Water relations of two rapidly expanding species in deforested localities, Calamagrostis epigeios and Calamagrostis arundinacea, were compared. After short- or long-term water stress, water content and specific leaf area were more reduced in C. epigeios than in C. arundinacea. After short-term stress, osmotic potential was similar in both species, but after long-term stress, it was much lower in C. epigeios plants. Abscisic acid and proline contents were higher in stressed plants of C. epigeios than in those of C. arundinacea.

A transgenic expression system of Chlorella kessleri using the gene for β-glucuronidase (GUS) was developed. Cells of this unicellular green alga were bombarded with the plasmid pBI 121, which bears β-glucuronidase under the control of CaMV 35S promoter and the kanamycin resistant gene. Maximum GUS activity was obtained after 48 h of bombardment using a helium pressure of 900 kPa; GUS activity was then assayed for many generations. The stable transformants were able to grow on kanamycin containing medium after repeated passages between selective and nonselective medium and exhibited GUS activity comparable to that of control cells. Stable transformed cells were confirmed by polymerase chain reaction (PCR) and Southern hybridization of GUS probe with the genomic DNA of C. kessleri.

The short-term relationships of monoterpene emission with temperature and relative humidity were studied in Pinus halepensis L. and Quercus ilex L. seedlings grown in air-conditioned chamber. In P. halepensis terpene emission rate increased with temperature (from 15 to 35 °C) and relative humidity (from 40 - 60 to 65 - 95 %). In Q. ilex, a terpene non-storing species, it increased with temperature only at high relative humidities but not at relative humidities lower than 60 %.

After inoculation of Brassica juncea leaves with Alternaria brassicae, activities of the cell wall degrading enzymes, polygalacturonase (EC 3.2.1.15) and cellulase (EC 3.2.1.4) decreased in leaf blight resistant cultivar RC-781 and increased in the susceptible cultivar Varuna upto 3 d. In the leaves of both the cultivars 11 poly-peptides were observed in the absence of A. brassicae inoculation. After inoculation in the resistant cultivar RC-781 there was no change in the polypeptide pattern, while in the susceptible cultivar Varuna, four polypeptides (43.7 to 58.8 kDa) disappeared only at 3^rd day after inoculation.

The potassium uptake by potato tuber discs tissues freshly cut and after 24 h of ageing in the presence or not of abscisic acid was investigated. Uptake kinetics revealed a biphasic dependence on external K⁺ concentrations. At concentration less than 10 mM, uptake was mediated by a saturable component and a linear component became apparent at higher concentrations. At low K⁺ concentrations (lmM), the capacity of K⁺ uptake diminished by 2 times after ageing. Treatment of tissues with ABA increased the rate of K⁺ uptake. In both fresh and aged tissues the uptake was strongly enhanced by fusicoccin and decreased by several metabolic inhibitors and ATPase inhibitors, underlying the active nature of uptake and suggesting the involvement of a plasmalemma H⁺-ATPase in K⁺ transport system.

Two newly developed salt-tolerant genotypes of spring wheat, S24 and S36 and their salt-tolerant parents, LU26S (from Pakistan) and Kharchia (from India) along with a salt-sensitive cv. Potohar were grown in full strength Hoagland's nutrient solution with 0 or 125 mM NaCl. At the onset of the booting stage third leaf from top was sampled for protein analysis. Total soluble protein content increased due to salt treatment in all cultivars/lines but this increase was more marked in salt-sensitive cv. Potohar and low in salt-tolerant S24 as compared with the other lines. Patterns of labelled polypeptides in all cultivars/lines were identical; the differences were only quantitative (for instance, 29 kD and 48 kD polypeptides were reduced significantly due to NaCl treatment only in the cv. Potohar).

This work describes in vitro morphogenesis and plantlet regeneration from seeds of the naturally polyembryonic tree Syzgium alternifolium. The basal medium (BM) comprised half strength Murashige and Skoog's (MS) salts, B₅ vitamins, 2 mg dm^-3 glycine, 250 mg dm^-3 ascorbic acid and 20 g dm^-3 sucrose. Addition of auxins like indole-3-acetic acid (IAA), 1-naphthalene acetic acid or 2,4-dichlorophenoxyacetic acid to the basal medium induced formation of roots or callus from the dicotyledonous as well as tricotyledonous seeds. In contrast, cytokinins like N⁶-benzyladenine (BA), kinetin, 2-isopentenyl adenine, thidiazuron alone or a combination of BA and auxins induced development of adventitious shoots. The medium containing 3.0 mg dm^-3 BA and 0.5 mg dm^-3 IAA induced the highest number of adventitious shoots (32 - 33) from dicotyledonous seed with an average length of 4.1 cm within 6 weeks of incubation. Rooting of 80 % adventitious shoots was achieved by dipping the shoots in 100 mg dm^-3 IAA for 15 min. About 70 % of the rooted shoots were successfully established in pots after hardening.

Simulated acid rain (SAR) combined with higher concentration of aluminium (SAR+Al) influenced the ecophysiology of three arbuscular mycorrhizal fungi (AMF) in both the germination and symbiotic phases of their life cycle. Acaulospora tuberculata, an isolate from the soil with low pH, exhibited a higher tolerance to environmental stress as compared to Glomus mosseae and G. fistulosum. This higher tolerance may be related to the edaphic conditions of soil of the isolate origin. The histochemical staining of the alkaline phosphatase and NADH-diaphorase activities in the extraradical mycelium (ERM) of the AMF proved to be more sensitive indication of negative effects of the SAR or SAR+Al stress compared to commonly measured parameters of the AMF such as mycorrhizal colonisation or growth of the ERM.

21-d-old seedlings of the soybean (Glycine max) cvs. Essex and Forrest were treated with NaCl in a step-wise manner over 9 d (3 d 30 mM, 3 d 70 mM, and 3 d 100 mM) and maintained under 100 mM NaCl for an additional 14 d. During salt treatment, osmotic potential decreased more in cv. Forrest relative to cv. Essex. In non-stressed leaf tissue, cv. Forrest contained more trigonelline (TRG) relative to cv. Essex. During salt treatment, TRG amounts increased in cv. Forrest but were unchanged in cv. Essex. Both cvs. osmotically adjusted in response to salt stress; the maximal osmotic adjustment was 0.80 and 0.18 MPa in cv. Forrest and cv. Essex, respectively.

Carbon translocation was affected by shade in different tropical tree species differing in successional status and degree of shade tolerance. Plants of the early-successional shade-intolerant species Cecropia pachystachya and Schizolobium parahyba and of the late-successional shade-tolerant species Myroxylon peruiferum and Hymenaea courbaril were grown under full sun (FS) and natural shade treatments (NS) and assessed for [¹⁴C]-sucrose translocation. Most of the ¹⁴C was retained in the fed leaf after a 24 h translocation period. Under FS, the growing apical part of the plant was the most intense sink for most species. Shade affected growth and sink intensity differently in early and late successional species. Growth was more markedly affected in the early species. Whereas these continued to invest carbon into the growing apical part of the plant under shade conditions, the late successional species invested relatively more into other sinks.

In four genotypes of chickpea (Cicer arietinum L.) BG 362, BG 372, BG 329 and C235 the relationship between somatic embryogenesis of leaf explants and ethylene and methane evolution was studied. In BG 362, which was more embryogenic than other genotypes, a higher ethylene:methane ratio of 5.8:1 at day one after inoculation in the induction medium and a lower ethylene:methane ratio of 2.89:1 in the maturation medium was found. On the contrary, in BG 372 with the least embryogenic potential, a lower ethylene:methane ratio of 1.7:1 in the induction medium and a higher ethylene:methane ratio of 4:1 in the maturation medium was found. Thus, these ratios in induction and maturation stages seems to be markers for embryogenesis in leaf explants of chickpea.

Plants of bean (Vicia faba L. cv. Calvor 103) were salt-stressed with NaCl and CaCl₂ in concentrations inducing soil osmotic potentials (ψ_soil) from 0 to -1.2 MPa and were sprayed with proline (8.7 µM) and glycinebetaine (8.5 µM) solutions. Bean plants respond to increasing soil salinity by decreased leaf relative water content and osmotic potential. Salinity decreased the contents of dry mass, chlorophyll, soluble and hydrolysable sugars, soluble proteins and enhanced content of total free amino acids, Na⁺, Ca²⁺ and Cl^-. The ratio of K⁺/Na⁺ was decreased on salinization. The membranes of leaf discs from salt-stressed plants appeared to be less stable under heat stress (51 °C) than that of unstressed plants. The reverse was true for discs placed under dehydration stress (40 % polyethylene glycol 6000). Proline and glycinebetaine application reduced membrane injury, improved K⁺ uptake and growth. Also both solutes increased chlorophyll contents.

An improved version of a simple histochemical test for the in situ assaying the production of hydrogen peroxide in living plant tissue was demonstrated. The test solution containing 50 mM KI in a 4 % potato starch solution was directly applied to the fresh cut surface of the tissue to be tested. Incorporation of an enhancer potassium permanganate (1 % final concentration) into the test reagent resulted in a ten times greater hydrogen peroxide mediated oxidation of iodide ions to iodine, especially in the case when, e.g. suboptimal concentration of H₂O₂ is present or endogenous catalase decomposes the H₂O₂ in tissue as quickly as it is evolved. Subsequently, iodine is complexed by the starch to form a coloured product. H₂O₂ production by wound-induced oxidative burst or lignification can be easily discriminated due to the dual colour response.

Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply.

A fully habituated (auxin- and cytokinin-independent) self-regenerating (organo-genic) sugar beet cell line (HO) and a fully habituated non-organogenic one (HNO) derived from the former one, were analyzed as to their nuclear size and DNA content. Flow cytometry and image analysis were used and cells of certified diploid leaves of the same sugar beet strain served as controls. The HNO cells had been shown previously to have many characteristics of cancerous cells. The analyses made on leaves and HNO cells indicated the presence of only one population of cycling cells. In HO cells, two cycling populations were detected: the first one had the same DNA content as the leaves while the second one contained two fold more DNA than the first population. HNO cells showed the higher nuclear size and DNA content. HNO cells also showed evidence of aneuploidy. Thus, nuclear size, DNA content and ploidy level increase together with the neoplasic progression to culminate in HNO cells with the loss of organogenic totipotency.