Externí autoři: Jiří Malbeck

In Norway spruce, as in many other conifers, the germination capacity of somatic embryos is strongly influenced by the desiccation phase inserted after maturation. The intensity of drying during desiccation eminently affected the formation of emblings (i.e., seedlings developed from somatic embryos). Compared to non-desiccated embryos, the germination capacity of embryos desiccated at 100% relative humidity was about three times higher, but the reduction of relative humidity to 95% and 90% had a negative effect on the subsequent embryo development.

The aim of this study was to characterise the changes in concentration and composition of antioxidants during ripening, harvest and after 3 and 6 months of storage in three commercially successful scab-resistant and powdery mildew-tolerant apple cultivars selected in the Institute of Experimental Botany. The detailed description of free and glycosylated phenolic acid profiles and content of 6 selected carotenoids - neoxanthin, violaxanthin, antheraxanthin, lutein, zeaxanthin and ß-carotene will serve for outcomes of major characteristics of these apple cultivars.

The present study investigated how different storage conditions affect antioxidant levels in three scab-resistant and powdery mildew-tolerant apple cultivars. The contents of carotenoids, along with free and glycosylated phenolic acids, were quantified in harvested apples and apples stored in boxes with controlled atmospheric conditions (1.2% O₂ and 2.2% CO₂) and temperature (1 °C), boxes with regulated temperature (1 °C) and storage rooms with a temperature between 1 and 4 °C.

Phenolic compounds (phenylpropanoids with an aromatic ring bearing one or more hydroxyl groups and various other substituents) are produced by plants as secondary metabolites, ranging from simple monomers to very large polymers. Due to their antioxidant activity they play crucial roles in plant defences against both biotic and abiotic stressors, moreover they are an important component of animal diet and they are highly beneficial for human health.

Phenolic compounds play important roles in plant defences against both biotic and abiotic stressors, and many in crop plants are highly beneficial for human health, but their quantities and profiles are influenced by numerous factors. Thus, the purpose of this study was to quantify free and glycosylated phenolic acids in apples (important sources of beneficial phenolics) in the course of fruit development, at harvest and during 5 months of storage.

Seed dormancy is an adaptive mechanism that allows seed germination under suitable environmental conditions. Germination of stored dormant seeds proceeds after dormancy breaking induced by stratification. To improve understanding of dormancy breaking in beechnuts, we: investigated effects of moisture content and temperature during storage; analysed contents of abscisic acid, abscisic acid metabolites and indole-3-acetic acid in embryonic axes during storage and stratification; and histochemically localized storage proteins.

Phenolic compounds constitute a substantial group of phenylpropanoids which are produced by plants as secondary metabolites with antioxidant properties. The spectrum and concentrations of phenolic acids serve as a convenient marker of plant resistance to biotic stresses. Phenolics form also an important component of animal diet. Apples are a widely available fruit exhibiting significant concentrations of antioxidants, especially phenolics and carotenoids. Generally, the concentrations and composition of antioxidants vary during ripening and subsequent handling of harvested fruits.

Somatic embryogenesis techniques have been developed for most coniferous species, but only using very juvenile material. To extend the techniques’ scope, better integrated understanding of the key biological, physiological and molecular characteristics of embryogenic state is required. Therefore, embryonal masses (EMs) and non-embryogenic calli (NECs) have been compared during proliferation at multiple levels.

In summary, the exposure of Norway spruce EC to UV-B radiation at different stages of maturation had the strongest effect on cell viability of embryos at early stages of development and resulted in the inhibition of somatic embryo development and/or the substantial decrease in the number of embryos. The extent of cell damage was dependent on the UV-B dose applied, as well as the embryo developmental stage, and might be related to differentiation of the outermost cell layers and formation of protoderm.