, seedling growth, values of cell survival, and content of water and chlorophyll of the crops formed the system of bioefficacy study. The allelopathic impact of the oil vapours from the eucalypt tree becomes evident from the negative response of the parameters studied. The impact of the E. citriodora oil vapours compared to that ofE. globulus oil or the pure terpenes was seen to be relatively greater in almost all parameters under investigation. A strong reciprocal correlation that exist between the concentration and the seedling growth or the water content of the crops under study supports the dose linked allelopathic phenomenon. It is suggested that oil vapours ofEucalyptus exert their effect through impairing the respiratory as well as photosynthetic ability of the target plants.

The changes in ubiquitin mRNA level in intact plants of both susceptible (cv. Spunta) and partially resistant (cv. Pampeana-INTA) potato cultivars after inoculation with low doses (l0³ sporangia cm^-3) ofPhytophthora infestons were studied after 72 h of treatment. Inoculation leads to 5-fold accumulation of potato ubiquitin transcripts in both cultivars. This result supports the connection between ubiquitin expression and defense reaction in plants.

Wounding both cotyledons ofBidens pilosa (var.radiatus) induces the inhibition of hypocotyl growth. The wound signal is transmitted very rapidly from cotyledon to hypocotyl and can be visualized by the change in nucleotide pools. First we have shown that the irradiance of the plant can change the ATP level without plant wounding. Therefore, plants were harvested at the start of the light period. Under these conditions, we have determined in hypocotyl the levels of adenosine triphosphate (ATP), guanosine triphosphate (GTP) and non adenylic triphosphates (NTP), and adenylate energy charge (AEC) after wounding. We have observed a transient (2 min) increase in the ATP level followed by a decrease 5 to 30 min later. A similar result was obtained for the GTP level but with some delay. The GTP level increased in 5 min and then decreased after 60 min. For the NTP level the decrease is effective from 5 to 60 min after wounding. The calculation of AEC has shown that a very tight control in the level of ATP may be involved in response to wounding.

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.

The effects of fusaric acid, a phytotoxin produced byFusarium pathogens, on the metabolism of isolated maize root mitochondria and on maize seed germination and seedling growth were investigated. The phytotoxin inhibited basal and coupled respiration when succinate and α-ketoglutarate were the substrates. Coupled respiration dependent on NADH was inhibited, but basal respiration was not. Consistently, succinate cytochromec oxidoreductase activity was decreased whereas NADH cytochromec oxidoreductase was not affected. The ATPase activities of carbonyl cyanide p-trifluoro-methoxyphenyl hydrazone stimulated mitochondria and of freeze-thawing disrupted mitochondria were inhibited. These results indicate that the phytotoxin impairs the respiratory activity of maize mitochondria by at least three mechanisms: (1) it inhibits the flow of electrons between succinate dehydrogenase and coenzyme Q, (2) it inhibits ATPase/ATP-synthase activity and (3) it possibly inhibits α-ketoglutarate dehydrogenase. Seed germination and seedling growth were also affected by fusaric acid with the most pronounced effect on root development. These effects can possibly contribute to the diseases ofFusarium- infected plants

Buthionine sulfoximine (BSO) specifically inhibits γ-glutamylcysteine synthetase and decreases a cellular level of glutathione (GSH) in maize seedling roots. Exogenous GSH restores Zn-phytochelatins synthesis in BSO-treated maize plants.

Amphistomatous C₃ (Nicotiana tabacum L., Datura stramonium L.) and C₄ (Sorghum saccharatum Pers. and Zea mays L.) species were examined to find how (if at all) their inherent differences in water-use economy are reflected in apparent cuticular transpiration or vice versa. Transpiration efficiency (TE) was calculated from steady state photosynthesis (A) and transpiration (E) rates estimated for the upper side of the leaf after light induction of stomata opening. Apparent cuticular transpiration ('E_c) was measured as the part of transpiration which was not eliminated by convective counteraction of the air stream passing across the amphistomatous leaf: total pressure difference (AP) across the leaf was increased and the minimal value of E_ΔPτ0 was taken as the apparent cuticular transpiration rate ('E_c). 'E_c was treated relative to E at AP equal to zero (E_GDP=0), E'_cr. Measurements were carried out under two leaf-air vapour pressure differences (VPD).
E_r (i.e. E_GDPτ0/E_GDP=0) versus GDP patterns differed qualitatively between the investigated C₃ and C₄ plants. TE increased and 'E_cr decreased from tobacco, stramony, maize to sorghum for both VPD of air. 'E_cr and TE were approximately linearly related, the slope being dependent on VPD. The increase in VPD resulted in larger E and slightly smaller epidermal conductance (g) at GDP equal to zero. Both E'_cr and E'_cr decreased markedly at the same time especially, for species with high TE. The results were considered as an indirect confirmation that E'_c values estimated by the technique used reflect species-specific differences in external peristomatal and cuticular vapour loss, at least in a relative sense.

Phaseolus vulgaris L. seedlings were grown under different air humidities simulating conditions during micropropagation (very high humidity duringin vitro cultivation and low air humidity after transferex vitro). The functional stomatal apparatus developed after a short period of growth at low air humidity at the beginning of plant ontogeny or after transfer from high to low air humidity, but not in plants grown steadily under high air humidity. The ability of stomata to regulate gas exchange was not persistent and disappeared after transfer of plants from low to high humidity.

Morphology of pollen grains collected from healthy and virus infected plants ofChenopodium quinoa L.,Chenopodium album L. andNicotiana tabacum L. cv. Samsun was investigated using scanning electron microscopy (SEM). Pollen grains from tobacco plans infected with tobacco mosaic virus (TMV) were smaller, with rounded shape and conspicuous deformation of aperture unlike oval and smooth pollen grains from healthy plants. No morphological alterations were observed inC. quinoa andC. album plants infected with TMV and cucumber mosaic virus (CMV). Polyacrylamide gel electrophoresis of pollen proteins revealed substantial quantitative and qualitative differences in protein components of pollen grains collected from healthy and virus infected plants

The net photosynthetic rate (P_N), stomatal conductance (g_s) and transpiration (E) ofHardwickia binata Roxb. leaves were reduced due to decrease in the leaf water potential (ψ_w) from -2.0 to - 5.7 MPa. P_N partially recovered in the treated plants upon rewatering. Decrease in g_s due to water stress may be the main factor for reduction of P_N.

Foliar sprays with N ⁶-(m-hydroxybenzytyadenosine, (mOH)-[9R]BAP, one of the synthetic cytokinins, were applied to field-grown sugar beet twice during the vegetation period: before full canopy closing (I), 6 weeks before harvest (II) or both. Application of (mOH)[9R]BAP retained high cytokinin content that usually declines prior to harvest. The total content of isoprenoid cytokinins at harvest was 2.6-fold higher in (mOH)[9R]BAP-treated plants as compared to the controls. Treatment I had no significant effect on contents of chlorophylls (Chl)a andb and carotenoids, nor on the rates of net photosynthesis (P_N) or photorespiration (R_l), or on CO₂ compensation concentration (Γ) measured during the whole vegetation period on detached leaves under optimum environmental conditions. Increased values in P_N, R_L and Chla andb contents were found in variantsII and I+II linked with a delay in leaf senescence before harvest. Transpiration rate and stomatal conductances of adaxial and abaxial epidermes were not significantly affected by any treatment.

Echinochloa colona regeneration via organogenesis in callus cultures derived from leaf base and mesocotyl expiants andin vitro flowering were achived. Shoot bud regeneration was achieved on Murashige and Skoog's (MS) basal medium supplemented with 6.66 μM 6-benzylaminopurine (BAP), 2.68 μM 1-naphthalene acetic acid (NAA) and 3 % (m/v) saccharose. Regenerated shoots were rooted on half strength basal MS medium with 2 % (m/v) saccharose devoid of growth regulators. About 90 -95 % of rooted plantlets survived in the greenhouse.In vitro flowering was induced in the regenerated shoots derived from callus on half strength MS medium supplemented with 4.4 μM BAP, 74.07 μM adeninesulphate, 0.72 μM gibberellic acid, and 3 % (m/v) saccharose. The frequency ofin vitro flowering was 80 - 90 % in three repeated experiments. Fertile seeds were recovered fromin vitro grown plantlets which were subsequently germinated into plants.

Plants of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance were grown in sand with nutrient solutions. 35-d-old plants were subjected to 5 levels of salinity created by adding NaCl, CaCl₂ and Na₂SO₄. Growth reduction caused by salinity was accompanied by increased Na⁺ and Cl^- concentrations, Na⁺/K⁺ ratio, and decreased concentration of K⁺. The salt tolerant cv. Kharchia 65 showed better ionic regulation. Salinity up to 15.7 dS m^-1 induced increased uptake of Na⁺ and Cl^- but higher levels of salinity were not accompanied by further increase in uptake of these ions. Observed increases in Na⁺ and Cl^- concentrations at higher salinities seemed to be the consequence of reduction in growth. Uptake of K⁺ was decreased; more in salt sensitive cultivar. This was also accompanied by differences in its distribution.

The treatment ofLemna minor L. plants with Pb(NO₃)₂ for 90 min, 8 and 24 h resulted in intensified deposition of (l,3)-P-glucan (callose) in plants roots. It was localized in the protodermis of the root tip, and in the center of the stele in the region at the proximal part of the root cap and slightly above

The plants of mustard (Brassica juncea L.) were treated with 0, 25 and 50 ΜM gibberellic acid (GA₃) at three fully developed leaf stage (30 d after sowing). Effect of GA₃ on carbonic anhydrase activity, photosynthetic rate, leaf area index and dry mass was studied at 50, 70 and 90 d after sowing. At harvest 1000 seed mass, pod number and seed yield were recorded. GA₃ treatment (50 ΜM) enhanced all the characteristics studied.

Leaf gas exchange, plant growth and leaf ion content were measured in wheat (Triticum durum L. cv. HD 4502) exposed to steady- state salinities (1.6, 12.0 and 16.0 dS nr^-1) for 8 weeks. Salinity reduced leaf area and number of tillers, and increased Na⁺ and Cl^- concentrations in leaves. Leaf- to- leaf gradients of these ions were observed. The oldest leaf contained 6 to 8 times more Na⁺ and Cl^- than the flag leaf. Net photosynthetic rate (P_N), transpiration rate (E) and stomatal conductance (g_S) were the highest in flag leaf, declined in the middle and fully expanded leaves, and were minimum in the oldest leaves. These processes were reduced by salinity with similar leaf- to- leaf gradients. Intercellular CO₂ concentrations in the older leaves were higher than in the flag leaf in non-saline plants, and increased similarly with salinity. Leaf age was the major factor in reducing P_N, and senescence processes were promoted by salinity.

Sugar beet grown in pots was sprayed with N⁶-(m-hydroxybenzyl)adenosine, (mOH)- [9R]BAP, one of the synthetic cytokinins. Root tissue was then examined for respiration and for H⁺-adenosinetriphosphatase activity and both leaf and root tissue served as the object for 6-deoxy-D-glucose and 2-aminoisobutyric acid uptake estimations. Treatment with (mOH)[9R]BAP depressed the uptake of oxygen by the roots of both young and old plants by 17 - 30 % while addition of (mOH)[9R]BAP to the respiring slices decreased it by 10 - 23 %. Uptake of 6-deoxy-D-glucose was mostly diminished byin vivo spraying with the cytokinin (by up to 12 % in leaves and by up to 60 % in roots), as well as by adding it to the experimental vessel (insignificantly in the leaves but by up to 80 % in the roots). The H⁺-ATPase activity was stimulated bothin vivo andin vitro appreciably in young plants but not at all in plants at the end of their vegetation period.

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.

A hypothesis of existence of a general adaptation syndrome (GAS), in which different types of stress evoke similar coping mechanisms, resulting in adaptations, is tested for plants. As stress coping mechanisms, oxy-free radical scavengers and antioxidants, osmoregulation, the role of abscisic acid, jasmonates, nitric oxide, synthesis of heat shock proteins and phytochelatins as heavy metal detoxifiers are discussed.