Environmental contaminants like polycyclic aromatic hydrocarbons can influence many biochemical and physiological processes in plants. The effect of 0.1, 1 and 5 mg l -1 of fluoranthene (FLT) in combination with indole-3-acetic acid (IAA, 0.1 mg l -1 ) or a combination of IAA and N 6 -benzyladenine (BA, both 0.1 mg l -1 ) on the growth and production of ethylene, ethane and CO 2 in Pisum sativum L. cultivated for 21 days in vitro was investigated. In 21 days old plants also net photosynthesis rate, content of FLT and cytokinins were evaluated. FLT 5 mg l -1 significantly inhibited the growth of pea after 21 days in both IAA and IAA ? BA treatments, increased production of ethylene (by 11% in IAA and 14% in IAA ? BA treatments, respectively) and ethane (by 28 and 18%) and decreased production of CO 2 (by 23 and 29%). The net photosynthesis rate decreased in response to FLT concentration by up to 51% under saturating irradiation (600-1,200 lmol m -2 s -1 ), as found in IAA ? BA ? FLT 5 mg l -1 treatment. The content of FLT in pea plant shoots well correlated with increasing FLT treatment in both IAA and IAA ? BA medium. The content of cytokinins in pea shoots changed in response to FLT treatment. FLT 5 mg l -1 caused a rise in level of trans-zeatin (by 16% in IAA and 9% in IAA ? BA treatments, respectively), dihydrozeatin riboside (by 27 and 50%), benzyladenine (by 3 and 80%), benzyladenine riboside (by 44 and 17%) and meta-topolin riboside (by 139 and 214%), no change in isopentenyladenine level and a decrease in metatopolin level (by 33% in IAA and 36% in IAA ? BA treatments, respectively). Cultivation of plants in vitro allowed not only to assess their growth, photosynthetic activity and the level of cytokinins, but also to extend the knowledge about the effect of PAHs on production of gaseous stress indicators like ethylene, ethane and CO 2 . Recorded changes in all studied parameters show, that persistent organic pollutants like PAHs can negatively influence plant growth and development.

The influence of increasing concentrations (0.1, 1.0 and 5.0 mg l -1 ) of fluoranthene (FLT) on growth, endogenous abscisic acid (ABA) level and primary photosynthetic processes in 21-day-old pea plants (Pisum sativum L.) in vitro was investigated. Murashige and Skoog's (MS) medium, with or without FLT, was enriched with indole-3-acetic acid (IAA; 0.1 mg l -1 ) or a combination of IAA (0.1 mg l -1 ) plus N 6 -benzyladenine (BA; 0.1 mg l -1 ). The level of endogenous ABA significantly increased with increasing FLT concentrations in the presence of both IAA and IAA plus BA. An increased level of endogenous ABA was observed in plants treated with IAA alone. The growth of shoot, callus and the content of photosynthetic pigments (chlorophyll a and b, carotenoids), in both IAA-and IAA plus BA-treated plants, were significantly stimulated by FLT at its lowest concentration (0.1 mg l -1 ) assayed in this study. However, FLT at higher concentrations (1.0 and 5.0 mg l -1 ) significantly inhibited all these parameters. Chlorophyll fluorescence imaging showed that FLT only at the highest concentration (5.0 mg l -1 ) in the presence of IAA (0.1 mg l -1 ) significantly increased F 0 , but decreased F V /F M and U II .

The paper deals with problems associated with preparation and collection of samples when estimating the production of ethylene and content of ACC (1-aminocyclopropane-1-carboxylic acid) in plants by means of gas chromatography. A proper method of sampling can significantly influence not only the reliability of obtained data but also their interpretation. Attention was paid to cultivation of plant material, sampling vessels, conditions of ethylene production, sampling procedure, and storage of gaseous samples. The estimation of ACC as a precursor of ethylene is more laborious but it supplements the information about the endogenous level of ethylene in a given part of the plant organism. The authors describe the sampling procedure, methods of sample preservation, extraction and purification, and also the method of oxidation of ACC to ethylene. In the final part of this study the authors evaluate the time consumption and difficulty of individual methods and describe their advantages and disadvantages as compared with other, alternative methods.

The uptake and metabolism of trans-zeatin and/or dihydrozeatin, in correlation with cytokinin oxidase/ dehydrogenase (CKX) and b-glucosidase activity, were studied in leaf segments derived from wild-type (WT) and transgenic (T) tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) during in vitro induction of shoot organogenesis. T explants harbored the maize gene Zm-p60.1 b-glucosidase. Higher levels of shoot regeneration were observed on T explants in the early stages of cultivation. In WT explants, the content of cytokinin (CK)-O-and N-glucosides increased. In T explants, a higher content of Z-9-riboside and Z-9-riboside-5 0 -monophosphate and higher CKX activity during the early stage of cultures were found. A positive correlation was obtained for bioactive CK content and the organogenic response in T explants.Our results indicate a connection between the organogenic capacity of tobacco explants, metabolism of endogenous CKs and uptake of exogenous CKs from the cultivation medium.

No abstract