Abstract Water level fluctuation and inorganic nitrogen enrichment are two serious problems caused by anthropogenic disturbances in aquatic ecosystems. They cause resource fluctuation and thus might influence the invasive-ness of alien plants. Alternanthera philoxeroides is an amphibious and widespread clonal plant which exhibits significant invasiveness. This experimental study examined the plant's morphological traits under different nitrogen concentrations and water levels. The responses of A. philoxeroides to water levels and nitrogen concentrations were similar for both land-like and riverbank-like initial conditions. A. philoxeroides showed an escape strategy of shoot elongation when its growth was suppressed by shallow submergence. No toxic symptoms but increased clonal spread was observed at high nitrogen concentrations, suggesting that A. philoxeroides not only tolerated but benefitted from nitrogen-polluted water. High nitrogen level mitigated the negative effects of submergence on its leaf survival, thereby enhancing its adaptation to water level fluctuation. Such strong adaptability and clonal spread helps A. philoxeroides to grow and invade successfully in shallow eutrophic water.

Abstract During greening, excised etiolated barley leaves and cucumber cotyledons that were depleted of exogenous Ca2+ by a chelating agent (ethylene glycol-bis (beta aminoethyl ether)-N,N,N`N`-tetraacetic acid, EGTA) showed ∼50% reduced chlorophyll (Chl) accumulation and ∼30% accumulation of apoprotein of the light-harvesting chlorophyll a/b-binding protein complex of photosystem II (LHCPII). The Ca2+ channel blocker lanthanum chloride (LaCl3) applied to cucumber cotyledons reduced LHCPII accumulation more than EGTA did. In both plant mate-rials, cytokinins enhanced chlorophyll accumulation by 50-60% and this effect was completely canceled by EGTA application. Hormones significantly increased LHCPII accumulation but EGTA application reduced that effect in barley leaves by ∼30% and in cucumber cotyledons by ∼80%. A similar effect was observed in LaCl3-treated cotyledons. CaCl2 application boosted chlorophyll accumulation in both plant materials. CaCl2 applied together with cytokinin reduced the hormonal effect on chlorophyll accumulation by ∼38% in barley leaves and 23% in cucumber cotyledons, but almost totally inhibited cytokinin-stimulated LHCPII accumulation. Our results indicate that calcium variously mediates the effect of cytokinin on chlorophyll and LHCPII accumulation. Cytokinin-induced enhancement of chlorophyll accumulation seems totally dependent on the exogenous pool of Ca2+, while Ca2+-dependent and Ca2+-independent pathways are involved in the hormonal effect on LHCPII accumulation. The effect of cytokinin on the increase of light-induced LHCPII accumulation appears to be sensitive to exogenously applied Ca2+, which almost totally blocked the hormonal effect. Our results give indirect evidence that the responses to cytokinin and light act on different events leading to Chl and LHCPII accumulation.

Abstract Fruit quality is closely related to the structure of the fruit peel, especially the epidermis and cuticle which form a barrier between its internal and external environments. This study used light, scanning and transmission elec-tron microscopy to examine changes in the epidermal structures of fruits of the Polish apple cultivar Malus domestica Borkh. cv. Ligol at three maturity stages. The single-layered epidermis was covered with cuticle and crystalline wax platelets. In the fruit set stage the fruit surface exhibited numerous nonglandular trichomes, stomata, microcracks and crystalline wax platelets. The surface of fruits at harvest and after 6-month controlled-atmosphere storage exhibited lenticels and horizontally or vertically oriented wax platelets. During fruit devel-opment there was an increase in epidermal cuticle thickness and a reduction in epidermal cell convexity and number of lenticels. After the storage period fruit weight declined, microcracks deepened and widened, and cuticular waxes accumulated. The cuticle was made up of two layers, lamellar and reticulate. In successive fruit development stages the width of the lamellar layer increased considerably. In the fruit set and harvest maturity stages the epidermal cells contained numerous mitochondria and plastids with starch grains. After the storage period there were fewer amyloplasts and the cell vacuoles contained flocculent residue and dark deposits.

Abstract Using monoclonal antibodies (mAbs) JIM13, JIM15 and MAC207, we investigated the temporal and spatial dis-tribution of some arabinogalactan protein (AGP) epitopes in cells of the Bellis perennis L. anther at different developmental stages. AGP epitopes recognized by JIM13 were detected in the protoplasts of tapetal cells, dividing microsporocytes, and microspores; AGP epitopes recognized by JIM15 were present in the cytoplasm of tapetal cells only at the stage with tetrads of microspores in the anther loculus. AGP epitopes recognized by MAC207 were present in the cells of different somatic tissues of the flower bud, but after asymmetric mitosis in the microspore they appeared abundantly in the protoplasts of immature pollen and were still present in mature pollen grains. Callose, revealed by mAb, appeared at the same stage of microsporocyte division as AGPs labelled with JIM13 and JIM15. We discuss the differences in callose and AGP localization and the possible role of the latter during anther development.

Abstract Gene flow among individual trees of Pinus sylvestris and P. mugo putative hybrid swarms in Slovakia was fol-lowed at four localities using the species-diagnostic cpDNA trnV-trnH/Hinf I restriction profile. Variable proportions of P. sylvestris and P. mugo haplotypes were revealed among the sampled localities. Low between-habitus consistency of the trees and their cpDNA haplotypes indicates the hybrid nature of the swarms. Molecular analy-sis based on mutual comparison of the haplotypes of a given tree and its embryos suggests direct and recipro-cal hybridization between trees of the P. sylvestris and P. mugo haplotypes. Besides conspecific embryos resulting from hybridization of trees with the same haplotype (P. sylvestris × P. sylvestris and P. mugo × P. mugo), hybrid embryos of P. sylvestris × P. mugo (8.03%) and P. mugo × P. sylvestris (11.50%) were also detected in open-pollinated offspring. The results are discussed from the standpoint of primary and introgressive hybridization between the parental species.

Abstract Worldwide chromosome number information has been compiled from the literature for monocotyledonous genera whose members have been cytologically studied in the last three years from Kangra District (Himachal Pradesh) and Kashmir (Jammu & Kashmir) in the Western Himalayas, comprising 143 species of 86 genera in 12 families, many in the family Poaceae. Chromosome number information from the literature is supplemented with new and varied reports for 54 species/56 taxa from the present study. Overall, the chromosome numbers range from 2n=10 to 2n=120. Some species in all genera show a large number of cytotypes, clearly highlighting the role of inter- and intraspecific genetic diversity as well as polyploidy and dysploidy. The basic chromosome numbers in all 86 genera are reconsidered. Monobasic genera are more common in Poaceae, and polyba-sic genera are more common in the other 11 families. Polyploidy in the different genera ranges from 3x to 40x, and is quite high in certain genera (18x in Avena, Bothriochloa, Isachne, Helictotrichon and Panicum; 19x in Saccharum; 24x in Tradescantia; 28x in Eleocharis; 32x in Cyperus; 36x in Andropogon; 38x in Poa; 40x in Dioscorea). An updated checklist of chromosome number variability in these genera is given for India and world-wide.

Abstract The influence of sodium alginate sterilization on the viability and mitotic activity of embedded protoplasts was studied in protoplasts of Brassica oleracea subsp. alba and rubra isolated from hypocotyl tissue and leaves of seedlings or plants grown in vitro. Both leaf and hypocotyl-derived protoplasts were more viable and divided more frequently when embedded in filtrated alginate. Division frequency was highest in cv. Reball F1 and the mitotic activity of its protoplasts was three times higher when embedded in filtrated alginate (36.1 ± 6.8%) than when cultured in autoclaved alginate (10.9 ± 5.0%). Protoplast-derived calli colonies were transferred to solid regeneration media and plants of all tested accessions were obtained.

Abstract Conditioned medium (CM) is a general term describing media in which cells have already been cultivated for some time. Such media, usually clarified by filtration, have been used by plant biotechnologists as additives sup-porting the growth of cell suspensions, organs and whole plants. This study examined the effect of CM obtained from green alga Desmodesmus subspicatus on the growth and functioning of the photosynthetic apparatus of Nicotiana tabacum and Arabidopsis thaliana in culture in vitro. Plants where cultured on CM diluted 1.25-, 2-and 5-fold with MS medium. The increase in fresh and dry weight was highest in tobacco and Arabidopsis cultured on CM/2 and CM/1.25 media. Those two concentrations also increased the amount of chlorophylls in both plants tested. CM improved parameter PI (reflecting the photosynthetic “vitality” of the organism) and electron transport efficiency, and increased the fraction of active reaction centers. Analysis of chlorophyll fluorescence in vivo suggests that the improvement of these plants grown in the presence of algal CM may result from stimulation of photosynthesis. Algal CM offers a convenient, cheap, universal supplement for stimulating the growth of higher plants in vitro.

Abstract Nutrition is one of the most important factors influencing quantitative and qualitative plant yield. This study examined the effect of manganese (Mn) in nutrient solution on photosynthetic activity parameters, and the relations between photosynthetic activity parameters, yield and plant nutrient status in tomato (Solanum lycoper-sicum L.). Mn supplementation significantly modified the nutrient content of leaves. Macronutrient content var-ied less than micronutrient content. The optimal Mn concentration differed between the studied cultivars. Both Mn deficit and Mn excess caused a decrease of tomato yield. Gas exchange parameters, relative water content (RWC) and specific leaf area (SLA) were measured in fully expanded tomato leaves. Certain levels of Mn were found to be needed for proper plant function and future yield, and toxic effects of excess Mn were noted. Changes in PN (net photosynthetic rate) were found to be the first signal of plant response to higher Mn supply, while yield was as for optimal Mn concentrations. Under Mn treatment, uptake of some nutrients increased. A higher level of absorbed Mg led to a higher photosynthesis rate and increased stomatal opening. PN and gs (stomatal con-ductance) also increased, while Ci (intercellular CO2 concentration) decreased, indicating proper CO2 consumption during the assimilation process.

Abstract To achieve a better understanding of accumulation of paclitaxel and related taxanes in Himalayan yew (Taxus wallichiana Zucc.) callus mass, induction and growth of calli from needles and petioles under light-emitting diodes (LEDs) and production of paclitaxel and baccatin were investigated. Calli were induced from needles and petioles on Gamborg's B5 medium supplemented with 1 mg·l-1 kinetin and 4 mg·l-1 2,4-D under different com-binations of blue and red LEDs. Calli were further cultured in that medium under the same lighting conditions. Callus induction from needles and petioles and growth was better under blue LEDs than under red LEDs and fluorescent light. The combinations of blue and red LEDs produced variable results. The paclitaxel content of these calli was quantified by high-performance liquid chromatography. The paclitaxel content of calli derived from needles was 0.00628% and the 10-DAB (10-Deacetylbaccatin III) content was 0.00366%. The paclitaxel content of calli derived from petioles was 0.00412%, and no 10-DAB was detected.

Abstract Extensive studies have been performed to elucidate the role of brassinosteroids (BRs), an important class of phy-tohormone in plant growth, development, and photomorphogenesis. Different wavelengths of light recognized by photoreceptors play a crucial role in plant development. The role of different photoreceptors in BR signaling has not been analyzed. Here we used photoreceptor single mutants, double mutants and even a quadruple mutant to analyze BR-dependent hypocotyl growth and gene regulation. All the photoreceptor mutants differed from the controls in their response to BR, and hypocotyl elongation as well as BR marker gene regulation were inhibited by application of propiconazole (PCZ), a BR biosynthesis inhibitor. In addition, altered Phytochrome and Cryptochrome expression in brassinosteroid insensitive 1 mutant bri1-5 and brassinazole-resistant 1 dominant mutant bzr1-D indicated that BR negatively regulates photoreceptors in transcriptional levels. This is the first study to investigate the connections between BR and photoreceptors in Arabidopsis.

Abstract The effect of two in planta factors (growth conditions, genotype) and two in vitro factors (time of embryo rescue, embryo rescue medium) on doubled haploid (DH) plant production in bread wheat via maize technique was investigated in nine F1 hybrids produced after crossing four bread wheat cultivars. During the first year one group of F1 plants was grown in a field and at the proper stage pollinated with maize pollen (sweet corn popu-lation). In parallel, a second group of F1 plants was grown in a growth chamber and pollinated as in the former group. In the second growing season the experiment was repeated but only field-grown plants were used. All the produced haploid embryos were cultured in three different media and the resulting 146 haploid plants were sub-sequently treated with aqueous solution of colchicine. Finally, 86 doubled haploid plants were obtained. We noted that the growing conditions of the parental plants and the intervening time between day of pollination and day of embryo rescue influenced the percentage of haploid embryo production. Culture medium also influenced haploid and doubled haploid plant production. The two media (MS/2, B5) were found equally effective. Most of the haploid embryos originated from the Penios × Acheloos cross, whereas most of the doubled haploid plants were produced from the KVZ × Penios cross. Doubled haploid plants were produced from all crosses.

Abstract Hydrolyzable tannins and products of their hydrolysis, ellagic acid (EA) and gallic acid (GA), are important con-stituents of many medicinal plants and exhibit various biological activities. Geum rivale and G. urbanum are traditional herbal remedies rich in tannin compounds. The aim of the study was to quantitate free and total EA and GA in aerial and underground parts of G. rivale and G. urbanum. After optimization of extraction, both compounds were quantitated by reversed phase HPLC (RP-HPLC). EA was more abundant than GA in the inves-tigated material, and underground parts of G. rivale were the richest source of total EA and GA.

Abstract The study used fluorescence microscopy to examine changes in cytoskeleton configuration during development of the embryo suspensor in Gagea lutea and to describe them in tandem with the development of the embryo proper. During the early phase of embryo suspensor development, tubulin and actin filaments were observed in the cytoplasm of the basal cell from the micropylar to the chalazal ends of the cell. Around the nucleus of the basal cell were clusters of numerous microtubules. These accumulations of tubulin arrays congregated near the nucleus surface; numerous bundles of microtubules radiated from the nucleus envelope. At this time, microfil-aments formed a delicate network in the cytoplasm of the basal cell. In the fully differentiated embryo suspensor, microtubules were observed at the chalazal end of the basal cell. Numerous bundles of microtubules were visualized in the cytoplasm adjacent to the wall separating the basal cell from the embryo proper. Microfilaments formed a dense network which uniformly filled the basal cell cytoplasm. There were some foci of F-actin material in the vicinity of the nucleus surface and at the chalazal end of the basal cell. In all studied phases of embryo suspensor development a prominent cortical network of actin and tubulin skeleton was observed in embryo proper cells.

Abstract Many Asteraceae species have been introduced into horticulture as ornamental or interesting exotic plants. Some of them, including Solidago and Galinsoga, are now aggressive weeds; others such as Ratibida are not. Special modifications of the ovule tissue and the occurrence of nutritive tissue have been described in several Asteraceae species, including invasive Taraxacum species. This study examined whether such modifications might also occur in other genera. We found that the three genera examined - Galinsoga (G. quadriradiata), Solidago (S. canadensis, S. rigida, S. gigantea) and Ratibida (R. pinnata) - differed in their nutritive tissue structure. According to changes in the integument, we identified three types of ovules in Asteraceae: “Taraxacum” type (recorded in Taraxacum, Bellis, Solidago, Chondrilla), with well-developed nutritive tissue having very swollen cell walls of spongy structure; “Galinsoga” type (in Galinsoga), in which the nutritive tissue cells have more cyto-plasm and thicker cell walls than the other integument parenchyma cells, and in which the most prominent character of the nutritive tissue cells is well-developed rough ER; and “Ratibida” type (in Ratibida), in which the nutritive tissue is only slightly developed and consists of large highly vacuolated cells. Our study and future investigations of ovule structure may be useful in phylogenetic analyses.