Engineered nanomaterials are increasingly used in everyday life applications and, in consequence, significant amounts are being released into the environment. From soil, water, and air they can reach the organelles of edible plants, potentially impacting the food chain and human health. The potential environmental and health impact of these nanoscale materials is of public concern. TiO₂ and ZnO are among the most significant nanomaterials in terms of production amounts. Our study aimed at evaluating the effects of large-scale TiO₂ (~100 nm) and ZnO (~200 nm) nanoparticles on soybean plants grown in vitro. The effect of different concentrations of nanoparticles (10, 100, 1000 mg/L) was evaluated regarding plant morphology and metabolic changes. ZnO nanoparticles showed higher toxicity compared to TiO₂ in the experimental set-up. Overall, elevated levels of chlorophylls and proteins were observed, as well as increased concentrations of ascorbic and dehydroascorbic acids. Also, the decreasing stomatal conductance to water vapor and net CO₂ assimilation rate show higher plant stress levels. In addition, ZnO nanoparticle treatments severely affected plant growth, while TEM analysis revealed ultrastructural changes in chloroplasts and rupture of leaf cell walls. By combining ICP-OES and TEM results, we were able to show that the nanoparticles were metabolized, and their internalization in the soybean plant tissues occurred in ionic forms. This behavior most likely is the main driving force of nanoparticle toxicity.

This article presents a new acclimatization method, ex vitro acclimatization in float hydroculture. This protocol ensures the ex vitro acclimatization of the plantlets obtained in vitro in the rooting stage or the ex vitro rooting and acclimatization of the shoots obtained in the multiplication stage. Our hydroculture method is different from the techniques of flotation hydroculture because no fertilizers or plant growth regulators or other biostimulators are used and water oxygenation by bubbling is not provided. Ex vitro rooting and acclimatization in one stage without an in vitro rooting stage in floating cell trays was successfully carried out in Rubus fruticosus and Rosa hybrida cultivars, whereas ex vitro acclimatization of in vitro-rooted plantlets was successfully carried out in Rubus idaeus, Ribes nigrum, Prunus cerasus × P. canescens, Lycium barbarum ( Goji berry ), Amelanchier canadensis, Drosera rotundifolia , Drosera capillaris , and Nephrolepis sp. In another set of experiments, the floating cell trays were replaced with layers of floating perlite and the latter method was also tested for non-rooted shoots obtained in vitro in the multiplication stage or rooted plantlets obtained in the rooting stage. Direct ex vitro rooting in floating perlite was successful in ‘Tayberry’ ( Rubus fruticosus × Rubus idaeus ) (78.12% rooting); Amelanchier canadensis , Rubus fruticosus ‘Chester’, Rubus idaeus ‘Erntesegen’, Vaccinium macrocarpon, and Vaccinium corymbosum with rooting percentages above 80%; and Rubus idaeus ‘Willamette’ and Rosa hybrida ‘Cristiana’ with rooting percentages above 80%.

Evaluation of genetic fidelity of in vitro-propagated blackberry plants using RAPD and SRAP molecular markers | Orsolya Borsai, Monica Hârța, Katalin Szabo, Cristina-Daniela Kelemen, Flavia Andreea Andrecan, Maria-Maruni Codrea, Doina Clapa | Agricultural Journals

Stress caused by drought is an important factor that affects the growth and development of highbush blueberry plants. In vitro screening for drought stress tolerance is of major importance in identifying cultivars that have optimal stress tolerance and productivity. The aim of this study was to evaluate the responses of five in vitro-grown highbush blueberry cultivars (Bluecrop, Brigitta Blue, Duke, Goldtraube and Hortblue Petite) under drought stress. Five concentrations of polyethylene glycol (PEG 6000), 0 g/L, 10 g/L, 20 g/L, 30 g/L, 40 g/L, 50 g/L, were applied to induce drought stress in the culture media. Significant differences were found in shoot length and number, proliferation rate, fresh weight, dry weight, water content, chlorophyll, and carotenoid content. Drought stress had a negative impact on shoots length, chlorophyll, and carotenoid content for all highbush blueberry varieties. The conclusion of the study highlights that Goldtraube had the highest drought tolerance efficiency, followed by Bluecrop, Hortblue Petite, Duke, and Brigitta Blue.

An efficient micropropagation protocol for Rheum rhabarbarum L. was developed in this study. The in vitro rhubarb plants obtained in the multiplication stage (proliferation rate: 5.0 ± 0.5) were rooted in vitro (96% rooting percentage) and acclimatized ex vitro in floating perlite, with 90% acclimatization percentage. To assess the genetic fidelity between the mother plant and in vitro propagated plants, sequence-related amplified polymorphism (SRAP) markers were used. All banding profiles from the micropropagated plants were monomorphic and similar to those of the mother plant indicating 100% similarity. Regarding the polyphenolic profile, gallic, protocatechuic, p-hydroxybenzoic, vanillic, chlorogenic, caffeic, syringic, p-coumaric and ferulic acid were present in different amounts (2.3–2690.3 μg g⁻¹ dry plant), according to the extracted matrix. Aglicons and glycosides of different classes of flavonoids were also identified. The rhizome extracts (both from in vitro and field grown plants) contained resveratrol, a stilbene compound with high antioxidant properties, ranging between 229.4 to 371.7 μg g⁻¹ plant. Our results suggest that in vitro propagation of Rheum rhabarbarum L. represents a reliable alternative to obtain a large number of true-to-type planting material with high bioactive compound content of this valuable nutritional and medicinal species.