Showing papers in "Biologia Plantarum in 2005"

Differences in antioxidant activity in response to salinity stress in tolerant and susceptible wheat genotypes

Abstract: Effects of long-term sodium chloride salinity (100 and 200 mM NaCl; ECe = 6.85 and 12.3 dS m−1) were studied in tolerant (Kharchia 65, KRL 19) and susceptible (HD 2009, HD 2687) wheat genotypes. NaCl decreased relative water content (RWC), chlorophyll content (Chl), membrane stability index (MSI) and ascorbic acid (AA) content, and increased the contents of hydrogen peroxide, thiobarbituric acid reactive substances (TBARS), and activities of superoxide dismutase (SOD), ascorbate peroxidase (APOX) and glutathione reductase (GR). Kharchia 65 showed lowest decline in RWC, Chl, MSI and AA content, lowest increase in H2O2 and TBARS contents and higher increase in SOD and its isozymes, APOX and GR, while HD2687 showed the highest decrease in AA content, highest increase in H2O2 and TBARS contents and smallest increase in activities of antioxidant enzymes. KRL 19 and HD 2009 showed intermediate response both in terms of oxidative stress and antioxidant activity.

Effect of arsenic on some physiological parameters in bean plants

Abstract: The objective of the study was to investigate the effect of different arsenic concentrations on some physiological parameters of bean (Phaseolus vulgaris L.) cultivars Plovdiv 10 and Prelom in the early growth phases. Seedlings, grown in sand with Hoagland-Arnon nutrient solution in a climatic box, were treated with 0, 2, 5 mg(As) dm−3 as Na3AsO4 (pH 5.5). After 5 d of As treatment, the changes in leaf gas-exchange, water potential, chlorophyll and protein contents, peroxidase activity and lipid peroxidation in roots were recorded. Physiological analysis showed a minor negative effect of arsenic at concentration 2 mg(As) dm−3, but at the higher dosage of 5 mg(As) dm−3 growth, leaf gas-exchange, water potential, protein content and biomass accumulation were reduced in both cultivars. The peroxidase activity and lipid peroxidation increased considerably at 5 mg(As) dm−3, which is a typical reaction of the plants to a presence of oxidative stress.

Changes in antioxidant enzymes activity and oxidative stress by abscisic acid and salicylic acid in wheat genotypes

Abstract: Abscisic acid (ABA) and salicylic acid (SA) were sprayed on leaves of wheat genotypes C 306 and Hira at 25 and 40 d after sowing under moderate water stress (-08 MPa) imposed by adding PEG-6000 in nutrient solution ABA and SA increased the activities of superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase in comparison to unsprayed control plants Both ABA and SA treatments decreased the contents of hydrogen peroxide and thiobarbituric acid reactive substances, a measure of lipid peroxidation, compared to unsprayed plants The beneficial effect of increase in antioxidant enzymes activity and decrease in oxidative stress was reflected in increase in chlorophyll and carotenoid contents, relative water content, membrane stability index, leaf area and total biomass over control plants The lower concentrations of ABA (05 mM) and SA (10 mM) were generally more effective than higher concentrations

Changes in phytohormone contents in chickpea seeds germinating under lead or zinc stress

Abstract: The present work describes the changes that take place in phytohormone contents in germinating chickpea (Cicer arietinum cv. Aziziye-94) seeds in response to heavy metal stress. For this aim, endogenous abscisic acid (ABA), gibberellic acid (GA3), zeatin (Z) and zeatin riboside (ZR) contents were followed for 24, 48 and 72 h in chickpea seeds germinating at the concentrations of 0.1, 1.0 and 5.0 mM Pb or 0.1, 1.0 and 10 mM Zn. The results showed that Pb and Zn significantly delayed and impeded the germination of chickpea seeds. The negative effect of Pb on germination was higher than that of Zn. Further, Pb increased ABA and Z contents while decreased GA3 content in the germinating seeds. The high concentrations of Zn (1.0 and 10 mM) decreased contents of Z, ZR and GA3 while 0.1 mM Zn increased the content of the same hormones. The ABA content was enhanced by Zn in all concentrations used.

Plant water status, H2O2 scavenging enzymes, ethylene evolution and membrane integrity of Cicer arietinum roots as affected by salinity

Abstract: The chickpea genotype, CSG-8962 was raised in screenhouse to study salinity induced changes in ethylene evolution, antioxidative defence system and membrane integrity in relation to changes in plant water and mineral content. At vegetative stage (60 d after sowing), the plants were exposed to single saline irrigation (0, 2.5, 5.0 and 10.0 dS m−1). Sampling was done 3 d after saline treatments. The other sets of treated plants were re-irrigated with water and sampled after further 3 d. The Ψw of leaf and Ψs of leaf and roots decreased from −0.47 to −0.61 MPa, −0.67 to −1.23 MPa and from −0.57 to −0.95 MPa, respectively, with increasing salinity. Similarly, RWC of leaf and roots reduced from 87.5 to 72.3 % and 96.7 to 84.35 %, respectively. The decline in Ψs of roots was mainly due to accumulation of proline and total soluble sugar. With salinity, increase in ethylene evolution, 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC oxidase activity was reported. Similarly, marked increase in H2O2 content (20 − 182 %) and lipid peroxidation (43 − 170 %) was observed. The defense mechanism activated in roots was confirmed by the increased activities of superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX), glutathione transferase (GTase), glutathione reductase (GR) and catalase (CAT) but ascorbic acid (AA) content was decreased. About 3-fold increase in Na+/K+ ratio and 2.5 fold increase in Cl− content was observed. Upon desalinization, a partial recovery was observed in most of the parameters studied.

The effects of NaCl on growth, water relations, osmolytes and ion content in Kochia prostrata

Abstract: The effects of NaCl (0, 50, 100, 150 and 200 mM) on growth, water relations, glycinebetaine, free proline, ion contents, stomata number and size of Kochia prostrata (L.) Schard were determined. Shoot and root fresh and dry matter, root and shoot length, relative growth rate, net assimilation rate, relative water content, water use efficiency, soluble sugars and glycinebetaine contents were not changed at low NaCl concentrations, but they were significantly decreased at 200 mM NaCl. The K+, Mg2+ and Ca2+ contents, water potential, chlorophyll a+b and carotenoides contents, and stomata number and size were reduced already at low concentrations of NaCl. In contrast, the Na+, Cl− and proline contents increased several times with increasing NaCl concentration. Kochia prostrata is a salt tolerant species, the optimal growth of this plant occurred up to 150 mM NaCl. The mechanisms of salt tolerance in the plant may be balance among ion accumulation and production of glycinebetaine, proline, soluble sugars for maintenance of pressure potential.

Responses of antioxidative system to chilling stress in two rice cultivars differing in sensitivity

Abstract: The responses of antioxidative system of rice to chilling were investigated in a tolerant cultivar, Xiangnuo-1, and a susceptible cultivar, IR-50. The electrolyte leakage and malondialdehyde content of Xiangnuo-1 were little affected by chilling treatment but those of IR-50 increased. Activities of suoperoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase, and ascorbic acid content of Xiangnuo-1 were remained high, while those of IR-50 decreased under chilling. The results indicated that higher activities of defense enzymes and higher content of antioxidant under stress were associated with tolerance to chilling.

The effect of NaCl on antioxidant enzyme activities in potato seedlings

Abstract: The effect of NaCl on the growth and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated in the seedlings of four potato cultivars (Agria, Kennebec; relatively salt tolerant, Diamant and Ajax; relatively salt sensitive). The shoot fresh mass of Agria and Kennebec did not changed at 50 mM NaCl, whereas in Diamant and Ajax it decreased to 50 % of that in the controls. In Agria and Kennebec, SOD activity increased at 50 mM NaCl, but no significant changes observed in Diamant and Ajax. At higher NaCl concentration, SOD activity reduced in all cultivars. CAT and POD activities increased in all cultivars under salt stress. Unlike the other cultivars, in Ajax seedlings, APX activity increased in response to NaCl stress. We also observed new POD and SOD isoenzyme activities and changes in isoenzyme compositions under salt stress. These results suggest that salt-tolerant potato cultivars may have a better protection against reactive oxygen species (ROS) by increasing the activity of antioxidant enzymes (especially SOD) under salt stress.

Target sites of aluminum phytotoxicity

Abstract: The primary phytotoxic effect of aluminum (Al) is confined to the root apex. It is a matter of debate whether the primary injury of Al toxicity is apoplastic or symplastic. This review paper summarizes our current understanding of the spatial and metabolic sites of Al phytotoxicity. At tissue level, the meristematic, distal transition, and apical elongation zones of the root apex are most sensitive to Al. At cellular and molecular level, many cell components are implicated in Al toxicity including DNA in nucleus, numerous cytoplastic compounds, the plasma membrane, and the cell wall. Although it is difficult to distinguish the primary targets from the secondary effects so far, understanding of the target sites of Al toxicity is helpful for elucidating the mechanisms by which Al exerts its deleterious effects on root growth.

Heat stress effects on ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco binding protein and Rubisco activase in wheat leaves

Abstract: Changes in chlorophyll content, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) binding protein (RBP), Rubisco activase (RA), Rubisco large (LS) and small (SS) subunits, and electrolyte leakage were investigated in wheat leaf segments during heat stress (HS) for 1 h and for 24 h at 40 °C in darkness or in light, as well as after recovery from heat stress (HSR) for 24 h at 25 °C in light. The 24-h HS treatment in darkness decreased irreversibly photosynthetic pigments, soluble proteins, RBP, RA, Rubisco LS and SS. An increase in RA and RBP protein contents was observed under 24-h HS and HSR in light. This increase was in accordance with their role as chaperones and the function of RBP as a heat shock protein.

Interactions between abscisic acid and cytokinins during water stress and subsequent rehydration

Abstract: With the aim to contribute to elucidation of the role of phytohormones in plant responses to stresses the endogenous contents of abscisic acid (ABA) and cytokinins (CK) were followed in French bean, maize, sugar beet, and tobacco during water stress and subsequent rehydration. The effects of pre-treatments with exogenous ABA or benzyladenine (BA) before imposition of water stress were also evaluated. The content of ABA increased by water stress, and with the exception of bean plants increased content of ABA remained also after rehydration. In all plant species the ABA content was further increased by ABA pre-treatment, but in bean and maize it decreased by BA pre-treatment. The highest total content of CK was observed in bean and the lowest in maize during water stress. In their spectrum, the storage CK were dominant in bean, and inactive CK in tobacco while in sugar beet and maize all groups were present in comparable amounts. In all plant species, the contents of CK increased during water stress and with exception of bean they decreased back after rehydration. ABA pre-treatment further increased contents of CK in water-stressed bean and tobacco. BA pre-treatment increased contents of CK in sugar beet and tobacco after rehydration.

Hormone-induced protection of sunflower photosynthetic apparatus against copper toxicity

Abstract: The effects of excess Cu as affected by the application of exogenous hormones (gibberellic acid - GA3 and indole-3-acetic acid - IAA) with respect to sunflower (Helianthus annuus L.) growth, physiology, and metabolism were studied. Application of 100 μM IAA lessened the toxic effects of 80 μM Cu in roots indicating greater root length and root hair formation, while addition of 100 μM GA3 ameliorated the toxic effect mainly to the shoot. The content of photosynthetic pigments significantly declined under Cu stress, whereas application of hormones led to a substantial preservation of chlorophylls and carotenoids. Under Cu stress, the rate constant of energy trapping by photosystem 2 (PS2) reaction centres (RCs) was reduced as a result of physical dissociation of the light-harvesting complex (LHC) from PS2 core, while application of IAA and especially GA3 resulted in stability of the LHC of PS2 RCs. The drop in net photosynthetic (PN) and transpiration (E) rates with preserved or slightly reduced variable to maximum fluorescence ratio (Fv/Fm) in the presence of 80 μM Cu could be explained by a possible inhibition of the enzymatic processes in the Calvin cycle. Application of 100 μM IAA and 100 μM GA3 lessened Cu effects mainly on PN. Water use efficiency was also improved under hormone exposure.

Cannabis sativa L. growing on heavy metal contaminated soil: growth, cadmium uptake and photosynthesis

Abstract: The effects of different cadmium concentrations [17 mg(Cd) kg−1(soil) and 72 mg(Cd) kg− 1(soil)] on Cannabis sativa L. growth and photosynthesis were examined. Hemp roots showed a high tolerance to Cd, i.e. more than 800 mg(Cd) kg−1(d.m.) in roots had no major effect on hemp growth, whereas in leaves and stems concentrations of 50 – 100 mg(Cd) kg−1(d.m.) had a strong effect on plant viability and vitality. For control of heavy metal uptake and xylem loading in hemp roots, the soil pH plays a central role. Photosynthetic performance and regulation of light energy consumption were analysed using chlorophyll fluorescence analysis. Seasonal changes in photosynthetic performance were visible in control plants and plants growing on soil with 17 mg(Cd) kg−1(soil). Energy distribution in photosystem 2 is regulated in low and high energy phases that allow optimal use of light and protect photosystem 2 from overexcitation, respectively. Photosynthesis and energy dissipation were negatively influenced by 72 mg(Cd) kg−1(soil). Cd had detrimental effects on chlorophyll synthesis, water splitting apparatus, reaction centre, antenna and energy distribution of PS 2. Under moderate cadmium concentrations, i.e. 17 mg(Cd) kg−1(soil), hemp could preserve growth as well as the photosynthesis apparatus, and long-term acclimation to chronically Cd stress occurred.

Cadmium uptake, localization and detoxification in Zea mays

Abstract: Cadmium uptake, translocation and localization in maize roots and shoots at the tissue and cellular level were investigated. Metal accumulation in plant organs as well as symptoms of Cd toxicity were closely correlated with an increase in Cd concentration applied (5 - 300 μM). Most of the metal taken up was retained in roots, mainly inside the cells of endodermis, pericycle and central cylinder parenchyma. Accumulation of phytochelatins and related peptides also depended on Cd concentration in the nutrient solution.

UV-B radiation and cadmium induced changes in growth, photosynthesis, and antioxidant enzymes of cyanobacterium Plectonema boryanum

Abstract: UV-B (0.4 W m−2) irradiation and cadmium (2 and 8 μM) treatments separately inhibited the survival, growth, pigment content, and photosynthetic electron transport in Plectonema boryanum. Phycocyanin was the main target to UV-B and Cd and it was followed by chlorophyll a and carotenoids. UV-B and Cd caused strong inhibition on activities of photosystem 2 (PS2) and the whole electron transport chain, whereas photosystem 1 (PS1) was the least affected. UV-B and Cd treatment accelerated respiration, lipid peroxidation, and the activities of superoxide dismutase and catalase. However, enhancement in catalase activity was considerably less (5 − 50 %) as compared to SOD activity. As compared to individual treatment, the effect of their combination (UV-B + Cd) was more detrimental to the above parameters. A synergistic interaction of UV-B and Cd is probably due to increased cadmium uptake as a result of increased membrane permeability caused by lipid peroxidation in P. boryanum after UV-B exposure.

Gas exchange characteristics and water relations in two cultivars of Hibiscus esculentus under waterlogging

Abstract: Thirty-day-old plants of two okra cultivars, Sabzpari and Chinese-red, were subjected for 30 d to normal watering or continuous flooding. Continuous flooding did not cause any adverse effect on shoot fresh and dry biomass. Leaf water potential and pressure potential of both cultivars increased significantly due to waterlogging, but there was a slight increase in leaf osmotic potential. Chlorophyll a and b contents decreased significantly and chlorophyll a/b ratio increased. Waterlogging caused a significant reduction in net photosynthetic rate, water use efficiency and intrinsic water use efficiency, but stomatal conductance and intercellular CO2/ambient CO2 ratio remained unchanged.

Cell death behind invisible symptoms: early diagnosis of ozone injury

Abstract: A simple histo-cytochemical method, combining Evans blue staining to assess cell death and in vivo 3,3′-diaminobenzidine uptake for H2O2 localisation, has been used to evaluate O3 damages in leaf tissues of three Phaseolus vulgaris L. cultivars (Cannellino, BLF, Saxa) with different sensitivity to the pollutant. Bean plants were exposed to a single pulse of O3 (150 ± 10 mm3 m−3 × 3 h) and leaves were examined at different time-span after fumigation. Cannellino proved to be the most sensitive, showing chlorotic spots 2 h after fumigation and chlorotic lesions 24 h later. In BLF, necrotic spots appeared 4 h after fumigation and reddish necrotic lesions (bronzing) developed in further 24 h. Saxa remained symptomless up to 10 d of observation, thus appearing tolerant. The early appearance of symptoms in Cannellino correlated with H2O2 accumulation in leaf tissues and consequent extensive cell death, involving both palisade and spongy mesophyll. H2O2 accumulation was observed also in BLF, though to a lesser extent and dead cells were rare at 2 h after fumigation. However, they increased in number 24 h later, forming small groups in the palisade mesophyll. These groups further enlarged in the next 24 h, again involving only palisade mesophyll. In Saxa leaves, H2O2 accumulation was found only in the epidermal cells, though the number of dead cells was very similar to BLF, at least up to 24 h after fumigation. However, in Saxa, dead cells have been always found singly scattered through the palisade mesophyll, or forming very small groups around substomatal cavity, thus remaining invisible at a macroscopic level.

Effects of short-term soil flooding on stomata behaviour and leaf gas exchange in barley plants

Abstract: Exposure of barley plants (Hordeum vulgare L.) to soil flooding for 2 to 24 h reduced the net photosynthetic rate and transpiration rate. Stomatal conductance also decreased in flooded plants. Stomatal closure started within 2 - 6 h and stomata remained closed up to 24 h of treatment.

Water stress-induced oxidative damage and antioxidant responses in micropropagated banana plantlets

Abstract: Oxidative injury and antioxidant responses were investigated in two banana genotypes (Musa AAA 'Berangan' and Musa AA 'Mas') subjected to 40 % PEG-induced water stress. PEG treatment resulted in oxidative injury, as expressed in increased lipid peroxidation and reduced membrane stability index, in both cultivars; however, greater oxidative injury was detected in 'Mas'. Under PEG treatment, catalase activity and glutathione reductase activity were enhanced in both cultivars, but were higher in 'Mas'. Ascorbate peroxidase activity was enhanced in 'Berangan' under water stress, but was unaffected in 'Mas'. Meanwhile, superoxide dismutase activity was inhibited in both cultivars under water stress, but higher activity was detected in 'Berangan'. Higher ascorbate peroxidase and superoxide dismutase activities were associated with greater protection against water stress-induced oxidative injury.

Salt tolerance of two aquatic macrophytes, Pistia stratiotes and Salvinia molesta

Abstract: The physiological responses to NaCl salinity were investigated in two floating aquatic macrophytes, Pistia stratiotes L and Salvinia molesta L With the increasing NaCl concentration a decrease in chlorophyll and carotenoid contents was recorded in Salvinia as compared to Pistia Also a greater increase in H2O2 accumulation and lipid peroxidation was observed in the shoot and root tissues of Salvinia as compared to Pistia The superoxide dismutase, glutathione reductase, catalase and guaiacol peroxidase activities, and ascorbate and glutathione contents increased in Salvinia and Pistia shoot and root tissues in response to NaCl

Acibenzolar-S-methyl induced resistance to Phytophthora capsici in pepper leaves

Abstract: The leaves of pepper (Capsicum anuum L.) were inoculated with Phytophthora capsici Leonian 3 d after treatment with acibenzolar-S-methylbenzo [1,2,3]thiadiazole-7-carbothioic acid-S-methyl ester (ASM) and resistance to Phytophthora blight disease was investigated. Results showed that P. capsici was significantly inhibited by ASM treatment by up to 45 % in planta. The pepper plants responded to ASM treatments by rapid and transient induction of L-phenylalanine ammonia-lyase (PAL), increase in total phenol content and activities of chitinase and β-1,3-glucanase. No significant increases in enzyme activities were observed in water-treated control plants compared with the ASM-treated plants. Therefore it may be suggested that ASM induces defense-related enzymes, PAL activity, PR proteins and phenol accumulation in ASM-treated plants and contribute to enhance resistance against P. capsici.

Micropropagation of Lavandula dentata from axillary buds of field-grown adult plants

Abstract: Axillary buds from adult field-grown plants of Lavandula dentata L. were used to evaluate the effect of growth regulators and culture media on the in vitro shoot proliferation and growth. The highest multiplication rate was obtained using Murashige and Skoog (MS) medium supplemented with a combination of 2.2 μM of benzyladenine and 2.5 μM indole-3-butyric acid. The best condition for rooting was MS medium plus 2.5 μM naphthaleneacetic acid. Rooted plantlets were successfully transferred to soil. Short-term culture derived plants (6 month) exhibited a normal development, but a low frequency of not heritable morphological changes were detected in long term culture derived plants (more than 1 year).

In vitro regeneration and bulblet growth from lily bulbscale explants as affected by retardants, sucrose and irradiance

Abstract: Bulbscales of oriental lily hybrid Star Gazer were used as the explants. Bulblets were formed on the basal portion of the excised bulbscales on MS medium supplemented with growth retardants, different sucrose concentrations and exposed to continuous light or dark. Alar, Cycocel and Paclobutrazol in concentration 1 mg dm−3 produced higher number of bulblets as compared to the control. The number of bulblets, however, decreased with the increase in concentration of the growth retardants. The number of bulblets was higher at 90 than at 60 g dm−3 sucrose and when the bulbscales were exposed to continuous light than to darkness. The growth retardants, higher sucrose concentration and continuous dark stimulated fresh mass of bulblets. The number of bulblets having roots and leaves decreased in medium with Alar, Cycocel and Paclobutrazol as compared to the control. A few bulblets produced roots and leaves in medium with 90 g dm−3 sucrose and none of the regenerated bulblets produced leaves under continuous dark.

Efficient regeneration of Brassica napus L. hypocotyls and genetic transformation by Agrobacterium tumefaciens

Abstract: An efficient system for shoot regeneration and Agrobacterium-mediated gene transfer into Brassica napus was developed through the modification of the culture conditions. Different concentrations of benzyladenine (1.5, 3.0 and 4.5 mg dm−3) and thidiazuron (0.0, 0.15 and 0.30 mg dm−3) were evaluated for shoot regeneration of 7, 14 and 21-d-old hypocotyl explants. Maximum shoot regeneration frequency was obtained in 21-d-old explants using 4.5 mg dm−3 benzyladenine and 0.3 mg dm−3 thidiazuron. Under above culture condition, the highest percentage of shoot regeneration frequency was 200 %. Agrobacterium-infected explants grown on the selection medium gave rise to transgenic shoots at a frequency of 11.8 %. Transformed shoots rooted when cultured on a medium supplemented with 2 mg dm−3 of indolebutyric acid and 10 mg dm−3 kanamycin. The rooted plantlets were successfully established in the soil and developed fertile flowers and viable seeds. Evidences for transformation were confirmed by GUS assay and PCR analysis.

Establishment of callus and cell suspension cultures of Centella asiatica

Abstract: Methods for induction of callus and cell suspension cultures have been developed for the medicinally important herb Centella asiatica (L.) Urban. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) analysis showed the presence of asiaticoside in the in vitro grown leaves, callus and cell suspension cultured cells.

Somatic embryogenesis in Pinus nigra: embryogenic tissue initiation, maturation and regeneration ability of established cell lines

Abstract: The effect of plant growth regulators (PGR), 6-benzyladenine (BA), 2,4-dichlorophenoxyacetic acid (2,4-D), α-naphthaleneacetic acid (NAA) and sugars (sucrose, maltose, glucose, fructose) on the initiation of somatic embryogenesis of Pinus nigra Arn. was investigated. Megagametophytes containing immature zygotic embryos have been used as explants. The experiments were done in the years 2000 and 2001. Higher initiation frequencies were obtained in 2001 when the zygotic embryos showed uniformity, being in the precotyledonary stage of development. Embryogenic tissue initiation occurred on all the media tested, including PGR-free medium. Relatively high initiation frequencies were obtained on media containing either NAA (9.09 %) or 2,4-D (7.14 %) alone. Somatic embryos were present as bipolar structures and showed differences in morphological features among cell lines. Plantlet regeneration occurred in cell lines containing bipolar somatic embryos composed of compact meristematic embryo “head” and suspensor organized into bundles.

Alleviation of salt stress by low dose γ-irradiation in rice

Abstract: The effects of salt stress on the growth, photosynthesis, and antioxidative ability of the rice (Oryza sativa L.) plants raising from γ-irradiated seeds were investigated using two cultivars, Ilpumbyeo and Sanghaehyanghyella. The 50 and 100 mM NaCl solutions caused a remarkable decrease of the early germination rate and seedling growth. However, the salt stress-induced inhibition of the growth was significantly alleviated in the γ -irradiated plants. The chlorophyll contents and the effective quantum yield of photosystem 2 (Φ PS 2) were lower in the NaCl-treated plants than in the control ones, while the non-photochemical quenching was higher in the former ones. Activities of the antioxidant enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased with increasing NaCl concentrations, and the irradiated groups had even higher SOD and APX activities than the non-irradiated ones. These alleviation effects were observed similarly in both the cultivars tested.

Seed protein electrophoresis of some cultivated and wild species of Chenopodium

Abstract: Seed protein profiles of 40 cultivated and wild taxa of Chenopodium have been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The relative similarity between various taxa, estimated by Jaccard’s similarity index and clustered in UPGMA dendrogram, is generally in accordance with taxonomic position, crossability relationships and other biochemical characters. Eight accessions of C. quinoa studied are clustered together and show genetic similarity with closely related C. bushianum and C. berlandieri subsp. nuttalliae. The taxa included under C. album complex are clustered in two groups which show that these taxa are a heterogenous assemblage and their taxonomic affinities need a reassessment. Other wild species studied are placed in the dendrogram more or less according to their taxonomic position.

Agrobacterium -mediated transformation of Pisum sativum in vitro and in vivo

Abstract: Six pea (Pisum sativum L.) cultivars (Adept, Komet, Lantra, Olivin, Oskar, Tyrkys) were transformed via Agrobacterium tumefaciens strain EHA105 with pBIN19 plasmid carrying reporter uidA (β-glucuronidase, GUS, containing potato ST-LS1 intron) gene under the CaMV 35S promoter, and selectable marker gene nptII (neomycin phosphotransferase II) under the nos promoter. Two regeneration systems were used: continual shoot proliferation from axillary buds of cotyledonary node in vitro, and in vivo plant regeneration from imbibed germinating seed with removed testa and one cotyledon. The penetration of Agrobacterium into explants during co-cultivation was supported by sonication or vacuum infiltration treatment. The selection of putative transformants in both regeneration systems carried out on media with 100 mg dm−3 kanamycin. The presence of introduced genes was verified histochemically (GUS assay) and by means of PCR and Southern blot analysis in T0 putative transformants and their seed progenies (T1 to T3 generations). Both methods, but largely in vivo approach showed to be genotype independent, resulting in efficient and reliable transformation system for pea. The in vivo approach has in addition also benefit of time and money saving, since transgenic plants are obtained in much shorter time. All tested T0 – T3 plants were morphologically normal and fertile.

Effect of γ-radiation on development, yield and quality of microtubers in vitro in Solanum tuberosum L.

Abstract: Explants obtained from in vitro-propagated plantlets of two potato cultivars, Shepody and Atlantic, were treated with five doses of γ-radiation (0, 2, 4, 6 and 8 Gy) to investigate the stimulating effects of low irradiation on the production and quality of microtubers in vitro. Microtubers of both cultivars treated with γ-radiation initiated 5 d earlier than in the non-irradiated control. The whole period of microtuberization was prolonged by 10 - 15 d with 4, 6 and 8 Gy irradiation treatment for cv. Atlantic. Irradiation of the plantlets (4 Gy) led to a significant increase not only in the microtuber number (116.7 and 34.5 % over the control) but also in the fresh mass (77.6 and 23.2 % in Shepody and Atlantic, respectively). Low dose irradiation (2 - 4 Gy) increased the starch content of microtubers. High doses (6 - 8 Gy) enhanced ascorbic acid and reducing sugar contents. 4 - 6 Gy doses also effectively increased the protein contents of microtubers.