Search

Plasma technology, relatively new in the fields of biomedicine, agriculture, and ecology, is the subject of intensive research as a prospective means of decontamination of various microorganisms (bacteria, viruses, and fungi). The objectives of the present study were to follow the effect of cold atmospheric plasma (CAP) treatment on in vitro grown plum plants (Prunus domestica L. 'Kyustendilska sinya' cv.) and the possibility of eradicating or inactivating plum pox virus (PPV) causing Sharka disease by CAP. The source tree is naturally co-infected by PPV (both M and D strains). In the experiments, two different plasma sources were used. First, a surface-wave-sustained Argon plasma torch and second, an underwater diaphragm discharge. For the treatments, nodal segments (10 mm in length) from in vitro cultured plum plants with or without one leaf were prepared. Apical shoots from treated plants (PPV-positive and negative clones as well non-treated controls) were cultivated in vitro for four passages. Then they were rooted and acclimatized to ex vitro conditions, and their virus status was observed periodically for more than 3 years after treatment for the appearance of Sharka symptoms. All plants, acclimatized to ex vitro conditions, were tested for PPV by immune capture–reverse transcription–polymerase chain reaction (IC-RT-PCR). As a first step in understanding the plasma treatment of living plants, a plasma treatment variant causing no damage must be established; this has been done in our previous works. Treatment of plants by plasma with parameters that have been carefully selected leads to better development than the non-treated plants. In the treated in vitro plants, no significant differences were found in the number and length of shoots compared to the control plantlets. In ex vitro acclimated plants, greater stem length was reported, but no differences in leaf number were observed. No significant differences in growth were recorded between the control and plants that were treated twice or three times. At this stage, 3 years after ex vitro cultivation in a greenhouse, Sharka symptoms were not registered on treated in vitro negative PPV plants, and the virus was not detected by IC-RT-PCR. Very mild symptoms were showing in CAP-treated PPV-positive plants. Development of typical Sharka symptoms on non-treated controls were observed. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) have become an alternative light source to the fluorescent lamp (FL) for the maintenance of plant tissue cultures due to their low heat emission, low power consumption and the ability to fine-tune the light spectrum. In this study, the effect of LEDs on the growth and leaf stomata features of in vitro cultivated raspberries (Rubus idaeus L. 'Lloyd George') was examined. The plantlets were grown in vitro under a lighting system based on the Philips GreenPower LED research module. Four groups of LEDs emitting white (W), red (R), blue (B), and mixed (W:R:B: far red = 1:1:1:1) lights and FL (control) were used. As a second control (marked as EV), plants grown in the multiplication and rooting stage under fluorescent lamps and then acclimatized ex vitro in a greenhouse for 90 days in natural light were included. Relative growth rate (RGR), protein content as well as stomata morphology and density of the plantlets were analysed after three passages under corresponding light treatment. The results show that different LEDs specifically affect the growth and size of leaf stomata and density of in vitro cultured raspberry plants and can be applied as an effective modulator of morphogenesis during micropropagation. The combination of white, blue, red and far red LED stimulated the accumulation of biomass and proteins, as well as the formation of a higher number of stomata on the lower surface of the leaves, which would be a prerequisite for more effective control of water loss from plantlets during the ex vitro acclimatization. [ABSTRACT FROM AUTHOR]

In recent years, light emitting diodes (LEDs), due to their low energy consumption, low heat emission and specific wavelength irradiation, have become an alternative to fluorescent lamps (FLs) in plant tissue culture. The aim of this study was to investigate the effects of various LED light sources on the in vitro growth and rooting of plum rootstock Saint Julien (Prunus domestica subsp. insititia). The test plantlets were cultivated under a Philips GreenPower LEDs research module illumination system with four spectral regions: white (W), red (R), blue (B) and mixed (W:R:B:far-red = 1:1:1:1). The control plantlets were cultivated under fluorescent lamps (FL) and the photosynthetic photon flux density (PPFD) of all treatments was set at 87 ± 7.5 μmol m−2 s−1. The effect of light source on the selected physiological, biochemical and growth parameters of plantlets was monitored. Additionally, microscopic observations of leaf anatomy, leaf morphometric parameters and stomata characteristics were carried out. The results showed that the multiplication index (MI) varied from 8.3 (B) to 16.3 (R). The MI of plantlets grown under mixed light (WBR) was 9, lower compared to the control (FL) and white light (W), being 12.7 and 10.7, respectively. In addition, a mixed light (WBR) favored plantlets' stem growth and biomass accumulation at the multiplication stage. Considering these three indicators, we could conclude that under the mixed light, the microplants were of better quality and therefore mixed light (WBR) was more suitable during the multiplication phase. A reduction in both net photosynthesis rate and stomatal conductance in the leaves of plants grown under B were observed. The quantum yield (Yield = FV/FM), which represents the potential photochemical activity of PS II, ranged from 0.805 to 0.831 and corresponded to the typical photochemical activity (0.750–0.830) in the leaves of unstressed healthy plants. The red light had a beneficial effect on the rooting of plum plants; the rooting was over 98%, significantly higher than for the control (FL, 68%) and the mixed light (WBR, 19%). In conclusion, the mixed light (WBR) turned out to be the best choice during the multiplication phase and the red LED light was more suitable during the rooting stage. [ABSTRACT FROM AUTHOR]

In recent years, the light emitting diodes (LED) have become an alternative to the fluorescence lamp source of light for plant tissue culture, due to their low energy consumption, low heat emission, specific wavelength irradiation etc. The aim of this study was to investigate the effect of LEDs on the growth of in vitro cultivated raspberry (Rubus idaeus L. 'Lloyd George'). The plantlets were cultivated in vitro under an illumination system based on Philips GreenPower LED research module. Four groups of LEDs emitting in white (W), red (R), blue (B), mixed (W:R:B:far-red=1:1:1:1) lights and fluorescent lamps (control) were used in our studies. Growth parameters, some physiological and biochemical characteristics of the plantlets were measured after three four weeks passages under corresponding light treatment. Our results indicated that different LEDs specifically influence the growth and development of in vitro cultivated raspberry plantlets and could be applied as an efficient lighting system for rapid in vitro micropropagation of Rubus idaeus L. The combination of blue, red, far red and white LEDs (1:1:1:1) stimulated the growth and biomass accumulation, as well as the intensity of net photosynthesis. For optimal results, it would be advisable to shorten the culture period to 3 weeks. This effective and affordable protocol would support the commercial micropropagation of raspberries and other soft fruits. [ABSTRACT FROM AUTHOR]

Rooting in vitro is considered one of the main problems in the micropropagation of woody species. The aim of the present study was to optimise the rooting and acclimatization of micropropagated pear plants through applying a new plant-growth biostimulator of natural origin, Charkor (Agrobiotech, Ukraine). Charkor contains metabolism products of symbiotic fungus-endophyte of ginseng roots, cultivated in vitro. Microshoots of pear rootstock OHF 333 (Pyrus communis L. 'Old Home' x 'Farmingdale') were rooted on DKW (Driver and Kuniyuki, 1984) media supplemented with Charkor (0.1 ml l-1, 0.3 ml l-1 or 0.5 ml l-1) and 10 µM indolyl-acetic acid (IAA; alone or in combinations). Plantlets cultivated on a medium free of growth regulators served as a control. After three weeks on rooting media, plants were transferred for acclimatization in pots (peat: perlite 2:1). Data on fresh weight of leaves, roots, stems and dry matter, leaf area, mean number of leaves per plant, stem and root length, chlorophyll fluorescence and net photosynthetic rate were recorded 20 days after acclimatization. The best result was obtained with plants treated with10 µM IAA (alone) and in combination with 0.5 ml l-1 Charkor. [ABSTRACT FROM AUTHOR]