Matilda Djukic

Lead uptake increases drought tolerance of wild type and transgenic poplar (Populus tremula x P. alba) overexpressing gsh 1

Growth and development of plants largely depends on their adaptation ability in a changing climate. This is particularly true on heavy metal contaminated soils, but the interaction of heavy metal stress and climate on plant performance has not been intensively investigated. The aim of the present study was to elucidate if transgenic poplars (Populus tremula x P. alba) with enhanced glutathione content possess an enhanced tolerance to drought and lead (Pb) exposure (single and in combination) and if they are good candidates for phytoremediation of Pb contaminated soil. Lead exposure reduced growth and biomass accumulation only in above-ground tissue of wild type poplar, although most of lead accumulated in the roots. Drought caused a decline of the water content rather than reduced biomass production, while Pb counteracted this decline in the combined exposure. Apparently, metals such as Pb possess a protective function against drought, because they interact with abscisic acid dependent stomatal closure. Lead exposure decreased while drought increased glutathione content in leaves of both plant types. Lead accumulation was higher in the roots of transgenic plants, presumably as a result of chelation by glutathione. Water deprivation enhanced Pb accumulation in the roots, but Pb was subject to leakage out of the roots after re-watering. Transgenic plants showed better adaptation under mild drought plus Pb exposure partially due to improved glutathione synthesis. However, the transgenic plants cannot be considered as a good candidate for phytoremediation of Pb, due to its small translocation to the shoots and its leakage out of the roots upon re-watering.

Micropropagation of Endangered and Decorative Species Dianthus pinifolius Sibth. et Sm.

The aim of this study was to establish an efficient protocol for the in vitro propagation of the endangered, endemic and decorative species Dianthus pinifolius Sibth. et Sm. The effects of different concentrations of 6-benzylaminopurine (BAP) and naphtalenacetic acid (NAA), and different explant types (single-node cuttings, terminal buds and shoot cuttings) on shoot multiplication were examined on Murashige and Skoog (MS) and half-strength MS media. The best results were obtained for shoot cuttings on the MS medium supplemented with 0.5 mg/L BAP and 0.1 mg/L NAA, achieving a maximum rate of regeneration (100%) and a total of 15.4 newly-developed shoots per explant. The highest rooting rate (96.7%) was obtained on MS medium containing 1 mg/L NAA, while the acclimatization of the microplants obtained to ex vitro conditions was successful (88.9%).

Micropropagation of Achillea millefolium L. on half-strength MS medium and direct rooting and acclimatization of microshoots in hydroponic culture.

The aim of this study was to determine the possibility of micropropagation of the medicinal plant A. millefolium on half-strength MS medium and ex vitro rooting and acclimatization of the obtained microshoots in hydroculture in order to establish an efficient production method. Two explant types were used: basal and terminal cuttings, and better results were achieved when terminal cuttings were used. The development of shoots in the multiplication phase was successful with a regeneration percentage of 100%. Ex vitro rooting in a modified Hoagland nutrient solution was successful (83%), but the percentage of in vitro rooting on half-strength MS medium without hormones was higher (95%). However, bearing in mind that mass production of A. millefolium is more efficient when the phase of in vitro rooting is excluded, this method could be recommended for commercial propagation of this medicinal plant. It is necessary to conduct additional research in order to optimize the composition, EC and pH value of the hydroponic nutrient solution. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

Effect of explant type on the rooting and acclimatization of Dianthus serotinus Waldst. & Kit.

The effect of the concentration of MS salts and explant type on D. serotinus rooting and acclimatization was investigated in order to optimize a protocol for the micropropagation of this species. The obtained results showed that explant type as well as the concentration of MS salts had a significant effect on rooting, and the highest rooting rate (85-86,7%) was achieved when culturing single-node cuttings and terminal buds on a half-strength MS medium supplemented with 0,5 mgL-1 NAA. Nevertheless, mean number of roots per explant was higher on the MS media (15,3-18,6) than on the half-strength MS media (11,8-13,4). The best acclimatization rate was obtained in a 4:1 mixture of peat and sand (83,3-86,7%). The explant type from which in vitro plantlets developed had no effect on the acclimatization rate. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

Effects of the time of cuttings collection and IBA concentration on the rooting of softwood cuttings from elite trees of Cornelian cherry (Cornus mas L.) in Belgrade area.

In this study, the effect of concentration of indole-3-butyric acid (IBA) (powder dip), cutting type as well as the time of taking cuttings on the rooting of softwood cuttings of cornelian cherry was examined. Four types of cuttings were used: basal cuttings, terminal cuttings, basal cuttings with 2-year-old wood and terminal cuttings with 2-year-old wood. The obtained results showed that IBA concentration, cutting type and time of collecting have significant effect on rooting. The best results were obtained using 1% IBA and cuttings collected in the second term (in mid-July) had a higher rooting percentage. Terminal cuttings treated with 1% IBA (powder dip) should be used for optimum results. In that case the rooting percentage was very high (over 90%) in both terms of cuttings collection. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Istraživanje klimatskih promena na životnu sredinu: pracenje uticaja, adaptacija i ublažavanje]

Quick-dip and contact method of cutting rooting of Zelkova carpinifolia (Pall.) K. Koch as an alternative non-invasive species

Two methods of rooting of Zelkova softwood cuttings were analyzed: (1) quick-dip method and (2) contact method - the thin polyethylene film (20 mm) laid directly over the cuttings during the rooting process. The control for contact method was a low tunnel with a thick polyethylene film. One group of cuttings in the contact method was treated with quick-dip (IBA 2,500 μg•mL-1, carrier-ethyl alcohol) during 5 sec, and the other group was treated with water solution of IBA (50 μg•mL-1) in 24-hour treatment. The third group was control - untreated cuttings. The same groups of cuttings were also used in low tunnels. The number and length of primary and secondary roots were measured on rooted cuttings. The results of all treatments show that contact method in combination with water solution of IBA was the best with 92% of rooted cuttings. No significant differences were obtained between this treatment and quick-dip + contact method (85.3%). Rooting of cuttings under low tunnel was significantly lower. In general, contact method was better than low tunnel, disregarding the carrier used. These results recommend the almost unknown contact method in nursery propagation of Zelkova, as an alternative, non-invasive species for the conditions in Serbia.

Influence of partial serotiny of Aleppo pine, Italian, and Arizona cypress on seed germination

The usability of seeds for the production of seedlings, as well as the utilisation potential of seeds for natural regeneration was assessed by the comparative analysis of seed germination from the cones of different ages of three species with partial serotiny (P. halepensis Mill., Cupressus sempervirens L., Cupressus arizonica Greene). In cypress, serotiny is not so expressed as to be a reserve for extraordinary situations (fire). Fouryearold Aleppo pine cones should be collected for production purposes. Serotinous cones up to ten years old are efficient for natural regeneration of Aleppo pine forest after fire.

Spontaneous changes a basis for new ornamental woody plant cultivars

In nursery stock production of some ornamental woody plants the appearance of spontaneous variability was identified in the form of atypical pigmentation of leaves (albinism, variegated, red colored), leaves shape (jaggy) and dwarfs. Mutated plants with variegated leaves were observed among hybrid plane (Platanus x acerifolia (Ait.) Willd.), Siberian elm (Ulmus pumila L.), laurel cherry (Prunus laurocerasus L.) and Lawson false-cypress (Chamaecyparis lawsoniana (Murr.) Parl.) Seedlings. The type of variegation and frequency were analyzed. Among plane tree and Siberian elm seedlings there were observed red colored leaves. Atypical, jaggy shaped leaves were found among laurel cherry seedlings. Dwarf growth was identified at Siberian elm and birch (Betula pendula Roth.) where also found fruits at one year seedling. There were not significant differences in some morphological and physiological properties in plane tree seedlings with various pigmented leaves. .