Accumulation of ABA in shoots during 30-min dehydration of wheat seedlings was accompanied by the decline in the content of zeatin nucleotide and the accumulation of zeatin 9-N-glucoside. The total content of zeatin derivatives as well as the content of free base of zeatin remained almost constant.

Thirty-day-old seedlings of two jute species (Corchorus capsularis L. cv. JRC 212 and C. olitorius L. cv. JRO 632) were subjected to short-term salinity stress (160 and 200 mM NaCl for 1 and 2 d). Relative water content, leaf water potential, water uptake, transpiration rate, water retention, stomatal conductance, net photosynthetic rate and water use efficiency of both jute species decreased due to salinity stress. The decrease was greater in C. olitorius than in C. capsularis and with higher magnitude of stress. Greater accumulation of Na+ and Cl- and a lower ratio of K+/Na+ in the root and shoot of C. olitorius compared with C. capsularis were also recorded. Pretreatment of seedlings with kinetin (0.09 mM), glutamic acid (4 mM) and calcium nitrate (5 mM) for 24 h significantly improved net photosynthesis, transpiration and water use efficiency of salinity stressed plants, the effect being more marked in C. olitorius. Among the pre-treatment chemicals, calcium nitrate was most effective.

An efficient micropropagation protocol was developed for an important medicinal plant, Plantago major L. For this purpose, it is recommended to culture shoot-tips on modified MS medium [412.5 mg dm-3 NH4NO3 and 340 mg dm-3 KH2PO4] supplemented with 50 g dm-3 glucose and 0.5 μM 6-benzylaminopurine. Maximum rooting frequency was obtained at 1 μM naphthaleneacetic acid.

Molecular markers were used to detect the influence of high concentrations of 2,4 dichlorophenoxyacetic acid (2,4-D) in the callusing media on DNA variations in regenerated rice plants. Restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) and polymerase chain reaction (PCR) based RFLP analysis were carried out on 12 somaclones of Oryza sativa L. cv. B-370. In vitro culture induced DNA variations were detected in the regenerated plants but the effect of high auxin concentration in the medium could not be revealed. In a second study, fingerprinting of 15 semi-dwarf, high yielding somaclones of B-370 was carried out using RAPD technique. Amplification using 20 random primers produced a total of 167 DNA bands out of which 97 bands were polymorphic. A total of 32 unique DNA bands were detected across all the somaclones and they could be grouped based on their similarity to B-370. RAPD analysis helped to reveal similarity or differences among the somaclones while fingerprinting using additional RAPD markers was not successful.

Proline (Pro) accumulation in leaf discs of the NaCl-treated salt sensitive Lycopersicon esculentum was higher than in the salt tolerant L. pennellii. The magnitude of Pro accumulation differed when leaf discs of both species were floated in the light or under darkness, and in various incubation media: buffer solutions (pH from 3.9 to 7.8), abscisic acid, isobutyric acid, NH4Cl, malate, citrate, and mixtures of NaCl and KCl, NaCl and CaCl2, and NaCl and mannitol. Under darkness, Pro accumulation in L. esculentum was not regulated by salts. Conversely, the light-independent NaCl-induced Pro accumulation observed in L. pennellii became light-dependent when CaCl2 was added. The different expression patterns of Pro accumulation reinforce the proposal of two Pro metabolic pathways in the domestic and the wild tomatoes.

Changes in growth characteristics and photochemical activities inVigna unguiculata L. Walp seedlings maintained at constant temperature of 10, 20, 30 and 40 ‡C under control and ultraviolet-B enhanced radiation (UV-B) were investigated. UV-B retarded the shoot elongation and also leaf expansion to a great extent at 30 ‡C but produced only marginal changes at 20 and 40 ‡C. Similar response was also observed with respect to changes in leaf fresh and dry masses and total chlorophyll (Chl) content under these temperatures. At 10 ‡C the total Chl content was 3-fold higher under the treatment than under control conditions. In seedlings growing at 20 and 30 ‡C the overall photosynthetic electron transport (H₂O -> methyl viologen) showed a significant enhancement during the 36-h UV-B treatment and thereafter a gradual reduction. Although a similar trend was found in photosystem 1 (PS1), the inhibition even after 60 h of UV-B treatment was not statistically significant. Photosystem 2 (PS2) activity was inhibited in seedlings treated for 60 h by UV-B at 20 and 30 ‡C. However, no inhibition was observed at 40 ‡C. No detectable photochemical activity was found in seedlings grown at 10 ‡C under either control or UV-B enhanced irradiation although the chloroplasts contained Chl.

Dry matter production of shoots and roots and the diurnal fluctuation of titratable acidity of single leaves were investigated in the CAM plant Agave attenuata during the first 70 d after germination. The plants were grown either in vermiculite sub-irrigated with a nutrient solution or in in vitro cultures on an inorganic nutrient agar. Two types of culture tube covers were used: either airtight closures or polypropylene caps with membranes permeable to air.
In the earliest ontogenetic phases of development (cotyledon and primary leaf stage), the plants were already able to carry out considerable nocturnal organic acid accumulation. In vitro cultivated plants, from the beginning of their development, were also capable of diurnal acid fluctuation, though of distinctly weaker activity than the pot plants. The mean relative growth rates (RGR) of pot culture plantlets approached a third of perennial herbaceous plants. Plantlets grown in in vitro culture reached only half to the one quarter of the RGR of pot plants. The reduced yield could be attributed to the low CO2 supply in the culture tubes and the less than optimal water and nutrient supply in the agar medium.

Pepper species and cultivars, Capsicum annuum cv. Bell Boy, C. annuum cv. Kulai and C. frutescens cv. Padi, differing in drought tolerance were investigated for their water relations, stomatal responses and abscisic acid (ABA) content during water stress. C. frutescens cv. Padi exhibited a greater osmotic adjustment than C. annuum cultivars. Stomatal conductance of cv. Bell Boy was more sensitive to water stress than that of cvs. Kulai and Padi. In all pepper genotypes, stomatal closure was triggered in the absence of a large decrease in leaf water status. ABA content in xylem sap and leaf was higher in C. annum cultivars compared to C. frutescens cv. Padi.

Total genomic DNA isolated from maize hygromycin B resistant cell line(hygr-G204) was used to transform the maize hygromycin B sensitive cell line(hygs-G204) to the hygr-phenotype using polyethyleneglycol treatment and the transformed calli were selected using hygromycin B. The primary transformant maize plants were regenerated and analysed at the molecular level using DNA hybridization, transgenome rescue and histochemical β-glucuronidase assay. The results indicated that genomic DNA-mediated transformation can lead to transfer, expression and stable integration of a DNA fragment into the host genome.

After treatment with increased quantities of nitrogen and Azotobacter strains, activities of antioxidant enzymes superoxide dismutase, peroxidase and catalase, content of chlorophylls and carotenoids, soluble proteins and dry matter in leaves of sugar beet increased.

The first step during shoot primordia development in Papaver somniferum L. was the differentiation of globular meristemoids, resulting from localized cell division in callus tissue. During meristemoid maturation differences observed were in mitotic activity, cytoplasmic density, starch distribution, and in cell size, cell shape, and nucleus size to cell size ratio between peripheral and central meristemoid cells. Cell specialization within the meristemoids is a prerequisite for shoot primordia development.

Growth rate of fruit of Actinidia deliciosa (A. Chev.) Liang and Fergusoncv. Hayward, measured as increase in fresh mass, followed a simple sigmoidal trend showing two stages in all the seasons studied (1987 - 1989). However, growth profiles were statistically different from year to year in both shape and mean reached. The data suggest an important effect of climatic factors on growth, mainly rainfall, which may explain the differences in growth curves between seasons. Significant correlations between relative growth index and length and/or diameter were found which can be used for a non-destructive determination of Actinidia deliciosa fruit growth.

A spermine-resistant mutant of Arabidopsis thaliana (L.) Heynh. was isolated from M2 population of ethylmethanesulphonate-mutagenized seeds. The mutant was resistant to seed germination inhibition by spermine, but was as sensitive as the wild-type to spermidine and putrescine. In addition, the mutant displayed developmental abnormalities such as frequent cauline leaves, increased number of branches with inflorescence, reduced apical dominance, flowers subtended by bracts, disrupted floral organs with homeotic conversions. Genetic analysis indicated a single recessive nuclear mutation that was allelic to apetala2-1 (AP2-1). The new mutant allele of AP2 locus was accordingly numbered as AP2-10.

Zygotic embryos of Karwinskia parvifolia, isolated from seeds obtained from different regions of Mexico, were cultured on Woody Plant Medium (WPM) supplemented with 0.06 µM indole-3-acetic acid, 0.03 µM gibberellic acid, and 2 µM 6-benzylaminopurine. The growth of embryos and multiplication of shoots from stem segments were achieved. Rooting of excised shoots could be initiated on basal WPM medium with prolonged subculture period to 2 months, or on WPM medium supplemented with 10 µM 1-naphthaleneacetic acid. Multiplication capacity of shoots and rooting of K. parvifolia differed in dependence on the origin of explant material. The shoot multiplication was much lower than that of Karwinskia humboldtiana. The rooting depended on the origin of K. parvifolia seeds. The regenerated plants were successfully transferred to glasshouse.

The physiological responses of alfalfa (Medicago sativa L. cv. Gilboa) to salinity (100 mM NaCl) and some inorganic nutrients (K+, Ca2+ and N as NO3-) were investigated. Salinity caused a substantial reduction in biomass, carbon assimilation rate, stomatal conductance, water use efficiency, leaf area, relative growth rate, NO3- content and nitrate reductase activity, whereas, transpiration rate was slightly affected. Inclusion of K+, Ca2+ and N as NO3- in plant nutrient medium in combination or alone brought about a marked stimulation in control plants and moderated the salinity caused reductions in NaCl treated plants. In addition, plants also exhibited differences in these parameters at two growth stages.

Effect of two important mycotoxins, aflatoxin B1 and citrinin (concentration 2 g m-3) at various combinations (i.e., 1:1, 1:2, 2:1, 1:3 and 3:1, v/v) on seed germination, seedling growth, chlorophyll, carotenoid, starch, sugar, protein and nucleic acid contents, α-amylase activity, and respiration quotient was studied in maize cv. Suwan composite. The maximum and minimum inhibitions were recorded in most of the above parameters (except starch) at 3:1 and 1:3 combination ratios of these toxins, respectively. However, the inhibition rates varied with the treatments.

We obtained transformed bean shoots by electroporation of intact bean cells with the plasmid pDPG165 containing bar gene conferring herbicide resistance to plants. Transformed shoots were selected from electroporated callus on herbicide containing media. Data of molecular analysis (PCR and Southern blotting) confirmed the insertion of bar gene in the genome of herbicide resistant shoots. Detailed procedures for obtaining regenerative bean callus, optimization of electroporation of intact cells and transgenic shoots are given.

Cadmium, copper and zinc ions at high concentrations partially released scarified freshly-harvested seeds ofStylosanthes humilis from physiological dormancy. This response to toxic metals increased along with seed postharvest ageing. Cobalt and silver ions, and abscisic acid impaired metal-promoted germination.

Supply of 0.01 to 1.0 mM lead acetate to greening pea(Pisum sativum L.) leaf segments either in the absence or in the presence of inorganic nitrogen lowered total chlorophyll (Chl) content. During a time course study, there was not any appreciable effect of Pb²⁺ upto 4 h but thereafter Pb inhibited Chl synthesis. While supply of succinate, cysteine dithiothreitol, 5,5-dithio-bis-2-nitrobenzoic acid and NH₄C1 had no protective action against Pb²⁺ toxicity, and glycine, glutamate 2-oxoglutarate, MgCl₂, KH₂PO₄, CaCl₂, KC1 protected only partially, reduced glutathione (GSH) could completely overcome the inhibition of Chl biosynthesis by the metal. It is suggested that Pb²⁺ interferes with Chl biosynthesis through GSH availability

When the proper stimuli are given, somatic plant cells may form adventitious embryos, roots or shoots. The three pathways of regeneration show apparent similarities. They consist of three analogous phases: 1) dedifferentiation (during which the tissue becomes competent to respond to the organogenic/embryogenic stimulus), 2) induction (during which cells become determined to form either a root, a shoot or an embryo), and 3) realization (outgrowth to an organ or an embryo). The first phase may involve a period of callus growth (indirect regeneration), but often cells present in the explant become competent without cell division or without cell division at a large scale (direct regeneration). In an explant, only very few cells show the organogenic/embryogenic response. In direct regeneration, the three regenerative pathways start from cells in different tissues. This is most obvious when the different types of regeneration occur in the same explant. The hormonal trigger for the dedifferentiation phase is a general one, probably auxin. During the induction phase, each pathway requires specific hormonal triggers. During the realization phase, hormones should be absent or at low concentration. The successive steps in the regeneration process coincide with events on the molecular and biochemical levels, but so far no coherent picture has emerged. In particular during the early stages of regeneration, research on these levels is hampered by a technical problem, viz., the very low proportion of cells that participate in the process of regeneration. New methods may overcome this problem.