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Genetic stability of plants during in vitro propagation and conservation is one of the important aspects of plant biotechnology. In the present study, micropropagated P. lentiscus L. shoot cultures, which are cultivated for the mastic resin, have been cold stored up to 12 months at 4°C in the dark for different durations (2, 4, 6, 8, 10 and 12 months) and genetic alterations in cold storage conditions were evaluated. Growth parameters such as proliferation rate, shoot numbers per explant, shoot lengths and shoot forming capacity were also calculated. Since the highest proliferation rate (100 %) was obtained in 6 month-stored shoot cultures without any severe influence of cold stress on proliferation ability, amplified fragment length polymorphism (AFLP) and inter-retrotransposon amplified polymorphism (IRAP) marker systems were used to determine genetic stability in the plantlets after this storage period. Totally, 702 scorable bands were produced by 10 AFLP primer pairs. Genetic similarity value of the non-stored (control) plant and coldstored clones ranged from 0.66 to 0.84 with a mean of 0.74. In the case of IRAP, 159 bands were produced by 8 IRAP primers. Genetic similarity value of the non-stored plant and cold-stored clones varied from 0.65 to 0.83 and the average genetic similarity value was determined as 0.72. The genetic similarity indices revealed that genetic variability was similar in both techniques. Our results showed that tissue culture and especially cold storage of P. lentiscus L. may result transposons activation, thus could cause genetic instability.
This study was aimed at developing an efficient protocol for regeneration of Pseudostellaria heterophylla plantlets and induction of polyploidy. Calli of P. heterophylla (Miq) from stems, leaves and buds as explants could not differentiate into plantlets. However, young embryo segments used as primary explants produced embryonic calli on MS medium containing 5.0 mg/L 2,4-D and 0.5 mg/L KT. After the embryonic calli with granular protuberances were transferred to MS medium containing 0.5 mg/L BA, they developed shoots and then rooted to form plantlets. Polyploidy was induced when embryonic calli were placed in liquid MS medium containing 0.5% colchicine for 4 days, followed by culturing in solid medium to induce differentiation. Polyploidy was identified by the number of chromosomes and the size of plantlet stomata. The tetraploid plantlets produced larger root tubers than the diploid plantlets.
 The essential oils (EOs) and static headspaces (HSs) of in vitro plantlets and callus of Mentha x piperita were characterized by GC-MS analysis. Leaves were used as explants to induce in vitro plant material. The EO yields of the in vitro biomass were much lower (0.1% v/w) than those of the parent plants (2% v/w). Many typical mint volatiles were emitted by the in vitro production, but the callus and in vitro plantelet EOs were characterized by the lack of both pulegone and menthofuran. This was an important difference between in vitro and in vivo plant material as huge amounts of pulegone and menthofuran may jeopardise the safety of mint essential oil. Regarding the other characteristic volatiles, menthone was present in reduced amounts (2%) in the in vitro plantlets and was not detected in the callus, even if it represented the main constituent of the stem and leaf EOs obtained from the cultivated mint (26% leaves; 33% stems). The M. piperita callus was characterized by menthol (9%) and menthone (2%), while the in vitro plantlet EO showed lower amounts of both these compounds in favour of piperitenone oxide (45%). Therefore, the established callus and in vitro plantlets showed peculiar aromatic profiles characterized by the lack of pulegone and menthofuran which have to be monitored in the mint oil for their toxicity.
In vitro plantlets and callus of M. longifolia were established and their volatile constituents characterized by GC-MS analysis of their headspaces (HSs) and essential oils (EOs). Significant quali-quantitative differences were found in the aromatic fingerprints in comparison with the M. longifolia parent plants. In fact, limonene and carvone were the main constituents in the EOs of the mother plants, while the aroma of the in vitro plant material were especially enriched in oxygenated terpenes. In particular, huge amounts of piperitenone and piperitenone oxide (75 %) were found for in vitro plantlets, while trans-carvone oxide (19 %) and trans-piperitone epoxide (9 %) were found in callus EO. However, the established in vitro plant material showed lack of pulegone and menthofurane, thus preserving an important feature observed in the volatile fingerprint of the parent plants. In fact, because of their well-known toxicity significant amounts of pulegone and menthofurane may compromise the safety using of mint essential oil. Therefore the in vitro M. longifolia plantlets and callus may be regarded as a potential source of a safe flavouring agent.
Strawberry is propagated vegetatively. Nowadays, traditional bare-root transplants are often replaced with plantlets (plug plants) produced from runner tips. The nutrient level and type of growing medium may influence the quality of planting material. Phosphorus and potassium are important elements for plant metabolism. Insufficient supply of plants with these elements negatively influences the rooting and plant vegetative growth. The objective of the study was to evaluate the influence of substrate and monopotassium phosphate (MKP) on rooting and quality of strawberry plantlets grown in the greenhouse soilless system. ‘Elsanta’ mother plants were planted in containers and set on a special rack in the greenhouse. Emerging plantlets were set (clipped with metal clips) in micro-pots filled with peat or coconut substrate. Four concentrations of MKP in the growing medium were applied: 0, 0.22, 0.44, 0.66 g dm-3. Rooting of plantlets was carried out before cutting them off from the mother plants for a period 7, 10 or 14 days. The investigations have showed a very similar dynamics of root formation both in coconut substrate and in peat. A significant effect of the application of monopotassium phosphate on rooting of strawberry plantlets was observed. The optimal dose of MKP depended on the length of rooting period of plantlets. After 7 days of rooting the highest root weight was recorded in case of plantlets rooted in the growing media supplemented with 0.44 or 0.66 g dm-3 MKP. After 10 and 14 days of rooting even the lowest dose of MKP (0.22 g dm-3) resulted in significantly stronger root growth in comparison with not fertilized control plantlets. MKP also significantly influenced the growth of plantlets after transplanting them into bigger containers. The highest quality plantlets were obtained at the dose 0.44 or 0.66 g MKP dm-3 of substrate.
The aim of the work was to find how the abiotic stress factors, such as Zn and Ti ions, influenced on growth factor and accumulation of some elements in plantlets of C. asiatica (L.) Urban Apiaceae). Plantlets were cultured on Nitsch and Nitsch (NN) or Schenk and Hildebrandt (SH) modified media with various growth regulators. Zn ions as ZnSO₄ were additionaly put into medium in 4 concentrations for 3 to 7 weeks. Ti ions as 0.04% solution of Tytanit - foliar fertilizer were added into medium or stems of plantlets were soaking in solution only or with subsequent rinsing in sterile water. The concentrations of selected bioelements: Cu, Mn, Zn, Fe, Ca and Mg (determined by ASA using Spectrophotometer SP 1900 Pye Unicam in “free” (soluble in water) and “bound” (in cell structure) forms were evaluated The observations have shown that Zn and Ti application influenced on the weight and development of Centella asiatica cultured in vitro and caused changes in their mineral composition. Important differences in concentration of evaluated elements were found in studied samples. The content of analysed bioelements was dependent not only on Zn concentration in the medium but also of the form of Ti application or of the duration of the experiment.
Micropropagation of a mature female Taxus cuspidata tree with paclitaxel and cephalomannine content in the needles of 457.6 μg g-1 DW and 340.9 μg g-1 DW, respectively, was elaborated using shoot tips as explants. A new yew clone derived from a seed of the mother plant was also obtained. Single shoots developed from shoot tips on WP mineral basal medium with B5 vitamins (WP-B5) supplemented with 20 mg l-1 BAP and 5 mg l-1 activated charcoal were propagated by 1 cm long segments cultured on hormone-free medium. When WP-B5 medium with 0.3 mg/l 2-iP and 0,1 mg/l IAA was used 92% of shoots rooted within three months. Paclitaxel content in shoots growing on solid medium and in a mist trickling bioreactor was 45.6–86.5 μg g-1 DW. Plantlets from in vitro culture, grown in pots contained 99.0–213.1 μg g-1 paclitaxel and 558.0 μg g-1 DW cephalomannine.
The aim of the present work was to determine the carbohydrate content in plantlets of Clematis pitcheri cultured in vitro depending on the temperature (15°C, 20°C and 25°C) and sucrose (10 and 30 g·dm⁻³) and nitrogen (100% and 50% of normal MS strength) level in the medium. 100% N meant 1.90 g KNO₃ and 1.65 g NH₄NO₃, and 50% N meant 0.950 g KNO₃ and 0.825 g NH₄NO₃ in 1 dm⁻³ of MS medium. The highest accumulation of starch in shoots took place at 30 g·dm⁻³ of sucrose and lower level of nitrogen compounds in the medium. Also, at 30 g·dm⁻³ of sucrose in the medium the content of fructose in shoots was higher and independent from the level of nitrogen. The temperature of 25°C stimulated glucose accumulation in shoots at the highest degree at 30 g·dm⁻³ of sucrose and lower level of nitrogen. Regardless of the treatment, no sucrose was found in plantlets. Generally, the higher concentration of sucrose in the medium the higher content of sum of carbohydrates in plantlets. A lower nitrogen compound level (50% N) led to increase of glucose and starch content in shoots, and had a smaller effect on the level of fructose. Shoots cultured at the temperature of 20°C and 25°C accumulated more carbohydrates than at 15°C.
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