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An efficient and reproducible system for Agrobacterium-mediated transformation of the pear (Pyrus communis L.) cultivar Spadona was developed. Leaf explants of in vitro propagated plants were cocultivated with the disarmed Agrobacterium strain EHA105 harboring the plasmid pME504, carrying the uidA-intron and nptII genes. Under selective conditions, 5% of the plantlets regenerated and were positively stained for GUS. However, most of the GUS-positive plants re-callused and subsequently died, leaving only 0.3-0.8% of these plantlets to reach maturity. In order to identify transformed shoots at early stages of regeneration, we introduced the green fluorescent protein (GFP) into the pear cultivar Spadona using the plasmid PZP carrying the nuclear-targeted GFP and nptII genes. High expression levels of GFP were detected in transgenic cells as early as 7 days after transformation. GFP marked-callii and transformed plants were observed after 14 and 24 days, respectively. Fluorescence microscopy screening of transformed plant material, under the selection of kanamycin, increased the transformation frequency to 3.0-4.0%. We conclude that the introduction of GFP improves the selection of transformed plants of Spadona pear.

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Plant tissue cultures have been widely used in both fundamental and applied types of research on various biological species, and the scientific interest to transfer that technology in industrial scale has been rapidly growing. The use of in vitro technology for commercial propagation of different plant species and the production of bioactive compounds from them has become profitable industry worldwide. In the past decades, the progress in plant tissue culture technology was directed towards the introduction of the liquid medium for cultivation under submerged conditions in different bioreactor types, and automation of the entire process. Some applications of modified bioreactor systems and their importance for the advancement of plant biotechnology in the fields of agriculture, medicine, and pharmacy are discussed in this review.

It was investigated the propensity for induction of somatic embryogenesis in vitro from seedless grape cultivars and hybrid combinations in liquid culture giving an account of the effect of explant age, genotype and growth regulators in the culture medium. We established that embryogenic structures were formed in all studied treatments and genotypes but there were specifi cs toward development of somatic or zygotic embryo. Comparing the capability for embryo formation, seed buds isolated 10 and 30 days after pollination showed increased regeneration capacity. Following the experimental protocol the best embryogenic ability was established for Rusalka3-inbred and the hybrid combination Russalka X Alicante Buchet. Regarding the effect of the growth regulators NOA in combination with BA promoted better frequency of embryo formation than 2,4-D. The genotype Russalka 3 demonstrated highest propensity for embryogenesis in vitro.

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The compounds, derivatives of olive leaves have a high antioxidant activity. The content of the total phenolic compounds (TPC), antioxidant activity (AOA) and HPLC polyphenol profile of methanol extracts from the leaves of the olive cultivars Chondrolia Halkidiki, Kalamon, Koroneiki grown in the nursery (in vivo) and in vitro plants of Chondrolia Halkidiki were compared. The results obtained for TPC varied between 9.2±0.5 mgGAE*gDW -1 and 16.4±0.5 mgGAE*gDW -1 . Antioxidant capacity was determined by four methods DPPH, ABTS, FRAP and CUPRAC. The highest results for TPC and AOA were achieved for the leaves of Chondrolia Halkidiki grown in vitro. A high correlation between the results gained from the TPC and AOA was established. Conducted HPLC analysis revealed the presence of 3,4-dihydroxybenzoic, caffeic, sinapic and ferulic acids and quercetin, hesperidin and luteolin and the quercetin glycosides rutin and hyperoside.

The influence of the carbohydrate source on the process of somatic embryogenesis of seedless grape cultivar Russalka 3 was studied. Seed bud explants isolated from self pollinated inflorescence 60 days after blooming were cultured on media enriched with Sucrose, Sorbitol, Maltose and combination Glucose+Fructose. Both, somatic and zygotic embryogenesis proceeded simultaneously. As optimal carbohydrate source for somatic embryo induction and development in all studied growth regulator treatments was defined the combination of Glucose +Fructose, promoting the highest morphogenic replay.