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Ionic liquids (ILs) are a promising alternative to the traditional organic solvents, but their toxic effects cause significant adverse environmental effects and their toxicity assessment have been suggested. The effect of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) on photosynthesis was studied in Arabidopsis thaliana. Apparent effects on chlorosis and inhibition of photosynthetic capacity were observed. As [Bmim][BF4] concentrations increased, a time-dose effect was also observed. The maximum quantum yield (Fv/Fm), and the actual quantum yield of photosystem II (ΦPSII), both decreased; at the same time, the expression of psbA, a key gene of the photosystem II electron transport, was reduced by [Bmim][BF4] treatment. The synthesis of the large and small subunits of Rubisco were not affected by treatment. On the other hand, Rubisco activase (RCA) was significantly suppressed at the transcriptional level. Our results suggest that photochemistry of PSII as well as Rubisco activation are involved in ILs resistance. [ABSTRACT FROM AUTHOR]

Photosynthetic diatoms are exposed to a rapid and unexpected variations in light intensity that can modulate the contents of photosynthetic pigments and the carotenoid profile. In this study, the influence of light availability on photoprotection in the diatom Phaeodactylum tricornutum was investigated. Experimental cultures were exposed to three irradiances (100, 200 and 400 µmol photons m−2 s−1) and two light: dark cycles (12:12 and 24:00 h) that resulted in different light energy daily doses (D = 4.32 mol photons m−2), where the treatments were named in NDxh (N = amount of daily doses D, and x = photoperiod in hours). The samples treated at different doses were compared in terms of cell growth, chlorophyll-a fluorescence, pigment content and gene transcription levels. Specific growth rate was 1.9-fold higher in 8D24h daily dose (34.56 mol photons m−2) with 3 times higher light absorption in comparison to the lowest light energy dose. Also, at higher light intensities the content of chlorophyll-a, fucoxanthin and diadinoxanthin in P. tricornutum was lower, while the regulation of the xanthophyll cycle was achieved by the highest light energy doses. The transcriptional profiles of ZEP1, ZEP2, VDL1 and VDL2 genes were influenced by the highest light energy doses, on the other hand VDE and ZEP3 genes were poorly regulated by light. In addition, a similar transcription pattern was found for two isoforms of ZEP genes as well as in VDL genes. This study demonstrated that light energy doses and irradiances affect the photoacclimation and photoprotection responses. [ABSTRACT FROM AUTHOR]

Climacteric fruit maturation is polygenic, complex process. Gene activity has a significant effect on the quality characteristics of the fruit for harvest and storage. Existing methods generally allow determining the degree of ripeness at harvest (point '0'). Since there is no method defining onset of the climacteric stage of the fruits, an attempt to identify the functional molecular marker that would determine a physiological ripeness of the fruit several days in advance before harvest was conducted. The analysis of changes in transcript of ten selected genes, and evaluation of the correlation of these genes with changes in fruits quality of two apple varieties Golden Delicious (winter cv.) and McIntosh (autumn cv.), allowed to identify a potential marker, activated a few days before harvesting the fruits. Overexpression of the starch glucosidase gene (StG) in the late fruits has been observed prior to the onset of ethylene production. The results confirm that it could be a potential functional marker useful for assessment of physiological ripeness status of cvs Golden Delicious and McIntosh.