biologia plantarum

International journal on Plant Life established by Bohumil Němec in 1959

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Results 991 to 1020 of 6293:

Interactions of lichens with heavy metals

M. Bačkor, S. Loppi

Biologia plantarum 53:214-222, 2009 | DOI: 10.1007/s10535-009-0042-y

Recent developments in knowledge about the interactions between lichens and heavy metals at different levels, from populations to cells and from ecology to molecular biology are reviewed. Sources of heavy metals, mechanisms of heavy metal accumulation and detoxification by lichens are discussed. Special emphasis is placed on ultrastructural changes as well as physiological parameters such as membrane integrity, pigment composition, chlorophyll a fluorescence, photosynthesis, respiration, contents of ATP, amino acids, ergosterol, ethylene, non-protein thiols, activity of antioxidant enzymes and expression of stress proteins.

Stem respiration of Norway spruce trees under elevated CO2 concentration

M. Acosta, R. Pokorný, D. Janouą, M. V. Marek

Biologia plantarum 54:773-776, 2010 | DOI: 10.1007/s10535-010-0140-x

Measurements of stem respiration were conducted for a period of four years (1999-2002) in 14-year old Norway spruce (Picea abies [L.] Karst) trees exposed to ambient (CA) and elevated CO2 concentration (CE; ambient plus 350 μmol mol-1). Stem respiration measurements of six trees per treatment were carried out 2-3 times per month during the growing season. Stem respiration in CE treatment was higher (up to 16 %) than in CA treatment. Temperature response of stem respiration (Q10) for the whole experimental period ranged between 1.65-2.57 in CA treatment and 2.24-2.56 in CE treatment. The mean stem respiration rate normalized to 10 °C (R10) in CA and CE treatments ranged between 1.67-1.95 and 2.19-2.72 μmol(CO2) m-2 s-1, respectively. Seasonal variations in stem respiration were related to temperature and tree growth.

Photosynthesis and chlorophyll fluorescence response to low sink demand of tubers and roots in Dahlia pinnata source leaves

S. T. Yan, X. D. Li, W. D. Li, P. G. Fan, W. Duan, S. H. Li

Biologia plantarum 55:83-89, 2011 | DOI: 10.1007/s10535-011-0011-0

Photosynthetic rate (PN) and chlorophyll (Chl) fluorescence induction of source leaves in response to a low sink demand created by girdling the branch (GB) between the root-tuber-system and the leaves were studied in Dahlia pinnata L. cv. Rigolet during the stage of rapid tuber growth in the greenhouse. GB resulted in significantly lower values of PN, stomatal conductance (gs), and transpiration rate (E), but in higher leaf temperature (Tl) compared with those of controls. With exception of maximum quantum yield of photosystem 2 (PS 2) photochemistry (Fv/Fm) and maximum ratio of quantum yields of photochemical and concurrent non-photochemical processes in PS 2 (Fv/F0), no significant differences were observed in Chl fluorescence parameters between girdled and control leaves on days 1 and 2 after GB, indicating no apparent damage in the photosynthetic apparatus. However, longer girdling duration resulted in higher non-photochemical Chl fluorescence quenching (NPQ), but lower Fv/F0, actual efficiency of energy conversion in PS 2 under steady-state conditions (ΦPS2), and photochemical quenching coefficient (qP) in comparison with controls from 10:00 to 16:00 or 15:00 on days 4 and 5, respectively, indicating reversible injury in the photosynthetic apparatus.

Effects of cadmium on gas exchange and phytohormone contents in citrus

M. F. López-Climent, V. Arbona, R. M. Pérez-Clemente, A. Gómez-Cadenas

Biologia plantarum 55:187-190, 2011 | DOI: 10.1007/s10535-011-0028-4

The effect of increased Cd2+ concentrations in the watering solution on citrus physiology was studied by using two citrus genotypes, Cleopatra mandarin and Carrizo citrange. Cadmium content in roots and leaves was tested together with measurements of leaf damage, gas exchange parameters, and hormonal contents. Citrus roots efficiently retained Cd2+ avoiding its translocation to the shoots and Cleopatra mandarin translocated less Cd2+ than Carrizo. With increasing Cd2+ concentration all gas exchange parameters were decreased more in Carrizo than in Cleopatra mandarin. Cd-induced increases in abscisic acid and salicylic acid contents were observed in leaves but not in roots of both genotypes.

Pseudomonas fluorescens mediated systemic resistance in tomato is driven through an elevated synthesis of defense enzymes

S. C. Vanitha, S. Umesha

Biologia plantarum 55:317-322, 2011 | DOI: 10.1007/s10535-011-0045-3

Pseudomonas fluorescens was used as a biological control agent against bacterial wilt disease caused by Ralstonia solanacearum. Activities of phenylalanine ammonia lyase (PAL), guaiacol peroxidase (POX), polyphenol oxidase (PPO) and lipoxygenase (LOX) increased in P. fluorescens pretreated tomato seedlings, which were later inoculated with R. solanacearum and activities of PAL, POX, PPO and LOX reached maximum at 12, 9, 15 and 9 h, respectively, after inoculation. Reverse transcription - polymerase chain reaction (RT-PCR) confirmed the maximum induction of all these enzymes in P. fluorescens pretreated seedlings.

Residual sexuality and its seasonal variation in natural apomictic Paspalum notatum accessions

R. N. Rebozzio, M. E. Sartor, C. L. Quarin, F. Espinoza

Biologia plantarum 55:391-395, 2011 | DOI: 10.1007/s10535-011-0062-2

Traditionally, tetraploid Paspalum notatum was considered an obligate or a facultative apomict according to cytoembryological analyses. The degree of facultativeness was usually determined by the relative amount of mature ovules bearing aposporous or meiotic (sexual) embryo sacs, or both together. We established, through progeny tests conducted with the aid of AFLP markers, the degree of residual sexuality expressed in four selected biotypes. The results showed it to be substantially and significantly lower than predicted by previous embryological analyses for the same biotypes. Moreover, the lowest expression of residual sexuality was coincident with maximum flowering period. Seed development in facultative apomictic P. notatum shows a definite bias against meiotic embryo sacs.

Arabidopsis Ca2+-dependent protein kinase CPK3 mediates relationship of putative inositol triphosphate receptor with slow-type anion channel

A. Cousson

Biologia plantarum 55:507-521, 2011 | DOI: 10.1007/s10535-011-0117-4

It has been suggested in Arabidopsis thaliana (L.) Heynh. cv. Columbia that, contrary to 30 μM abscisic acid (ABA), 20 μM ABA induces guard cell Ca2+ mobilization through activating phosphoinositide-specific phospholipase C (PI-PLC)-dependent inositol 1,4,5-triphosphate (IP3) production. Here, it was investigated whether Ca2+-dependent protein kinase, CPK3 or CPK6 would mediate ABA-induced stomatal closure downstream of IP3 production. In the knockout cpk3-1 mutant, the PLC inhibitor (U73122) adjusted 20 μM ABA-induced stomatal closure to the extent observed in the knockout cpk6-1 and cpk3-1cpk6-1 mutants and the wild type, whereas, in the wild type, the inhibitor of IP3-induced Ca2+ mobilization, xestospongin C (XeC), adjusted this closure to the extent observed in the cpk3-1 mutant. The Ca2+ buffer, EGTA and XeC positively interacted with the slow anion channel blocker, anthracene-9-carboxylic acid (9-AC) to inhibit 20 μM ABA-induced stomatal closure, which was suppressed in the dexamethasone-inducible AtPLC1 antisense transgene or the knockout cpk3-1, cpk6-1, cpk3-1cpk6-1 and NADPH oxidase atrbohD/F mutants. Discrete concentrations of 9-AC or another slow anion channel blocker (probenecid) negatively interacted with the Ca2+ buffer, BAPTA or the inhibitor of cyclic ADP-ribose-induced Ca2+ mobilization, ruthenium red, to inhibit 30 μM ABAinduced stomatal closure in the wild type but not in the cpk6-1, cpk3-1cpk6-1 and atrbohD/F mutants. Based on so far revealed features of the tested compounds and plant materials, interpretation of the results confirmed that guard cell ABA concentration discriminates between two Ca2+ mediations and outlined that one of them sequentially implicates CPK6, PLC1, a putative IP3 receptor homologue, CPK3, and the slow anion channel, whereas the other one excludes AtPLC1-dependent IP3 production and CPK3.

Gametes with somatic chromosome number and their significance in interspecific hybridization in Fuchsia

R. S. Talluri

Biologia plantarum 55:596-600, 2011 | DOI: 10.1007/s10535-011-0133-4

Sexual polyploidization has both a theoretical as well as an applied significance. Morphological screening for large pollen grains and shape of pollen produced by the individual, cytological investigation of hybrid progeny, and unbalanced separation of chromosomes at anaphase I in pollen mother cells were used to detect the gametes with somatic chromosome number in Fuchsia. The interspecific hybrids of F. fulgens (sect. Ellobium) × F. magellanica (sect. Quelusia), F. fulgens (sect. Ellobium) × F. splendens (sect. Ellobium), and F. triphylla (sect. Fuchsia) × F. splendens (sect. Ellobium) produced at the University of Auckland, New Zealand, showed both large and normal pollen grains in the same anther indicating the presence of unreduced gametes. Cytological investigation carried out on the hybrid progeny of F. fulgens (diploid, 2n=22, sect. Ellobium) × F. magellanica (tetraploid, 2n=44, sect. Quelusia) and F. triphylla (diploid, sect. Fuchsia) × F. arborescens (diploid, sect. Schufia) revealed unexpected chromosome numbers of 2n=44 and 2n=33, respectively. In general, the hybrids showed low fertility caused by genetically unbalanced gametes resulted from random disjunction of chromosomes at anaphase I. Studies on meiosis together with the presence of different shapes and sizes of pollen grains in Fuchsia proved indirectly that unreduced gametes are the products of first division meiotic nuclear restitution. These unreduced gametes were viable irrespective of pollen shape, their predominance in the hybrids, nuclear DNA amount and species phylogenetic position.

Guard cells on adaxial and abaxial epidermes of Erythrina corallodendron sepals

B. Huang, Y. Wang, S. Huang, S. Ma

Biologia plantarum 55:716, 2011 | DOI: 10.1007/s10535-011-0174-8

This study investigated guard cells on the adaxial and the abaxial epidermes during Erythrina corallodendron sepal development. On the adaxial epidermis, the morphology of guard cells was highly variable and changes in aperture induced by abscisic acid (ABA) were observed in 9.1 % stomata, while on the abaxial epidermis 86.7 % stomata responded to ABA. On the adaxial epidermis, stomata did not close even when guard cell pressure potential was reduced to zero by plasmolysis, even if fluorescein diacetate revealed that guard cells were alive. It was concluded that guard cells on the adaxial and the abaxial epidermes of sepals sensed environmental conditions differently, maybe due to different guard cell wall elasticity.

Hexanoic acid 2-(diethylamino)ethyl ester enhances chilling tolerance in strawberry seedlings by impact on photosynthesis and antioxidants

X. -J. Fu, A. S. Maimaiti, H. -M. Mou, Q. Yang, G. -J. Liu

Biologia plantarum 55:793, 2011 | DOI: 10.1007/s10535-011-0190-8

Strawberry (Fragaria ananassa Duch.) seedlings were pretreated with hexanoic acid 2-(diethylamino)ethyl ester (DA-6) in concentrations of 0, 10, 20 and 40 mg dm-3 and then subjected to chilling and rewarming. The effects of applied DA-6 on the generation of reactive oxygen species (O2 -, H2O2), lipid peroxidation, proline accumulation and photosynthesis were evaluated. Pretreatment with DA-6 alleviated the inhibition of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities caused by chilling stress thus reducing O2 - and H2O2 production and lipid peroxidation in pretreated plants. DA-6 pretreatment also accelerated accumulation of proline and reduce the decrease in proline content after rewarming. DA-6 pretreatment increases maximum quantum yield of photosystem 2 (Fv/Fm), actual photochemical efficiency of photosystem 2 (ΦPS2), photochemical quenching coefficient (qP) and net photosynthetic rate (PN) and decreases non-photochemical quenching coefficient (qNP) of the seedlings under chilling stress. DA-6 pretreatment also increased the recovery rate of photosynthesis after rewarming.

A low-noise multi-channel device for the monitoring of systemic electrical signal propagation in plants

P. Ilík, V. Hlaváčková, P. Krchňák, J. Nauą

Biologia plantarum 54:185-190, 2010 | DOI: 10.1007/s10535-010-0032-0

Long-distance electrical signals generated in locally stimulated plants are linked with systemic physiological responses. The propagation of electrical signal through a plant can be measured by multiple electrodes attached to different sites of a plant body. As this signal has to be measured with the sensitivity of tens of microvolts, it can be easily disturbed by power-line hums or external electromagnetic fields. These disturbances can mimic the action potentials generated by a plant. In this work, we present a brief summary of various experimental approaches to the measurement of surface electrical potential (SEP) on a plant and a description of our multi-channel device for the SEP measurement. The main advantages of our measuring system are galvanic separation of the measuring unit, resulting in the elimination of power-line disturbances, and simple and stable contact of Ag/AgCl-peletted electrodes with the plant surface, facilitated by an ordinary gel used in human electrocardiography. These improvements enabled us to detect unperturbed variation (slow) and action (fast) potentials on a plant, as demonstrated by the four-electrode measurement of the electrical signal propagation in a locally wounded tomato plant.

Cloning and characterization of two osmotin isoforms from Piper colubrinum

T. Mani, S. Manjula

Biologia plantarum 54:377-380, 2010 | DOI: 10.1007/s10535-010-0068-1

In the present study, we report the cloning and sequence characterization of two isoforms of osmotin, an antifungal PR-5 gene homologue, from a salicylic acid-induced subtracted cDNA library earlier generated in Piper colubrinum. The larger form of the gene is 693 bp long, encoding a 21.5 kDa protein. The smaller form comprises a 543 bp long coding sequence which code for a protein of 16.4 kDa. A notable feature of the smaller form was a prominent internal deletion of 150 bp besides certain point mutations. Cloned isoforms of osmotin from resistant species could be candidates for molecular breeding for the improvement of black pepper as well as candidates for the study of structure based mechanism of antifungal activity attributed to PR-5 family.

Endogenous brassinosteroids in wheat treated with 24-epibrassinolide

A. Janeczko, J. Swaczynová

Biologia plantarum 54:477-482, 2010 | DOI: 10.1007/s10535-010-0084-1

The aim of the study was to examine the effect of exogenous 24-epibrassinolide on its uptake and content of endogenous brassinosteroids in wheat seedlings. 24-Epibrassinolide was applied at two concentrations (0.1 and 2.0 μM) and in three different methods: by soaking seeds, by drenching and by spraying plants. Brassinosteroids were determined by high-performance liquid chromatography combined with electrospray mass spectrometry. Three important brassinosteroids, 24-epibrassinolide, brassinolide and castasterone, were detected in the wheat leaves, but their contents varied with leaf insertion and plant age. Increased 24-epibrassinolide content in the leaf tissue was found when this hormone was applied by soaking or drenching. Additionally the seed treatment influenced brassinosteroid balance in seedlings. The growth response of wheat seedlings treated with 24-epibrassinolide has been also investigated.

Sugarcane genes differentially expressed during water deficit

F. A. Rodrigues, J. P. Da Graça, M. L. De Laia, A. Nhani-Jr, J. A. Galbiati, M. I. T. Ferro, J. A. Ferro, S. M. Zingaretti

Biologia plantarum 55:43-53, 2011 | DOI: 10.1007/s10535-011-0006-x

To identify genes that are up and down-regulated by water deficit in sugarcane we used the macroarray methodology and the expression level of 3 575 independent sugarcane cDNAs was measured by hybridization with RNA extracted from plants submitted to mild, moderate and severe water deficit. We identified approximately 1 670 differentially expressed genes from which 62 % were up-regulated by different stress-conditions, whereas many repressed genes were exclusive for each time-point. Analysis of similarity showed that approximately 24 % of the differentially expressed genes shared homology with proteins involved in different processes such as signal transduction, hormone metabolism, photosynthesis, transcription and stress response. Transcripts with no known function accounted for approximately 39 % and those without similarity represented 36 % of the sequences. Five genes analyzed by RT-PCR confirmed the macroarray results.

In vitro cloning of Azadirachta indica from root explants

K. Arora, M. Sharma, J. Srivastava, S. A. Ranade, A. K. Sharma

Biologia plantarum 55:164-168, 2011 | DOI: 10.1007/s10535-011-0023-9

In vitro cultures of Azadirachta indica A. Juss. were raised by first culturing the root segments on modified Murashige and Skoog (MS) medium supplemented with 8.88 μM 6-benzylaminopurine (BAP), 9.84 μM N6-(2-isopentenyl) adenine (2iP), 5.71 μM indole-3-acetic acid (IAA), 81.43 μM adenine hemisulphate and 2.27 μM putrescine for 2 d followed by their transfer to the same medium except containing one-tenth of the initially used concentrations of BAP, 2iP and IAA. The regenerated shoots sustained proliferation in the basal medium supplemented with 1.11 μM BAP, 1.43 μM IAA and 135.72 μM adenine hemisulphate. The isolated shoots were rooted to produce plantlets in the presence of 2.46 μM indole-3-butyric acid (IBA). The plantlets showed uniform luxuriant growth under field conditions. True-to-type nature of the field-grown root-regenerated plants was ascertained by random amplified polymorphic DNA (RAPD) analysis.

Chromosome doubling can increase heat tolerance in Lonicera japonica as indicated by chlorophyll fluorescence imaging

W. D. Li, X. Hu, J. K. Liu, G. M. Jiang, O. Li, D. Xing

Biologia plantarum 55:279-284, 2011 | DOI: 10.1007/s10535-011-0039-1

Imaging fluorometry was applied to investigate the tolerance of Japanese honeysuckle (Lonicera japonica Thunb.) of different ploidy levels to heat stress. Seedlings of L. japonica, the diploid cv. Damaohua and the tetraploid cv. Jiufengyihao, were exposed to heat stress of 42 °C for 6 h and a recovery for 10 h. Heat stress significantly decreased maximum photochemical efficiency, electron transport rate, effective quantum yield of photosystem 2, and photochemical quenching of both cultivars, but it decreased the non-photochemical quenching (NPQ) only in the tetraploid. Heat stress increased the content of total soluble sugars, proline, and malondialdehyde in both cultivars while it increased NPQ only in the diploid. Our findings suggest that the tetraploid showed to be more resistance to heat stress than the diploid of L. japonica, which was indicated by different chlorophyll fluorescence imaging techniques and metabolic changes. Moreover, the degree of recovery in the tetraploid was higher than that of the diploid. The tetraploid also possessed thicker epidermis (both upper and lower) and palisade tissue as well as denser pubescence.

Improved cryopreservation procedure for long term storage of synchronised culture of grapevine

K. Vasanth, M. A. Vivier

Biologia plantarum 55:365-369, 2011 | DOI: 10.1007/s10535-011-0056-0

Anther-derived pre-embryogenic masses (PEMs) of callus, established via suspension cultures, were encapsulated to form synthetic seeds suitable for cryopreservation. The synchronised suspension culture proliferation necessitated the optimisation of plant growth regulators for different cultivars. The growth phase and density of the culture were also important as well as the exposure of cells to vitrification solution containing 0.75 M sucrose with 0.1 M CaCl2 and 2.0 % sodium alginate (pH 5.7). Pre-treatment of the encapsulated cells for 2 d with Nitsch and Nitsch (NN) medium containing 0.75 M sucrose solution followed by dehydration for 4 h in a laminar flow box provided maximum cell viability, which varied from 0 to 40 %. The embryo proliferation from the cryopreserved beads involved warming them and then transfer to NN medium containing glutamine (50 mg dm-3) and activated charcoal (2.5 %). The maximum number of embryos obtained was 31-53 per bead. Subculture into the same medium induced secondary embryogenesis, which was initiated from the meristematic region, radicle, and root cap. Proliferation and maturation of secondary embryos was faster than of primary embryos. No phenotypic variation or abnormal structures compared to the control were observed in the regenerated plantlets.

Microsporogenesis and pollen formation in cassava

C. Wang, Z. Lentini, E. Tabares, M. Quintero, H. Ceballos, B. Dedicova, C. Sautter, C. Olaya, P. Zhang

Biologia plantarum 55:469-478, 2011 | DOI: 10.1007/s10535-011-0112-9

This article describes the complete microsporogenesis and pollen formation in cassava (Manihot esculenta Crantz) at the various developmental stages (pollen mother cell, meiosis, tetrads, early free spore, mid uninucleate, late uninucleate, binucleate and mature pollen grain). Light microscopy, transmission electron microscopy and confocal laser scanning microscopy were used for the study. Floral bud size and other inflorescence characteristics were correlated with specific stages of the microspore development. This association allows a rapid selection of floral buds with similar microspore developmental stages, useful when a large number of homogeneous cells are needed for analysis and for in vitro induction of androgenesis. This article also compares methods for digestion the exine wall in microspores.

Selection of co-transformed Dendrobium Sonia 17 using hygromycin and green fluorescent protein

C. S. Tee, M. Maziah, C. S. Tan, M. P. Abdullah

Biologia plantarum 55:572-576, 2011 | DOI: 10.1007/s10535-011-0128-1

Dendrobium Sonia 17 calluses were used for co-transformation study using particle bombardment. The bombarded transformed callus tissues were selected using half-strength MS medium containing 25 mg dm-3 hygromycin. Expression of green fluorescent protein (GFP) was observed in the callus and protocorm-like body (PLBs) tissues survived on the selection medium. The presence of green fluorescence protein (sgfp), hygromycin-B-phosphotransferase (hptII) and β-glucuronidase (uidA) genes in the transformed tissues were verified using PCR, Southern blot and dot blot analyses. Based on the results from PCR and expression of sgfp and uidA genes in the calluses and PLBs survived from hygromycin selection, we reported the co-transformation of sgfp, hptII and uidA genes into Dendrobium Sonia 17. GFP-expressing tissues were also observed in the regenerated transformed plantlets.

Adventitious root system reduces lead uptake and oxidative stress in sunflower seedlings

J. Strubińska, A. Hanaka

Biologia plantarum 55:771, 2011 | DOI: 10.1007/s10535-011-0185-5

In this work, the effect of lead on sunflower seedlings with two root system types: primary - formed from embryonic tissues and adventitious - originating from hypocotyl after cutting off primary roots was investigated. The seedlings were subjected to Pb(NO3)2 in doses: 0, 0.5, 2.5, 5 and 20 mg(Pb) dm-3 for a week. Lead accumulation, seedling length and mass as well as selected parameters representative of oxidative damage (malondialdehyde) and protection (superoxide dismutase and glutathione) were used to compare stress response of plants. The comparison showed significant differences between plants with different root systems in almost all the parameters and the plants with adventitious root were more tolerant to lead.

Isolation and functional analysis of cDNAs similar to Hyp-1 involved in hypericin biosynthesis from Hypericum erectum

M. L. Jin, J. C. Ahn, B. Hwang, H. -S. Park, H. S. Lee, D. -W. Choi

Biologia plantarum 54:725-729, 2010 | DOI: 10.1007/s10535-010-0129-5

Hypericin, a naphthodianthrone, has been identified as the principal active compound found in St. John's wort (Hypericum perforatum L.). To generate a gene resource for hypericin and other valuable metabolites, we generated expressed sequence tags (ESTs) from H. erectum. Analyses of the ESTs enabled us to select three cDNAs, HeHyp1, HeHyp2, and HeHyp3, evidencing significant sequence homology to Hyp-1 that were involved in hypericin biosynthesis from H. erectum. The deduced amino acid sequence of HeHyp1 cDNA exhibits 95 % identity with Hyp-1. The HeHyp2 and HeHyp3 polypeptides also exhibit 81.1 % identity with Hyp-1. The transcripts of HeHyp1, HeHyp2, and HeHyp3 were detected in the root, stem, leaf, flower, and callus cells. Study using recombinant protein suggests that Hyp-1, HeHyp2, and HeHyp3 may be involved in the biosynthetic of hypericin or other emodin derivatives.

Glutathione in adaptation of Arabidopsis thaliana to cadmium stress

M. Wójcik, A. Tukiendorf

Biologia plantarum 55:125-132, 2011 | DOI: 10.1007/s10535-011-0017-7

The role of glutathione (GSH) in the adaptation of wild type Arabidopsis thaliana plants to Cd stress was investigated. The nutrient solution (control or containing 50 or 100 μM Cd) was supplemented with buthionine sulfoximine (BSO; 50, 100, 500 μM, to decrease the GSH content in plants) or GSH (50, 100, 500 μM, to increase its content in plants) in order to find how GSH content could regulate Cd stress responses. BSO application did not influence plant biomass, while exogenous GSH (especially 500 μM) reduced root biomass. BSO (500μM) in combination with Cd (100 μM) increased Cd toxicity on root growth (by over 50 %), most probably due to reduced GSH content and phytochelatin (PC) accumulation (by over 96 %). On the other hand, combination of exogenous GSH (500 μM) with Cd (100 μM) was also more toxic to plants than Cd alone despite a significant increase in GSH and PC accumulation (up to 2.7 fold in the roots). This fact could indicate that the natural content of endogenous GSH in wild type A. thaliana plants is sufficient for Cd-tolerance. A decrease in this GSH content led to decreased Cd-tolerance of the plants but an increase in GSH content did not enhance Cd-tolerance, and it showed even toxic effect on the plants.

Effects of leaf soluble sugars content and net photosynthetic rate of quince donor shoots on subsequent morphogenesis in leaf explants

M. Mingozzi, S. Morini, M. Lucchesini, A. Mensuali-Sodi

Biologia plantarum 55:237-242, 2011 | DOI: 10.1007/s10535-011-0034-6

The effects of different growth conditions (ventilated and closed vessels, medium with 0, 15 and 30 g dm-3 sucrose) during proliferation of donor quince (Cydonia oblonga Mill.) shoots (stage I) on net photosynthetic rate and soluble sugars content were evaluated. In order to assess the influence of these physiological parameters on morphogenesis, leaf explants harvested from donor shoots were induced to form somatic embryos and adventitious roots under ventilated and closed Petri dishes (stage II). Natural ventilation and low sucrose contents (0-15 g dm-3) promoted the photosynthetic rate of quince shoots whereas biomass accumulation was the highest in those shoots cultured with 30 g dm-3 sucrose in both vessel types and 15 g dm-3 sucrose under natural ventilation. Increasing sucrose content in the medium induced greater accumulation of sucrose in leaf tissues of donor shoots. The content of reducing sugars was higher than that of sucrose, and it appeared to be higher in shoots cultured under natural ventilation compared to those in closed vessels. Somatic embryogenesis and root regeneration were influenced by stage I and II treatments. A significant correlation between sucrose content in the leaves of donor shoots and the number of somatic embryos regenerated was found, suggesting that identification of biochemical and physiological characteristics of donor shoots associated with increased regeneration ability might be helpful for improving morphogenesis in plant tissue culture.

Physiological effects of exogenous nitric oxide on Brassica juncea seedlings under NaCl stress

C. -L. Zeng, L. Liu, B. -R. Wang, X. -M. Wu, Y. Zhou

Biologia plantarum 55:345-348, 2011 | DOI: 10.1007/s10535-011-0051-5

The study was conducted to investigate the physiological effects of exogenous NO on potherb mustard (Brassica juncea Coss.) seedlings under salt stress. The plants were grown in Hogland nutrient solution for 15 d and treated with 150 mM NaCl, NO donor sodium nitropruside (SNP) and NO scavenger methylene blue (MB-1) for 4 d. The NaCl stress increased superoxide dismutase, peroxidase and ascorbate peroxidase activities and malondialdehyde (MDA) and free proline contents, and decreased soluble protein content. However, the application of exogenous NO limited the production of MDA and free proline, while markedly promoted SOD, POD and APX activity.

Extracellular matrix as the early structural marker for Centella asiatica embryogenic tissues

K. S. Lai, K. Yusoff, M. Maziah

Biologia plantarum 55:549-553, 2011 | DOI: 10.1007/s10535-011-0123-6

Embryogenic and non-embryogenic calli were induced from the Centella asiatica leaf explants on Murashige and Skoog medium supplemented with kinetin and 2,4-dichlorophenophenoxyacetic acid. The extracellular matrix (ECM) layer was seen on the surface of embryogenic cells but not on the non-embryogenic cells. The ECM formed bridges with net-like material between the embryogenic cells. This network like structure was believed to play an important role in plant morphogenesis and can serve as an early structural marker of embryogenic competence in Centella asiatica calli culture.

Molecular characterization of ginseng farnesyl diphosphate synthase gene and its up-regulation by methyl jasmonate

O. T. Kim, K. H. Bang, S. J. Jung, Y. C. Kim, D. Y. Hyun, S. H. Kim, S. W. Cha

Biologia plantarum 54:47-53, 2010 | DOI: 10.1007/s10535-010-0007-1

We isolated a gene encoding for farnesyl diphosphate synthase (FPS) from Panax ginseng, a species that produces a large quantity of triterpene saponins such as ginsenosides. The deduced amino acid sequence of PgFPS was 77, 84 and 95 % identical to those of Arabidopsis, Hevea, and Centella. Southern blot analysis indicated that P. ginseng contained more than two genes encoding for FPS. When the cDNA of PgFPS was expressed in Escherichia coli, the recombinant enzyme, purified with a His-tag column, was found to possess FPS activity. When cultures of ginseng hairy root were treated with 0.1 mM methyl jasmonate (MJ), PgFPS mRNA was detected within 12 h of the treatment, and achieved maximum after 24 h. Also FPS activity in the hairy root cultures after 12 h of MJ treatment was higher than that of the control.

Expression of two genes of paclitaxel biosynthetic pathway during germination of Taxus baccata zygotic embryos

K. Bruňáková, J. Koąuth, Z. Katkovčinová, M. Lázárová, E. Čellárová

Biologia plantarum 54:515-519, 2010 | DOI: 10.1007/s10535-010-0090-3

The spatial and temporal expression of dbat and dbtnbt genes involved in the later steps of paclitaxel biosynthesis in relation to baccatin III and paclitaxel accumulation in Taxus baccata L. germinating embryos and seedlings was investigated. The steady-state of mRNA transcripts was measured by quantitative real time polymerase chain reaction (qRT-PCR), the content of taxanes was determined by HPLC. The spatial distribution of the metabolites was found to be in accordance with the transcript level of the respective genes. Higher content of mRNA transcripts in shoots of yew seedlings responded to higher content of taxanes in stems and needles. The highest increase in the transcript level of both genes was observed 8 d after placing the embryos on germination medium, before elongation of embryonic axis and emergence of the radicle. The pattern of temporal dbat expression was in line with the expression of the dbtnbt gene. The temporal distribution of the precursor baccatin III correlated well with paclitaxel, the final product of the pathway.

Efficient biolistic transformation of the moss Physcomitrella patens

M. ©mídková, M. Holá, K. J. Angelis

Biologia plantarum 54:777-780, 2010 | DOI: 10.1007/s10535-010-0141-9

High rates of homologous recombination (HR) in comparison to other plants make the moss Physcomitrella patens an attractive model organism for genetic studies as well as biotechnological applications. We describe a simple protocol for the efficient biolistic transformation of protonemal tissue with minimum tissue handling steps. The transformation efficiency depends on the biolistic conditions. The bombardment of tissue with 1 μm gold particles yielded between 20 and 40 stable transformants per 1 μg of DNA. Transformation with circular plasmids generates higher frequencies of random transgene integration, whereas linear plasmids are more efficient in generating gene-targeted insertions.

Response of antioxidant enzymes to high NaCl concentration in different salt-tolerant plants

S. Mallik, M. Nayak, B. B. Sahu, A. K. Panigrahi, B. P. Shaw

Biologia plantarum 55:191-195, 2011 | DOI: 10.1007/s10535-011-0029-3

The effects of NaCl on the H2O2 content and the activities of catalase (CAT) and superoxide dismutase (SOD) were studied in diverse group of plants, such as a unicellular alga, Chlorella sp., an aquatic macrophyte, Najas graminea, and a mangrove plant, Suaeda maritima, all showing high tolerance to NaCl. Significant accumulation of H2O2 was observed in all the tested plants upon their exposure to 255 mM NaCl. The activity of both CAT and SOD increased significantly in response to the NaCl treatment. Growing the plants in presence of 255 mM NaCl also resulted in the synthesis of new isoforms of both CAT and SOD.

Genetic variation within and among small isolated populations of Santalum album

K. G. Srikanta Dani, P. Ravikumar, R. Pravin Kumar, A. Kush

Biologia plantarum 55:323-326, 2011 | DOI: 10.1007/s10535-011-0046-2

A combination of directed amplification of minisatellite DNA (DAMD) and random amplification of polymorphic DNA (RAPD) primes were used to assess the genetic variation within and between three isolated populations of Indian sandalwood (Santalum album). Eleven primers used in this study amplified 65.99 % polymorphic bands. Analysis of molecular variance revealed a high genetic variation among these populations (ϕST = 0.549). There are indications of clonality within the existing Indian sandalwood populations which can be attributed to habitat fragmentation, isolation and vegetative reproduction.

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